ABSTRACT. This study aimed to evaluate forage yield, tiller population density, canopy height, nutritional value as well as cattle performance in alternate stocking from three tropical forage cultivars. The experiment followed a randomized block design, in a 3 x 3 factorial scheme with three replications. Three forage cultivars (Marandu, Massai and Xaraés) distributed in nine hectares were evaluated in three dry season periods (transition wet/dry, dry, and end of dry season), with repeated measures over time. The following variables were evaluated: canopy height, leaf: stem ratio, forage mass, leaf mass, stem mass and dead material mass. Total digestible nutrients, crude protein and in vitro dry mass digestibility were evaluated regarding forage nutrition. Animal performance, using 36 eleven-month-old animals (half-blood Nelore), was evaluated by the daily average gain and weight gain by area. During pre-grazing, canopy height presented interaction among forage cultivars and the evaluated periods. The average daily gain showed no interaction among cultivars and period of the year the similarity in animal performance among the cultivars Marandu and Massai show that the Massai grass can be used as an alternative for forage diversification under an alternate management system.

RESUMEN Este estudio tuvo como objetivo analizar la eficacia de diferentes principios activos de preemergencia sobre la supresión del banco de semillas de malezas y el crecimiento de la soya. Los experimentos se llevaron a cabo en una finca de producción agrícola comercial ubicada en el municipio de Brejo (MA, Brasil), durante la cosecha 2019/2020. El diseño experimental fue en bloques al azar con nueve tratamientos y cuatro repeticiones. Los tratamientos consistieron en el control (sin aplicación de preemergencia), S-metolaclor, flumioxazin + imazetapir, flumioxazin, imazetapir, trifluralin, diclosulam, diclosulam + imazetapir, y clomazona + carfentrazone-etil. Se realizaron estudios fitosociológicos antes y después de la siembra (10 y 36 d después de la aplicación - DDA) para controlar la competencia entre malezas. Se identificaron 19 especies de malezas, distribuidas en 17 géneros y 13 familias botánicas. Las especies Scoparia dulcis, Richardia scabra y Cyperus iria obtuvieron los índices fitosociológicos más altos (123.77, 28.62 y 28.29, respectivamente), estimados a los 36 DDA. La flumioxazina y el diclosulam fueron los más eficientes en la supresión de la competencia de malezas, con solo 15.63 y 16.13 plantas m-2. Las puntuaciones más altas de fitotoxicidad (3.0) se encontraron a los 10 DDA con la aplicación de S-metolaclor, flumioxazina + imazetapir, trifluralina y diclosulam + imazetapir. Se recomienda el control preemergente con flumioxazina y diclosulam para las condiciones edafoclimáticas en la mesorregión este del estado de Maranhão, Brasil.

ABSTRACT This study aimed to analyze the efficacy of different pre-emergence active ingredients on the suppression of the weed seed bank and the growth of soybeans. The experiments were carried out on a commercial farm located in Brejo (MA, Brazil), during the 2019/2020 harvest. The experiment was designed in randomized blocks with nine treatments and four replicates. The treatments consisted of control (without pre-emergence application), s-metolachlor, flumioxazin + imazethapyr, flu-mioxazin, imazethapyr, trifluralin, diclosulam, diclosulam + imazethapyr, and clomazone + carfentrazone-ethyl. Phytosociological surveys were carried out in pre- and post-planting (10 and 36 d after application - DAA) to control weed competition. Nineteen species of weeds were identified, distributed in 17 genera and 13 botanical families. The species Scoparia dulcis, Richardia scabra, and Cyperus iria exhibited the highest phy-tosociological indices (123.77, 28.62, and 28.29, respectively), estimated at 36 DAA. Flumioxazin and diclosulam were the most efficient in suppressing weed competition, with only 15.63 and 16.13 plants m-2. The highest phytotoxicity scores (3.0) were found at 10 DAA with the application of s-metolachlor, flumioxazin + imazethapyr, trifluralin, and diclosulam + imazethapyr. The pre-emergent control using flumioxazin and diclosulam is recommended for the edaphoclimatic conditions in the Eastern mesoregion of the state of Maranhão, Brazil.

