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Revista Brasileira de Ciência do Solo, Volume: 45, Publicado: 2021
  • Training pedologist for soil mapping: Contextualizing methods and its accuracy using the project pedagogy approach Division – Soil In Space And Time

    Costa, Elias Mendes; Ceddia, Marcos Bacis; Santos, Felipe Nascimento dos; Silva, Laiz de Oliveira; Rezende, Igor Prata Terra de; Fernandes, Douglath Alves Correa

    Resumo em Inglês:

    ABSTRACT There is a growing demand for more detailed knowledge about soils, their functions, and connections with human activities and environmental services. In Brazil, where soil survey and mapping have been scarce since the 1990s, there is a remarkable sense of urgency. Recently, a national soil program was created (PronaSolos) to attend to the massive demand for soil information. PronaSolos is an effort to return to the systematic soil mapping of the national territory, which requires many pedologists who master the traditional knowledge of soil mapping, but above all, the modern and accurate digital soil mapping (DSM) techniques. Based on these aspects, this study aims to address the technical and educational aspects inherent in the training process of new pedologists by contextualizing different soil mapping methods using the pedagogy project approach (PPA). Specifically, the study sought to assess the following subjects: (i) evaluate the learning process of different apprentices in performing soil survey and mapping in a small training area; (ii) compare maps generated by conventional soil mapping (CSM) and DSM using two probabilistic design for validation (SRS -Simple Random Sampling and SSRS - Stratified Simple Random Sampling). The DSM techniques evaluated were: Multinomial Logistic Regression - MLR and Random Forest - RF. For the course, four apprentices were selected and trained in both CSM and DSM techniques. Finally, they were asked about the learning process in the PPA and improvement for future courses. This study showed that: a) the PPA is promising to train new pedologists since, by mixing theoretical activities and contextualized practices (a project in progress), it not only awakens great motivation and critical capacity but also develops the ability for apprentices to find solutions in a area in constant evolution; b) the quality of the maps changed significantly according to the validation sample design applied. The CSM present better quality than DSM, mainly when using SSRS. The RF presented equivalent accuracy to CSM using SRS. Irrespective to validation sample design, the MLR presented the lowest accuracy; c) The CSMs presented higher user’s accuracy while the DSMs presented higher producer’s accuracy; d) The quality of CSM generated by the apprentices was not clearly related to the previous experience and knowledge in soil science.
  • Andic properties in soils with histic horizon “O” in the highlands of Southern Brazil Division – Soil In Space And Time

    Santos Junior, Jaime Barros dos; Almeida, Jaime Antonio de

    Resumo em Inglês:

    ABSTRACT Soils with andic properties are characterized by a low apparent density, variable charges, large amounts of allophanes, imogolite, ferrihydrite, and/or organo-metallic complexes with Al, and present high phosphate retention. Soils derived from non-pyroclastic materials rich in silicates, formed under a cold and humid climate, a large amount of organic carbon, acid weathering, andic properties can manifest when a large amount of Al is present in the form of organo-metallic complexes. This study aimed to evaluate the characteristics and geographical expression of soils with such properties in areas of altitude in the extreme south of Brazil, on the escarpment edges of the Serra Geral Formation, under a cold and humid climate. The sampling points were selected based on environmental characteristics such as geomorphology, geology, the coloration of the superficial horizon of the soil, and position in the landscape, covering a linear distance of approximately 185 km at the escarpment edge between the states of Santa Catarina and Rio Grande do Sul. Soil samples were described and collected from ten soils with histic horizon O, three soils with humic horizon, and one soil with histic horizon H. The undisturbed soil samples were collected using volumetric metallic cylinder to determine the soil bulk density. Organic matter, pH(H2O), P retention, and selective dissolutions of Al, Fe, and Si analyses were performed. The Cambissolos Hísticos and Organossolos Fólicos showed andic properties, while the Cambissolos Húmicos and Organossolo Háplico did not meet one or more criteria, as required by the Brazilian Soil Classification System and the World Reference Base for Soil Resources. The horizons with andic properties were classified as aluandic, based on the predominance of Al associated with organic complexes. The cold climate and high cloudiness of the highest altitude areas in the extreme south of Brazil, occurring in a narrow strip of the escarpment of the Serra Geral Formation in the states of Santa Catarina and Rio Grande do Sul, allow the formation of a constantly humid environment. This environment favors the acid weathering of the source material, accumulation of organic matter in the soil, and its stabilization by the formation of organo-metallic complexes, mainly Al-humus. The combination of these factors gives the soils with histic horizons O a low bulk density, high phosphate retention, and Alo + ½Feo ≥2 % values, meeting the criteria required for andic properties.
  • Amazonian Dark Earths in Rondônia State: Soil properties, carbon dating and classification Division – Soil In Space And Time

    Cavassani, Rafael de Souza; Anjos, Lúcia Helena Cunha dos; Pereira, Marcos Gervasio; Garcia, Andrés Calderin

    Resumo em Inglês:

    ABSTRACT Throughout the Amazon region, dark-colored soils with increased fertility are identified and referred as Amazonian Dark Earths (ADE). These unique soils are characterized by an anthropic surface horizon with dark colors, presence of charcoal and artifacts, in contrast with surrounding non-ADE soils. The ADEs show extraordinary properties such as the capacity of maintaining the dark colors and high nutrient levels after years of farming, even under the highly favorable climatic conditions for oxidation of organic matter and weathering of nutrients of Amazon region. The ADE are considered islands of fertility in the Amazon biome, as well as very important models for research, in terms of agricultural and environmental sustainability, carbon sequestration, nutrient bioavailability, food security, and for anthropological studies. However, there are many unanswered questions regarding the extent of human alterations, how they were formed, and their classification in the taxonomic systems. Therefore, the objectives of this study were to identify, describe, and characterize soil profiles of ADEs, located in the Southern region of Rondônia State, Brazil, and to contribute to their classification according to the Brazilian Soil Classification System (SiBCS) and the World Reference Base (WRB). Five soil profiles were described and sampled; P1 to P3 were under grass pastures, P4 and P5 under forest and crops with no-till, respectively. The morphological, physical, and chemical attributes, as well as contents of Fe, Al, Si, and Ti oxides and extractable iron forms were characterized. The anthropic horizons exhibited dark colors, artifacts, charcoal, sandier textures, predominantly granular structures, abrupt or clear transitions, and mostly wavy and irregular boundaries. Values of pH, Ca 2+ , Mg 2+ , exchangeable bases (S), CEC, and C were high in all anthropic horizons. Compared to non-ADE soils in the Amazon region, phosphorus contents were superior in all anthropic horizons, with the highest values in surface horizons of P1, P2, and P3. According to SiBCS, P1 was classified as Cambissolo, P2 as Argissolo , and P3, P4, and P5 as Latossolos. Except for P4, where values of extractable P by Mehlich-1 are lower than 30 mg kg -1 , all soils fulfilled the requirements for the anthropic horizon in the SiBCS, and new classes at the subgroup level were proposed. In the WRB, P4 and P5 were classified as Ferralsols. The other profiles were classified as Anthrosols. The radiocarbon dates (C 14 ) of charcoal fragments, obtained using a mass accelerator, showed ages between 940 ± 40 and 1230 ± 60 years BP.
  • Soil classes and properties explain the occurrence and fruit production of Brazil nut Division – Soil In Space And Time

    Silva, Camila Santos da; Silva, Lucielio Manoel da; Wadt, Lucia Helena de Oliveira; Miqueloni, Daniela Popim; Silva, Katia Emidio da; Pereira, Marcos Gervasio

    Resumo em Inglês:

    ABSTRACT Soil properties and classes can influence the occurrence of plants and the production of Brazil nut fruits and may have a different distribution between sites. This study aimed to evaluate the relationship of plants’ occurrence, production of Brazil nut fruits, and spatial variability of the properties in different soil classes in two Brazil nut stand in the state of Acre, Brazil. The study was conducted in two plots in two native Brazil nut stand, Cachoeira (CP01 and CP02 - plots 1 and 2) and Filipinas (FP01 and FP02 - plots 1 and 2). The soil profiles were described morphologically. Sixty soil samples were collected in each plot. The chemical properties, granulometry, soil density, particle density, and estimated total porosity were determined. The average fruit production was calculated by counting the fruits in a sample of Brazil nut trees. Subsequently, the trees were divided into three classes of production: low (≤1.5 can; the can unit has 18-L, which is able to hold 59 and 77 fruits, respectively, for Cachoeira and Filipinas), medium (1.6 to 3.9 cans), and high (≥4.0 cans). The can unit is the traditional measure of volume in the region and varies according to the locality. Cluster analysis was performed to determine whether there was a difference between Brazil nut stands and soil profiles, and geostatistics was used to evaluate the spatial dependence of soil properties. The highest occurrence of Brazil nut trees with high fruit production (≥4.0 cans) was found in the Latossolo Vermelho Distrófico argissólico (Oxisol) and Argissolo Vermelho-Amarelo Distrófico típico (Ultisol). However, the Argisol also hosted the plants with the lowest productions (≤1.5 can). The pH, total organic carbon, sum of bases, P, N, granulometry, and porosity showed a greater spatial variability, and FP02 showed a greater number of properties with high spatial variability compared to the other areas. Although the occurrence of plants and the production of Brazil nut fruits ( Bertholletia excelsa ) were associated with the classes and the physical and chemical properties of the soil, pyxidium production differed between areas. In general, soil physical properties were limiting factors for Brazil nut production and/or higher tree occurrence. Filipinas environment showed a low fruit production and a greater spatial variability of soil properties compared to Cachoeira.
  • Edaphic fauna and soil properties under different managements in areas impacted by natural disaster in a mountainous region Division – Soil Processes And Properties

    Lima, Sandra Santana de; Aquino, Adriana Maria de; Silva, Rafaela Martins da; Matos, Priscila Silva; Pereira, Marcos Gervasio

    Resumo em Inglês:

    ABSTRACT Soil invertebrate fauna plays a major role in several environmental processes, and its absence can negatively impact ecosystem health. This study aimed to assess the recovery of epigeal and edaphic invertebrate faunal communities following an environmental disaster, with landslides, mudflow, and river floods, in sites under different management systems, the effects of cover crops on invertebrate fauna, and their relationship with soil physical and chemical properties in the mountainous region of Rio de Janeiro State, Brazil. The following sites were evaluated: CF, a site under conventional farming without any record of natural hazard events; LS, a site impacted by an intense landslide event that left the area buried by mudflow; RO1, a site affected by river overflow and treated with NPK fertilizer and poultry litter; RO2, a site affected by river overflow and subjected to liming and heavy fertilization with NPK; and RO3, a site affected by a less intense river overflow and subjected to fertilization with poultry litter and NPK fertilizer. At each site, epigeal and edaphic fauna were sampled using pitfall traps and a monolith sampler, respectively. Physical (soil temperature, moisture, aggregate stability, and density) and chemical (pH in water, Ca2+, Mg2+, Al3+, K+, P, cation-exchange capacity, and total organic carbon) properties were determined in the 0.00-0.05 and 0.00-0.10 m layers. The predominant epigeal faunal groups were Entomobryomorpha, Poduromorpha, Diptera, and Coleoptera; and the predominant edaphic faunal groups, Coleoptera and Oligochaeta. There was a positive correlation between Coleoptera larvae, Hymenoptera, and species richness with total organic carbon. Coleoptera larvae were positively associated with biogenic aggregate stability, whereas Coleoptera was positively associated with physicogenic aggregate stability. Oligochaeta showed a positive correlation with soil moisture. Cover crops favored the development of epigeal and edaphic faunal groups that enhance soil properties through organic matter fragmentation and decomposition, and structural engineering. The strong correlation between soil chemical, physical, and biological properties demonstrate the importance of monitoring these components to assess the recovery of disaster-affected areas.
  • Epi and endosaturation affecting redoximorphic features and pedogenesis in subtropical soils with high textural contrast developed from sedimentary rocks Division – Soil In Space And Time

    Almeida, Jaime Antonio de; Santos, Pablo Grahl dos

    Resumo em Inglês:

