Journal of Biology, Agriculture and Healthcare www.iiste.org ISSN 2224-3208 (Paper) ISSN 2225-093X (Online) Vol.5, No.8, 2015 156 Effect of Low Rates of Nitrogen and Phophorus Fertilizers on Growth and Yield of Intercropped Pigeonpea with Sorghum in Makurdi, Nigeria Moses Onyilo Egbe 1* , Nmadzuru Badeggi Ibrahim 2 and Fidelis Terngu Aor 3 1&3. Department of Crop Production, University of Agriculture, P.M.B.2373,Makurdi,Nigeria 2. Department of Soil Science, University of Agriculture, P.M.B.2373,Makurdi, Nigeria *E-mail of the corresponding author: onyiloegbe@yahoo.co.uk Abstract Nitrogen (N) and phosphorus (P) are the most limiting nutrient elements in the soils of the tropics. A field experiment was conducted at the Teaching and Research Farm of the University of Agriculture, Makurdi during the 2013 and 2014 cropping seasons to determine the influence of low rates of nitrogen and phosphorus fertilizers on the performance of pigeonpea intercropped with sorghum. The treatments comprised of two cropping systems (sole and intercropped pigeonpea with sorghum) in factorial combination with two nitrogen rates (10, 15 kg/ha), two phosphorus rates (20, 30 kg/ha) and N + P (N10P20, N10P30, N15P20, N15P30) and the check (N0P0) laid out in Randomized Block Design. The treatments were replicated three times. Results indicated that intercropping decreased pigeonpea nodule number and root weight at 50%flowering, dry pod and grain weights at harvest. The combinations of N and P fertilizers produced significantly higher nodule number, root weights, dry pod and grain weights of pigeonpea than either N or P alone in both cropping systems. N10P30 produced significantly higher dry grain yield of pigeonpea than all other treatments, except N15P20 and N15P30. Sorghum grain yield was highest at N15. These results showed that low rates of N and P has potential for the production of intercropped pigeonpea with sorghum. The significant interaction between cropping systems and fertilizer indicated further research needs for intercropping systems as distinct from monoculture. Key words: nitrogen, phosphorus, pigeonpea, sorghum, intercrop 1. Introduction The decline in soil productivity in the tropics and particularly in dry land areas continue to be a major concern due to its direct implication on food security. Mixed culture of legumes and cereals is a common practice in tropical agriculture that serves as a solution to infertile soils (Olujobi and Oyun, 2012). Egbe and Bar-Anyam (2010) reported that reasonable yields are obtained from pigeonpea/sorghum intercropping with zero fertilizer application in the Southern Guinea Savanna ecology of Nigeria. This is because legumes such as pigeonpea meet some of their N requirement through N 2 fixation, thus sparing some of the soil N to the subsequent crops in addition to the residual N that accrues, due to nodule decay, senescence and fallen leaves. However, the amount of soil nutrients supplied by these systems is not sufficient to solve the crop productivity problem in a sustainable manner because of sustained nutrient export in harvested products (Sanginga et al., 1997). To feed the continuously growing world population requires sustainable food production in both nutrient stressed environments (low-fertility soils) and fertile soils. It is therefore important to add fertilizers to our crops to ensure higher yields. Nitrogen (N) and Phosphorus (P) are the most limiting nutrient elements in the soil of the tropics. However the costs of these N and P fertilizers are continuously increasing due to limited supply. Farmers resort to zero application of fertilizers to their farms since they cannot afford these fertilizers in the needed quantities. However, a potential for high yields may exist even when low rates of these fertilizers are applied in some crops. Low N and P in nutrient stressed environments have been reported to increase yields by some researchers (Nakano et al., 2002). This study therefore sought to explore this possibility through the use of pigeonpea and sorghum intercropping at low rates of fertilizer. The objective of the study was to determine the influence of low rates of nitrogen and phosphorus fertilizers on the performance of pigeonpea intercropped with sorghum in Makurdi environment. 2. Materials and methods A field experiment was conducted during the growing seasons of 2013 and 2014 at the Teaching and Research farm of the Federal University of Agriculture, Makurdi (Latitude 07 ° 45`-07 ° 50` N, Longitude 08 ° 45`-08 ° 50 E, elevation 98m) in Benue State, located in the Southern Guinea Savanna of Nigeria. The objective of the experiment was to determine the influence of low rates of nitrogen and phosphorus fertilizers on the performance of pigeonpea intercropped with sorghum.