Legume Nitrogen Derived from Different Sources as Affected by Rhizobial Inoculant in a Bangladesh Soil

摘要

Field experiments were conducted to study the effect of rhizobial Inoulant on the quantity of legume nitrogen (N) derived from different sources using nitrogen-15 (15N) tracer. Three different legumes (ntil,mungbean and soybean) were tested with and without rhizo-inoculant in 15N isotope treated micro-plots laid out in a split-plot arrangement and a randomized complete block design with three replications and a non-nodulated wheat crop included as reference in aseparate plot. Results showed that soybean produced the maximum number of nodules (33.4 nodules per plant) and the highest nodule dry weight (190.5 mg/plant) under inoculated conditions. The maximum total N recorded in inoculated soybean seed and stover were 112.6 and 77.0 kg N/ha, respectively, while the minimum values of 23.0and 18.1 kg N/ha were obtained from un-inoculated mungbean. Nderived from the atmosphere (Ndfa) ranged from 25.9 kg N/ha in un-inoculated mungbean to 159.6 kg N/ha in inoculated soybean. Due to inoculation, Ndfa increased by 123.87, 118.52 and 212.18 percent in lentil, mungbean and soybean, respectively. The maximum N derived from the soil (Ndfs) was 34.3 kg N/ha in un-inoculated soybean, while the inoculated mungbean derived the lowest N (10.4 kg N/ha) from the soil.The study revealed that all legumes received more N from fertilizer sources under un-inoculated than inoculated conditions. However, under inoculated conditions most (80.7-84.1 percent) of total plant N came from the atmosphere. With inoculation, comparatively less N was taken by the legume plants from soil (12.2-14.8 percent) and fertilizer (3.6-4.3 percent) sources.