Scielo RSS <![CDATA[Engenharia Agrícola]]> vol. 37 num. 3 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[THERMAL EFFICIENCY OF DIFFERENT COVERAGE MATERIALS IN REDUCED MODELS OF ANIMAL HUSBANDRY FACILITIES: A CASE STUDY]]> ABSTRACT This study aimed to assess different combinations of coverage materials in reduced models of animal husbandry facilities based on thermal comfort indices. It was conducted in an experimental area of the Research Center in Ambience located in São Paulo State, Brazil (22°42′30″ S and 47°38′00″ W). The performance of ceramic and fiber-cement (white painted) tiles was assessed associated with two types of polypropylene commercial linings (lining A and B) installed below the roof, and a thermo-reflective screen (lining C) installed above the fiber-cement roof. Microclimatic assessment of distorted reduced-scale models was performed at 15-minute intervals by registering the air temperature, black globe temperature, relative humidity and air velocity. Subsequently, black globe humidity index, specific enthalpy, and radiant heat load were calculated. The experimental design was randomized block design with 5 treatments and 15 blocks (replications), totaling 75 experimental units. The reduced-scale models with lining B presented a reduction for all thermal comfort indices. Lining C, installed on the coverage, showed no upgrading of environmental thermal conditions. Thus, lining B presented a better thermal performance regardless the tile type. <![CDATA[SIMULATION OF VENTILATION SYSTEMS IN A PROTECTED ENVIRONMENT USING COMPUTATIONAL FLUID DYNAMICS]]> ABSTRACT Computational simulations of mass and energy flow help in implementing alternative cooling systems in protected environments. The aim of this study was to model and simulate the interaction between external and internal environments of a protected environment by means of computational fluid dynamics (CFD) techniques and validate micrometeorological variables for subsequent comparison between natural and indirect ventilation by ground heat exchangers. At the first phase, the micrometeorological variables global solar radiation (Qg), air temperature (Tair), and air relative humidity (RH) were monitored. The second phase consisted of the numerical modeling of finite volumes, with validation through recorded data, as well as simulation and comparison of two ventilation systems. The functional relationship between simulated and recorded meteorological elements presented a good linear association, with coefficients of determination of 0.97, 0.93, and 0.94 for Qg, Tair, and RH, respectively. Simulation of indirect ventilation system by ground heat exchangers presented a reduction of 4 °C in Tair and 15% in RH compared to that recorded inside the environment. The natural ventilation system allowed a reduction of 1 °C in Tair when compared to the protected environment. <![CDATA[BIOGAS PRODUCTION IN DAIRY CATTLE SYSTEMS, USING BATCH DIGESTERS WITH AND WITHOUT SOLIDS SEPARATION IN THE SUBSTRATES]]> ABSTRACT This research aimed to evaluate the biogas production during the anaerobic biodigestion process of dairy cattle manure, with and without solids separation. Sixteen biodigesters of the batch type were used, each one with 2L of capacity, supplied with manure in four different conditions: (1) pure manure, after washing the floors of the free stall system; (2) manure after the solids separator; (3) manure after the solids separator and sand decanter and (4) manure with the solid retained in separator solids, dissolved in water. The hydraulic retention time was of 196 days. The highest reductions of volatile solids (VS) were obtained for the biodigesters supplied with manure that went through some process of solids separation. The highest potential of methane production(CH4) obtained was of 0.2686 m³ CH4 kg −1 of added VS, supplied to digesters with manure after solids separator. The best potential for biogas and methane production was observed when there was a reduction of the solids concentration in the manure and, in this case, the hydraulic retention time can be reduced, which reduces the volume of the biodigester and the cost of implementation and maintenance, but the highest biogas production occurred in the biodigesters without solids separation. <![CDATA[RESIDUAL BIOMASSES IN THE MICRO-REGION OF DOURADOS (MS): ASSESSMENT AND AVAILABILITY FOR ENERGY IN AGRICULTURE THERMAL CONVERSION]]> ABSTRACT This research presents results of the assessment of solid biofuels (residual biomasses from agricultural crops) in the state of Mato