PLANTAS DE COBERTURA SOLTEIRA, CONSORCIADA E POLICULTIVOS ANTECEDENDO MILHO E SOJA EM SOLOS DE BAIXA E ALTA FERTILIDADE

Abstract

No-tillage system is currently the main cultivation system adopted in Brazil, requiring the cultivation of cover crops in the off-season and maintenance of residues on the soil surface. Black oats are the main cover crop alternative for the southern region of Brazil, however, they may have temporary nitrogen immobilization. The previous cultivation of cover crops can directly affect the productivity of corn and soybean crops. In order to solve the problem, the objective of this work was to evaluate the performance of cover crops in single, intercropping and polyculture with 6 and 8 species in soils with low and high fertility in soil protection, accumulation and release of nutrients and their effects on corn and soybean productivity. Two experiments were developed in the 2018/2019 agricultural year, in the city of Guarapuava - PR in experimental areas of UNICENTRO. Both in a randomized block design with 4 replications and 3 treatments. For the Experiment I the treatments were: black oats, black oats + oil radish, and black oats + oil radish + vetch + white oats + ryegrass + rye + white lupine + blue lupine. For the Experiment II were: black oats, black oats + oil radish and black oats + oil radish + white oats + rye + white lupine + vetch. The following were evaluated: soil cover rate by cover plants, biomass production, nutrient accumulation and release and biomass decomposition rate. For corn and soybean crops, biometric variables and grain yield were evaluated. All treatments showed high soil protection capacity at 70 days after sowing (DAS). Single cultivation showed higher biomass production in soils with low fertility. The treatments with more than one species showed higher biomass production in soils with high fertility. For the Experiment I, single and polyculture cultivation showed the highest residual biomass and the greatest efficiency in nutrient release at 120 days after management (DAM). In the Experiment II, the intercropping and polyculture showed the highest residual biomass at 120 DAM, and the single crop showed effective release of nutrients with shorter ½ life times. Corn productivity was not influenced by the increase in the number of species. For soybeans, the highest productivity was obtained after single cultivation and intercropping.