    ABSTRACT Soils in the Depressão Central and Campanha Gaúcha in Rio Grande do Sul State, Brazil, developed from sedimentary rocks are mainly Alfisols (Luvissolos, Planossolos and Plintossolos) and Ultisols (Argissolos) with high textural contrast between A and/or E horizons and clayey B horizons. Red Ultisols dominate in well-drained areas in the summit. But many soils present redoximorphic features on the backslope and footslope, with mottled and/or nodules similar to plinthite due to the oscillating of the water table above the rock or poorly permeable saprolite. Identifying morphological features, mineralogical and chemical properties, and parent material differences are essential to identify the main processes responsible for their genesis. Knowledge of the relative distribution of different forms of iron in the soil is also of particular interest when interpreting pedogenesis. This study aimed to evaluated the main process responsible for the high textural contrast in soils developed from different sedimentary lithologies, and how the redoximorphic features observed in some soils may be related to genesis of plinthites and ferrolysis processes. The study area is located in the hydrographic basin of Rio Santa Maria, in the city of Rosário do Sul – RS, Brazil (30° 15’ 28” S and 54° 54’ 50” W), average altitude of 132 m and Cfa-type climate. Topolithosequences were defined based on soils developed from lithogies of Piramboia and Sanga-do-Cabral geological formations, by choosing soil profiles according to the source material, variations in relief, altitude and hydrological conditions. Morphological descriptions, particle size determinations, chemical analysis, mineralogy of the clay fraction by XRD analysis, determination of the main forms of iron, tests to identify plinthite were performed. Argiluviation, ferrolysis and plinthization were the most active processes identified in the genesis of most studied soils. The high textural contrast on these soils was not solely due to clay illuviation processes but also ferrolysis and lithological discontinuities in some soils, indicating polygenetic origin. Redoximorphic features in most soil revealed that iron segregation in most soils occurs like mottles and not plinthite, since they did not remain aggregated after the various wetting and drying cycles.
  • Teaching soil science: The impact of laboratory and field components on the knowledge and attitude toward soil Division – Soil In Space And Time

    Neaman, Alexander; Stange, Christian; Zabel, Sarah; Minkina, Tatiana M.; Yáñez, Carolina; Burnham, Elliot; Otto, Siegmar

    Resumo em Inglês:

    ABSTRACT The concept of attitude toward soil is emerging, with a slim choice of scales available to collect hard data. There is also a dearth of standard scales to acquire precise data on students’ knowledge of soil. Therefore, the objectives of the present study were: (1) to devise appropriate scales to quantify theoretical soil knowledge and attitude toward soil, and (2) to quantify the effect of laboratory studies and fieldwork on students’ theoretical soil knowledge and attitude toward soil. The study is based on data collected from undergraduate students of the introductory soil science course. Participating students were randomly divided into two groups. Teaching of the control group (n = 38) was classroom-based, while teaching of the intervention group (n = 43) was complemented with laboratory studies and fieldwork. Our test design included a pre-test and post-test. It appears that theoretical soil knowledge and students’ attitude toward soil can be improved using classroom-based education alone, without any need for laboratory or field components. However, future studies would be needed to develop questionnaires covering hands-on soil knowledge to better gauge the impact of lab work and field classes on student learning. The present study is an important step to elaborate reliable scales suitable for quantifying students’ knowledge and attitude toward the soil. It is impossible to test academic assumptions or create theoretical foundations for soil science education without a reliable device to weigh analytical concepts.
  • Fine-scale soil mapping with Earth Observation data: a multiple geographic level comparison Division – Soil In Space And Time

    Safanelli, José Lucas; Demattê, José Alexandre Melo; Santos, Natasha Valadares dos; Rosas, Jorge Tadeu Fim; Silvero, Nélida Elizabet Quiñonez; Bonfatti, Benito Roberto; Mendes, Wanderson de Sousa

    Resumo em Inglês:

    ABSTRACT Multitemporal collections of satellite images and their products have recently been explored in digital soil mapping. This study aimed to produce a bare soil image (BSI) for the São Paulo State (Brazil) to perform a pedometric analysis for different geographical levels. First, we assessed the potential of the BSI for predicting the surface (0.00-0.20 m) and subsurface (0.80-1.00 m) clay, iron oxides (Fe 2 O 3 ), aluminum (m%) and bases saturation (V%) contents at the state level, which are important properties for soil classification. In this task, legacy soil samples, the BSI and terrain attributes were employed in machine learning. In a second moment, we evaluated the capacity of the BSI for clustering the landscape at the regional level, comparing the predicted patterns with a legacy semi-detailed soil map from a smaller reference site. In the final stage, the predicted soil maps from the state level were investigated at the farm level considering several sites distributed across the São Paulo state. Our results demonstrated that clay and Fe 2 O 3 reached the best prediction performance for both depths at the state level, reaching a RMSE of less than 10 %, RPIQ higher than 1.6 and R 2 of at least 0.41. Additionally, the predicted landscape clusters had a significant association with the main pedological classes, subsurface color, soil mineralogy and texture from the legacy semi-detailed soil map. Illustrative examples at the farm level indicated great capacity of BSI in detecting the variations of soils, which were linked to several soil properties, such as texture, iron content, drainage network, among others. Therefore, this study demonstrates that BSI is valuable information derived from optical Earth Observation data that can contribute to the future of soil survey and mapping in Brazil (PronaSolos).
  • Optimized data-driven pipeline for digital mapping of quantitative and categorical properties of soils in Colombia Division – Soil In Space And Time

    Coca-Castro, Alejandro; Gutierrez-Díaz, Joan Sebastián; Camacho, Victoria; López, Andrés Felipe; Escudero, Patricia; Serrato, Pedro Karin; Vargas, Yesenia; Devia, Ricardo; García, Juan Camilo; Franco, Carlos; González, Janeth

    Resumo em Inglês:

    ABSTRACT Soil maps provide a method for graphically communicating what is known about the spatial distribution of soil properties in nature. We proposed an optimized pipeline, named dino-soil toolbox, programmed in the R software for mapping quantitative and categorical properties of legacy soil data. The pipeline, composed of four main modules (data preprocessing, covariates selection, exploratory data analysis and modeling), was tested across a study area of 14,537 km 2 located between the departments of Cesar and Magdalena, Colombia. We assessed the feasibility of the toolbox to model three soil properties: pH at two depth intervals (0.00-0.30 and 0.30-1.00 m), soil taxonomy (great group) and taxonomic family by particle-size, according to a set of 25 environmental factors derived from auxiliary layers of climate, land cover and terrain. As a result, we successfully deployed the proposed semi-automatic and sequential pipeline, yielding rapid digital soil mapping (DSM) outputs across the study area. By providing multiple outputs such as tables, charts, maps, and geospatial data in four main modules, the pipeline offers considerable robustness to support outcomes and analysis of a DSM project. Future studies might be interesting to expand on further machine learning frameworks for predictive modeling of soil properties such as ensembles and deep learning models, which have shown a high performance for DSM.
  • Occurrence of arbuscular mycorrhizal fungi in leaf litter and roots of shaded coffee plantations under organic and conventional management Division – Soil Processes And Properties

    Díaz-Ariza, Lucía Ana; Rivera, Emma Lucía; Sánchez, Natalia

    Resumo em Inglês:

    ABSTRACT Evidence of arbuscular mycorrhizal fungal colonization of mat litter in various ecosystems plus previous reports of external mycelium of those fungi and mycorrhizal roots in litter from coffee plants and shade trees on coffee plantations suggest that they have a relationship with closed direct nutrient cycling between organic matter and living roots. This relationship was first proposed more than 50 years ago. Mycorrhizal symbiosis in tropical crops is affected by agricultural management practices. This study aimed to assess the occurrence of arbuscular mycorrhizal fungi in leaf litter from three shaded Colombian coffee agroecosystems under organic and conventional management. One is managed chemically, one organically, and one with a combined use of organic and chemical inputs. Leaf litter and roots were collected from the three coffee plots at three decomposition stages. Each plot represented a distinct fertilization and tree dominance pattern different from the other two plots. Arbuscular mycorrhizal fungi were found in decomposing leaves. The chemically managed plot showed statistical differences (p<0.05) with respect to the other plots, it had the greatest amounts of arbuscular mycorrhizal fungal root colonization (48.76–70.51 %), litter colonization (36.2–69.91 %), external mycelium length (28.66–48.33 m g-1), and spore number (451.27–681.2 spores in 20 g of dry soil). In contrast, conditions on the combined management coffee plot results in smaller means of the variables evaluated. Arbuscular mycorrhizal fungal root colonization and nitrogen content of leaf litter varied among the decomposition stages (p<0.05). Litter quality of different tree species may have influenced colonization of plant matter within each plot. We found evidence of typical structures of arbuscular mycorrhizal fungi within and among decomposing leaf litter and roots growing into the mat litter in tropical agroecosystems. This supports the thought that these fungi have a role in carbon and nutrient recycling, which are influenced by agricultural management practices and plant population composition.
  • Outstanding impact of Azospirillum brasilense strains Ab-V5 and Ab-V6 on the Brazilian agriculture: Lessons that farmers are receptive to adopt new microbial inoculants Division – Soil Processes And Properties

    Santos, Mariana Sanches; Nogueira, Marco Antonio; Hungria, Mariangela

    Resumo em Inglês:

    ABSTRACT For decades, researchers around the world search for strategies aiming at higher sustainability in agriculture. The microbial inoculants or biofertilizers are biotechnological products used for different purposes, the main one being to totally or partially replace chemical fertilizers, with an emphasis on N-fertilizers, reducing costs of production and decreasing the contamination of the soil, water, and atmosphere. Depending on the microorganism and the inoculated crop, inoculants can also induce plant protection to abiotic and biotic stresses and positively modify their physiology. Although inoculation studies and the use of inoculants by farmers date more than a century ago, they have gained more notoriety in the past decade. Brazil has a long tradition in the use of rhizobial inoculants, especially for the soybean crop, but it was only in 2009 that the first commercial inoculant carrying the plant-growth-promoting Azospirillum brasilense strains Ab-V5 (=CNPSo 2083) and Ab-V6 (=CNPSo 2084), identified by our research group, reached the market. One decade after the release of these two strains, 10.5 million doses were commercialized for grasses, including corn, wheat, rice, and pastures of brachiarias, and co-inoculation of legumes, such as soybean and common bean. Several research groups in Brazil presented impressive results of increases in root growth, biomass production, grain yield, uptake of nutrients and water, and increased tolerance to abiotic stresses due to the inoculation with Ab-V5 and Ab-V6. In this review, we gathered the results obtained so far in one decade with these two strains in several grasses and legume crops, confirming their versatility and indicating that with convincing, reliable, and consistent results, the Brazilian farmers are receptive to the adoption of new sustainable technologies based on microorganisms.
  • Rock size fragments reduction allow including their effect on water retention properties determined with a dew point potentiometer Division – Soil Processes And Properties

    Gubiani, Paulo Ivonir; Pereira, Caroline Andrade; Cauduro, Jussara Santoli; Campbell, Colin; Rivera, Leonardo; Pigatto, Cassiano Salin; França, Jéssica Silveira

    Resumo em Inglês:

    ABSTRACT The relation between water content and water potential is a key soil hydraulic property. The presence of rock fragments in soils can affect this property in bulk soil. In this study, we focused on the relation property determined with a WP4 dew point potentiometer. The objective was to evaluate the hypothesis that breaking large gravel-size particles into smaller fragments is a suitable strategy for accurate WP4 measurements in coarse materials without affecting the retention properties. Ten initial samples of basalt rock fragments with different weathering degrees were collected from the A horizon of an Entisol (Neossolo). Rock fragments initially sized between 38 to 4 mm were successively fractured into smaller fragments (size classes of 4-2, 1-0.25, and <0.25 mm). For each size class, the retention properties (water content versus water potential) were determined with WP4 equipment. No significant effect of fragment size was detected on the determined retention properties. Using supplementary water retention data from a previous study, we found an overestimation of water retention at -1.5 MPa ranging from 0.08 to 0.12 g g-1 when rock fragments were removed, which is of the order of magnitude to the available water capacity of several soils. This study showed that fragments larger than the diameter of the WP4 sample cup could be broken to sizes smaller between 4 and 0.25 mm without affecting the retention properties. This is a suitable strategy to allow accurate WP4 measurements in coarse materials while considering the effect of such coarse material on retention properties.
  • Characterization and manipulation of montmorillonite properties towards technological and environmental applications Division – Soil Processes And Properties

    Melo, Vander Freitas; Salata, Regiane; Abate, Gilberto; Azevedo, Antonio Carlos; Kummer, Larissa