Grosso do Sul, in the period 2007-2012, for energy in agricultural uses. It is pointed out the available quantity, its geographic location at micro and meso regions and energy conversion potential. The methodology is based on a survey on municipal agricultural production of the Brazilian Institute for Geography and Statistics (quantity and local availability, per year) followed by determination of the amounts of agricultural assessed residues, and then applying equations from the literature to estimate the amount of energy (J) and power (kW) obtained from the thermal conversion of residual biomasses. Results are presented for three residual biomasses from agricultural crops (corn cobs, rice husk and sugarcane bagasse) with cartograms for all micro regions at the state of Mato Grosso do Sul, graphics for quantification in the cities where crops production occurs and a table for total energy obtained by conversion processes. For the whole state of MS, Dourados micro region was identified as the most promising for energy in agriculture with three main cities (Dourados, Rio Brilhante and Maracaju), by solid biofuel availability to provide about 11% of the total electrical energy consumption in 2014. <![CDATA[DIFFERENT SOYBEAN PLANT POPULATIONS UNDER CENTRAL PIVOT IRRIGATION]]> ABSTRACT Planting density can influence the competitiveness among plants mainly by water, nutrients and solar radiation, directly affecting yield. The purpose of this study was to evaluate the productivity of different soybean cultivars at different planting populations under irrigated and rainfed conditions. The experiment was conducted during the 2014/15 growing season, under center pivot irrigation in Chapadão do Sul – MS, Brazil. The experimental design was randomized complete block design with split-plot, as follows: Irrigated and Rainfed (plots) x Six cultivars (subplots) x Three Plant Populations (sub-subplots) with 4 replications. The irrigation management was realized by Penman-Monteith-FAO method. The cultivars used were: NA 5909 RR, DM 5958 IPRO, Anta 82 RR, M 7110 IPRO, Desafio RR and M 7739 IPRO. Populations indicated by the holders of the seeds were tested, and also population 20% above and 20% below with the hypothesis that in different humidity conditions, different cultivars may have different answers depending on their populations. In rainfed condition productivity and mass of one hundred grains were influenced by water deficit. Cultivar Desafio RR presented the best performance under irrigation, with productivity of 6174 kg ha−1. <![CDATA[A STUDY OF THE IMPACT OF LAND USE AND OCCUPATION ON BASIN WATER QUALITY THROUGH MULTIVARIATE STATISTICS]]> ABSTRACT Without effective actions to improve environmental management, water resources tend to become scarce. Thus, this study aimed to understand the processes influencing the physical, chemical, and biological properties of the water due to land uses and occupation in the Ipê stream basin, in Ilha Solteira - SP (Brazil), regarding the dependence of the analyzed variables. Monitoring of chemical, physical, and biological water quality was performed from 2006 to 2011, and the records of land use and occupation in 2011. A factorial multivariate analysis allowed us to understand that the processes in densely populated areas increased degradation of water by the input of organic loads, yet those of farming areas enhanced the degradation of the chemical and physical quality of spring waters. Therefore, installing irrigation systems near populated areas, for crops consumed in natura, may compromise this agricultural activity, as well as the absence of water filtration systems downstream agricultural areas. Furthermore, we concluded that multivariate statistics is a powerful tool to detect these influencing processes in water quality. In this study, this type of analysis played an important role isolating the processes acting on water quality. <![CDATA[CHARACTERIZATION OF CLOGGING MATERIAL FROM HORIZONTAL SUBSURFACE FLOW CONSTRUCTED WETLAND SYSTEMS]]> ABSTRACT This study aimed to characterize the material composition responsible for clogging the porous medium of horizontal subsurface flow constructed wetland (HSSF–CW) systems, which is detrimental to a proper system operation. Six completely clogged HSSF–CWs were used after treatment of swine wastewater. Operating conditions of these systems were named CW–C (HSSF– CW 1 and HSSF–CW 4, non-cultivated, i.e. controls), CW–T (HSSF–CW 2 and HSSF–CW 5, cultivated with Tifton 85 (Cynodon spp.)), and CW–A (HSSF–CW 3 and HSSF–CW 