Intercropping Millet with Soybean for Forage Yield and Quality.

Intercropping millet (Pennisetum glaucum) with soybean (Glycine max Var.Williams) may increase forage yield and quality of millet and soybean due to efficient use of resources in intercropping ratios. The objectives of this study were to evaluate the effects of nitrogen fertilizer and different planting patterns on forage yield and quality of millet-soybean intercrops. Two field experiments were conducted at the research farm of University of Tehran in 2007 and 2009 growing seasons. Eighteen treatments were arranged in a four-replicated split plot with three levels of nitrogen (0. 37 and 74 kg ha^-1) as main plots and four intercropping ratios consisting of 50% millet:  50% soybean (one row of each plant), 50% millet: 50% soybean (two rows of each plant), 60% millet: 40%soybean, 40%: millet: 60% soybean along with pure stands of millet and soybean as subplot.  Nitrogen fertilizer increased forage dry matter of millet in consecutive years whereas, soybean showed a negative response to the higher nitrogen fertilizer. Due to higher monthly temperature and precipitation during the growing season in the first year, yields were higher in the first year compared to the second year. Regardless of sole cultures, highest forage dry matter of millet and soybean were recorded in %60 millet: %40 soybean and %40 millet: %60 soybean, respectively. Nitrogen fertilizer and intercropping ratios also affected crude protein (CP), dry matter digestivity (DMD) and water soluble carbohydrate (WSC), significantly. As nitrogen fertilizer was increased, CP was increased in forage samples of millet while there was not a significant increase in CP concentrations of soybean forage in 37 and 74 kg N ha^-1. In contrast, nitrogen decreased DMD and WSC concentrations in both plants. The highest amount of CP was obtained from the sole culture of soybean while the highest CP was observed in 50:50 ratios in millet compared to its sole culture. In this study, the LER exceeded unity, indicating the advantage of intercropping over sole cropping system.