ABSTRACT

 Studies on the effect of alley cropping system on the productivity of arable crops (60-day cowpea and 1TA 331 upland rice cultivar) and plantain cultivars (Agbagba, PITA 14 and PITA 17) were undertaken at Umudike, Nigeria. A 5 x 3 factorial experiment in randomized complete block design (RCBD) with three replications was used to evaluate the effect offour alley woody species (Cajanus cajan, Flamingia macrophylla, Gliricidia sepium, Leucaena leucocephala) and control — Zero alley woody species, on the grain yields of 60-day cowpea, 1TA 331 upland rice and the three plantain cultivars (Agbagba, PITA 14 and PITA 17). Alley species had no significant effect on the yields of the 60- day cowpea and the ITA 331 upland rice in 2006 and 2007. The grain yields of cowpea and the upland rice were significantly higher in 2007 than in 2006. Cajanus cajan had significantly higher leaf + twig biomass in 2006 and 2007 than F macrophylla, L leucocephala and G. sepium which had statistically similar leaf + twig biomass. Leaf number and leaf area as well as the number of suckers produced by plantain cultivars were not significantly affected by Alley species plantain cultivars and Alley species X plantain cultivars treatment interactions. Agbagba and PITA 17 plantain cultivars gave significantly the highest and least plantain bunch yields respectively. The leaves of the four alley woody species utilized in this study had comparatively high nutrient contents - N(2.73 - 3.85%), P(0.23 - 0.34%), K(0.65 - 0.84%), Na(0.l8 - 0.50%), Ca(2.82 - 4.01%), Mg(1.22 - 1.58%) and high nutritive values, dry matter content (89.90 - 93.20%), mineral ash (4.80 - 6.80%), crude fiber (6.80 - 9.28%), organic matter (17.36 - 28.30%), carbohydrate (59.18 - 64.48%), fat/oil (1.28 - 2.14%), crude protein (17.06 - 24.06%), nitrogen free extract (52.38 - 57.04%), energy value (344.50 - 364.20 g-cal '), including vitamin contents — vitamin C (30.80 — 48.40mg 100g '), riboflavin (0.02 — 0.32mg 100g ■'), thiamine (1.18 - I.50mg 100g "'), niacin 2.22 - 3.03mg 100g ’’), Bcarotinoid (65.69 -88.74 p), In 2006. the pre-alley cropping study site had some heavy metal contents, namely: Fe, Pb, Zn, Cn, Ni and Cd. However, in the post-alley cropping site in 2007, the heavy metal contents significantly decreased due to litter decomposition of leaf prunnings, nutrient cycling and absorption in the soil.