Effect of phosphorus application and soybean cultivar on grain and dry matter yield of subsequent maize in the tropical savannas of north-eastern Nigeria
Soybean can contribute to soil N, which may partly be used to improve maize production in northeast Nigeria. However, the efficiency of soybean to fix N can be limited by soil P deficiency. This studyevaluated the effect of P application and soybean cultivars on dry matter and grain yield of subsequent maize for two years (2005 - 2006) at Miringa and Azir. Experimental design was a split-plot with threereplications. The main plots contained P levels of 0, 20 and 40 kg P/ha and subplots had four soybean cultivars. Maize was planted in the harvested soybean plots. Application of P to soybean at 20 and 40kg/ha significantly increased dry matter and grain yield of succeeding maize. Differences in grain yield were significant between all P rates in Miringa (2005) and Azir (2006) but only between 0 and 40 kg P/hain Azir (2005) and Miringa (2006). The grain yields of maize following late-maturing soybean cultivars were significantly higher than those following the early maturing cultivars in 2005. The maize yieldincreases could however, not be explained by total soil N, available P, and N and P uptake. Other rotation effects beyond N supply by the preceding soybean may be responsible for the yield increasesof maize