6, cultivated with alligator weed (Alternanthera philoxeroides)). The results showed that most of the clogging material was composed of total fixed solids (95, 84, and 82% in CW–C, CW–T, and CW–A, respectively). However, total volatile solids (TVS) mostly affected pore clogging. The larger accumulations and productions of TVS in CWs might have originated from dead plants. <![CDATA[SIMANIHOT: A PROCESS-BASED MODEL FOR SIMULATING GROWTH, DEVELOPMENT AND PRODUCTIVITY OF CASSAVA]]> ABSTRACT The objective of this study was to propose a model, named Simanihot, for simulating growth, development and yield of tuberous roots in cassava, with a choice of two soil water balance models. The model works on a day time step and is calibrated for five cassava cultivars (Fepagro –RS 14, Estrangeira, Cascuda, São José e Paraguaia), with different branching habits and different purpose of use (pasture, food and industry). The model has a graphical interface, where the user can choose one out of two soil water balance models, depending upon the number of known soil variables and details the user wants to know about soil water content. <![CDATA[DYNAMIC TRACTION OF A MECHANIZED SET BASED ON TECHNICAL AND OPERATIONAL PARAMETERS]]> ABSTRACT The objective of this study was to evaluate and model the traction performance parameters of a tractor 4x2 FWD, according to the tractor speed, the internal pressure and the type of tires construction. For each type of tire construction was assembled an experiment in which we evaluated the influence of internal pressures of the front and rear tires and the speed of the mechanical assembly. It was found that the sliding of the diagonal run, presented significant effect in all variables analyzed, since the radial showed no influence of the factors evaluated. The power available in the drawbar was higher when the tractor was equipped for radial tires. The response variables, fuel consumption schedule and specific fuel consumption were more sensitive to the speed of the internal tire pressure. The fuel consumption per area worked, did not affect the analyzed variables. As for the effort prediction models in the tractor drawbar, it was only possible for diagonal run, which are influenced by speed and internal pressure levels of the front and rear tires. <![CDATA[SPRAY DRIFT AND PEST CONTROL FROM AERIAL APPLICATIONS ON SOYBEANS]]> ABSTRACT Pesticide drift is an issue in modern farming, mainly for crops under constant spraying as soybeans. This study aimed at assessing drift and pest control for aerial applications in soybean crops. Hydraulic nozzles and rotary atomizers, regulated to a wide spectrum of droplet sizes, sprayed thiamethoxam plus lambda-cyhalothrin using an agricultural aircraft Ipanema 202A at volume rate of 20 L ha−1. Treatments consisted of testing two devices: a rotary cage atomizer (Micronair AU 5000) with blade angles of 65° for larger droplets, and with angle of 55° for smaller ones; and a set of adjustable nozzles (Stol model) with deflector angle of 90° for smaller droplets, and with angle of 30° for larger ones. Drift was evaluated through quantification of active ingredient, by means of liquid chromatography, on nylon strings set 20, 40, 80, 160 and 320 m downwind from the applied area. Control efficiency was measured by counting caterpillars and stinkbugs found five days after spray. Rotary atomizers produced lesser drift compared to adjustable nozzles at the designed setting. Furthermore, drift can be reduced through a suitable regulation of the devices, keeping an effective pest control. <![CDATA[SPECTRUM, VELOCITY AND DRIFT OF DROPLETS SPRAYED BY NOZZLES WITH AND WITHOUT AIR INDUCTION AND MINERAL OIL]]> ABSTRACT The aim of this study was to evaluate the spectrum, the velocity and the potential drift risk of droplets sprayed by nozzles with and without air induction, with the addition of mineral oil to the spray solution. The experiment was conducted in a completely randomized design with five replications; in a factorial model 2 × 2 (two spray nozzles and spray solution with and without mineral oil Assist®). Spray nozzles with and without air induction were evaluated, with nominal flow rate of 1.14 L min−1 and pressure of 300 kPa. The spectrum and the velocity of droplets were evaluated directly, using a droplet analyzer (VisiSize D30) in real time based on the analysis of high-resolution images. The drift potential was evaluated in an open circuit wind tunnel. The data were submitted to analysis of variance and comparison test. In general, the addition of mineral oil (1.5% V V−1) resulted in an increase in the velocity of droplets, reduced drift and more homogeneous droplet spectrum. Air induction nozzles promoted larger and less homogeneous droplets, but they little affected the velocity of the droplets. There is an inverse correlation between drift potential and volume median diameter (VMD), which indicates that VMD can be used to predict the behavior of drift risk. <![CDATA[SHIFTS AND HARVESTING SYSTEMS ON QUALITY OF IMPURITIES SAMPLES IN SUGARCANE]]> ABSTRACT Semi-mechanical and mechanical harvesting methods may influence the content of impurities in harvested sugarcane. This study aimed to evaluate the quality of three mechanical methods of sugarcane harvesting: one semi-mechanical, and two mechanical ones - self-performed and outsourced, during three working shifts. As quality indicators, both mineral and vegetal impurities were accounted. About 50 random samples were collected in the studied area during 35 harvest days and in three working shifts, for each harvesting method. Mineral impurities showed similar behavior for both self-performed and outsourced mechanical harvesting, thus displaying a low variability. On the other hand, vegetal impurities showed to be unstable for all three shifts. Additionally, the statistical process control analysis showed that the semi-mechanical method had the greatest variability. <![CDATA[REACTION KINETICS OF OZONE GAS IN WHEAT FLOUR]]> ABSTRACT The implementation of the ozonation process in the milling industry to control insect pests and improve wheat flour qualities requires understanding the behavior of ozone during ozonation. Therefore, this study aimed to investigate the reaction kinetics of ozone gas in wheat flour. Wheat flour ozonation at concentrations of 0.54, 1.07, 1.61 and 2.14 mg L−1 was used in a prototype consisting of a cylinder and a mixing system with a helical thread. The iodometric titration method was used to quantify the ozone concentration in the air stream. The reaction kinetics were characterized by determining the saturation time and the decomposition kinetics (decay rate and half-life time). With increasing ozone concentration, less time was required to saturate the wheat flour. The saturation times were 812, 434, 370 and 342 min for ozone concentrations of 0.54, 1.07, 1.61 and 2.14 mg L−1, respectively. Increasing the ozone concentration did not influence the constant decay rate and half-life time. The ozone decomposition kinetics could be represented by a first-order model, with a decay rate constant of 0.23±0.008 min−1 and a half-life time of 3.02±0.081 min. <![CDATA[CHEMICAL CHANGES IN BEAN GRAINS DURING STORAGE IN CONTROLLED CONDITIONS]]> ABSTRACT Bean (Phaseolus vulgaris L.) is a traditional food in the diet of Brazilians, due to its low fat content and it is rich in vitamins, protein, fiber, carbohydrates and minerals. One of the major problems related to this product is storage without temperature and humidity control, causing quality reduction of this legume. This study aimed to evaluate the effects suffered by cooking time parameters, seed coat color, phytate and minerals (P, Ca, Mg and Mn) content during storage. The grain varieties: BRS Madrepérola, BRS Estilo, BRS Pontal and CNFC 10467, from the pinto group, were stored in hermetic acrylic containers with humidity and temperature controlled for a period of 108 days. All varieties had better results of the parameters studied when they were stored under the condition of 15°C and 45% of RH. The grain stored in the condition of 27°C and 75% of humidity for 108 days showed Hard-to-cook characteristic effect. All minerals studied showed a strong correlation with the cooking time. CNFC 10467 and Madrepérola varieties are more similar, as the parameters examined. <![CDATA[SPATIAL CORRELATION OF SOYBEAN PRODUCTIVITY, ENHANCED VEGETATION INDEX (EVI) AND AGROMETEOROLOGICAL VARIABLES]]> ABSTRACT The survey information from growing regions, the interaction with the vegetation index and climatic variables is of great importance in the search for soybean productivity increase. Paraná is the second largest soybean producer in Brazil and presents great spatial variability, both in periods of the crop cycle as in soil and climate. The objective of this study was to analyze the spatial correlation of soybean productivity, the enhanced vegetation index (EVI) and agrometeorological variables (water balance, global radiation and average temperature) in the state of Paraná, on a decendial scale, using the Moran global autocorrelation index between