Interaction of correction of soil acidity with nitrogen in the stable carbon accumulation in the soil

Abstract

Direct seeding increases the carbon level (C) of the soil in order to ease its decomposition, by adding plant residues and by better soil aggregation. It has been shown that C is more stable in smaller soil aggregated, and that liming and nitrogen fertilization can cause the greatest accumulation of stable C. The hypothesis of the present study is that the interaction of factors can result in a greater accumulation of C in the soil or in each of these isolated factors. Thus, the objective of this research is to evaluate the effect of the application of lime and plaster, associated or not with nitrogen fertilization, soil aggregation, carbon accumulation, humic acid, fulvic acid and humine, related to or stable carbon accumulation with as aggregate classes in a second crop soybean and corn production system. The experiment will be installed in field conditions, in Botucatu-SP, in continuation of a long-term experiment, in which soybeans and corn of second crop response is studied, calibration and plaster, as well as the response of corn to nitrogen. The treatments consist of a combination of: control (without limestone and plaster), limestone and limestone + plaster, in addition to four doses of N (0, 80, 160, 240 kg ha-1 of N). The soil will be sampled from depths of 0-10, 10-20, 20-40, 40-60 cm. The aggregate classes will be selected using the wet sifting method and classified as: sand and iron concretions, macroaggregates, microaggregates, silt and clay. The levels of N, C and the humic acid and fulvic acid ratio in the soil and aggregates will be evaluated. The results will be submitted to analysis of variance, Tukey's Test, correlation and polynomial regression. (AU)