    Resumo em Inglês:

    ABSTRACT The combination of pillarization and charge neutralization with Li+ can make montmorillonite an important support material for industry and decontamination of pollutants in soil and water. Montmorillonite characterization techniques were described in detail, and pillarization procedures were used, after Li+ saturation, to modify and manipulate the chemical and mineralogical surface properties of this montmorillonite. Eight samples were produced: 1) natural montmorillonite (Chisholm Mine - MMT); 2) Li+ saturated montmorillonite (MMTLi); 3) polyethylene glycol (PEG) Al-pillared montmorillonite (AlPEG); 4) PEG Al-pillared montmorillonite saturated with Li (AlPEGLi); 5) Al-pillared montmorillonite with 14 h contact time (Al14h); 6) Al-pillared montmorillonite Al14h saturated with Li (Al14hLi); 7) Al-pillared montmorillonite with 0 h contact time (Al0h); and 8) Al-pillared montmorillonite Al0h saturated with Li (Al0hLi). The natural sample was identified as interlayered montmorillonite composed of chlorite layers or with a high degree of Al-hydroxy filling. Concerning the total permanent charges, 70 % occurred by isomorphic substitution of Al3+ by Mg2+ in octahedral layer and 30 % of Si4+ by Al3+ in tetrahedral layer. The pillarization method using the PEG produced a small number of stable pillars. The new milder pillarization method (Al0h) did not cause damage in the formation of Al-hydroxy. In this method, the resulting pillars were more homogeneous in size. Thereby, the Al0h Li method has been shown to produce a supporting material with a constant interlayer spacing, increased of the specific surface area (SSA), and drastic reduction of the cation exchange capacity (CEC) as compared to MMT. This modified mineral can be used in, for example, decontamination of polluted water with nonionic organic pollutants.
  • Estimating lateral flow in double ring infiltrometer measurements Division – Soil Processes And Properties

    Boeno, Daniel; Gubiani, Paulo Ivonir; Lier, Quirijn de Jong Van; Mulazzani, Rodrigo Pivoto

    Resumo em Inglês:

    ABSTRACT The steady infiltration rate of soil profiles is commonly determined for irrigation and soil conservation planning, but the divergence of methods reduces the reliability of measurements. In this study, the steady infiltration rate measured with a double ring infiltrometer (isr-dri) in different layers of a soil profile was compared between layers and with the steady vertical saturated flow rate estimated by the Richards equation (isr-hy). The measurements of isr-dri at the top of the A, E, and Bt horizons were compared to each other and also compared with the isr-hy to detect the occurrence of lateral flow in double ring infiltrometer measurements. The isr-dri in the A horizon (236 mm h-1) was around 10 times higher than in the Bt horizon (20 mm h-1), which implies in a lateral flow of almost 90 % in the surface horizon. The occurrence of lateral flow in double ring infiltrometer measurements was also shown by comparing isr-dri with the vertical saturated flow rate estimated with the Richards equation, isr-hy. The main conclusion is that isr-dri measured at the soil surface overestimates the steady infiltration rate of soil profiles when underlying horizons are less permeable and more restrictive to water flow. In these cases, the use of an effective saturated hydraulic conductivity of the soil profile would imply inaccurate planning of drainage, irrigation, and soil conservation designs.
  • Mulching films affecting soil bacterial and fungal communities in a drip-irrigated potato soil Division – Soil Processes And Properties

    Wang, Wen; Han, Lu; Zhang, Xiong

    Resumo em Inglês:

    ABSTRACT Film mulching is an effective water-saving and yield-increasing measure for potato production in Northwest China. However, the response mechanism of microbial communities to mulching films in the soil is still unclear. In this study, polyethylene film mulching (PM), biodegradable film mulching (BM), liquid film mulching (LM), and non-mulching (NM) were applied on the drip-irrigated soil to investigate the effects of mulching films on soil bacterial and fungal communities through DNA sequencing, Pearson correlation analysis, and redundancy analysis. The results showed that LM treatment significantly increased the contents of soil mineral N (SMN), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) (p<0.05) in comparison with NM. The soil treated with LM presented high bacterial OTUs (operational taxonomic units), Chao1, ACE, and Shannon indices; however, the same indexes of fungi were low in LM and BM treatments. At the phylum level, Proteobacteria, Actinobacteria, and Chloroflexi were dominant bacterial communities. The LM treatment increased the OTUs of Proteobacteria ; PM treatment increased the OTUs of Actinobacteria and Chloroflexi. Ascomycota was the dominant fungal community, which were decreased in soil under mulching films. In terms of soil properties, DON was closely correlated (p<0.05) with the microbial OTUs, Chao1, and ACE indices. The DOC and SWC (soil water content) contributed 51.2 % to the change of bacterial structure; however, the fungal structure was less sensitive to the variation of soil properties. Our results indicate that liquid film mulching favors increasing the diversity and abundance of dominant bacterial species, which were associated with the variation of soil properties.
  • Mycorrhizal inoculation and phosphorus fertilization show contrasts on native species of the Brazilian Atlantic Forest and Cerrado Division – Soil Processes And Properties

    Prates Júnior, Paulo; Moreira, Bruno Coutinho; Silva, Marliane de Cássia Soares da; Diogo, Nayron Vilela; Luz, José Maria Rodrigues da; Jordão, Thuany Cerqueira; Paiva, Haroldo Nogueira de; Kasuya, Maria Catarina Megumi

    Resumo em Inglês:

    ABSTRACT Restoration of degraded sites by using native plants like Plathymenia reticulata Benth. and Melanoxylon brauna Schot. is advisable. However, seedlings of both species, when raised on commercial substrates, may present low survival. This study aimed to evaluate the growth of seedlings under inoculation with arbuscular mycorrhizal fungi (AMF). The seedlings were raised on soil sampled from near an adult plant of the same species. The P. reticulata and M. brauna seedlings were grown with or without the inoculation of a mix of three species of AMF (Rhizophagus clarus, Claroideoglomus etunicatum, and Gigaspora albida), and five doses of P (0, 50, 150, 300, and 450 mg dm-3 of P). All seedlings were inoculated with Bradyrhizobium sp., isolated from each species. After 90 days, P. reticulata inoculated with AMF showed higher growth and nutrient content than those uninoculated, and the maximum plant growth was obtained when received 160 to 280 mg dm-3 of P. On the other hand, no effects of AMF inoculation or phosphate fertilization were observed on M. brauna. For both species, no effect of inoculation was observed on mycorrhizal colonization, and M. brauna, unlike P. reticulata presented a considerable number of nodules. We conclude that inoculation with AMF and P fertilization improves the growth of P. reticulata seedlings but does not promote the growth of M. brauna; presenting the necessity to investigate each species.
  • Terracing increases soil available water to plants in no-tillage Division – Soil Processes And Properties

    Freitas, Letiéri da Rosa; Gubiani, Paulo Ivonir; Mulazzani, Rodrigo Pivoto; Minella, Jean Paolo Gomes; Londero, Ana Lúcia

    Resumo em Inglês:

    ABSTRACT Several management practices can increase soil water storage capacity, but their effectiveness to minimize the adverse effects of drought depends on their potential to increase the soil available water to plants. Terracing is an effective option to increase soil water storage, but its effect on available water to plants in no-tillage system is still a knowledge gap. In this study, we monitored soil water content at eight layers down to 1.6 m in two zero-order paired catchments for 16 months. Presence of five broad-based terraces in one of the catchments was the main difference between the two. Water availability to plants over time was expressed as a fraction of available water capacity (FAW). Positive differences of FAW between the terraced and non-terraced catchments were noticed over periods of rainfall shortage, but they were barely perceptible in periods of abundant rainfall. Over the 16 months, the frequency of FAW higher than 0.75 was between 46 and 50 % in the non-terraced catchment, and between 67 and 75 % in the terraced catchment. This benefit of terracing is more noticeable in thicker upper-section of the soil profile evaluated and with greater number of terraces upstream from the point of observation. We concluded that terracing in no-tillage turn excess rainfall into noticeable positive increases in available water to plants in the following periods of rainfall shortage.
  • Shaking settings to reduce the breakdown of Entisol fragile particles in texture analysis Division – Soil Processes And Properties

    Gubiani, Paulo Ivonir; Almeida, Thiago Assunsão de; Mulazzani, Rodrigo Pivoto; Pedron, Fabrício de Araújo; Suzuki, Luis Eduardo Akiyoshi Sanches; Pereira, Caroline Andrade

    Resumo em Inglês:

    ABSTRACT Finding the proper shaking setting to ensure total particle dispersion without altering the content of sand, silt and clay in soils composed of fragile particles such as saprolite fragments is still a research gap. This study aimed to identify the best shaking setting to optimize particle dispersion and minimize particle change in samples of Entisol (Neossolos). Samples were dispersed using an electric mixer at 12,000 rpm for 5, 15, 30 and 60 min, a horizontal shaker at 150 cycles min-1 for 1, 2, 4, 8 and 16 h with and without the use of nylon spheres, and an ultrasonic shaker at 70 and 110 J mL-1 for approximately 20 and 30 min, respectively. All the treatments affected particle distribution. Coarse sand reduced up to 14 % and clay content increased up to 18 % with the horizontal shaker with nylon spheres and the electric mixer. These changes were attributed to the breakdown of saprolite fragments, which represented around 1/3 of the coarse sand. Our results showed that the best setting was the horizontal shaker at 150 cycles min-1 for 1 to 2 h without using nylon spheres. This option allowed optimizing particle dispersion and minimizing changes in particle size distribution.
  • Use of nuclear techniques in soil science: A literature review of the Brazilian contribution Division – Soil Processes And Properties

    Pires, Luiz Fernando; Cássaro, Fábio Augusto Meira; Correchel, Vladia

    Resumo em Inglês:

    ABSTRACT This review presents the basic research and some applications of the gamma-ray attenuation, neutron gauges, and 137Cs fallout techniques for studying soil physical processes and properties. The selected studies aimed to give the readers a general idea of the use of these nuclear techniques carried out by Brazilian researchers in the past decades. It is expected to assist future researchers by identifying knowledge gaps and opportunities for applying the methods presented here. Around 100 studies were selected for this review. The papers dealing with gamma-ray attenuation are mostly related to the analysis of soil radiation interactions, the measurement of basic soil physical properties, the evaluation of hydraulic conductivity, water retention curve, and soil mechanical analysis. Neutron gauge applications are related to monitoring the water distribution and balance at the field scale, procedures for calibrating the existing gauge for the Brazilian soils, and analyzing the spatial and temporal variability of the soil water content. The 137Cs methodology involves studies about the erosion and sediment deposition in small watersheds and riparian zones, the spatial variability of 137Cs inventories at reference sites, and the measurement of sediment spatial distributions. Future studies with the gamma-ray attenuation methodology should focus on a better comprehension of the photon interaction with the soil and a correct selection of photon energies to investigate contrasting soils. This is mandatory for adopting it as a reliable tool for soil characterization. This review also revealed that the challenges for the future use of the 137Cs fallout technique involve the continuous decrease of the 137Cs activity worldwide, including in Brazil. Advances in detection systems (gamma spectrometers) will be required to overcome this issue. Future studies should focus on the use of correction factors related to the enrichment of fine particles during the transport of sediments to improve the estimates obtained through the conversion models. The use of neutron gauges to detect soil water content at the field scale depends on the adoption of reliable calibration curves. Then, comprehending how soil properties alter this curve and how it affects the water balance is a study of great interest. Motivated by strict regulations on the use of radioactive materials, the adoption of gauges with less activity is becoming a new goal. Thus, the development of more effective systems of neutron detection is crucial.
  • Hierarchical feedbacks of vegetation and soil carbon pools to climate constraints in Brazilian ecosystems Division – Soil Processes And Properties

    Souza, Ivan Francisco de; Gomes, Lucas de Carvalho; Fernandes Filho, Elpídio Inácio; Silva, Ivo Ribeiro da

    Resumo em Inglês:

