Effect of Legume Integration and Phosphorus Use on Maize N and P Concentration and Grain Yield in Kabete - Kenya

Aims: Investigate effect of legume integration and phosphorus application on nitrogen (N) and phosphorous (P) concentration and yield of maize.

Place and Duration of Study: The study was carried out in Kabete Field Station of the University of Nairobi during the long (LRS) and short rainy (SRS) seasons of 2012.

Methodology: A split plot layout in a randomized complete block design (RCBD), with three replicates was used. The main plots were sole maize, intercropping (chickpea/maize; lupin/maize) and rotation systems (chickpea-maize; lupin-maize) systems. The sub plots were Minjingu rock phosphate (MPR) and triple superphosphate (TSP) fertilizers, applied at 60 kg P ha-1. Maize P and N concentrations were measured at seedling, mid-flowering and physiological maturity/harvest. Maize grain and dry matter (DM) yield were determined at physiological maturity.

Results: During the LRS, significantly (P=0.05) higher maize P concentrations were recorded in chickpea/maize intercrop (C/M) with TSP at seedling; sole maize, chickpea/maize (C/M) and lupin/ maize (L/M) intercrops, with MPR and TSP at mid flowering and L/M intercrop with TSP at harvest. In the SRS at seedling and harvest stages, significantly higher values were recorded in the lupin-maize rotation (L-M) with MPR. At mid flowering, significantly higher P values were observed in L/M with MPR. During the LRS, N concentration in maize was significantly higher in L/M with TSP and L/M with MPR at seedling and mid flowering stages, respectively. At harvest L/M with TSP had significantly higher values. In the SRS, maize N concentration was significantly higher in L-M and chickpea-maize (C-M) rotation with MPR and sole maize with TSP at seedling; and L/M with MPR and TSP, at mid flowering and harvest, respectively. During the LRS, maize grain yields were significantly higher in L/M with TSP and MPR and C/M with MPR. In the SRS, significantly higher maize grain yields were recorded in L/M with TSP and L-M with MPR. DM yields in the LRS were significantly higher in L/M with TSP applied. In the SRS, DM yields were significantly higher in L/M with MPR, C/M with MPR, L-M with MPR and C-M with MPR.

Conclusion: The integration of MPR or TSP and legumes increased maize N and P concentration and yields. The use of cost effective MPR in an intercropping system may be preferred by small holder farmers.