Pigeon pea-Groundnut Intercrop Maize Rotation Cropping System: A Tool for Improving Maize Production in Malawi

A two year study to investigate how to optimally utilize applied mineral nutrients by maize grown in rotation with pigeon peagroundnut intercrop is under way at Chitedze Agricultural Research Station (S 130 59’ 23.2", E0330 38’ 36.8"). An experiment with eight treatments replicated three times in a randomized complete block design has been established. Two pigeon pea varieties, long and medium duration and groundnut (CG7) were grown as monocultures and intercrops. The intercrops involved planting either of the pigeon pea varieties with groundnut. Baseline soil data indicate that the soil is acid (mean pH=5.3), with low N (mean %N = 1.33), marginally adequate P (mean = 21.7 ug/g) and low organic carbon (mean %OC= 1.5%), suggesting low soil fertility. Grain yield assessment for the groundnut indicate a mean yield range of 549-873 kg/ha across the treatments with mean biomass yield range of 413-656 kg/ha. Extremely low pigeon pea grain yield was observed in the two varieties (mean range of 3-227 kg/ ha), attributed largely to late planting that resulted into flower abortion and poor pod filling. Initial assessment of the biomass from the defoliating leaves of the pigeon pea varieties indicate a mean yield range of 1,047-2,114 kg/ha. Nutrient analysis of the yield components in this system is underway for quantificationof nutrient uptake and partitioning to the grain by the legumes. The pigeon pea has since been ratooned with its biomass and that of groundnut incorporated into the soil. Maize will be planted in the second season thus transforming the system into a maize pigeon pea intercrop. A detailed study on the decomposition and mineralization pattern of nutrients from the incorporated biomass and subsequent uptake by the maize crop will be conducted in the second season. Mineral fertilizer will be applied at different rates to maize for the assessment of the potential to improve nutrient use efficiency by the maize crop in this system.