Yield of Para Grass (Brachiaria mutica) as Influenced by Source, Rate and Frequency of Application of Fertilizer Nitrogen.

Abstract

Ammonium sulphate, ammonium nitrate and urea at rates of 100and 200kg per ha per year were applied to a Para grass pasture in the wet tropics over three periods of about a year each. In the first period, a single initial application was compared with three splits at about 15 week intervals. In the second and third periods, comparison was between 4 splits at 12 week intervals and 8 splits at 6 week intervals. Dry matter yields averaged 36 kg per kg N applied for ammonium nitrate, 29 kg for ammonium sulphate and 25 kg for urea. Response to frequency of application was small. There was little residual effect beyond six weeks after application. Response appeared almost linear to increasing rates up to 50 and perhaps even 200kg per ha per application. Nitrogen content of herbage cut at 6 to 8 week intervals averaged about 1%, with very little effect of treatments. Recovery of applied nitrogen averaged 42, 28 and 27 per cent in the three successive periods.