Effects of Intra-Row Spacing of Pearl Millet (Pennisetum glaucum (L.) R. Br) and Cropping Systems on the Productivity of Soybean-Pearl Millet Intercropping System in a Southern Guinea Savanna Location, Nigeria. (Part I)

A field experiment was conducted from June to November, during the 2013 and 2014 cropping seasons at the Research Farm, University of Agriculture, Makurdi, Nigeria, to evaluate the effects of intra-row spacing of pearl millet and cropping systems on the productivity of soybean-pearl millet intercrop and to assess the yield advantages of the intercropping system. The experiment was a 3x4 factorial arrangement of treatments, fitted in a randomized complete block design (RCBD), replicated four times. The cropping systems (sole soybean, sole pearl millet and soybean-pearl millet intercrop) constituted the main plots, while the intra-row spacing of pearl millet (15 cm, 20 cm, 25 cm and 30 cm) into soybean were allocated to the subplots. Results of study showed that to maximize intercrop yields of soybean and pearl millet in a soybean-pearl millet intercrop, the optimal intra-row spacing for pearl millet is 30 cm. Intercropping soybean and pearl millet significantly (P ≤ 0.05) reduced yields of soybean (25.0 % and 22.2 % respectively, in years 2013 and 2014) and that of pearl millet (34.4 % and 33.3 % respectively, in years 2013 and 2014). Though, the highest land equivalent ratio (LER) values, highest land equivalent coefficient (LEC) values and lowest competitive ratio (CR) values were recorded for pearl millet sown into soybean at the intra-row spacing of 15 cm, however, highest aggressivity was obtained sowing pearl millet into soybean at the intra-row spacing of 25 cm, the level at which both crops dominated each other.