Direct and residual effects of phosphate fertilizer on maize (<i>Zea mays</i> L.) grown on an Ultisol in Kumasi, Ghana

Abstract

Long-term field experiments were conducted for 13 cropping seasons on a Typic Paleustult in Ghana to study response of maize (Zea mays L.) to P fertilization, evaluate the relative efficiency of broadcast versus band applications, estimate residual effects of applied P and determine the critical P level for maize. The results showed no significant direct effect of P fertilization on maize yield for the first four crops. Thereafter, grain yields consistently and significantly increased due to the residual effects of applied P and the effects increased as the broadcast rates increased but decreased when banded P rates increased. The overall residual effect of the banded P was significantly superior to the broadcast application. The critical P level for maize on this soil was estimated to be 12-16 ppm Bray 1 P. There was a significant direct effect of applied P on grain yield for the tenth through the thirteenth crops when the available P level in the soil was below the critical level.