Effects of Intra-Row Spacing of Pearl Millet (Pennisetum glaucum (L.) R.Br.) and Cropping Systems on Growth and Yields of Soybean-Pearl Millet Intercrop, in the Southern Guinea Savanna, Nigeria

Field experiments were separately conducted from June to November, in year 2012 at the Research Farm, University of Agriculture, Makurdi, Nigeria and at a Farm in Ibi, Nigeria, to evaluate the effects of intra-row spacing of pearl millet and cropping systems on growth and yields of soybean-pearl millet intercrop, as well as assessing the yield advantages of the intercropping system. The experiment was a 2 x 4 factorial combination of treatments, fitted in a randomized complete block design (RCBD), with four replications. The cropping systems constitute the soles and the intercrop, while the intra-row spacing of pearl millet into soybean were at 15 cm, 20 cm, 25 cm and 30 cm. Results of study showed that sowing pearl millet into soybean at the intra-row spacing of 30 cm produced the highest pearl millet yields of 4.7 t ha-1 and 4.9 t ha-1 respectively, at Makurdi and Ibi locations, as well as producing the highest soybean yields at both locations. In Makurdi, intercropping pearl millet with soybean significantly (P ≤ 0.05) decreased yield of pearl millet by 32.4 % and that of soybean by 29.4 % compared to sole cropping of the component crops, while at Ibi, intercrop yields of pearl millet and soybean were respectively reduced by 35.9 % and 30.0 % compared to their sole yields. Sowing pearl millet into soybean at the intra-row spacing of 30 cm also gave the highest total intercrop yields, highest land equivalent coefficient (LEC) values, highest land equivalent ratio (LER) values of 2.97 and 2.71 and highest percentage (%) land saved (66.3 % and 63.1 % respectively, recorded at Makurdi and Ibi locations). The implication of study showed that it is most advantageous having both crops in intercrop when pearl millet was sown into soybean at the intra-row spacing of 30 cm. This should therefore, be recommended for the southern guinea savanna, Nigeria.