    ABSTRACT: It remains unclear whether temperature and precipitation exert independent control on tropical vegetation and soil C pools. Likewise, it is unknown whether the feedbacks of tropical C pools to climate constraints vary with nutrient availability. These aspects are critical to improving our ability to predict the response of tropical C pools to climate dynamics. This review aimed to assess climate data and the spatial distribution of vegetation and soil C pools across the Brazilian territory to investigate i) whether mean annual precipitation (MAP) and temperature (MAT) exert independent effects on tropical C pools; ii) whether vegetation and soil C pools exhibit hierarchical feedbacks to climate; and iii) how these feedbacks reflect soil nutrient availability. To account for MAP and MAT effects on tropical C cycling, we calculated Ecosystem Effective Moisture (EEM), i.e., the difference between MAP and potential evapotranspiration. We gathered substantial evidence suggesting that under high MAT and MAP controlling EEM, plants exchange more C for water and resorb more nutrients (especially P), which limitations in plant litter reduce microbial-derived C inputs into soil organic matter. Frequent soil saturation under high EEM favors denitrification rates (“open” N cycle), allowing continuous mineralization of litter and shallow soil C pools to release nutrients, sustaining high plant C pools. With decreasing MAP levels, ecosystem C pools depend on MAT controlling evapotranspiration and EEM. Accordingly, decreasing MAP under high MAT reduces EEM, with vegetation and soil C pools co-limited by low net primary productivity (NPP), frequent fire and/or nutrient losses. Otherwise, decreasing MAP and coupled to cool temperatures allow EEM to remain positive, forcing plants to increase deep-rooting and/or shed their leaves, which nutrients are immobilized with microbial-derived C into mineral-organic associations, favoring high soil C pools. Combined, the evidence gathered suggests that the sensitivity of tropical ecosystems to global increases in temperature should not be overlooked, especially if coupled to reductions in precipitation. Overall, the horizontal distribution of vegetation and soil C pools is best described by EEM rather than temperature or precipitation alone, whereas the vertical partition of C in plant-soil systems reflects biotic responses to climate-nutrient constraints.
  • Interplays between Atta ants (Formicidae: Attini), soils and environmental properties in the Brazilian Neotropics: a preliminary assessment Division – Soil Processes And Properties

    Schaefer, Carlos Ernesto Gonçalves Reynaud; Henriques, Renata Jordan; Gomes, Lhoraynne Pereira; Gorsani, Rodrigo Gomes; Santos, Michel Filiphy Silva; Fernandes, Daniela Pinto de Souza

    Resumo em Inglês:

    ABSTRACT Leaf-cutting ants are the most important herbivore in the neotropics, represent active agents of pedobioturbation, and are regarded as ecosystem engineers. These ants have a wide variety of ecological functions, such as pollination, seed dispersal, and tree-growing control. Despite this importance, little is known on their distribution in relation to possible soil and environmental conditions that affect Atta ants occurrence. This study aimed to spatialize the main occurrences of Atta species in the Brazilian territory and evaluate the main environmental conditions driving ants species in the Brazilian tropical landscapes, at a preliminary basis. We compiled data of occurrence for 12 Atta species from Global Biodiversity Information Facility (GBIF) databases, and scientific literature (up to 2019) for each Atta species. To each point, we obtained the respective geoenvironmental data as soil properties, biome, geology, vegetation land use, and climate variables. From these data, possible zonalities of occurrence of 9/10 Atta species were discussed. We applied the principal components analysis (PCA) and Canonical Correspondence Analysis (CCA) to identify the environmental gradient and investigate the possible interplay between variables and species. Soil, vegetation, and land use attributes are the main drivers on the distribution of Atta at local scale where their evolutionary physiological and foraging adaptations allow them to nest and maintain the fungi culture. At broader scales, climatic attributes are key drivers of Atta distribution across Brazil, and also influence pedogenic processes. Our study demonstrates that species of Atta ants are not randomly dispersed in Brazil and are strongly associated with complex and diverse Brazilian landscapes. We remark that further studies on the distribution of leaf-cutting ants of the Atta genus in Brazil, as well as their evolutionary phylogenetics, are needed, based on larger database.
  • Contribution of enzymes to soil quality and the evolution of research in Brazil Division – Soil Processes And Properties

    Sobucki, Lisiane; Ramos, Rodrigo Ferraz; Meireles, Leonardo Arocha; Antoniolli, Zaida Inês; Jacques, Rodrigo Josemar Seminoti

    Resumo em Inglês:

    ABSTRACT Extracellular soil enzymes are fundamental for the functioning of ecosystems. Several processes in the soil depend on the activity of these enzymes, including plant decomposition, soil organic matter formation/mineralization, and nutrient cycling. Moreover, extracellular enzyme activity occurs in the soil and is therefore influenced by environmental factors. Due to the high sensitivity to these factors, extracellular enzymes are used for monitoring soil quality. This review aimed to present the main contributions of soil enzymes to agriculture, emphasizing the dynamics of elements in the soil and the environmental factors that modulate enzyme activity. With this knowledge, the relationship of extracellular enzymes to soil quality is demonstrated and their use as a tool for soil monitoring. Finally, the evolution of research on soil enzymes in Brazil is presented, and the perspectives of basic and applied studies necessary to expand the knowledge and use of enzymes in soil management are pointed out. Soil enzymes play a key role in numerous soil processes, thereby making them useful indicators of productive capacity and soil quality. Research on enzymes in soil has developed significantly in the last two decades, which has made it possible for farmers to analyze and interpret enzyme activity in the soil in the laboratory.
  • Clonal teak litter in tropical soil: decomposition, nutrient cycling, and biochemical composition Division – Soil Use And Management

    Cavalcante, Valéria Santos; Santos, Márcio Luiz dos; Cotta, Luisa Carla; Neves, Júlio César Lima; Soares, Emanuelle Mercês Barros

    Resumo em Inglês:

    ABSTRACT: Litter decomposition dynamics and nutrient release are also dependent on their biochemical composition, and such information is important for adequate nutritional management but is still incipient for plants like teak. This study aimed to evaluate the decomposition dynamics, nutrient release, and biochemical composition of clonal teak litter. The study was conducted in areas of clonal teak stands, in São José do Rio Claro, Mato Grosso, Brazil. Litter collectors were arranged in the area to collect material along the entire dry period. Subsequently, this litter was placed in litter bags, which were distributed in the area. The litter bags were collected every month, for 0.91 years, to determine the dry matter and mineral nutrient contents, in order to estimate the decomposition and nutrient release. Litter biochemical composition was determined at the times of 0, 0.25, 0.58, 0.75, and 0.91 years. Teak litter, essentially leaves, had a half-life time (t1/2) of dry matter and C of 0.74 years, due to the high content of insoluble lignin, which corresponds to 2.28 Mg ha-1 of dry matter and 1.2 Mg ha-1 of C. The t1/2 values of N and P release (1.20 and 1.01 years) were higher than those of K, Ca, and Mg (0.08, 0.47, and 0.66 years, respectively). Hence, the nutrient release rate of the litter followed the descending order: K > Ca > Mg > P > N. The litter biochemical composition at the end of the experimental period showed reductions of 18.7 % in polysaccharides and holocellulose, 56 % in polyphenols, 56.3 % in tannins, 22.2 % in extractives, and 28.5 % in soluble lignin; and increases of 25.6 % in insoluble lignin and 22.6 % in total lignin. These data are useful for the balance of carbon and mineral nutrients and to support fertilization management in teak plantations in low-fertility soils.
  • Different N-fertilization sources affecting the native soil organic matter mineralization on Technosols under iron ore tailing Division – Soil Use And Management

    Oliveira, Paula Afonso de; Assis, Igor Rodrigues de; Dias, Luiz Eduardo; Silva, Ivo Ribeiro da; Barbosa, Gustavo Magalhães Nunes; Teixeira, Rafael da Silva; Campos, Rafaella

    Resumo em Inglês:

    ABSTRACT: Accidents related to the rupture of iron ore tailings dams have dramatically impacted on the Brazilian natural ecosystem. So, the development of strategies to recover soil organic matter levels and build-up Technosols are required. This study aimed to evaluate the effect of N-mineral and -organic fertilization and the rhizospheric effect on soil organic matter mineralization from Technosols built under iron ore tailings. The experiment was carried out in a greenhouse; we used a factorial scheme 2 × 2 × 3: without and with the plant Crotalaria juncea ; without and with mineral fertilization; and three different organic fertilization (without organic fertilization, sewage sludge, and household waste composting), with four randomized blocks. The experimental units were PVC columns installed with a top layer of iron ore tailing from a dam, where gases were sampled to determine the CO2-C, CH4-C concentrations, and CO2-δ13C. The organic fertilization promoted a positive priming effect of 184 %. However, with mineral fertilization, no effect was observed in soil derived-CO2-C accumulated and priming effect. Similarly to non-planted soil, the planted soils with mineral and organic fertilization promoted a steady reduction in soil derived-CO2-C accumulated and rhizosphere priming effect. The soil with mineral fertilization improved in 5.52 and 0.45 g per column the shoot and root dry matter of Crotalaria when compared to the soil without mineral fertilization. In summary, the organic fertilization in Technosols built over iron ore tailings dams during revegetation was not enough to ensure the plant development and preservation of soil organic matter. However, the combination of mineral and organic fertilization promoted negative rhizosphere priming effect and a significant increase in plant biomass.
  • Universality of Kenworthy and DRIS norms for prata and cavendish bananas grown in two environments Division – Soil Use And Management

    Rodrigues Filho, Vagner Alves; Neves, Júlio César Lima; Donato, Sérgio Luiz Rodrigues; Guimarães, Bruno Vinícius Castro

    Resumo em Inglês:

    ABSTRACT Tissue analysis results are interpreted by comparing them with nutrient standards; however, using universal standards may lead to a misleading nutritional diagnosis. This study aimed to evaluate the degree of universality of Kenworthy and DRIS norms for irrigated ‘Prata-Anã’ (AAB) and ‘Grande Naine’ (AAA) banana plants grown in two environments. The study was carried out using a database containing leaf nutrient contents and yield data of two farms located in Ponto Novo, Bahia State, and Missão Velha, Ceará State, Brazil. A reference population was that with yields above the average yield plus 0.5 standard deviation. Using a reference population, the mean, standard deviation, and coefficient of variation of nutrient content and dual nutrient ratios were calculated for each site × cultivar combination. To verify the homogeneity of variance among populations, F-test was used (p≤0.05). Means were compared using t-test (p≤0.05). Differences in climate and soil at each farm explain the high frequency of significant differences found between norms for each site. Kenworthy norms established for interpreting leaf nutrient contents of P, K, Ca, Mg, S, Cu, Fe, Mn, and Zn for ‘Prata-Anã’ grown in Ceará were higher than those in Bahia, while for N and B contents, the norms were higher in Bahia. This is due to differences in soil fertility and alkalinity affecting nutrient availability as well as non-nutritional factors. Kenworthy and DRIS norms for ‘Prata-Anã’ and ‘Grande Naine’ bananas grown in Ceará have higher variability and are greater than for those grown in Bahia. Norms are less convergent for ‘Prata-Anã’ than ‘Grande Naine’. Site- and cultivar-specific norms are recommended over universal ones for assessing the nutritional status of ‘Prata-Anã’ and ‘Grande Naine’ banana plants cultivated in different environments.
  • Soil spectral library of Piauí State using machine learning for laboratory analysis in Northeastern Brazil Division – Soil Use And Management

    Mendes, Wanderson de Sousa; Boechat, Cácio Luiz; Gualberto, Adriano Venicius Santana; Barbosa, Ronny Sobreira; Silva, Yuri Jacques Agra Bezerra da; Saraiva, Paloma Cunha; Sena, Antonny Francisco Sampaio de; Duarte, Lizandra de Sousa Luz

    Resumo em Inglês:

    ABSTRACT Soil chemical and physical analyses are the major sources of data for agriculture. However, traditional soil analyses are time-consuming, not cost-efficient, and not environmentally friendly. An alternative to traditional soil analyses is soil spectroscopy. This technique is a low-cost and quick analytical method, which can be implemented in a laboratory and/or in-situ. Nevertheless, some spectrometers are expensive and do not contemplate the entire spectrum. Despite this limitation, the main objective of the study was to create a soil spectral library of the Piauí State using only the 1000–2500 nm range. In this sense, it was evaluated and standardized the soil spectral library by accessing the combination of smoothing, standard normal variate, continuum removal, and Savitzky-Golay derivative spectral preprocessing procedures with partial least squares, random forest, and cubist machine learning algorithms. It was collected 262 geo-referenced soil samples at the layer of 0.00–0.20 m across the entire Piauí State, representing most of its soil variability. The soil properties evaluated were pH(H2O), sand, clay, and soil organic carbon (SOC) contents. This study demonstrated that the Standard Normal Variate was one of the most promising preprocessing procedures to improve model predictions for pH(H2O), sand, and clay. For SOC and pH, the best overall results were without preprocessing the soil spectra. Moreover, the cubist model was the most accurate in predicting soil properties. Finally, our study showed evidence of the potential and feasibility of using this soil spectral library to estimate soil properties such as pH(H2O), sand, clay, and SOC.
  • Refining phosphorus fertilizer recommendations based on buffering capacity of soils from southern Brazil Division – Soil Use And Management

