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| Effects of green manure on N runoff losses of rice system under reduced 40% chemical fertilizer input in the middle and lower reaches of the Yangtze River |
| Received:October 15, 2024 |
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| KeyWord:rice;green manure;runoff losses;nitrogen patterns;modeling |
| Author Name | Affiliation | E-mail | | ZHOU Guodong | College of Geography and Remote Sensing/College of Agricultural Science and Engineering, Hohai University, Nanjing 210024, China | | | LIANG Hao | College of Geography and Remote Sensing/College of Agricultural Science and Engineering, Hohai University, Nanjing 210024, China | haoliang@hhu.edu.cn | | WEI Cuilan | College of Environment and Ecology, Jiangsu Open University, Nanjing 210036, China | | | ZHOU Guopeng | School of Resource & Environment, Anhui Agricultural University, Hefei 230036, China | | | XU Changxu | Institute of Soil & Fertilizer and Resource & Environment, Jiangxi Academy of Agricultural Sciences, Nanchang 330200, China | | | GENG Mingjian | College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China | | | WU Ji | Institute of Soil and Fertilizer, Anhui Academy of Agricultural Sciences/Key Laboratory of Nutrient Cycling and Resource Environment of Anhui Province, Hefei 230031, China | | | CAO Weidong | State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China/Key Laboratory of Plant Nutrition and Fertilizer, Ministry of Agriculture and Rural Affairs/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China | caoweidong@caas.cn |
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| Abstract: |
| To provide a theoretical basis for accurately evaluating the environmental benefits of GM in paddy fields. In this study, we used a multi-point network observation investigate the effect of GM combined with reduced N fertilizer on N runoff loss in paddy fields. This research aims to Field experiments were conducted at four experimental stations in Nanjing（Jiangsu Province）, Jingzhou（Hubei Province）, Chizhou（Anhui Province）, and Gaoan（Jiangxi Province）. The experiment consistently included four treatments at each site：winter fallow with conventional fertilization（FR）, winter fallow with conventional fertilization and straw return（FRS）, winter milk vetch and rice with 40% N reduction（MR）, winter milk vetch and rice with 40% N reduction and straw return（MRS）. The N concentration in ponding water of the paddy fields was measured multiple times on the day of fertilization（before fertilization）and within 10 days after fertilization. Combined the rainfall-water table measurement with the water balance model of paddy fields, we analyzed the effects of GM combined with reduced N fertilizer on N runoff loss and its morphological characteristics in the middle and lower reaches of the Yangtze River. The results showed that the peak and average total N（TN）concentrations under GM treatments（MR, MRS）were reduced by 11.1% - 57.9% and 17.1% - 27.3%, respectively, compared to conventional treatments（FR, FRS）The model-simulated rice field ponding water depth and runoff consistency indices ranged from 0.738-0.985 and model simulation efficiencies ranged from 0.737-0.986, indicating the model′ s reliability in quantifying N loss from different treatments. The TN runoff loss from the FR, FRS, MR, and MRS treatments ranged from 19.94-25.22, 17.71-22.36, 14.60-17.92 kg · hm-2, and 13.72-16.73 kg · hm-2, respectively. Compared to conventional treatments, GM treatments reduced TN runoff loss by 22.5%-45.6%. The most significant reduction was observed in Chizhou, Anhui Province, where GM had a more pronounced effect on N runoff loss before fertilization. GM mainly reduced the runoff loss of ammonium N（NH4+-N）and dissolved organic N（DON）, with reductions rate of 7.7%-43.4% and 3.7%-39.5%, respectively, indicating that GM effectively reduced N runoff loss primarily by decreasing NH4+-N and DON. In conclusion, GM combined with a 40% reduction in chemical fertilizers can significantly reduce the content of NH +4-N and DON in paddy fields, thereby decreasing the amount of total N（TN）loss and the risk of ponding water pollution. This green production model is worth promoting in the middle and lower reaches of the Yangtze River. |
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