RESPONSE OF DRY SEASON SORGHUM TO SUPPLEMENTAL IRRIGATION AND FERTILIZER-N AND FERTILIZER-P ON VERTISOLS IN NORTHERN CAMEROON

A series of trials was conducted to quantify response of dry season tr ansplanted sorghum to water and fertilizer application in order to tes t the hypothesis that soil moisture limits production more than nutrie nt supply. The trials were conducted at two field sites representative of a large land area in the Lake Chad Basin of Africa. Water was clea rly the limiting factor as grain yield response to two irrigations (10 cm total) was a statistically significant 58% over 3 years. One irrig ation during vegetative growth resulted in sorghum grain yield increas es of 24-29%. Response to P fertilizer was negligible. Response to N f ertilizer was 32% over three environments but was not statistically si gnificant at P<0.05. Future research should focus on improvements in s oil moisture availability, either through increased soil moisture stor age or through reduced evaporative losses.