Nodulation, biomass production, nutrient accumulation, carbon:nitrogen ratio and decomposition rate of various green manuring crops in submerged rice (Oryza sativa) soil.

摘要

An experiment was conducted during the 2001 and 2002 kharif season at Pantnagar, Uttarakhand, Uttar Pradesh, India, to study nodulation, biomass production, nutrient accumulation, C:N ratio and decomposition rate of four widely grown green manure crops, namely Crotalaria juncea, Sesbania cannabina, Sesbania rostrata and Vigna unguiculata in silty clay loam soil, slightly alkaline in reaction (pH 7.3), medium in organic carbon (0.604%), low in available N (238.0 kg/ha), medium in available P (19.9 kg/ha), and K (150 kg/ha). These crops recorded significant variations in nodules per plant (12.5-56.5), fresh and dry weight (32-263 mg per plant), green (9.4-34.3 t/ha) and dry biomass production (2.1-6.8 t/ha). Sesbania cannabina at 60 days gave maximum nodules per plant (56) and nodules fresh weight (606 mg per plant) and nodule dry weight (263 mg per plant). While Crotalaria juncea at 60 days gave maximum green biomass (34.3 t/ha) and dry biomass (6.8 t/ha). Nitrogen content in all green manuring crops decreased with advancement in age. However potassium content (1.74-2.05%) continued to increase with age of crops. The C:N ratio widened (13.8-19.0) with advancement in age and the ratio narrowed with the advancement of time of their incorporation for decomposition. After 30 days of incorporation decomposition percentage was higher for 30 days old crop followed by 45 and 60 days old crop..