Assessment of ammonia volatilization from paddy fields under crop management practices aimed to increase grain yield and N efficiency

By improving fertilization, irrigation and crop cultivation managements, rice yield and N efficiency can be increased to some extent. However, the environmental impacts under different integrated management have been rarely evaluated. Field experiments with four management practices were conducted in the Taihu Lake region to assess an important N loss pathway from paddy fields-NH3 volatilization for two consecutive rice seasons. The four treatments included control with 0 N fertilizer (CK), local conventional production practice (CT), integrated high-efficiency practice (HE), and high-yield practice (HY) with more nutrient inputs (relative to CT). NH3 volatilization was measured and plant samples were collected for determining the dry matter yield and apparent nitrogen recovery (ANR) efficiency. During the two rice-growing seasons, the HE treatment had 47.8 and 39.7 percentage points lower total NH3 losses, whereas the HY treatment had 12.6 and 48.9 percentage points higher those than the CT treatment. The HE and HY treatments resulted in significantly higher grain yield and ANR in the two seasons. The HE treatment had 11.1 and 18.0 percentage points higher yields than CT, while the HY treatment had 34.6 and 40.4 percentage points higher those than the CT treatment in the 2 years. The ANR was improved by 9.2 and 26.2 percentage points for the HE treatment, and by 9.4 and 15.6 percentage points for the HY treatment compared with the CT treatment. Furthermore, the ratio of ammonia emission to grain yield for HE treatment was 53.6 and 49.1 percentage points lower than CT treatment, and 44.2 and 51.8 percentage points lower than HY treatment during the two seasons, respectively. Therefore, the integrated high-efficiency practice is effective in reducing NH3 loss and increasing rice yield and nitrogen use efficiency (NUE), and can be used for the sustainable development of rice production systems in the Taihu Lake region. (C) 2013 Elsevier B.V. All rights reserved.