    Mumbach, Gilmar Luiz; Gatiboni, Luciano Colpo; Dall’Orsoletta, Daniel João; Schmitt, Djalma Eugenio; Grando, Douglas Luiz; Souza Junior, Abelino Anacleto de; Brignoli, Fernando Marcos; Iochims, Daniel Alexandre

    Resumo em Inglês:

    ABSTRACT The phosphorus (P) rates recommended for corrective fertilization-P of soils from southern Brazil may be insufficient to reach the critical level for optimal plant growth. This study aimed to quantify the fertilizer-P rates for total correction fertilization with varying soil buffering capacity in the states of Rio Grande do Sul (RS) and Santa Catarina (SC). Soil samples from 0.00-0.10 and 0.10-0.20 m layers were collected from 41 locations distributed in both states. Twelve P rates were applied to each soil, varying between 0 and 100 % of the maximum adsorption capacity (P-max), and incubated for 20 days. After incubation, the extractable P was determined by Mehlich-1. Based on the relationship between applied rates and extracted P, the P buffer capacity (trP_M1) of the soils was quantified, relating it to soil properties. The trP_M1 values, that is, amounts of P2O5 required to increase 1 mg dm-3 of P extracted by Mehlich-1, varied between 2.4 and 34.5 kg ha-1 of P2O5. A multiple explanatory equation for the variable P was generated, in which only P-max, clay content, and initial P availability have a significant effect. The P buffer capacity was significantly higher in the soils with the highest clay content, and there was a reduction in trP_M1 for soils with higher initial P availability. Considering 270 soil samples with low P, the P rate to reach the sufficient levels may be 2-folds higher than the values currently indicated for the RS and SC states, especially for soils with more than 40 % of clay. Phosphorus rates for corrective fertilization must be based on the soil clay content and in P initial availability. The fertilizer-P in clayey soils must be increased.
  • Physicogenic and biogenic aggregates under different management systems in the Cerrado region, Brazil Division – Soil Use And Management

    Pinto, Luiz Alberto da Silva Rodrigues; Torres, José Luiz Rodrigues; Morais, Igor de Sousa; Ferreira, Robert; Silva Júnior, Wanderson Farias da; Lima, Sandra de Santana; Beutler, Sidinei Júlio; Pereira, Marcos Gervasio

    Resumo em Inglês:

    ABSTRACT An important strategy for the sustainable management of Cerrado soils is no-till (NT) systems, which may improve soil properties, particularly aggregation. Soil aggregates can be categorized according to their formation pathways into physicogenic (Phy) and biogenic (Bio). This study aimed (i) to quantify the relative proportion of physicogenic and biogenic aggregates and (ii) evaluate the levels of total organic carbon and their respective humic and physical fractions in the aggregates’ formation pathways. The following managed and unmanaged sites were evaluated: a 6-year no-till site (6NT), an 18-year no-till site (18NT), a conventional tillage site (CT), and a reference Cerrado site (RS). Retained aggregates were analyzed morphologically, separated into Phy and Bio, and quantified. Subsequently, aggregates were subjected to total organic carbon (TOC) determination, fulvic acid carbon, humic acid carbon, humin carbon, particulate organic carbon (POC), mineral-associated organic carbon, and free light fraction carbon (FLFC). The proportion of Bio aggregates increased with decreasing management intensity. When TOC and humic acid carbon levels were compared between sites, it was found that Bio aggregates from 18NT and 6NT contained higher carbon content than Bio aggregates from CT. Particulate organic carbon and FLFC differed between aggregate types, with higher POC values observed in Bio aggregates from CT and 18NT and higher FLFC values in Bio aggregates from CT, 6NT, and 18NT. The practices adopted in the conservation management system favored biogenic aggregation in the Cerrado region, which can be proven through the study of the fractions of soil organic matter contained in these aggregates. The biogenic aggregation changed the SOM dynamics. Principal component analysis showed a clear distinction between conventional and conservationist management systems.
  • On-farm evaluation of regenerative land-use practices in a semi-arid pasture agroecosystem in West Texas, USA Division – Soil Use And Management

    Slaughter, Lindsey; Deb, Sanjit; Chakraborty, Somsubhra; Li, Bin; Bakr, Noura; Edwards, Bryanna; Weindorf, David

    Resumo em Inglês:

    ABSTRACT Continually rising scarcity in water and nutrient resources, especially in semi-arid agricultural systems, combined with increased frequency of extreme weather events such as drought, contribute to a growing need for resilient and regenerative agricultural ecosystems. However, evaluating a myriad of combinations of producer-led sustainable management practices in on-farm research remains challenging. Few studies have elucidated spatial variability in measured soil properties across the study area due to logistical and economic constraints. As such, this study aimed to: 1) establish soil health assessment and landscape variability data immediately after land-use change to a sustainable pasture management system, and 2) delineate relationships and predictive capability between measured soil health parameters. Soil samples were collected on May 23, 2018 in a grid pattern across two adjacent pastures on a farm in the semi-arid Southern High Plains (Texas, USA) that had recently been converted from long-term continuous cotton production to grazed pasture. Significant differences were found in soil chemical and biological properties between pastures (e.g., ~37 % reduction in microbial community size and 36 and 178 % greater electrical conductivity (EC) and Na contents, respectively, in the East pasture) that likely resulted from recent tillage and receiving irrigation compared to similar soil types and management history in the West pasture. Spatial diagrams of measured parameters revealed localization of measured properties, such as higher clay content and soil organic matter in the southeastern portion of the study area, and clear boundaries between pastures in terms of arbuscular mycorrhizal fungi (AMF) distribution. Soil physical and chemical properties were sufficiently correlated with biological measurements to predict soil microbial community size based on routine soil test analyses. The patterns of distributed elements evaluated in this study can provide a basis for management decisions on soil health and potential contaminant monitoring across the study area. These findings provide insight as to how novel, producer-designed soil health management practices in small semi-arid production systems impact soil properties, as well as help develop cost-effective predictive modeling solutions that aid long-term monitoring efforts. Such strategies will be critical tools in resource-scarce semi-arid regions such as those found in the current study region of Texas, as well as similar semi-arid regions such as northern China and northeastern Brazil. Overall, the results of this study provide direction for long-term soil health monitoring at this site, as well as a critical evaluation of relationships between soil health indicator measurements that aids interpretation and management planning.
  • Is cassava yield affected by inverting tillage, chiseling or additional compaction of no-till sandy-loam soil? Division – Soil Use And Management

    Reichert, José Miguel; Fontanela, Eracilda; Awe, Gabriel Oladele; Fasinmirin, Johnson Toyin

    Resumo em Inglês:

    ABSTRACT Defining a suitable soil tillage option that provides adequate soil physical conditions for optimum cassava (Manihot esculenta Crantz) productivity has not been adequately researched in southern Brazil. This study aimed to evaluate, in an Argissolo Vermelho-Amarelo Distrófico (Acrisol or Hapludalf), three tillage methods - conventional (inverting) tillage, chiseling, and long-term no-tillage (without and with, additional soil compaction), as affecting soil hydro-physical properties and cassava yield, in southern Brazil. Undisturbed and disturbed soil samples were collected from row and interrow positions, from the soil surface down to 0.40 m depth to determine soil bulk density, degree of compaction, porosity, water retention, plant available water, air and water permeability, mechanical properties (compressibility and elasticity), and chemical properties. The yield of cassava storage roots was obtained at crop physiological maturity. Conventional (inverting) and chisel tillage of soil previously under long-term no-tillage increased soil macroporosity - a composition or capacity physical property – of the surface soil, but did not improve the functioning/intensity properties air and water permeability. Soil reconsolidation over a short-time significantly affects soil structural condition, and thus soil tillage is not needed to improve soil structure. Additional compaction on the no-till soil causes detrimental consequences on composition/capacity and functioning/intensity physical properties. Nonetheless, neither improvement of soil structure by tillage nor further compaction affects cassava storage root yield in the sandy loam soil. Therefore, no-tillage is the best management system, in which soil loosening is done only during furrowing for cassava-stem planting.
  • Biochar and conventional compost reduce hysteresis and increase phosphorus desorbability in iron mining waste Division – Soil Use And Management

    Guedes, Rafael Silva; Pinto, Duane Azevedo; Ramos, Sílvio Junio; Dias, Yan Nunes; Caldeira Junior, Cecílio Fróis; Gastauer, Markus; Souza Filho, Pedro Walfir Martins e; Fernandes, Antonio Rodrigues

    Resumo em Inglês:

    ABSTRACT: Phosphorus (P) fixation in the soil reduces the utilization of this element by plants and can be one of the main problems for fertilization management in soils containing Fe oxides. As a strategy to minimize the effects of P retention, organic materials, such as biochar or commercial composts, may be useful tools to maintain P availability and delay immobilization of this element in the soil, thereby benefiting, for example, the rehabilitation of areas impacted by Fe mining. The objective of this study was to evaluate the kinetics of P sorption and desorption and the hysteresis index in red mining waste from Fe mining subjected to açaí biochar and commercial compost amendments. Therefore, a substrate collected from Fe mining waste piles in the Carajás Mineral Province was incubated for 30 days with açaí biochar, commercial compost, and açaí biochar + commercial compost at a ratio of 90 % mining waste and 10 % organic amendment (w/w). The P sorption and desorption kinetics were evaluated in a solution containing 10 mg L−1 P at times from 0.5 to 48 h; the data were modeled according to a pseudo-first-order equation considering two types of reaction sites, and the hysteresis index was obtained by the difference between the sorption and desorption isotherms. Treatment of the mining substrate with açaí biochar reduced P sorption, while P desorption was increased by up to 60 % by applying biochar and/or commercial compost. Açaí biochar also reduced the hysteresis of P sorption from 78 to 54.8 %, in addition to slowing P fixation in this substrate. Thus, this study showed that açaí biochar and commercial compost may maximize the benefits of phosphate fertilization during the rehabilitation of areas impacted by Fe mining. However, as these composts can cause different effects on P dynamics in mining waste, their effects on other elements, such as micronutrients, whose availability may be affected, are important to be evaluated.
  • Lime and phosphogypsum application management: changes in soil acidity, sulfur availability and crop yield Division – Soil Use And Management

    Besen, Marcos Renan; Ribeiro, Ricardo Henrique; Esper Neto, Michel; Minato, Evandro Antonio; Coneglian, Carolina Fedrigo; Kachinski, Wagner Deckij; Tormena, Cassio Antonio; Inoue, Tadeu Takeyoshi; Batista, Marcelo Augusto

    Resumo em Inglês:

    ABSTRACT Oxisols ( Latossolos ) are widely distributed in tropical zones and generally characterized by high levels of surface and subsurface acidity. In Brazil, most Oxisols are managed under no-till conditions with surface application of acidity amendments. This study aimed to evaluate lime application strategies (incorporated and surface) for achieving the desired soil base saturation (BS%) levels (44, 60, 70, and 90 %) and the effect of phosphogypsum + lime application on soil chemical properties as well as wheat and corn yield in southern Brazil. Lime incorporation was more effective in reducing the soil acidity and increasing Ca2+ and Mg2+ despite a decrease in organic matter at the soil surface. Phosphogypsum application increased S-SO42- and Ca2+ availability throughout the deeper soil layers and reduced the Mg2+ content in the surface layer. Wheat yield under incorporated lime conditions increased with BS% up to 75, but there was no response to surface application. When phosphogypsum was applied, the wheat yield increased by 8.4 %. For corn, incorporated lime increased the yield up to 445 kg ha-1, which was equivalent to the yield after phosphogypsum application. An increase in the S-SO42- level was the main factor related to the increase in crop yields. In the short term, our results suggest that phosphogypsum applied along with lime is more appropriate than incorporating lime under no-till management conditions.
  • Duromide increase NBPT efficiency in reducing ammonia volatilization loss from urea Division – Soil Use And Management