the 2010/2011 and 2012/2013 crop years. Similarity was found in the average productivities in 2010/2011 and 2012/2013. In 2011/2012 the state average was 2.38 t ha−1 lower in 10.19% compared to the national average, caused by the water deficit in flowering and grain filling phases. As a consequence, spatial autocorrelation indicated a higher similarity in productivity among municipalities with a Moran index of 0.735. The use of vegetation indices and agrometeorological variables allowed the identification of different sowing periods between regions and great climatic variability, influencing the soybean productivity. <![CDATA[SOIL MESO- AND MACROFAUNA IN TWO SOYBEAN CROPS AFTER SWINE WASTEWATER APPLICATION]]> ABSTRACT Hog raising generates a large amount of residues that is commonly discarded into the soil as fertilizer even with environmental risks. In this context, the aim of this study was to assess the application effects of different doses of swine wastewater (SW) associated with mineral fertilization on the abundance and diversity of organisms of soil meso- and macrofauna in two soybean crops. Treatments consisted of four doses (0, 100, 200, and 300 m3 ha−1) of SW with or without mineral fertilization in two soybean crop, totaling 24 experimental units. Soil meso- and macrofauna were sampled using pitfall traps installed at each plot. Samples were sorted and the organisms were separated and identified. The highest abundances were found between groups of springtails and spider mites. Soil meso- and macrofauna differed between soybean crops influenced by soil physical and chemical parameters. Doses of swine wastewater between 0 and 300 m3 ha−1 and mineral fertilization do not have effects on ecological indices of soil meso- and macrofauna. However, periodic applications over time change soil physicochemical variables, which may lead to negative effects in the long term. <![CDATA[GEOCHEMICAL BACKGROUND IN AN OXISOL]]> ABSTRACT Geochemical background establishment is indispensable to determine the actual state of contamination of soils and sediments. However, no scientific consensus exists regarding the methodology for determining these values. In this context, this study aimed to establish the geochemical background in an Oxisol (Rhodic Hapludox) by means of an integrated method that uses direct and indirect soil analyses to identify the most appropriate calculation methodology. Soil samples were collected in a permanent preservation area of the Cascavel River watershed, PR, Brazil. The elements Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn present in soil samples were quantified by flame atomic absorption spectrometry. The use of a permanent preservation area is the most effective method to establish the geochemical background in the Cascavel River watershed. However, soil chemical element concentrations have spatial variability and dependence, requiring the application of non-parametric statistical methods based on third quartile and median for establishing the geochemical background. <![CDATA[OPTIMIZATION OF ANAEROBIC TREATMENT OF CASSAVA PROCESSING WASTEWATER]]> ABSTRACT The main contribution of this research is to optimize the operating conditions of an anaerobic reactor applied to the treatment of wastewater from cassava starch production. A 20-L anaerobic reactor was used, operating in a batch system, with temperature control. Temperature and inoculum total volatile solids (TVSi) were controlled for evaluation of effects on the removals of chemical oxygen demand (COD) and reactor total volatile solids (TVSr) by means of a Central Composite Rotational Design (CCRD). Twelve trials were analyzed simultaneously by the desirable function approach. The higher COD removal (96.82%) was obtained at 42 °C and 12.0% TVSi. The largest TVSr removal (69.31%) was registered at 45 °C and 10.0% TVSi. Equations representative of the process were obtained from the responses of variables, being statistically significant at a 90% confidence level. Based on the desirability function approach, we can conclude that an optimal operational condition for the anaerobic reactor is at 39.7 °C and 10.8% TVSi. The estimated COD and TVSr removal efficiencies under these operating conditions were 90.45% and 63.12%, respectively. <![CDATA[CLIMATE CHANGE IMPACTS ON WATER DEMAND OF MELON PLANTS IN JAGUARIBE-APODI REGION, BRAZIL]]> ABSTRACT The aim of this study was to evaluate the impacts of climate change on irrigation water demand of melon plants grown in Jaguaribe-Apodi Irrigation District (DIJA), which is located