Maize and pigeon pea sole crop and intercrop nutrient response functions for Tanzania

Low soil fertility constrains crop productivity in Tanzania. Fertilizer recommendations were lacking for pigeon pea (Cajanus cajan (L.) Millsp.) sole crop (PPSC) and intercrop. Trials were conducted in eastern and northern Tanzania to determine: maize (Zea mays L.) (MSC), PPSC and intercrop (MzPpI) nutrient response functions; the agronomic and economic efficiency for applied nutrients; other nutrient deficiencies; and a means of calculating MzPpI response functions from MSC functions. The treatment structure allowed for determination of MSC and MzPpI response functions for N, P and K and of PPSC functions for P and K. Overall mean PPSC yield was 2.31 Mg ha(-1) with a 12% increase due to applied P. Yield of MSC was increased by N only and of MzPpI by N and P, although intercropped pigeon pea yield was not affected by nutrient application. Yields were not increased with K, Mg, S, Zn, and B application. Yield of MzPpI, as maize grain value equivalent, was more than with MSC but response to N were similar. The agronomic efficiency of fertilizer N at the economically optimal rate (EOR) for MSC was 32 kg kg(-1). The EOR of N were similar for MSC and MzPpI and was on average 27 kg ha(-1) less for the most compared with the least costly fertilizer N scenario with 3% less yield with the lower EOR. The coefficients for MzPpI N and P response functions can be estimated from MSC functions, hence reducing field research requirements for optimization of fertilizer use for MzPpI.