    Cassim, Bruno Maia Abdo Rahmen; Kachinski, Wagner Deckij; Besen, Marcos Renan; Coneglian, Carolina Fedrigo; Macon, Celso Rafael; Paschoeto, Gabriel Ferrari; Inoue, Tadeu Takeyoshi; Batista, Marcelo Augusto

    Resumo em Inglês:

    ABSTRACT Novel fertilizer stabilization technologies are needed to decrease ammonia (NH3-N) losses and increase nitrogen use efficiency. Duromide + NBPT is a new technology that combines two molecules, Duromide and NBPT, whose propose is to increase the efficiency of the urease inhibitor NBPT in reducing NH3-N loss from urea. Preliminary results showed that Duromide + NBPT can be a more effective product than just NBPT, particularly under low soil pH and high-temperature conditions. This study aimed to compare the effects of urea + Duromide + NBPT, urea + NBPT, and conventional urea on soil N losses by NH3-N volatilization. The field experiment was conducted on a Latossolo Vermelho Distroférrico (Oxisol) in Campo Mourão, Paraná, Brazil, using a randomized complete block design with treatments arranged in a 2 × 3 factorial, comprising two N doses (45 and 90 kg ha-1) and three N fertilizers (urea + Duromide + NBPT, urea + NBPT, and conventional urea). The NH3-N volatilization data were subjected to nonlinear regression using a logistic model. The NH3-N losses varied according to dose and fertilizer, reaching up to 12.4 % of the applied N in the conventional urea treatment. Urea + Duromide + NBPT was more efficient than urea + NBPT in decreasing NH3-N volatilization. Compared to conventional urea at doses of 45 and 90 kg ha-1 of N, urea + Duromide + NBPT reduced NH3-N volatilization losses by 35 and 54 % and from urea + NBPT by 15 and 33 %, respectively. The new stabilizing technology Duromide + NBPT reduced NH3-N losses by up to 33 % compared to NBPT alone. Ammonia volatilization was influenced by soil moisture. The volatilization peak, observed after 18-19 days of N fertilizer application, was triggered by rainfall events.
  • Assessing sediment yield and streamflow with SWAT model in a small sub-basin of the Cantareira System Division – Soil Use And Management

    Pontes, Lucas Machado; Batista, Pedro Velloso Gomes; Silva, Bárbara Pereira Christofaro; Viola, Marcelo Ribeiro; Rocha, Humberto Ribeiro da; Silva, Marx Leandro Naves

    Resumo em Inglês:

    ABSTRACT Hydro-sedimentological models might be useful tools for investigating the effectiveness of soil and water conservation practices. However, evaluating the usefulness of such models requires that predictions are tested against observational data and that uncertainty from model parameterization is addressed. Here we aimed to evaluate the capacity of the SWAT model to simulate monthly streamflow and sediment load in the Posses creek catchment (12 km2), Southeast Brazil. The SUFI-2 algorithm from SWAT-CUP was applied for calibration, testing, uncertainty, and sensitivity analysis. The model was calibrated and initially tested using discharge and sediment load data, which were measured at the catchment outlet. Additionally, we used soil loss measurements from erosion plots within the catchment as independent data for model evaluation. Average monthly streamflow simulations obtained satisfactory results, with Nash-Sutcliffe coefficient (NSE) values of 0.75 and 0.51 for the calibration and testing periods, respectively. Sediment load simulations also displayed satisfactory results for calibration (NSE = 0.65) and testing (NSE = 0.52). However, the comparison with independent plot data revealed that SWAT severely overestimated hillslope erosion rates and compensated it with high sediment channel deposition. Moreover, the model was not sensitive to the parameters used for calculating hillslope sediment yields. Therefore, it should be used with caution for evaluating the interactions between land use, soil erosion, and sediment delivery. We found that the commonly used outlet-based approach for model calibration and testing can lead to internal misrepresentations, and models can reproduce the right answer for the wrong reasons.
  • Soil chemical properties and wheat production in three Andisol with applications of materials from the cellulose industry Division – Soil Use And Management

    Hirzel, Juan; Meier, Sebastián; Morales, Arturo; Undurraga, Pablo; Salazar, Francisco

    Resumo em Inglês:

    ABSTRACT Soil acidity is one of the main factors that reduces productivity in agricultural crops, and it is corrected with materials that neutralize acidification. Among soils affected by acidity are those of volcanic origin. At least 30 % of agricultural soils in Chile are of volcanic origin, and acidity correction practices must be constantly performed. This study aimed to evaluate the effectively of two materials that may neutralize soil acidification and increase yield production in Chilean volcanic soils. An experiment was conducted during the 2019-2020 season, in which different acidity correction materials derived from the cellulose industry [Ash + Dregs (AD) and Ash + Dregs + Sludge (ADS)] were applied in three volcanic soils cultivated with wheat in southern Chile (Chillán, Temuco, and Osorno). Treatments were a control, CaCO3 at an adjusted rate to reach pH 6.0 and AD and ADS at the same rate as CaCO3 and twice the rate. Results indicated that the application of AD and ADS produced similar effects on pH(H2O), Ca2+, Mg2+, and Al3+ contents, cationic exchange capacity (CEC), and Al saturation compared with CaCO3 at the same rate; the effect was directly proportional to the rate used with each AD and ADS. Wheat production at each location was similar for AD, ADS, and CaCO3 at the same rate; however, it fluctuated between 10.1 and 10.4, 5.4 and 6.5, and 10.0 and 10.3 Mg ha-1 at Chillán, Temuco, and Osorno, respectively. Results indicate that these materials are an alternative to be used as a soil acidity correction amendment.
  • Forms of lime application and use of phosphogypsum in low acid soil in southern Brazil: soybean-wheat yield and soil chemical properties Division – Soil Use And Management

    Besen, Marcos Renan; Coneglian, Carolina Fedrigo; Cassim, Bruno Maia Abdo Rahmen; Kachinski, Wagner Deckij; Inoue, Tadeu Takeyoshi; Batista, Marcelo Augusto

    Resumo em Inglês:

    ABSTRACT Brazil is currently the leading country in no-till (NT) farming, particularly on Ferralsols (Latossolos), the most abundant soil type. These soils are characterized by subsurface acidity that cannot be effectively corrected by surface application of additives. In this situation, the use of phosphogypsum can be advantageous. This study aimed to assess the residual effects of lime and phosphogypsum application on a clayey Ferralsol, and four soybean and two wheat yields in southern Brazil. The area has been cultivated under no-till since 1975. The soil was limed to different base saturation (BS) levels (50, 60, 70, and 90 %) by surface application (SL) or lime incorporation (IL). Three combined treatments were also studied: (i) surface liming to 60 % BS plus standard (3.71 Mg ha-1) phosphogypsum dose (60G1), (ii) surface liming to 70 % BS + standard phosphogypsum dose (70G1); and (iii) surface liming to 70 % BS + double (7.42 Mg ha-1) phosphogypsum dose (70G2). Soil samples were collected 48 months after treatment. Soybean and wheat yield was not influenced by BS levels, however IL increased soybean yield in 2012/13, but reduced soybean and wheat yield in later crops. Phosphogypsum increased wheat yield by up to 12.8 % (2012 season) and 5.2 % (2015 season), but soybean was not influenced. Incorporated liming caused a decrease in soil Al3+ levels until 0.60 m depth, whereas SL decreased Al3+ levels until 0.30 m depth. Surface liming increased Mg2+ levels in the 0.40-0.60 m layer. Incorporated liming reduced soil organic matter in the surface layer. A double dose of phosphogypsum (7.42 Mg ha-1) had a greater residual effect in subsurface layers but caused a decrease in Mg2+ and K+ levels. Therefore, the standard phosphogypsum dose provided the best results. In the very clayey soil in subtropical environment, the effects of SL extend beyond surface layers and are preferable to those of IL, although production was not influenced by BS.
  • Geotechnical properties of some kaolinite-rich Brazilian Vertisols Division – Soil Use And Management

    Barbosa, Gustavo Magalhães Nunes; Marques, Eduardo Antonio Gomes; Ker, João Carlos; Assis, Igor Rodrigues de; Cunha, Tony Jarbas Ferreira; Souza, Luciano da Silva

    Resumo em Inglês:

    Abstract Vertisols presenting kaolinite codominance or prevalence were already reported in several countries worldwide. However, the literature has few studies focused on investigating the influence of this clay mineral in soil geotechnical behavior. This study aimed to carry out the characterization of Vertisols in Bahia State, Brazil, to understand the influence of physical, chemical, and mineralogical properties on their geotechnical behavior, as these soils have high natural fertility and have been used for agricultural activity, but with great risk due to their physical and geotechnical properties. Six Vertisols were selected, three located in Juazeiro County (Semiarid region) and the other three in Recôncavo region. Geotechnical characterization of selected soils was carried out in their respective diagnostic horizons by determining properties such as granulometric curve, Atterberg limits, clay activity, linear expansion coefficient, compaction capacity, cohesion (c), and internal friction angle (ϕ) of saturated soils. Soil expansion potential was associated with expansive clay contents and clay content in each soil sample. The best soil compaction efficiency was observed for kaolinitic Vertisol, which presented greater void ratio reduction and higher density due to moisture increase. In addition, c increased as kaolinite content also increased and decreased as clay content increased in soils presenting similar mineralogy. On the other hand, ϕ was influenced mainly by granulometry since higher sand and gravel levels enabled higher ϕ, regardless of clay type.
  • Concentration and removal of macronutrients by soybean seeds over 45 years in Brazil: a meta-analysis Division – Soil Use And Management

    Filippi, Dionata; Denardin, Luiz Gustavo de Oliveira; Ambrosini, Vítor Gabriel; Alves, Lucas Aquino; Flores, João Pedro Moro; Martins, Amanda Posselt; Pias, Osmar Henrique de Castro; Tiecher, Tales

    Resumo em Inglês:

    ABSTRACT A good soil fertility management for soybean production must consider the amount of nutrients that are exported by seeds. In recent decades, soybean yield has increased due to better crop management and genetic improvements, which may affect the amount of nutrients removed. Therefore, this study aimed (i) to analyze the relationship between the concentration of macronutrients in soybean seeds in Brazil with soybean yield and genotypes, and (ii) to update nutrient concentration values in soybean seeds for fertilizer recommendation purposes, comparing them with the values described in the main official fertilization recommendation systems used in Brazil. For this purpose, we used 3,017 observations obtained from 67 studies evaluating at least one macronutrient concentration [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S)] in soybean seeds in the last 45 years in Brazil (from 1974 to 2019). Results indicate that the concentration of macronutrients in soybean seed is affected by both soybean yield and genetic material. Modern genotypes of the Intacta Roundup Ready-2 group remove 15, 21, 18, 17, and 23 % more K, P, Ca, Mg, and S and 4 % less N compared to non-Roundup Ready genotypes. The increase in soybean yield was followed by an increase in the concentration of N and a decrease in the concentration of P and K in soybean seed. Data obtained from studies published between 2015 and 2019 indicates that soybean removes, on average, 57.2, 17.6, 5.5, 2.9, 2.6, and 2.5 kg Mg-1 of N, K, P, S, Ca, and Mg, respectively. These macronutrient concentrations in soybean seeds are in disparity with most reference values described in the official fertilization recommendation systems in Brazil, highlighting an urgent need to review the standard values for replacement fertilization of soybeans. Moreover, future studies should focus on the influence of genetics on soybean seeds composition to ensure high soybean productivity with rational use of fertilizers.
  • Forest harvest management systems and residual phytomass affecting physical properties of a sandy soil Division – Soil Use And Management

    Sena, Karla Nascimento; Maltoni, Kátia Luciene; Troleis, Maria Júlia Betiolo; Faria, Glaucia Amorim

    Resumo em Inglês:

