Nitrogen fertilization in coastcross grass: effects on nutrient extraction and apparent nitrogen recovery

[摘要] Contents, nutrient extraction, and apparent applied N recovery were determined in a coastcross pasture established on a dark red latosol (Hapludox), in São Carlos, SP, Brazil, receiving five rates of N as urea or amonium nitrate, surface-applied (0, 25, 50, 100, and 200 kg ha-1 cutting-1) in five consecutive periods, during the rainy season. Nutrient extraction increased with increasing nitrogen rates. When forage yield was high (treatment with 500 kg ha-1 year-1 of N) and for both fertilizers, macronutrient extraction was greater for K and N, followed by Ca, S, P, and Mg. Micronutrient extraction occurred in the following decreasing order: Fe, Mn, Zn, and Cu. Nitrogen recoveries from urea and ammonium nitrate surface-applied on coastcross pasture were calculated. Significant differences occurred within periods (P<0.05), depending on climatic conditions. Mean N recovery of urea was about 68% of that of ammonium nitrate. Recovery of ammonium nitrate-N ranged from 68 to 75% of applied N.

[学科分类] 兽医学

[关键词] ammonium nitrate;biomass production;Cynodon dactylon;nitrogen levels;nitrogen uptake;urea    IntroduçãoAs pastagens constituem o principal e mais barato componente da dieta de bovinos e;como tal;representam a base de sustentação da pecuária de corte no Brasil