Fontes de nitrogênio e alturas de resíduo em pastagens de capim-marandu

Abstract

The pasture is the main food source for cattle, being considered a source of low cost and widely used, thereby making farming systems based mainly in the production and cultivation of pastures. The objective of this study was to evaluate the productive parameters marandu grass pasture, their structural characteristics, water use efficiency, water uptake by the plant and to quantify the main soil chemical properties, when this species was fertilization submitted with different sources of nitrogen and postcrop residue heights. The experiment was conducted at the Experimental Farm, at the Unimontes, in Janaúba-MG, from December 2014 to November 2015 to pasture Urochloa brizantha cv. Marandu deployed since 2008. The design of randomized blocks with five replications was arranged in a factorial 3 x 2, with three sources of nitrogen (urea, ammonium sulphate and calcium nitrate) and 12 residue heights and 17 cm, corresponding respectively to the highest and lowest shear strength, determining the parameters of the forage production and its morphological components. To carry out the analysis of soil chemical properties was made in the same area during the same trial period an outline randomized blocks (ORB), three sources of nitrogen (urea, ammonium sulphate and calcium nitrate), with five repetition, totaling 15 experimental units, where the grass was maintained at 15 cm. Calcium nitrate and 12 cm residue improves the productive parameters marandu grass compared to urea and ammonium sulfate with 12 and 17 cm residue tall. The vegetal material remaining senescer height increases the available phosphorus in the soil and sulfate ammonium reduces the potassium content to the measured depth of 40 cm.