-The objective of this work was to evaluate the straw production and the agronomic performance of soybean intercropped with oversown forage species, in no-tillage system. A randomized complete block design was carried out with four replicates, in a 5×2+2 factorial arrangement, as follows: five forage species -Urochloa brizantha 'Marandu', Urochloa ruziziensis, Panicum maximum 'Mombaça', Panicum maximum 'Massai', and Pennisetum americanum -, intercropped with soybean over two crop years (2013/2014 and 2014/2015), plus two controls, with P. americanum sowed in succession to soybean or with soybean monocropping followed by winter fallow (traditional cultivation). Soybean yield components and forage straw yield were evaluated. None of the intercropping systems reduced soybean grain yield, compared with monocropped soybean. The oversown species can significantly improve soybean productivity, as is the case for soybean intercropped with P. maximum 'Mombaça', compared with soybean monocropping, followed or not by millet. Panicum maximum 'Mombaça' is the most effective forage species for dry matter accumulation in the fall/spring period.Index terms: Glycine max, integrated crop-livestock system, oversowing, plant cover, soil cover crops. Produção de palha e desempenho agronômico de soja consorciada com espécies forrageiras em sistema plantio diretoResumo -O objetivo deste trabalho foi avaliar a produção de palha e o desempenho agronômico de soja consorciada com espécies forrageiras sobressemeadas, em sistema plantio direto. Utilizou-se um delineamento de blocos ao acaso, com quatro repetições, em um arranjo fatorial 5x2+2, conforme a seguir: cinco espécies forrageiras -Urochloa brizantha 'Marandu', Urochloa ruziziensis, Panicum maximum 'Mombaça', Panicum maximum 'Massai' e Pennisetum americanum -consorciadas com soja, em duas safras agrícolas (2013/2014 e 2014/2015), além de dois tratamentos-padrão, com P. americanum em sucessão à soja ou com cultivo tradicional de soja e pousio no inverno (soja solteira). Avaliaram-se os componentes de produção da soja e a produtividade de palha das forrageiras. Nenhum dos consórcios diminuiu a produtividade de grãos da soja, em comparação ao cultivo solteiro. As espécies sobressemeadas podem aumentar significativamente a produtividade da soja, como no caso do consórcio da soja com P. maximum 'Mombaça' comparado ao cultivo da soja solteira, com ou sem milheto em sucessão. Panicum maximum 'Mombaça' é a espécie forrageira mais eficiente quanto ao acúmulo de matéria seca, no período outono/primavera.Termos para indexação: Glycine max, integração lavoura-pecuária, sobressemeadura, cobertura vegetal, cultivos de cobertura do solo.

Sustainable agricultural systems are necessary to improve soybean [Glycine max (L.) Merr.] seed yield and to increase nutrient use efficiency. Intensification of agricultural systems is an important tool to increase farmers’ profitability in the Cerrado region (Brazil), where soybean is rotated with corn in the same growing season. However, this intensification requires soybean cultivar with short growing periods which is achieved by indeterminate soybean cultivars. There is a lack of information regarding the nutrient uptake by soybean cultivars under intensive agricultural systems in the Cerrado. We sought to investigate soybean biomass production and soybean seed yield of determinate and indeterminate soybean cultivars. We also aimed to quantify the amounts of nutrients taken up by soybean biomass and seeds. Field research was conducted to evaluate 17 soybean cultivars commonly grown by farmers, and we considered the determinate and indeterminate soybean growth habit. Nutrient uptake and aboveground soybean biomass were higher under shorter soybean growth and development cycles. Nitrogen, phosphorus and potassium extraction in modern cultivars was higher than in cultivars used in past decades. Nutrient use efficiency was higher in determinate soybean cultivars than in indeterminate soybean cultivars.

Brazil is one the largest soybean and cattle producer worldwide and degrade pasture is one of the major problem in the Cerrado region. Integrated crop-livestock system is a key to increase grower income, to reduce crop yield loss by water deficit during growing season and to reclaim degraded pasture. However, forage production and its quality is important to evaluate under integrated crop-livestock system. The objective of this study was to evaluate forage production and the bromatological composition of different forage species in monoculture and in intercropping with soybean in an oversowing system. A completely randomized block design with four replications in a 5 × 2 + 1 factorial scheme, with five forage species (Urochloa brizantha cv. Marandu; U. ruziziensis; P. maximus cv. Mombaça; P. infestans cv. Massai and P. americanum) and two cropping systems (monoculture and a consortium with soybeans) and a standard treatment (P. americanum in succession with soybeans). The forage productivity and the bromatological composition of the forages were evaluated. The species U. ruziziensis, U. brizantha, M. maximum and P. infestans presented higher forage production capacity, when cultivated in consortium with soybeans and in monoculture, in relation to P. americanum. The cultivation of the forages U. ruziziensis, U. brizantha, M. maximum and P. americanum in monoculture produced higher productivity than that in consortium with soybeans. The forages U. ruziziensis and U. brizantha intercropped with soybean presented a better nutritional value over the autumn-winter period.

Soybean is the major crop in the Brazilian Cerrado region. Tocantins state has been increasing soybean production mostly into degraded pasture. However, cover crops such as forages crops are important to implement in regional soybean agricultural systems to increase systems resilience due to climate variability. There is a lack of information regarding to agronomic performance of soybean intercropped with cover crops under no-tillage. The experimental design was randomized complete blocks with four replications in factorial 7 × 2. Seven soybean cultivation systems were tested: 1) soybean intercropped with Urochloa brizantha cv. Marandu; 2) soybean intercropped with Urochloa ruziziensis; 3) soybean intercropped with Panicum maximum cv. Mombaça; 4) soybean intercropped with Panicum infestans cv. Massai; 5) soybean intercropped with Pennisetum americanum; 6) soybean followed by Pennisetum americanum; and 7) soybean and fallow. Two soil acidity and amelioration were tested: 1) with lime and gypsum application; 2) without lime and gypsum application. Soybean grain yield, plant height and number of pods per plant were different. Soybean grain yield were higher with lime ad gypsum application. The highest soybean plants height were observed in the treatments where lime and gypsum were applied, and with soybean intercropped with P. maximun and Millet. Soybean number of pods was positively affected P. infestans intercropped with soybean. There was no significant difference among treatments for mass per 100 seeds. Cover crops showed suitable to increase agronomic performance of soybean.

The objectives of this work were to evaluate the CO2 emission potential of an Oxisol under integrated crop-livestock and no-tillage systems in the Brasilian Savanna; and to analyze the impact of soil temperature and soil moisture as factors that regulate the seasonality and the emission of C-CO2 in these systems. Field-scale study was carried out at Fazenda Brejinho, in Pedro Afonso-TO, under Oxisol. The production systems studied were integrated crop-livestock and no-tillage under cropped with soybean and corn. The amount of carbon (C) released from the soil in the form of CO2 (C-CO2) was evaluated using cylindrical chambers installed in the field with a vial containing sodium hydroxide to collect CO2 released from the soil (soil emission) in an interval of 15 hours. Five evaluations were conducted over crops growing season, started in 01/26 through 06/16/2015. Data were tested to analysis of variance and the means were compared with Duncan test at 5%. The emission of C-CO2 differed between treatments in all evaluation periods. On average, the temperature ranged from 26.5 to 27.7 °C, the soil moisture ranged from 12.2 to 15.7% and the C-CO2 emission ranged from 87.4 to 119.9 mg m-2 h-1. Temperature, soil moisture and the production systems contributed to the emission and seasonality of carbon dioxide emissions. The integrated crop-livestock cropped with soybean/corn rotation was the system that had the lowest carbon dioxide emission.