Research article

N₂O emission in relation to plant and soil properties and yield of rice varieties

¹ Department of Environmental Science, Tezpur University, Tezpur-784028, Assam, India
² National Physical Laboratory, New Delhi, India

^* Corresponding author: kkbaruah2001@yahoo.com/kkbaruah@tezu.ernet.in

Accepted: 5 May 2010

Abstract

Nitrous oxide (N₂O) is a major greenhouse gas contributing to global warming. Rainfed rice fields are considered to be a notable source of atmospheric N₂O emission. To investigate the dynamics of N₂O emission and the relationship of plant and soil properties with emission of N₂O in rice, a field experiment was conducted. The five popularly grown rice varieties Luit, Disang, Kapilli, Siana and Phorma were grown in the fall season under rainfed conditions. N₂O emission was measured at seven-day intervals starting from the day of transplanting for the whole crop growing season. We also measured soil parameters, e.g. soil pH, soil temperature, soil organic carbon, soil NO-N, and field water level; and plant growth parameters: root-shoot dry weight, root length and leaf area. Our results show that N₂O emission from the plant varieties ranged from 1.24 μg to 379.40 μg N₂O-N m⁻²h⁻¹. Seasonal N₂O emission from the rice varieties ranged from 77 to 150 mg N₂O-N m⁻². Root dry weight, shoot dry weight, soil NO-N, root length, leaf area and field water showed relationships with N₂O emission. Root and shoot weight, soil NO-N and field water were found to be the main factors influencing N₂O emission. The varieties Phorma and Siana, with lower grain productivity but profuse vegetative growth, showed higher seasonal N₂O emission.