The effects of close grazing and cutting on the yield, persistence, and nitrogen content of four tropical legumes with Rhodes grass at Samford, south-eastern Queensland

Abstract

Four legumes, Lotononis bainesii, Ghcine javanica cv. Cooper, Phaseolus atropurptreus cv. Siratro, and Desmodium uncinatm cv. Silverleaf were grown with Rhodes grass (Chloris gayana). Under the frequent regular defoliation by grazing sheep, or by cutting at two inches, yield of all legume species steadily declined, and there was no difference between the effects of grazing and those of cutting. G. iavanica was more persistent under grazing and also in the undefoliated plots than the other species. White clover volunteered in the defoliated treatments and its dry matter yields were sometimes higher than the sown legume yields. Clover yield in the grazed plots was about twice that in the cut treatments and this was reflected by a higher nitrogen content, and subsequently a higher yield, in the grass component of the grazed plots. No positive differences could be detected between the effects of the four legumes on grass nitrogen or yield. On the undefoliated plots the legumes became dominant and suppressed the grass, except for L. bainesii, which almost disappeared in all plots.