Imapct of 10-Year Rice-Wheat Cropping System and Integrated Nutrient Management on Soil Properties and Crop Productivity in a Gypsum Amended Sodic Soil.
Anand Swarup Sr. and N.P.S Yaduvanshi. Central Soil Salinity Research Institute, Zarifa Farm, Kachwa Road, Karnal, 132001, India
Rice-wheat cropping system is predominant in the Indo-Gangetic Plains of India. The decline or stagnation in the yield of this system has been observed and ascribed to decrease in soil C and N and imbalance fertilizer use. We evaluated the impact of using organic/green manures in conjunction with inorganic fertilizers for 10 years (1994 – 2003) on the productivity of rice (Oryza sativa L.) – wheat (Triticum aestivum L.) system in gypsum treated sodic soil at experimental farm of Central Soil Salinity Research Institute, Karnal, India. The experimental soil (Acquic Natrustalf) had pH 8.7, exchangeable sodium percentage (ESP) 18.0, organic carbon 3.2 g kg-1, available P 11.8 kg ha-1 , available K 220 kg ha-1 , DTPA Zn 0.79 mg kg-1, DTPA Mn 3.7 mg kg-1 and DTPA Fe 4.5 mg kg-1. The treatments consisted of: T1, Control; T2, N120 kg ha-1; T3, N120 P26 kg ha-1; T3, N120 P26 K42 kg ha-1; (100% recommended); T5, N60 P13 K21 kg ha-1; (50% recommended); T6, T5 plus in-situ Sesbania aculeata green manuring before rice; T7, T4 plus in-situ Sesbania aculeata green manuring before rice; T8, T5 plus Farm Yard Manure (FYM) @ 10 Mg ha-1 before rice; T9, T4 plus FYM @ 10 Mg ha-1 before rice and T10, N180 P39 K63 kg ha-1; (150% recommended). The FYM was applied 15 days before transplantation of rice. In situ Sesbania aculeata was grown as a Green Manure (GM) crop every year (May to June) and incorporated before rice transplanting. Standard agronomic practices were followed for raising rice (July to October) and wheat (November to April) every year. Results showed that both rice and wheat responded significantly to fertilizer N and P. There was no response to K fertilizer. Increasing the dose of NPK from 50% to 100% and 150% significantly enhanced the grain yield of rice. However, there was no significant difference in the yield of wheat amongst 100 and 150% NPK. Highest yield of both crops was obtained with 100% NPK combined with GM or FYM. The results further showed that rice and wheat yields could be maintained even at 50% of the NPK dose when used in conjunction with FYM or GM. Incorportion of GM or FYM resulted in build-up of soil organic carbon,available N, P, K and Zn and greater nutrient uptake by the crops. The results suggest that integrated nutrient management is extremely important for sustaining rice-wheat system and improving fertility of sodic soils.