Effects of cutting frequency and levels of nitrogen fertilizer on herbage yield of a guinea grass (<i>Panicum maximum</i>) pasture.

Abstract

The effects of fertilizer-N application and cutting frequency on the herbage yield of Panicum maximum pasture were investigated in 2001 through 2004 in a sandy loam soil at Nsukka. The experiment was a 4 x 4 factorial arrangement laid out in a randomized complete block design with three replications. Treatments comprised four levels of Nitrogen of 0, 150, 300, and 450 kg N ha-1 and four harvesting frequencies of 3-, 6-, 9- and 12-weekly intervals, resulting in sixteen treatment combinations per block. Grass dry matter yield increased significantly (P < 0.05) from 7,799 to 10,993 kg ha-1 and from 5,715 to 14,220 kg ha-1 when the interval between cuts extended from 3 to 12 weeks at the first and fourth harvest years, respectively. Pasture plots cut at 3- or 6- weeks intervals exhibited much greater weed proportion than those cut at 9-, or 12-week interval. The total annual herbage dry matter yield increased significantly (P < 0.05) from 8,564 to 11,312 kg ha-1 and from 6,814 to 10,268 in 2001 and 2004, respectively, when fertilizer N was increased from 0 to 450 kg N ha-1. A combination of 12-weekly interval of cut with 300 kg N ha-1 gave a significantly higher forage grass herbage dry matter yield compared with the values got from 3- or 6-weekly interval combined with any N rate. Fertilizing at 300-450 kg N ha-1 when combined with cutting at 9 to 12-weekly interval between cuts was more effective in suppressing growth and proportion of weeds.

Keywords: Defoliation frequency, pasture, fertilizer-N, dry matter yield.