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| Characteristics and determinants of nitrogen and phosphorus runoff losses under different agronomic measures in double cropping paddy fields |
| Received:May 30, 2019 |
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| KeyWord:nitrogen;phosphorus;runoff loss;paddy fields;agronomic management factors |
| Author Name | Affiliation | E-mail | | YANG Kun-yu | Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
University of China Academy of Sciences, Beijing 100049, China | | | WANG Mei-hui | Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
University of China Academy of Sciences, Beijing 100049, China | | | WANG Yi | Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China | wangyi@isa.ac.cn | | YIN Li-ming | Hunan Institute of Water Resources and Hydropower Research, Changsha 410007, China | 921792236@qq.com | | LI Yong | Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China | | | WU Jin-shui | Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China | |
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| Abstract: |
| The typical central subtropical double-cropping rice ecosystem was observed in the Changsha County, Hunan Province, to determine the effects of different agronomic measures (e.g. fertilization, water management, straw returning, and bio-charcoal application) on nitrogen (N) and phosphorus (P) runoff losses, and to identify the key determinants of the NP runoff losses through the redundancy analysis method (RDA). The results suggested that:The total-N (TN) concentrations in surface ponding water peaked one day after fertilization (base fertilizer, tiller fertilizer, and heading fertilizer) under different agronomic measures in the paddy fields, and then decreased to a stable level 10 days after fertilization; the total-P (TP) concentrations peaked one day after base fertilization during the early rice season, while peaked five days after base fertilization during the late rice season. The NP concentrations in surface ponding water were strongly affected by the agronomic measures. Under the intermittent irrigation condition, organic fertilizer application, straw returning, and bio-charcoal application reduced the TN concentrations by 34.05%, 15.34%~19.76%, and 15.46%~17.47%, respectively, and straw returning and bio-charcoal application decreased TP concentrations by 6.33%~8.76% and 9.09%~13.66%, respectively, compared with the conventional chemical fertilizer application. The TP and TN were lost mainly in chemical forms of ammonium-N and particle-P in surface runoff of paddy fields, and the period within 10 days after fertilization was the window period for the NP runoff losses, when occurred 82.53%~97.66% and 6.73%~47.02% of TN and TP runoff losses during the whole cropping season, respectively. The RDA indicated that application of organic fertilizer promoted the TN and TP runoff losses, application of bio-charcoal increased the TN runoff loss, and straw returning reduced the TN runoff loss, in the paddy fields. Based on the comprehensive consideration on the potential and actual effects, and practice feasibility of agronomic measures, implementing efficient water management (especially during the window period) and straw returning should be the suitable strategy for preventing the NP runoff losses in the double rice ecosystem fields in the central subtropics. |
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