Extração de nutrientes do capim-marandu sob doses e fontes de nitrogênio

Abstract

It was evaluated the nutrient extraction of marandu grass, under doses and sources of nitrogen during a period of three years. The experiment was conducted from July of 2003 to March of 2006 in the Model Farm of University State of Goiás, in an area of 882m2 . The pasture had been used for more than ten years, and the herbage yield was low and considered moderately degraded. The experiment was arranged in a randomized complete block design with split-plots and three replications and in a 2x4 factorial, with two sources of N (ammonium sulfate and urea) and four doses of N (0; 100; 200 and 300kg/ha/yr). The sub-plots were represented by the years (2004; 2005 and 2006) referring to the time of pasture evaluation. In each one of the years, three cuts of forage plant evaluation were done. The maximum doses of nitrogen provided greater nutrient extractions. The decreasing order of nutrient extraction for marandu grass, in relation to the maximum doses of nitrogen was: macronutrients: K > N > Ca > Mg > P = S and micronutrients: Fe > Mn > Zn > Cu. The ammonium sulfate source extracted higher amounts of N, K, S, Zn, Cu, Mn and Fe, when compared with urea.