Assessment of nutrient and biomass yield of medium and long duration pigeon pea in a pigeon pea-groundnut intercropping system in Malawi

Abstract

Preliminary assessment of the performance of the medium and long duration pigeon pea in a pigeon pea- groundnut intercropping system was conducted at Chitedze Agricultural Research Station (S 13 0 59’ 23.2”, E033 0 38’ 36.8”) in the 2011/2012 cropping season. An experiment involving eight treatments replicated three times in a randomized complete block design was established. Two pigeon pea varieties, long (ICEAP 04000) and medium duration (ICEAP 00557) and groundnut (CG 7) 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 pH was acid to moderately acid both in the top (mean=5.4-5.7) and the sub soil (mean=5.4-5.6) in all the treatment plots, with mostly low to marginally adequate total nitrogen content both in the top (mean=0.08- 0.14%) and the sub soil (mean=0.09-0.13%). The soil organic carbon content was medium in the top soil (mean=0.9-1.6%) as well as sub soil (mean=1.1-1.6%) across the treatment plots. At the same time soil phosphorus was low to marginally adequate in the top soil (mean=16.8-27.6 mg kg -1 ) and marginally adequate in the sub soil (mean=20.8-25.6 mg kg -1 ), suggesting low soil fertility. The assessment of the above ground groundnut biomass indicate a mean yield range of 479-656 kg ha -1 . While the assessment of the total biomass yield of the pigeon pea varieties indicate a mean yield range of 2,034-2,593 kg ha -1 . In terms of estimated nitrogen yields returned to the soil, the medium duration pigeon pea-groundnut intercrop (mean=50.6 kg N ha -1 ) and the long duration pigeon pea-groundnut intercrop (mean=49.6 kg N ha -1 ) gave significantly (p<0.05) higher yields than by the monocultures of long duration pigeon pea (mean=41.1 kg N ha -1 ) and medium duration pigeon pea (mean=41.0 kg N ha -1 ). Statistically (p<0.05), the lowest amount of estimated nitrogen yield was generated by the groundnut sole crop (mean=12.8 kg N ha -1 ). Overall, the intercrops showed yield advantage (total LER >1.0) compared with the monoculture on equal land area. For the Malawian smallholder farmers, this suggests that mineral N supplementation in a legume-cereal rotation system for enhanced crop productivity might be less in the double legume-cereal rotation mode than in a legume monoculture-cereal rotation system.