Acúmulo de massa seca, nutrientes e decomposição de plantas de cobertura cultivadas isoladas e consorciadas, antecessoras à cultura da soja

Abstract

Crop rotation with cover crops provides more sustainable agriculture due to the diversification of species in the system, maintenance of soil cover and nutrient cycling, which may affect the soil chemical attributes, as well as the agronomic performance of the subsequent crop. The production of biomass, the nutrients accumulation, the decomposition rate and release of nutrients depend on the intrinsic factors of the species, management, climate and region; therefore, it is necessary to study at a local level the isolated and intercropped cultivated species in order to determine the appropriate management for each productive system Therefore, the objective of the work was to evaluate the production of biomass, the accumulation of macronutrients, the decomposition of the straw and the remaining nutrients in cover crops grown isolated or intercropped in different sowing proportions, as well as the chemical attributes of the soil and the agronomic performance of soybean crops in succession. The work was carried out in a clayey dystrophic Red Latosol, at the Federal University of Goiás, Regional Jataí. The experimental design used was randomized blocks, with four repetitions and with ten treatments: T1 - Fallow; T2 - Crotalaria ochroleuca; T3 - Raphanus sativus; T4 - Urochloa ruziziensis; T5: C. ochroleuca + R. sativus (CN); T6 - UR (double seeds); T7 - 25% of UR seeds + 75% of CN seeds; T8 - 50% of UR seeds + 50% of CN seeds; T9 - 75% of UR seeds + 25% of CN seeds; T10 - corn. After management the cut from T1 to T9, the production of dry biomass and the accumulation of macronutrients were evaluated. Samples supplied by biomass were stored in decomposition bags, which were discarded on the ground, being collected every 30 days to evaluate the recovery of the decomposition of the pallet and release macronutrients up to 90 days, as well as the half-life (T½). The soil was analyzed for chemical attributes. In soybean, the physiological, morphological, productive and studied grain components were applied. The data were submitted to analysis of variance and the Scott-Knott method, both with a 5% probability of error. Use the exponential regression model to adjust the decomposition capacity, nutrient release and T½. Although there are no differences between treatments, biomass production is considered ideal for the good maintenance of vegetation cover. T2 presents a greater accumulation of N and K, T3 of N, P and K and the consortium between them, T5, of N, P, K, Ca, Mg and S. T7 accumulates high levels of N, P, K , Mg and S, acts quickly in nutrient cycling, has good straw persistence, in addition to increasing the diversity of species in the system. T4 and T6 have the lowest vegetation rates due to normalized difference in the soybean R1 stage, however, the other components are not influenced by the cultivation of cover crops.