    ABSTRACT Organic carbon introduced in soils, mainly through organic matter, has a relevant role in various soil properties and is particularly important in sandy soils. In these soils, the input of organic material is necessary to ensure the sustainability of production systems. This study aimed to investigate the changes in total organic carbon content and its effect on physical properties in areas under different harvest management systems (HMS) after the harvest of eucalyptus. The study was performed in December 2017 in a Eucalyptus urograndis (clone E13) commercial plantation, in the municipality of Água Clara, Mato Grosso do Sul State, Brazil. The soil of this area was classified as a sandy-textured Neossolo quartzarênico, which corresponds to Quartzipsamments. Soil samples were taken from the 0.00-0.05, 0.05-0.10 and 0.10-0.20 m layers for determinations of aggregate stability, soil bulk density (BD), macroporosity (Macro), microporosity (Micro), total porosity (TP) and total organic carbon (TOC); and for calculation of carbon stock (CS). Total organic carbon and CS continued down into the 0.20-0.40, 0.40-0.60, 0.60-0.80, and 0.80-1.00 m layers. Soil mechanical penetration resistance (PR) was determined to the 0.40 m depth in 0.10 m intervals. Carbon content was evaluated in the aggregates of the 0.00-0.05 m layer after wet sieving in 2000, 1000, 250 and 53 µm diameter sieves. Statistical evaluation consisted of analysis of variance, the Tukey test, and regression for the sources of variation that showed significance at 5 %. The data suggest that keeping the residual phytomass on the soil surface can positively impact total organic carbon, with a smaller reduction under the cut-to-length harvest management system. However, carbon stock is greater at the layer of 0.20-0.60 m; as the soil has a sandy texture, carbon moves through the soil profile, which has lower soil mechanical penetration resistance at the surface layers (0.00-0.10 m), once more under the cut-to-length system. Maintaining crop residual phytomass on the soil surface in the cut-to-length harvest management system provides better soil physical conditions, with greater macroporosity (0.00-0.05 m), aggregates with more carbon, and lower soil mechanical penetration resistance compared to systems that maintain only part of the harvest residual phytomass or no residual phytomass on the surface.
  • Soil physical properties and interrill erosion in agricultural production systems after 20 years of cultivation Division – Soil Use And Management

    Pavei, Dorly Scariot; Panachuki, Elói; Salton, Júlio Cesar; Sone, Jullian Souza; Alves Sobrinho, Teodorico; Valim, Wander Cardoso; Oliveira, Paulo Tarso Sanches de

    Resumo em Inglês:

    ABSTRACT Agricultural management significantly influences soil physical properties and soil erosion. However, there are few studies investigating the long-term effects of agricultural management on soil erosion and physical properties. Here, we assessed the impacts of 20-year agricultural land uses under different management practices on soil physical properties and interrill erosion. This study was conducted on an experimental farm of the Embrapa Western Agriculture, Brazil, and the treatments consisted of soybean cropping under conventional tillage (CT) and no-tillage (NT), crop-livestock integration during the cropping phase (CL-C) and the livestock phase (CL-L), and Brachiaria decumbens pasture under rotational grazing (PP). Soil samples were taken to evaluate the soil physical properties, and 25 rainfall simulations with an intensity of 60 mm h-1 were carried out by using a portable rainfall simulator with runoff plots of 0.7 m2 to quantify surface runoff and interrill erosion. After two decades, the crop-livestock systems (CL-L and CL-C) presented better soil physical properties in the topsoil layer (0.00–0.05 m) with a higher level of aggregation. Soil and water losses ranged from 4.7 to 14.4 × 10-3 kg m-2 and 4.9 to 12.4 mm, respectively. A higher reduction in soil erosion was observed in NT, while CT showed the highest soil erosion rates. These findings indicate an opportunity for a reduction of soil erosion by 60 % by adopting crop-livestock integration comparing CL-C with CT, while livestock under an integrated system (CL-L) decreased water loss by 30 % compared with PP. This study is a starting point for future research, and the findings reveal the potential to minimize the agriculture footprint.
  • Managing runoff in rainfed agriculture under no-till system: potential for improving crop production Division – Soil Use And Management

    Hörbe, Tiago; Minella, Jean Paolo Gomes; Schneider, Fabio Jose Andres; Londero, Ana Lúcia; Gubiani, Paulo Ivonir; Merten, Gustavo Henrique; Schlesner, Alexandre

    Resumo em Inglês:

    ABSTRACT Strategies to mitigate degradation and ensure food and water security are among the main challenges in agricultural development. Unconsolidated information about the positive impact of conservationist practices on productivity increase is fundamental for their adoption by farmers. This study evaluated if the saved rainfall excess in catchment with terrace generates higher soybean and corn yield due to greater water availability in the crop rooting zone. Experiments were conducted in southern Brazil during the agricultural years of 2016/17 (soybean) and 2017/18 (corn) in two paired zero-order catchments (~2.4 ha) with similar topography and soil properties. One catchment has no terraces, while the other has five broad-based terraces as a complementary practice to control runoff. Soybean and corn yield was compared between catchments through five paired transects, totaling 47 sampling points. The fraction of available water (FAW – the current in relation to the total available water) was monitored at two points in each catchment, one at the base and the other at the top, considering the elevation. The FAW was monitored with CS616 probes at eight soil layers (from 0.00 up to 1.60 m) at each point during the crop growth cycle. The FAW was higher in the terraced catchment than the non-terraced catchment during the soybean (14 %) and corn (8 %) cycles. The terraced area provided higher soybean (12 %) and corn (10 %) than the non-terraced area. These results highlight the importance of terraces to increase productivity by managing runoff on hillslopes, indicating the potential of terraces to mitigate water deficits.
  • Soil chemical properties and nutrition of conilon coffee fertilized with molybdenum and nitrogen Division – Soil Use And Management

    Rosado, Thiago Lopes; Freitas, Marta Simone Mendonça; Carvalho, Almy Junior Cordeiro de; Gontijo, Ivoney; Pires, André Assis; Vieira, Henrique Duarte; Barcellos, Ronildo

    Resumo em Inglês:

    ABSTRACT Molybdenum (Mo) availability is strongly affected by soil pH, which determines the dynamics of electrical charges and the adsorption of molybdate. This study evaluated the effects of nitrogen (N) and Mo application on the chemical properties of a Latossolo Amarelo (Oxisol) and in Coffea canephora nutrition and productivity throughout two productive cycles under field conditions. The experiment was conducted from June 2018 to May 2020. The experimental design used was in randomized blocks, in a 2 × 5 factorial scheme, the first factor being the absence and presence (4 kg ha-1 yr-1) of molybdic fertilization and the second factor was the N dose (300, 500, 700, 900, and 1,100 kg ha-1 yr-1). At the end of each production cycle, soil samples were collected to evaluate the pH(H2O), pH(KCl), exchangeable aluminum, potential acidity, organic matter, and Mo, at layers of 0.00-0.20 and 0.20-0.40 m. Leaves were sampled from the coffee tree to determine Mo and N contents and the coffee beans were harvested to evaluate the yield of processed coffee. The results showed that urea has a high potential for soil acidification, influencing the values of exchangeable aluminum, potential acidity, and ∆pH, at layers of 0.00-0.20 and 0.20-0.40 m. The decrease in pH caused by increasing doses of N increased the density of positive electrical charges of the soil and reduced Mo content in the leaves of C. canephora by 67 %. The application of sodium molybdate via soil was efficient in providing Mo to Conilon coffee and provided a 3.7 % increase in the yield of processed coffee. Nevertheless, molybdic fertilization did not influence the Mo content in the soil in the evaluations carried out at the end of each production cycle.
  • Soil loss estimated by means of the RUSLE model in a subtropical climate watershed Division – Soil Use And Management

    Zanchin, Mayara; Moura, Maíra Martim de; Nunes, Maria Cândida Moitinho; Beskow, Samuel; Miguel, Pablo; Lima, Cláudia Liane Rodrigues de; Bressiani, Danielle de Almeida

    Resumo em Inglês:

    ABSTRACT Erosion process occurs naturally, shaping the Earth’s surface. Soil loss can cause harmful effects to the environment when intensive anthropic activities occur. Mathematical models have been used as effective and less costly alternatives for identifying sites highly prone to soil loss, especially at the watershed scale. In Brazil, the Revised Universal Soil Loss Equation (RUSLE) is one of the most commonly used soil loss prediction models. The RUSLE requires information on soil erodibility, rainfall erosivity, topography, land use and cover (C), and conservation practices (P) to estimate average annual soil losses. Images derived from remote sensing techniques are generally used to quantify the spatialization of C factor; however, the variation in land use throughout the year is not usually considered. This study aimed to estimate soil losses in an important subwatershed of Candiota river watershed (CRWsub) by using RUSLE, considering land use and rainfall erosivity in different periods of the year. The periods considered were P1 (January, February and March), P2 (April, May and June), P3 (July, August and September) and P4 (October, November and December). Based on the results, the lowest soil losses occurred in P1. Probably, the high vegetation cover in the soil increases its protection against rainfall erosivity. In P3, the heavy rainfall events are predominantly frontal, occurring in the same months as those when the preparation of the soil for later planting takes place; that is, there is no vegetation cover in this period, thus making the soil more prone to erosion. The use of different images to classify and identify land uses is the best way to understand soil losses throughout the year in the study area. It was possible to observe that agricultural areas are generally associated with greater soil losses in the subwatershed. In addition, the land uses were considered to vary quarterly, thereby making it possible to identify the periods most prone to erosion processes throughout the year. Finally, the erosion percentages in the subwatershed can be linked to the tolerance index for different land-uses, soil classes, and slope categories.
  • Interconnections among rural practices and Food-Water-Energy Security Nexus in the Atlantic Forest biome Division – Soil Use And Management

    Duarte, Gabriela Teixeira; Assis, Julia Camara; Silva, Rafaela Aparecida da; Turetta, Ana Paula Dias

    Resumo em Inglês:

    ABSTRACT Global agricultural production is expected to double by 2050 due to both global population increase and changes in diets as a consequence of growing incomes. This also means more pressure on water resources, as agriculture accounts for 70 % of global water withdrawal and for energy production as the entire food supply chain accounts for about 30 % of total global energy consumption. Although there are ongoing discussions related to the sustainability of food, water, and energy sectors, integrating these sectors is still rare and challenging. We investigated the effects of agricultural practices on the Food, Water and Energy (F-W-E) nexus security systems by evaluating the results reported in scientific literature. Focusing on the Brazilian Atlantic Forest biome as a study case, our main goals were 1) to elucidate the impacts of rural conservation practices on food, water, and energy production based on literature analysis, 2) to propose F-W-E attributes and evaluate how they are addressed by rural practices. Our findings demonstrated, in general, a positive impact of agricultural conservation practices on F-W-E security attributes. Indeed, 76 % of the combination between a conservational practice with a F-W-E attribute was positive. Some agricultural practices, such as no tillage are very well documented (45 % of all combinations), especially regarding their effects on soil quality parameters. We found few results connecting agricultural practice and energy aspects. These results are key elements that corroborate with the agriculture multifunctionality approach, and the results can better guide the planning of strategies in the agricultural sector and subsidize decision making.
  • Topsoil depth influences the recovery of rupestrian grasslands degraded by mining Division – Soil Use And Management

    Rezende, Lina Andrade Lobo; Fernandes, Geraldo Wilson; Braga, Ramon de Paula; Dias, Luiz Eduardo; Gomes, Vanessa Matos

    Resumo em Inglês:

    ABSTRACT Close association of iron mining and ferruginous rupestrian grassland places this ecosystem in a special condition of vulnerability, with a large number of degraded areas requiring restoration. Seedling transplantation and topsoil translocation can be used to recover native vegetation in degraded areas. This study aimed to experimentally test the application of two different topsoil depths (0.20 and 0.40 m) in a degraded area. We assessed the vegetation’s natural recovery and the survival of transplanted native species from rescue operations in four 200 m2 plots established in each topsoil depth. There was no influence of topsoil depth on the plant species survival, while the vegetation cover was greater on the thicker topsoil. However, exotic species with invasive potential contributed substantially to this vegetation cover, requiring management planning. Some planted native species stood out for their survival ability in the topsoil 49 months after planting. Application of 0.20 m topsoil layer showed to be able to provide native species’ natural recovery and survivorship.
  • Systemic Soil Fertility as product of system self-organization resulting from management Division – Soil Use And Management

    Anghinoni, Ibanor; Vezzani, Fabiane Machado

    Resumo em Inglês:

