Controlling Cyperus rotundus by direct seeding in cotton crops in Brazil

摘要

Weeds cause considerable crop damage in tropical countries. Cyperus rotundus is one of the most widespread species and is commonly found on highly fertile soils, and in sugarcane, fruit, cotton and soyabean crops. Chemical control is costly, not always technically satisfactory, and poses problems for subsequent crops. Direct seeding on a permanent plant cover is an effective way of controlling Cyperus more cheaply without completely eradicating it, due to shading and allelopathic effects. Such systems were set up by CIRAD and the Maeda group in northern Sao Paulo state, Brazil, in cotton crops with a dead guinea sorghum cover. Seed cotton yields varied from 2500 to over 3000 kg/ha, with production costs of around dollar 900/ha and net margins of dollar 600 toover dollar 800/ha. This trial demonstrated the merits of direct seeding as a weed control method.