Efeito da adubação nitrogenada combinada com aveia e ervilha como plantas de cobertura

Abstract

Food production aims atincreasing crop productivity, reducing inputs and costs, in addition to reducing the environmental impact. In agriculture, the use of cover crops is an ecological and economically viable alternative for soil management. Despite knowledge about the advantages of cover crops in terms of both productivity and soil management, informationon long-term crop diversification on soil nitrogen dynamics, as well as nutrient cycling and soil physical fertility, is still scarce. Thus, the objective of this research was to evaluate the effect of cover crops and nitrogen (N) rates on the agronomic performance of crops in different years on chemical and physical changes in the soil. The experiment was treated at the research center of the Institute of Rural Development of Paraná, located in Santa Tereza do Oeste - PR. The treatments were organized in subdivided plots according to the 2×5 scheme, the main plot being the winter cover crops [blackoats (Avena strigosa Schreb), cultivar IPR Cabocla and fodderpea (Pisum sativum ssp. arvense) cultivar IPR 83 ] and the sub-plots the rates of N applied in coverage (0, 25, 50, 75 and 100 kg ha-1 ) in the Summer grain producing crop [bean (Phaseolus vulgaris), corn (Zea mays L.) and soybean (Glycine max (L.) Merr.))]. The design employed was randomized blocks, with five replications. Soil chemical and physical attributes were quantified after eight years with this management. Soil chemical determinations were: pH in CaCl2 and phosphorus, potassium, calcium, magnesium and organic matter contents. Regression analysis was performed for factors of a quantitative nature and F testat 5% of significance for qualitative characteristics using statistical software Sisvar 5.6. CaCl2 pH, P and organic matter contents at all evaluated depths were not influenced by cover crops. Higher levels of K in the surface layers of the soil were observed with the blackoat crop. Higher levels of Ca (20-40 cm) and Mg (10-20 and 20-40 cm) were observed with the for age pea crop. The cover crops did not change the physical attributes of the soil, with the exception of macroporosity, in the 20-30 cm layer, which was higher with blackoat. The effect of cover crops on crop productivity varied according to the season and in which there was na effect, greater where the forage pea was the cover crop. The doses of N applied in coverage do not change the vast majority of the chemical and physical attributes of the soil and increased crop productivity in only three of the eight evaluated crops, two of which were beans and one was corn.