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A GIS‐based Upscaling Estimation of Nutrient Runoff Losses from Rice Paddy Fields to a Regional Level
Author(s) -
Sun Xiaoxiao,
Liang Xinqiang,
Zhang Feng,
Fu Chaodong
Publication year - 2016
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2016.05.0181
Subject(s) - surface runoff , environmental science , nutrient , fertilizer , hydrology (agriculture) , nonpoint source pollution , paddy field , agronomy , phosphorus , nutrient management , ecology , chemistry , biology , geotechnical engineering , organic chemistry , engineering
Nutrient runoff losses from cropping fields can lead to nonpoint source pollution; however, the level of nutrient export is difficult to evaluate, particularly at the regional scale. This study aimed to establish a novel yet simple approach for estimating total nitrogen (TN) and total phosphorus (TP) runoff losses from regional paddy fields. In this approach, temporal changes of nutrient concentrations in floodwater were coupled with runoff‐processing functions in rice ( Oryza sativa L.) fields to calculate nutrient runoff losses for three site‐specific field experiments. Validation experiments verified the accuracy of this method. The geographic information system technique was used to upscale and visualize the TN and TP runoff losses from field to regional scales. The results indicated that nutrient runoff losses had significant spatio‐temporal variation characteristics during rice seasons, which were positively related to fertilizer rate and precipitation. The average runoff losses over five study seasons were 20.21 kg N ha −1 for TN and 0.76 kg P ha −1 for TP. Scenario analysis showed that TN and TP losses dropped by 7.64 and 3.0%, respectively, for each 10% reduction of fertilizer input. For alternate wetting and drying water management, the corresponding reduction ratio was 24.7 and 14.0% respectively. Our results suggest that, although both water and fertilizer management can mitigate nutrient runoff losses, the former is significantly more effective. Core Ideas A new model based on GIS was used to estimate regional nutrient runoff losses from paddy fields. Regional variation of nutrient runoff losses was influenced by rainfall and fertilizer application. Increasing floodwater storage is more advisable than fertilizer reduction to reduce nutrient runoff losses.