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Abstract:Two separate field experiments were undertaken during the rainy seasons (AugustDecember) of 2010 and 2011 at the Teaching and Research Farm of the Federal University of Agriculture, Makurdi, Nigeria. The objective of the study was to evaluate some landraces of bambara groundnut intercropped separately with cowpea and maize at varying planting densities for nodulation, nitrogen (N) yield and fixation. Each experiment was a 2 x 3 x 3 split-split plot set out in a randomized complete block design with three replications. Intercropping decreased the number and weight of nodules; nitrogen derived from the atmosphere and fixed in both bambara groundnut/maize and bambara groundnut/cowpea intercropping systems. No significant differences were noticed between the landraces in N content of shoot and roots, but 'Okirikiri' had significantly higher N content (3.11 %) of pod with seed than the other two landraces. 'Okirikiri' and 'Adikpo' landraces fixed more N than 'Karo'. N fixed increased with decline in bambara groundnut planting density. Mean percentage of plant N derived from atmosphere varied from 49.80 in the bambara groundnut/maize systems to 56.80 in the bambara groundnut/cowpea intercrops, while N fixed was 11.27 kg/ha and 34.90 kg/ha in the respective intercrop systems. The expectation of enormous contribution of nitrogen fixation to bambrara groundnut yields and its residual effects on soil medium for ensuing crops may be an illusion with the use of the landraces tested in this work, except, probably when inoculated with the appropriate rhizobia?

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A field experiment was conducted in 2010 and 2011 at the Teaching and Research Farm, FederalUniversity of Agriculture, Makurdi, Nigeria. The aim was to determine the suitability of some landraces of bambara groundnut for intercropping at varying planting densities with maize. The experiment was a 2×3×3 split-split plot laid in a randomized complete block design with three replications. Intercropping decreased number of pods and grain yields of bambara groundnut component. Number of pods and grain yields increased with increased planting density. Productivity indices indicated that bambara groundnut/maize intercropping was productive, and maize was the dominant component. The marginal rate of returns for the best combinations was 116.13%, suggesting profitability of the intercropping systems.

Field trials were conducted during 2011 and 2012 cropping seasons at the Teaching and Research Farm of the University of Agriculture Makurdi, Benue State located in Southern Guinea Savanna of Nigeria. The objective of the study was to evaluate the response of some improved sweet potato varieties planted at three densities to intercropping with soybean. The experiment was a 2x3x3 split-split plot laid out in a randomized complete block design with three replications. The main plot consisted of two cropping systems [sole cropping (sweet potato, soybean) and intercropping (sweet potato + soybean). The sub-plot consisted of three sweet potato varieties (CIP440037, NRSP/05/007C and CIP440141). The sub-sub-plot treatment comprised of three sweet potato planting densities (25,000 plants/ha, 33,000 plants/ha and 50,000 plants/ha). Intercropping severely depressed the yields of both sweet potato varieties and the soybean component, such that intercrop yields were rarely above 50% of sole crop yields, irrespective of the sweet potato variety used. The number and weight of the sweet potato component was not significantly affected at the planting density of 50,000 plants/ha. Indices used to measure intercrop advantage showed that intercropping these sweet potato varieties with soybean was biologically efficient and percentage land saved varied from 23.08 and 32.43. Soybean was more competitive than sweet potato at all densities tested.