Tuesday, November 14, 2006 - 10:30 AM

Performance of Site-Specific Nutrient Management for Improving Productivity of Wheat under Rice-Wheat Cropping System in Punjab, India.

H.S. Khurana1, A.S. Sidhu2, Yadvinder Singh2, Bijay Singh2, and Steve Phillips1. (1) Virginia Tech, Dept of Crop and Soil Env Sciences, Eastern Shore AREC, Painter, VA 23420, (2) Punjab Agricultural Univ, Ludhiana-141004, Punjab, India

Yield increases in wheat (Triticum aestivum L.) under the rice-wheat cropping system in Punjab have slowed down in recent years. Further improvements are likely to occur in smaller increments through fine-tuning crop and soil management. For this, a new SSNM approach was planned and evaluated through on-farm experiments conducted for wheat crop from 2002 to 2005 at 56 farmers’ fields across six rice-wheat production domains of Punjab, India. Field- and season-specific NPK applications were calculated using Quantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) model. Nitrogen applications were fine-tuned based on field-specific monitoring of crop N status using chlorophyll meter while P and K applications were fine-tuned based on their respective input-output balances. Average wheat yield under SSNM increased by 0.5 Mg/ha (13%) compared to the current farmers’ fertilizer practice (FFP). These yield increases were associated with a 12% decrease in the average N rate and almost similar P rates but with larger amounts of fertilizer K as compared to FFP. Average N use efficiencies increased by 30 to 40%, mainly through the use of improved crop- and site-specific N management schemes. Compared to the FFP, N applications under SSNM were more uniform among farms, spread more evenly through the growing season and avoided heavy single applications at early growth stages. As a result, SSNM decreased the overall nitrate content in soil profile compared to the FFP but the effect was site-specific. Similarly, P and K balances became less negative under SSNM than under FFP by about 4 and 14 kg/ha, respectively.