Ammonia Emission from Rice–Wheat Cropping System in Subtropical Soil of India

Abstract

Ammonia (NH3) emission from rice (July–October) and wheat (November–April) cropping system was measured using the chemiluminescence method at the subtropical agricultural land of Delhi, India during 2009–2010 and 2010–2011. The measurement was carried out from the canopy height (1.2–1.3 m) during the different growth stages of rice and wheat crops to quantify NH3 emission and assess the variations in emission during the crop growth stages. The background atmospheric concentration of NH3 was measured at 5 m height at the study site and subtracted from the NH3 concentration at crop canopy height to quantify the emission of NH3 from crops. The NH3 emission in wheat crops were 35.9 ± 6.3, 24.5 ± 5.5, 15.8 ± 4.5, 18.6 ± 3.9, and 20.8 ± 3.8 µg m−2 d−1 during sowing, crown root initiation, panicle initiation, grain filling, and maturity stages, respectively. In rice crops, the emissions during transplanting, tillering, panicle initiation, grain filling, and maturity stages were 29.7 ± 7.4, 16.2 ± 3.7, 19.0 ± 3.7, and 18.4 ± 3.9 µg m−2 d−1, respectively. The emission was higher during sowing/transplanting compared to other stages in both the crops. About 9 % of applied fertilizer N was emitted as NH3 from the rice–wheat cropping system in the subtropical soils of India.