International Journal of Agriculture and Environmental Research ISSN: 2455-6939 Volume:03, Issue:02 "March-April 2017" www.ijaer.in Copyright © IJAER 2017, All right reserved Page 2655 CONTRIBUTION OF PIGEON PEA ROOTS TO NITROGEN AND PHOSPHORUS YIELDS IN THE PIGEON PEA-GROUNDNUT INTERCROP SYSTEM Austin T. Phiri* 1 , Ray R. Weil 4 , Jerome P. Mrema 2 , Enerst Semu 2 , G.Y. Kanyama-Phiri 3 , Julie Grossman 5 and Rebbie Harawa 6 1 Bvumbwe Agricultural Research Station, Box 5748, Limbe, Blantyre, Malawi 2 Sokoine University of Agriculture P.O. Box 3000 Morogoro, Tanzania 3 Lilongwe University of Agriculture and Natural Resources, Bunda Campus, P.O. Box 219, Lilongwe, Malawi 4 University of Maryland College Park, Md, 20742, USA 5 University of Minnesota 454 Alderman Hall, Department of Horticultural Science, University of Minnesota, 970 Folwell Avenue, St Paul MN 55018, USA 6 Alliance for a Green Revolution in Africa West End Towers, 4th Floor, Kanjata Road, Off Muthangari Drive, P.O. Box 66773, Westlands 00800, Nairobi, Kenya. *Corresponding Author ABSTRACT A study aimed at the assessment of the contribution of pigeon pea roots to N yield for the pigeon pea was conducted at Chitedze Agricultural Research Station (S 13 0 59’ 23.2”, E033 0 38’ 36.8”), Malawi in the 2012/2013 cropping season. Ten treatments, replicated three times were laid in a randomized complete block design. 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. Some of the plots were treated with triple super phosphate (TSP) at the rate of 25 kg P ha -1 . Analysis of soil samples collected in all treatment plots indicate that the soil had low fertility, having; low organic carbon (1.4 %), low cation exchange capacity (CEC) (NH4OAc) (3.5-3.6 cmol (+) kg -1 soil) and low N (0.12%), while plant available phosphorus (Mehlich 3) was marginally adequate both in the top and sub soil (μ=21.5 mg P kg -1 and 22.1 mg P kg -1 ). Assessment of pigeon pea