Pastagem irrigada de Panicum maximum Jacq cv Tanzânia adubada com fósforo e nitrogênio sobre a produção, valor nutritivo e atributos do solo no norte de Minas Gerais

Abstract

This work was carried out to evaluate the soil attributes under Tanzania grass pasture irrigated and fertilized with different doses of phosphorus and nitrogen at various times of sampling in the North of Minas Gerais. The experimental area was divided into strata, in a randomized block design with three replications in a sub-subdivided plots. The experiment started on September 4, 2010, when it was carried out an uniformization cut of the grass to 30 cm from the ground and finished on September 3, 2011. Subsequently, the plots and sub-plots were fertilized according to the experimental treatments proposed, being 0, 40, 80 and 120 kg ha-1 of P2O5 distributed in the plots, 0, 100, 200, 300 and 400 kg N ha-1 in subplots, and in sub-subplots the seasons. The phosphorus fertilization was made by coverage, with triple superphosphate, at the beginning of the experiment and the fertilization with nitrogen, made with urea, and distributed in the sub-plots, divided into five fertilization during the experiment, immediately after cutting the grass. Soil samples were collected to evaluate the chemical characteristics, taken at random, one in each subplot at depths of 0-2, 2-10 and 10-20 cm, being a collection at the end of each season (spring, summer, autumn and winter). There was an increase in pH of the soil with the time of sample collection, in all layers and for N doses, regardless of the seasons, there was a reduction of pH with increasing of quantities applied. It was verified reduction in levels of P available with sampling times and there was a linear increase of P availability with increasing doses of P2O5. For potassium there was an increased availability with the sampling times and doses of N. For Ca and Mg, in general, there was significant effect of the seasons and doses of P. Treatment effects were observed on soil CTC and it was found influence of the seasons and P levels in the values of bases saturation. It is concluded that the soil chemical properties vary at different depths, resulting from fertilization of the soil and the seasons.