ABSTRACT Using biological inputs to improve the efficiency of nitrogen fertilizers represents an alternative for the cultivation of grasses in tropical regions. Azospirillum brasilense is a species of plant growth promoting bacteria widely studied and used in inoculants. Thus, this study aimed to evaluate the performance of Mombasa grass ( Megathyrsus maximus ) in association with A. brasilense and nitrogen (N) fertilization. The study was conducted under field conditions in Araguaína-Tocantins State, between December 2017 and May 2018. The treatments were arranged in randomized blocks, in a 5 × 2 factorial arrangement, with five doses of N fertilization (0, 25, 50, 75, and 100 kg ha-1) combined with two inoculation treatments (inoculated and non inoculated), in four replicates. For the number of tillers and root production, the inoculation efficiency varied as a function of the supplied N doses. However, the percentage of leaf N was higher for inoculated plants regardless of the application of nitrogen. In the absence of nitrogen fertilization, it was possible to increase forage production by up to 36 % with inoculation.

RESUMO Objetivou-se com este trabalho avaliar a variabilidade espacial das respostas produtivas e estruturais do capim Marandu em função das características químicas do solo e da topografia do terreno. O experimento foi conduzido em uma topossequência, na escola de Medicina Veterinária e Zootecnia. Foram avaliadas as variáveis V, CTC, SB, m, pH, na profundidade de 0-20cm, profundidade efetiva, número de perfilhos (m2), produção de matéria seca (kg ha-1), altura do dossel forrageiro (cm). Foram coletadas 72 amostras em pontos georreferenciados em terreno declivoso. O solo foi classificado como Neossolo Quartzarênico Órtico na porção superior (Topo), Neossolo Litólico Eutrófico, no terço superior da encosta (ombro), Neossolo Litólico Eutrófico no terço médio da encosta (meia-encosta) e Neossolo Quartzarênico Hidromórfico no terço inferior (pedimento). Todas as variáveis avaliadas apresentaram dependência espacial com variogramas de estrutura bem definida. A pastagem apresentou heterogeneidade na morfologia do dossel em função da distribuição espacial da fertilidade do solo, resultando em dossel e produção de matéria seca mais elevada no topo e atingindo a menor produção no ombro da topossequência. O dossel forrageiro apresenta heterogeneidade na morfologia em função da distribuição espacial da fertilidade do solo e da profundidade efetiva, resultando na definição de duas zonas manejo: 1 à topo e pedimento; e 2 à ombro e meia encosta.

SUMMARY This work aimed to evaluate the spatial variability of structural and productive responses of Marandu grass depending on the chemical characteristics of the soil and topography. The experiment was conducted in a topossequence, school of Veterinary Medicine and Animal Science, The V variables were evaluated CTC, SB, m, pH at a depth of 0-20 cm, effective depth, number of tillers (m2), production dry matter (kg ha-1), when sward (cm). 72 samples were collected in georeferenced points on sloping ground. The soil was classified as Entisol in the upper portion (top), Udorthent Eutrophic the upper third of the slope (shoulder), Udorthent eutrophic in the middle third of the slope (half-slope) and Quartzips amment Hydromorphic in the lower third (pedimento). All variables presented spatial dependence with variograms of well-defined structure. The pasture presented heterogeneity in the morphology of the canopy due to the spatial distribution of soil fertility, resulting in canopy and producing higher dry matter at the top and reaching the lower production on the shoulder of topossequence. The sward has heterogeneity in morphology depending on the spatial distribution of soil fertility and the effective depth, resulting in the creation of two management areas: 1àtopo and pediment, and 2à shoulder and half hillside.

ResumoObjetivou-se avaliar o efeito da utilização de biofertilizante obtido através da biodigestão anaeróbica da cama de aviário nas características produtivas do capim Piatã, e nas características químicas do solo. Avaliou-se cinco doses de biofertilizantes (0; 10; 20; 30; 40m3.ha-1) em dois sistemas de cultivos (sistema monocultivo de capim Piatã e sistema consorciado de capim Piatã com sorgo forrageiro hibrido BRS 610). Foram verificadas as características agronômicas e estruturais submetidas às doses de biofertilizante nos dois sistemas de cultivos, verificado também a influência do biofertilizante nas características químicas do solo. Os dois sistemas de produção responderam de forma eficiente com a aplicação do biofertilizante, porém o colmo e o perfilhamento foram os principais componentes responsáveis pelo aumento de produtividade. As doses de biofertilizante trouxeram incrementos nas características químicas do solo, sendo identificado diferença apenas para K+ e matéria orgânica entre os sistemas de cultivos, evidenciando o sistema consorciado com as maiores extrações de nutrientes do solo pelas culturas. O biofertilizante mostrou ser satisfatório considerando incrementos obtidos na produção de forragem, no número de perfilho, área foliar, massa por perfilho sendo boa opção para melhoria da produtividade do capim Piatã, respondendo de forma positiva nos dois sistemas de produção.