between the states of Ceará and Rio Grande do Norte, in Northeastern Brazil. Future scenarios were developed using the Eta-CPTEC/HadCM3 climate change projections, after being submitted to downscaling method. We used a set of climate data from the same model for the period of 1961 through 1990, and further projections after bias correction. Local geographic coordinates were interpolated using GIS techniques. Reference evapotranspiration (ETo) was estimated from the monthly minimum and maximum mean temperatures, using a limited data method. The rainfall, temperature, ETo, and water demand future projections were mapped for the area of investigation to analyze spatial variability. ETA model simulations for climatic change showed growth in irrigation water demands due to evapotranspiration increase (from 28.4% to 33.4%), even though rainfall increases (between 61.9% and 89.9%). The increase in the average gross water demand is varied from 37.5% to 78.2% within the period of 2031 to 2060, respective to the common planting season. <![CDATA[EXCEL ADD-IN TO MODEL THE SOIL COMPRESSION CURVE]]> ABSTRACT Soil compression curve (CC) provides parameters to identify soil load-bearing capacity and susceptibility to compaction. An Excel add-in (ACC) incorporating graphical procedures for mathematical models for soil CC description and calculation of parameters was developed. By using the ACC, soil CC can be described by means of the Casagrande method, mathematically operationalized with the van Genuchten equation, with or without restrictions on its parameters, and by Dias Junior and Pierce method in its original form and also modified using the void ratio rather than soil bulk density. The ACC uses a single Excel spreadsheet for input and output data, in addition to a graphical interface and a tool for exporting editable charts. Compared to SAS statistical software, the ACC minimized the sum of squared residuals and estimated parameters of mathematical models with the same efficiency for 347 compression curves. The ACC programming script is available and can be modified or used as a framework for other programming projects. <![CDATA[BRILLIANT BLUE DYE REMOVAL IN FUNGICIDE SPRAYING]]> ABSTRACT The method used for removal of brilliant blue dye may have an influence in interpreting the results of spraying deposition studies. The aim of this study was to assess the number of washings and water volumes for brilliant blue dye removal from soybean leaflets and glass slides in fungicide sprayings with and without adjuvants. A completely randomized experimental design was used in a 3 × 3 × 2 × 4 factorial scheme. The factors consisted of number of washings (1st, 2nd, and 3rd), water volume (15, 20, and 30 mL), target type (soybean leaflets and glass slides), and spray solutions (fungicide ProdutorBR® 0.5 L ha−1 without and with the adjuvants vegetable oil Agr’óleo® 0.5% v v−1, mineral oil Nimbus® 0.5% v v−1, and surfactant Silwet® 0.04% v v−1). Sprayings were carried out by using the nozzle model TT110015 at a pressure of 300 kPa (medium droplets). After spraying, targets were washed and the amount of brilliant blue dye removed per target area was detected by spectrophotometry. Brilliant blue dye removal is higher in glass slide when compared to soybean leaflets. With a single washing, a higher difficulty in removing the brilliant blue dye was observed for fungicide with vegetable oil. Only the first washing and a water volume of 15 mL are insufficient for brilliant blue dye removal from soybean leaflets and glass slides. <![CDATA[ANAEROBIC DIGESTION STABILITY TEST BY SHEWHART CONTROL CHART]]> ABSTRACT The anaerobic digestion (AD) operation complexity raise the importance of stability testing to verify whether the operating conditions are under control and whether the process is working as required. The current method of verifying process stability is by a range of the ratio between volatile fatty acidity and total alkalinity (VFA/ TA) within which stable conditions are brought about; these rates vary with the content of organic material. A few indicators as pH or constant biogas production are also used. Therefore, the aim of this study was to propose the use of Shewhart control chart for individual measures as a stability test for AD, as well as to demonstrate its use in poultry litter AD. The method showed to be advantageous since it standardizes a variation range for the process according to the average and verifies the stability by direct measures, such as organic material removal efficiency and biogas production.