EFFECTS OF TILLAGE, CROPPING SYSTEM AND NPK FERTILIZER RATE ON PERFORMANCE OF MAIZE (Zea mays L.)/SOYBEAN (Glycine max L. (Merill)) INTERCROP IN THE GUINEA SAVANNAH AGROECOLOGICAL ZONE OF GHANA

Abstract

The study was conducted on the research field of Integrated Water and Agriculture Development (IWAD) located in the Mamprugu Moagduri District, Yagaba, during the 2015 cropping season. The study sought to determine the effect of tillage system, and NPK fertilizer on productivity and yield of maize-soybean intercrop system. The experimental design consisted of three factors: tillage system at three levels (plough, ripping and direct seeding), cropping system at two levels (sole maize and intercrop) and NPK fertilizer rate at three levels (0 kg/ha, half the recommended rate of 30-15-15 kg/ha and the full rate of 60-30-30 kg/ha). The treatments were laid out in a split-split plot design replicated three times. The tillage system was assigned to the main plot, cropping system to sub-plot and the NPK fertilizer rate being the sub-sub plot. Each sub-sub plot measured 5 x 5 m. A representative soil sample was taken before land preparation and after harvest. Two seeds of the maize variety (Pannar 35) were planted at a spacing of 80 cm x 20 cm. Soybean seeds were hand drilled at a spacing of 80 x 10 cm. Grain yield of maize was significantly influenced by sole fertilizer rate with highest yield occurring under the full rate (3.4 t/ha) compared to the half rate (2.7 t/ha), amounting to yield difference of 700 kg/ha. Yield of soybean under the integrated production was affected by interaction of tillage system and fertilizer rate. Highest yield was recorded under the ploughed condition at the full rate of fertilizer application, giving that production system the highest profit (3410 GHS/ha). Though sole maize, ploughed and with full rate of fertilizer application, gave similar benefit/cost ratio to the integrated production with half rate of fertilizer application, the intercropped system with half fertilizer rate resulted in 45% more increases in profit compared to the sole production with full fertilizer rate.