Effect of Competition on Nitrogen Status of Soybean (Glycine max (L) Merrill) and Millet (Panicum miliaceum L.) Intercropping under Low Input Agricultural System

This study was conducted to investigate the effect of interspecific competition on the biological nitrogen fixation of soybean and the role of Millet in improving the nitrogen efficiency index in different planting patterns of intercropping culture.The experiment was carried out as a randomized complete block design with four replications at the research farms of Sari University of Agricultural Sciences and Natural Resources in two years (2018-19). The experimental treatments were 0:100, 25:75, 50:50, 75:25, and 100:0 (Millet: Soybean respectively) based on replacement method.The different planting ratios had a significant effect on the average percentage of nitrogen derived from the atmosphere (Ndfa), the millet root activity, nitrogen efficiency index and the nitrogen yield content. The Ndfa percentage in different planting ratio was higher than the pure stand in the different growth stages. The nitrogen uptake index of Millet improved with increasing the number of planting rows in different ratios of intercropping. Increasing the Selection Effect (SE) of soybean at planting ratios of 25:75 and 50:50 (millet-soybean) reduced the nitrogen uptake efficiency of millet. Also, the planting ratio of 25:75 (millet-soybean) in the 90-day stage after planting had the lowest amount of root activity. The contribution of millet from the total amount of grain nitrogen in the planting ratio of 25:75 (millet-soybean) was less than one percent. Also, among the different intercropping ratios, the planting ratio of 75:25 (millet-soybean) with an average of 1.23 had a land equivalent ratio higher than one.