    ABSTRACT: Soil Fertility is one of the most relevant fields of Soil Science related to agricultural production, especially in tropical and subtropical environments, due to the prevalence of weathered and naturally unproductive soils. However, indicators of Soil Fertility currently used do not represent what actual happens in the soil; once must be understood as a process. The wisdom of this importance occurred in Antiquity and evolved until the mid-19th century, when the mineralist concept was proposed, which is still dominant in Brazil and worldwide. In this process, Soil Fertility has been associated with current perceptions, soil chemical properties and management systems in the development of agriculture over time. During the evolution of Brazilian agriculture, from the 1960’s onwards and most notable with the consolidation of conservation management in the 1990’s, Intrinsic limitations were increasingly evident on the ability of indicators to assess the actual level of Soil Fertility and the respective response of the plants. Concurrently, the view of the soil as an open system was strengthened, and the conception of fertility began to constitute a property that emerges from the functioning of the soil, whose processes are self-organizing, due to the continuous flows of energy and matter driven by organic compounds. In this context, we present a part of the history of Brazilian agriculture, relating it to its management and Intrinsic limitations of indicators to assess Soil Fertility due to changes in soil functioning. The Intrinsic limitations added to understanding based on a systemic approach of the functional processes of the soil are the practical and theoretical bases for the proposition of another concept: Systemic Soil Fertility .
  • N2O emissions from soils under different uses in the Brazilian Cerrado - A review Division – Soil Use And Management

    Sousa, Thais Rodrigues de; Ramos, Maria Lucrecia Gerosa; Figueiredo, Cícero Célio de; Carvalho, Arminda Moreira de

    Resumo em Inglês:

    ABSTRACT: The Cerrado (Brazilian savannah) is a biome of great socio-economic and environmental importance to Brazil. The rapid agricultural expansion in the Cerrado biome areas promoted biogeochemical cycles that affect nitrogen and carbon dynamics, leading to increased greenhouse gas (GHG) emissions. In Brazil, nitrous oxide (N2O) is the main gas in agriculture, and agricultural practices increase emissions into the atmosphere. This review aimed to assess the influence of agriculture on N2O emissions in the Cerrado region, based on existing data in the literature, and extract patterns of direct N2O emissions in different agricultural systems in the Cerrado from existing data. A systematic review of data from 36 scientific publications in the Cerrado region with several crop systems revealed that N2O emissions varied from 0.15 kg ha-1 in native cerrado to 4.84 kg ha-1 in conventional tillage. Agricultural systems, nitrogen fertilizer application, and crop residues influence N2O emissions. One of the strategies to mitigate emissions is the sustainable intensification of farming systems. Cumulative N2O emissions in the Cerrado range from 0.001 to 4.84 kg ha-1 in different land-use scenarios. Soil under the conventional tillage system (CT) had the highest emissions, with an overall average of 1.58 kg ha-1 of N2O, compared to no-till system (NT) (0.82 kg ha-1) and native Cerrado 0.15 kg ha-1. Integrated crop-livestock (ICL) systems in the Cerrado had emissions with an overall average of 1.68 kg ha-1, integrated crop-livestock-forest systems (ICLF) had 1.20 ha-1, and eucalyptus plantations had 0.48 kg ha-1.
  • No-tillage for flooded rice in Brazilian subtropical paddy fields: history, challenges, advances and perspectives Division – Soil Use And Management

    Sousa, Rogério Oliveira de; Carlos, Filipe Selau; Silva, Leandro Souza da; Scivittaro, Walkyria Bueno; Ribeiro, Pablo Lacerda; Lima, Cláudia Liane Rodrigues de

    Resumo em Inglês:

    ABSTRACT: No-tillage (NT) has been one of the main advances related to soil management in Brazilian agriculture in the last 30 years. However, its full adoption in lowland areas that are traditionally cultivated with flooded rice is still incipient (<5 %). The main reasons are associated with the soil hydromorphic condition and the management of highly recalcitrant residual crop biomass, demanding soil disturbance even occasionally. This review presents a historical survey about the soil management systems utilized in lowland areas in southern Brazil, emphasizing the experiences of NT adoption in areas with flooded rice. Results from studies focused on the main changes in chemical, physical, and microbiological soil properties due to NT adoption were addressed, as well as the NT effects on greenhouse gas emissions and crop yields. Finally, the main challenges and prospects for NT were discussed considering new emerging scenarios for flooded rice production in lowlands, especially soybean rotation and integrated agricultural production systems. No-tillage can increase the soil organic carbon, the cation exchangeable capacity and tends to promote the accumulation of nutrients as nitrogen in surface layers. Improvements in soil aggregation, porosity and water availability are usually observed in NT, but only if medium or long-term trials are considered. NT favors microbial activity in the shallower soil layer by promoting microbial biomass carbon (+45 %), microbial biomass nitrogen (+54 %) and basal respiration (+54 %) compared to conventional tillage (CT), while the activity of extracellular enzymes also may be stimulated. Crop yield tends to be similar among the soil managements systems over time. Seasonal CH4 emissions might be reduced by 21 % with NT adoption without increasing N2O. Plant breeding and geotechnology advances associated with soybean market valuation intensified the introduction of this crop in paddy fields. The main challenge for the full adoption of NT is the need for soil tillage after rice harvesting to correct soil surface irregularities or manage rice straw. In the future, advances in plant breeding and drainage techniques probably will favor the expansion of NT in southern Brazil lowlands. The traditional system of flooded rice cultivation, based on CT and monoculture associated with beef cattle under extensive grazing, is no longer viable and will not be further established.
  • Biogenic and physicogenic aggregates: formation pathways, assessment techniques, and influence on soil properties Division – Soil Use And Management

    Pereira, Marcos Gervasio; Loss, Arcangelo; Batista, Itaynara; Melo, Thadeu Rodrigues de; Silva Neto, Eduardo Carvalho da; Pinto, Luiz Alberto da Silva Rodrigues

    Resumo em Inglês:

    ABSTRACT: The soil particles can be gathered through physical and/or chemical processes in association with the biological activity, leading to the formation of aggregates. Soil aggregates has several functions in the soil, increasing macroporosity and water circulation - consequently reducing soil erosion and mechanical resistance to root growth, contributing to greater fixation of plants to the soil and absorption of water and nutrients, and protection of intra-aggregate organic matter. The aggregates were initially classified morphologically and in terms of their stability. In recent years, another way of evaluating aggregates, regarding their formation or origin pathway, has gained prominence in the studies conducted in Brazil. As for their origin, the aggregates can be classified morphologically as physicogenic, biogenic, or intermediate. This manuscript presents the techniques used to sample aggregates, the morphological patterns for their distinction observed in different soil classes and management types, and the chemical and physical properties. Additionally, we present analyses that are not commonly used to evaluate aggregates but which have the potential to be used as tools for a better understanding of their origin and to evaluate their modifications when subject to different types of management. In practical terms, identifying the aggregate origin and determining the related attributes allows recognizing the effect of vegetation/soil/management on soil aggregate forming agents, mainly roots and soil fauna, which reflects soil quality. For future studies, and especially to determine the importance of biogenic aggregation in improving edaphic properties, we suggest the use of micromorphology, near-infrared spectroscopy, X-ray computed tomography, clay dispersion analyses in addition with chemical, physical, and biological analysis. This approach can contribute to the identification of other patterns related to pedogenesis and the pathways of aggregate formation.
  • Growth and phosphorus uptake by cassava in P-deficient soil in response to mycorrhizal inoculation Division – Soil Use And Management

    Cavallari, Lucas Guilherme; Fernandes, Adalton Mazetti; Mota, Lydia Helena da Silva de Oliveira; Leite, Hugo Mota Ferreira; Piroli, Valkíria Luísa Borsa

    Resumo em Inglês:

    ABSTRACT Phosphorus (P) is one of the most difficult nutrients for plants to acquire because of its low content in the soil solution. Cassava (Manihot esculenta Crantz) has a thick and sparse absorbent root system; therefore, it is dependent on its association with arbuscular mycorrhizal fungi (AMF) for P acquisition from the soil. Thus, inoculation of cassava with AMF can improve the development of this root crop. This study evaluated the effects of soil disinfection (disinfected vs. natural) and the spore rates of Rhizophagus clarus inoculation (0, 50, 100 and 200 spores per plant) in greenhouse conditions on the initial growth, yield, P acquisition, and P use efficiency of cassava, as well as to evaluate the contribution of the native AMF to P acquisition from the soil. For cassava production in P-deficient soil, inoculation with Rhizophagus clarus significantly increased cassava growth, P uptake, and storage root yield only when the soil was disinfected. When the soil is not disinfected, native AMF contributes up to 86 % of the P taken up by cassava. However, high spore rates of Rhizophagus clarus in natural soil cause detrimental consequences for native AMF by reducing the colonization of the absorbent roots. Therefore, for cassava grown in natural soil under greenhouse conditions, a rate of 50 spores per plant of Rhizophagus clarus is sufficient to promote a 14.5 % increase in the yield of fresh storage roots. A management strategy that favors the native AMF multiplication in the soil is a potential strategy to improve P uptake and yield of cassava in P-deficient soils.
  • A teachers’ formative process in soil education takes place while integrated to their life stories Division – Soil, Environment And Society

    Bastos, Selma Barbosa; Vezzani, Fabiane Machado; Silva, Valentim da; Lima, Marcelo Ricardo de

    Resumo em Inglês:

    ABSTRACT The teacher’s formative process is developed by a critical reflective response to the paths of life, the profession, and its practices. The teacher’s formative process analysis should consider the process’s objectives (theoretical, practical, and emancipatory), and the dimensions that make up the teacher (person, practices, and profession). As a result, this study aims to introduce the elements that outline the categories stemming from the relationship matrix between the objectives and the dimensions, and use them to analyze a formative process in Soil Education assessed using Formative (Auto)biographical Narratives. The research subjects were 61 teachers active in the Public Education System in the cities of Campo Largo and Curitiba, state of Paraná, Brazil, who took part in the formative process known as Soil Program for Teachers within the Soil at School Project from the Federal University of Paraná, held in 2018. Data collection was performed through written narratives given in response to three groups of open-ended questions, which aimed to encourage teachers to think deep. We performed the Content Analysis in the narratives while differentiating expressions associated with the elements in each category, and, consequently, the frequency of the expressions was recorded. As for the Theoretical Objectives within the analysis of the Program, in which the teacher is the study object, we found that the teachers built and rebuilt knowledge and expertise about the soil while drawing on the relationship between the formative conceptual approaches and the recollection of their professional and personal experiences through the Narratives. Within the Practical Objectives, in which self-formation is analyzed, the Narrative influenced a critical and reflective perspective about the person, the practice, and the profession, while driving teachers to their self-formation and creating their professional identity. As for the analysis of the Emancipatory Objectives, which demonstrate the change of reality, the teacher’s transformation was seen in their change of attitude and practices, as well as in their intent to get involved with the school. We concluded that the elements proposed to outline the nine categories were effective to analyze the formative process in Soil Education, by taking into account, in an integral way, the Objectives of the analysis and the Dimensions that make up the teacher while in his/her formative process. We would also like to point out that the Narratives were an important instrument for continuous education in Soil Education.
  • Climate change adaptation and the agricultural sector in South American countries: Risk, vulnerabilities and opportunities Division – Soil, Environment And Society

    Taboada, Miguel Ángel; Costantini, Alejandro Oscar; Busto, Mercedes; Bonatti, Michelle; Sieber, Stefan

    Resumo em Inglês:

    ABSTRACT South America covers a vast area with diverse climates and landscapes, with high participation in the global production of food and fibers. It is crucial to understand the risks, vulnerabilities, and opportunities that climate change brings to this region. We analyzed the increasing tension between agribusiness models and smallholder models, the risks, opportunities, and main adaptation measures that can be adopted in the agricultural sector of the South American countries facing climate change. This study is a review of adaptation actions in the agricultural sector for the different regions of South America. Vulnerability exists, firstly, because rural populations are exposed in many of the countries, often with high rates of poverty and low rates of socioeconomic development. Concerning the adaptation measures already taken, there are numerous cases of interventions by national, provincial, and municipal states for planned measures. Farmers are very active in adopting autonomous measures. Many adaptation measures show co-benefits with climate change mitigation or the prevention of land degradation and desertification, but other adaptation measures do not go in this direction. In the forthcoming times, the region’s rich natural resources are going to be subjected to strong market pressures and climate change threats. It is key to generate strategies for the care of these resources for their permanence for future generations.
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