The knowledge of how soil management affects nitrogen (N) dynamic in long term can provide basis to develop production systems that optimize the cycling of this nutrient. The objective with this research is to assess the effect of soil managements, with cover crops and chiseling, in rotation with soybean, on N cycling and budget and soybean yield. The experiment has been running since 2003, in a clayey and structured Alfisol. The experimental design is a complete randomized block with a split-plot arrangement of treatments with four replicates. Plots consist in winter crops triticale (X Triticosecale) and sunflower (Helianthus annuus), and the subplots in spring crops pearl millet (Pennisetum glaucum), forage sorghum (Sorghum bicolor) and sunn hemp (Crotalaria juncea), besides chisel plow, made in 2003 and 2009. In summer, soybean (Glycine max) is sowed in all subplots. The N cycling and budget will be studied by soil evaluations, including total, organic, inorganic and microbial N; by rate net mineralization; by dry matter, nutrients accumulation, persistence and N release of straw of cover crops and soybean; by nutrition, biological N fixation, yield and N exportation of soybean; by evaluations of N losses by leaching, volatilization and denitrification, besides N inputs by atmospheric deposition and seeds. Results will be subjected to ANOVA and the means will be compared using the LSD test (p=0.05).
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