Effect of Intercropping and Crop Arrangement on Yield and Productivity of Late Season Maize/soybean Mixtures in the Humid Environment of South Southern Nigeria

Field experiments were carried out between September and December in 2007 and 2008 at Akamkpa (150 15'' N; 80 22'' E), Nigeria. The objective was to investigate yield and productivity of maize and soybean as sole crops and as additive mixtures (100:100) in response to five levels of nitrogen (0, 25, 50, 75 and 100 kg/ha) and five crop arrangements (sole maize at 53,333 plants/ha, sole soybean at 266,666 plants/ha and maize: soybean intercrop arrangements of 1:1, 2:2 and 1:2). The trial was a split-plot design in a randomized complete block with nitrogen in main plot and crop arrangement in sub-plot, with three replications. Intercropping had no significant effect on grain yield of maize in 2007. In 2008, maize grain yield grain yield reduction in mixture was 6 percent compared to sole cropping. Soybean seed yield reduction in mixture was 32 and 43 percents in 2007 and 2008, respectively. Crop arrangement significantly influenced yield components and yield in both maize and soybean. Planting maize and soybean in 1:1, 2:2 or 1:2 arrangement had no significant effect on maize in 2007 but depressed grain yield of maize by 38, 35 and 14 percents in 2008. Spatial arrangement of maize and soybean in 1:1, 2:2, and 1:2 depressed soybean yield by 51, 44 and 45 percents in 2007 and by 86, 64 and 73 percents in 2008. Intercropping reduced the relative maize grain yield by only 1 percent in 2007 and from 4 to 9 percents in 2008. Soybean relative yields were from 31 to 34 percent lower than sole crop yield in 2007 and 39 to 46 percent lower in 2008. The relative yield totals for both 2007 and 2008 were well above unity, an indication that the system was highly productive. This implies that intercrops were 64, 66 and 63 percents in 2007 and 43, 57 and 65 percents in 2008, more productive than the sole crops at 2:2, 1:2 and 1:1 arrangements, respectively. Late season maize and soybean may be planted in 2:2 or 1:2 arrangements to take advantage of optimum soybean seed yield and 65-100 percents of the maize grain yield in the humid South Southern Nigeria.