Response of napier grass (Pennisetum purpureum Schum.) to different levels of nitrogen fertilizer in the Philippines

Abstract

Napier grass is a high yielding and easy to propagate forage crop with broad ecological adaptation making it highly popular for smallholder farmers. Sustained production of forage is necessary for the nutrition of ruminant animals, which can be attained if the right amount of nitrogen fertilizer is applied. This study was conducted to: 1) evaluate the response of napier grass to different levels of nitrogen fertilization; 2) determine the appropriate nitrogen level for optimum napier grass production; and 3) assess the economic benefit of napier grass production under different levels of nitrogen fertilizer application. The study was laid out in a Randomized Complete Block Design (RCBD) with three replications and five treatments (T0 – Unfertilized, T₁–30kg N ha^-1, T₂–60kg N ha^-1, T₃–120kg N ha^-1, T₄–240kg N ha^-1).

Plant height, fresh herbage and dry matter yields were significantly affected by the different rates of nitrogen fertilizer. Plants applied with 240kg N ha^-1 were the tallest and had the heaviest fresh herbage and dry matter yields, but comparable to those plants applied with 120kg N ha^-1. Increasing the levels of nitrogen fertilization correspondingly improved the overall forage performance with optimum level at 120kg N ha^-1.

Cost and return analysis showed that plants applied with 240kg N ha^-1 resulted in the highest net income of PHP55,690 ha^-1 while the least net income of PHP17,213 ha^-1 was obtained with unfertilized plants.