Acúmulo e liberação de nitrogênio por culturas de cobertura sob sistema plantio direto em Mato Grosso

Abstract

The cover crops in production systems are an alternative to improve the productive capacity of agricultural areas. The objective of this work was to evaluate the potential of the cover crops and seedlings sowed in second crop on nitrogen cycle of the aerial part and its influence on the soybean yield in the crop under no-tillage. The experiment was accomplished in Rondonópolis UFMT campus, in red latosol dystrophic, with nine parcels and four repetitions. Each parcel was divided in: S1 - Fallow No-tillage, S2 - Conventional Planting, S3 - Crotalaria spectabilis, S4 - corn + C. spectabilis, S5 - Pennisetum glaucum, S6 - Urochloa ruziziensis, S7 - Sunflower + U. ruziziensis, S8 - Cajanus cajan, S9 - Corn + U. ruziziensis. They were qualified the accumulation and release of N promoted by the cover plants. These evaluations were fulfilled at flowering, senescence and desiccation of 2017 and repeated in 15, 30, 60, 90 and 120 days after the desiccation (DAD). The U. ruziziensis stood out when the accumulation of N in the desiccation moment towards the other treatments. The A. spectabilis also accumulated considerable quantities of nitrogen, justified by the crop´s capacity in effecting biological fixation. The U. ruziziensis and the C. spectabilis are able to provide high quantities of N to the successor harvest, even though it liberates the nitrogen quickly. C. spectabilis, Corn + C. spectabilis, P. glaucum, U. ruziziensis, Corn + U. ruziziensis present satisfactory results regarding soybean grain yield.