AbstractThe objective was to evaluate the effect of the use of bio-fertilizers obtained by anaerobic biodigestion Aviary bed productive characteristics of Piatã, grass and soil chemical characteristics. Assessed five doses of biofertilizers (0; 10; 20; 30; 40m3. Ha-1) in two cultivation systems (monoculture system of Piatã grass and grass intercropping system with hybrid forage sorghum Piatã BRS 610). Agronomic characteristics were verified and submitted to structural measures of biofertilizer in the two systems of crops, checked also the influence of biofertilizer in soil chemical characteristics. The two production systems responded efficiently with the application of biofertilizer, however the thatched roofs and tilling was the main components responsible for increased productivity. The doses of biofertilizer brought chemical soil characteristics increments, being identified only difference to K+ and organic matter between systems of crops, evidencing the Member with the highest extraction system of soil nutrients by crops. The biofertilizer proved satisfactory considering increments obtained in the production of fodder, in tiller number, leaf area, mass per tiller being good option for improving the productivity of grass Piatã, responding positively in both production systems.

A variação na relação Ca:Mg em corretivos da acidez do solo é a principal forma de alterar a disponibilidade desses nutrientes para as espécies forrageiras. O objetivo com o trabalho foi avaliar o efeito de diferentes proporções entre cálcio e magnésio na forma de CaCO3 e MgCO3 sobre as propriedades químicas do solo e as características agronômicas de espécies forrageiras em Araguaína, TO. O estudo foi sobre Neossolo Quartzarênico Órtico típico, com 5% de argila, com fatorial 3 x 5, sendo três as espécies forrageiras (Brachiaria brizantha cv. Xaraés, Panicum maximum cv: Mombaça e estilosante Campo Grande - Stylosanthes capitata e S. macrocephala) e cinco as relações de Ca:Mg no calcário (1:1; 2:1; 4:1, 6:1 e 8:1). Os tratamentos foram dispostos em delineamento em blocos ao acaso, com quatro repetições. Todos os tratamentos receberam dose equivalente de 4t/ha de calcário. As diferentes relações Ca:Mg influenciaram no desenvolvimento e produtividade das forrageiras entretanto, não se obteve comportamento coerente que indicasse a tendência de resposta das plantas ao aumento ou redução da relação Ca:Mg. Além disto, as diferentes forrageiras foram semelhantes em relação a química do solo, porém as relações Ca:Mg alteraram as propriedades químicas do solo.

The variation in the Ca:Mg ratio in amendments used to neutralize soil acidity is way of altering the availability of those nutrients in forage species and properties soil chemists. The objective of work was to evaluate the effect of different proportions of calcium and magnesium in of CaCO3 and MgCO3 on agronomy characteristics on soil chemist properties in forage species in Araguaína city, Tocantins state. The study was carried on Entisol, with factorial 3 x 5 and four replications. The treatments had consisted of ratio application equivalent the 4t/ha of calcareous, using mixtures of CaCO3 and MgCO3 in diverse ratios until reaching relations Ca:Mg of 1:1; 2:1; 4:1, 6:1 and 8:1, applied in Entisol, with 5% of clay, cultivated with three forages species (Brachiaria brizantha cv. Xaraés, Panicum maximum cv: Mombaça e Stylosanthes Campo Grande - Stylosanthes capitata e S. macrocephala). The different relations Ca:Mg was however influenced in development and productivity of forages, however was not coherent behavior that indicated the trend of reply of the plants to the increase or reduction of the relation Ca:Mg. Moreover, the different forages were been similar in relation the soil chemistry, however the relations Ca:Mg had modified the chemical soil properties.