Aplicação de nitrogênio no cultivo de milho, sob sistema plantio direto: efeitos na qualidade física do solo e características agronômicas

Abstract

This research was developed in the experimental area of ESALQ-USP, city of Piracicaba , state of Sao Paulo, in a soil of sandy-clay texture and aimed to evaluate the soil physical quality and maize agronomic characteristics with maize crop under different N doses and different tillage systems. The experimental design consisted of randomized blocks with four replicates. Treatments consisted of three nitrogen doses (N) (60, 120, and 180 kg ha-1) and a control. The ammonium sulfate fertilizer was applied at 30 kg ha-1 N during seeding, and the rest was applied as sidedressing when the plants had between six and eight leaves. Were determined the bulk density, microporosity, macroporosity and total porosity of soil, at depths of 0.05, 0.15, 0.25, 0.35 m, and the maize components yield. The soil physical properties tend to change over time and N levels, especially with regard to soil macroporosity and microporosity, conditioned by the structural change of the soil.