Influence of long-term use of inorganic and organic manures on soil fertility and sustainable productivity of rice (Oryza sativa) and wheat (Triticum aestivum) in Inceptisols

The effect of a permanent plot long-term field experiment of integrated nutrient management of farmyard manure, green manure and composted rice straw with inorganic fertilizers on sustainable productivity and soil properties in rice (Oryza sativa L.)–wheat (Triticum aestivum L. emend. Fiori & Paol.) cropping system was studied after 16 years of cropping cycles on Inceptisols. The experiment is in progress since 1991 at Indira Gandhi Krishi Vishwavidyalaya, Raipur. Over 16 years of the study period, highest rice and wheat yield was obtained when 50% of N was supplied through green manure in conjunction with 50% of NPK through inorganic fertilizers (50% recommended dose of fertilizer+ 50% N-green manure). Significant residual effect of green manure was also observed on the following wheat crop, 50% recommended dose of fertilizer + 50% N (green manure) also maintained the sustainability of the system. The sustainable yield index of rice and wheat was registered to 0.78 and 0.44 and 0.84 and 0.45 in the treatment of 100% recommended dose of fertilizer to both the crops and 50% recommended dose of fertilizer+ 50% N (green manure) in rice and 100% recommended dose of fertilizer in wheat as compared to 0.30, 0.19 and 0.64 and 0.33 in the control and farmer’s practice, respectively. In-situ application of green manure along with 50% of recommended dose of fertilizer is the most favourable treatment to have highest available N (255 kg/ha) in surface soil. The results show that available P content of soil increased significantly with farmyard manure, composted rice straw and green manure in conjunction with 50% recommended dose of fertilizer over initial value and control. Continuous use of fertilizers and intensive cropping had resulted in lowering the available K status of soil indicating the need of application of K to meet the crop requirement. While pH and EC were almost remained constant irrespective of the treatments.