NITROGEN FERTILIZATION ON MOMBAÇAGRASS: YIELD, CONVERSION EFFICIENCY AND APPARENT RECOVERY OF NITROGEN

Abstract

The objective of this research was to evaluate the monthly (MDMP) and total (TMDP) dry mass prduction, as well as the mass production durig rainy (DMPR) and dry (DMPD) seasons and accumulated dry mass production (ADMY), also, nitrogen nitrogen conversion efficiency (NCE) and nitrogen apparent recovery (NAR) in Mombaça-grass (Panicum maximum Jacq.) pasture, submitted to nitrogen doses. The treatments were constituted by doses of 0, 100, 300 and 500 kg/ha of nitrogen as ammonium sulfate. The MDMP oscillated in all applied nitrogen doses along the months of experiments. The largest TDMP, MDMP and DMPD, as affected by applied nitrogen doses, fitted to the lineal regression model (first year) and DMPD (in the second year), and for the second year TDMP and DMPR fitted to the polynomial of second degree, with no significant response on doses abov 455,80 and 438,00 kg/ha. Increasing doses of nitrogen caused the production of dry mass during both rainy and dry seasons. However, the efficiency on nitrogen conversion and the apparent nitrogen recuperation were decreased causing losses of nitrogen from the ecosystem, from the pasture to the environment. Within two years of testing the average dose of nitrogen of 307 kg/ha  was the one that revealed the most conversion efficiency of Mombasa-=grass fertilization.
 
KEY WORDS: Ammonium sulfate, management, nitrogen fertilization, Panicum maximum.