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| Runoff production process and nitrogen and phosphorus output characteristics from farmlands in the lower reaches of the Yangtze River under cauliflower and corn rotation |
| Received:March 18, 2021 |
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| KeyWord:natural rainfall;non-point source pollution;Chongming Island;farmland runoff |
| Author Name | Affiliation | E-mail | | ZHU Wenjun | College of Environmental Science and Engineering, Donghua University, Shanghai 201620, China
State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China | | | LI Jinwen | State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China | | | QIAN Xiaoyong | State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China | | | SHEN Genxiang | State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China | shengx@saes.sh.cn | | ZHANG Min | State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China | | | FU Kan | State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China | | | WANG Zhenqi | State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China | | | ZHAO Qingjie | State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai 200233, China | |
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| Abstract: |
| Nitrogen(N) and phosphorus(P) losses from farmlands are major causes of water eutrophication. The N and P nutrient runoff rates are affected by various factors, such as antecedent moisture content(AMC), rainfall levels, and tillage management, of which on-site monitoring methods are still unavailable. This study established an automatic sampling method to achieve high-frequency sampling and continuous monitoring of nutrient runoff loss under natural rainfall conditions. The study was conducted at an upland on Chongming Island, located in the lower reaches of the Yangtze River. The characteristics of rainfall runoff and N and P output under the corn-cauliflower rotation cropping system were analyzed. The soil water holding capacity was indicated by the CN, and the effect of AMC on CN at soil depths of 10, 30 cm, and 50 cm(AMC10, AMC30, AMC50) was studied. The change in nutrient output and the dilution effect of rainfall were studied using electrical conductivity(EC). The results showed that the peaks of the runoff velocity lagged behind that of the rainfall intensity. The CN of the field ranging from 37 to 88 was most significantly correlated with AMC10(y=293.40x-39.41, R2=0.790 5, P<0.01), but was not significantly correlated with AMC50(P>0.05). Plowing led to an increase in total P(TP) and dissolved total P(DTP) concentrations but had no obvious influence on the N concentrations. N concentrations in runoff decreased when runoff velocity increased, but P concentrations exhibited the opposite trend. The changes in EC and runoff velocity showed a completely opposite trend. Higher rainfall resulted in an increase in runoff flow, and the consequent dilution effects resulted in a decrease in EC. The changes in EC could reflect the concentration changes of total N(TN) and NO3--N, and the output characteristics of N. However, the output of P was different from the output of N. During events with higher runoff rates and lower EC, the concentration of P might be higher. |
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