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| Characteristics of Nitrogen Runoff from Paddy Fields in Guangdong Province |
| Received:November 22, 2014 |
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| KeyWord:paddy field;nutrient runoff;nitrogen load;Guangdong Province |
| Author Name | Affiliation | E-mail | | YAO Jian-wu | Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture, Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Guangzhou 510640, China | | | NING Jian-feng | Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture, Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Guangzhou 510640, China | | | LI Meng-jun | Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture, Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Guangzhou 510640, China | | | WANG Rong-hui | Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture, Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Guangzhou 510640, China | | | ZENG Zhao-bing | Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture, Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Guangzhou 510640, China | | | LUO Ying-jian | Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture, Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Guangzhou 510640, China | | | AI Shao-ying | Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture, Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Guangzhou 510640, China | shaoyingai@21cn.com | | LI Zhen-sen | Guangdong Master Station of Agricultural Environment Protection and Rural Energy, Guangzhou 510500, China | | | CHEN Wei-chao | Guangdong Master Station of Agricultural Environment Protection and Rural Energy, Guangzhou 510500, China | | | OU Ji-yin | Guangdong Master Station of Agricultural Environment Protection and Rural Energy, Guangzhou 510500, China | |
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| Abstract: |
| Nitrogen loss from agricultural fields is a important source for eutrophication in aquatic ecosystems. In this study, characteristics and potential environmental risks of nitrogen runoff were studied from 2008 to 2012 under conventionally managed paddy fields in Zengcheng, Qingyuan and Gaozhou, which represent central, north and western regions of traditional paddy production area in Guangdong Province, respectively. Nitrogen runoff from paddy fields occurred mainly during the early period of rice growth in these regions, which was associated with the local precipitation. In nitrogen fertilization treatment, concentrations of NH4+-N in runoff water were from 0.05 to 25.05 mg·L-1, 0.02 to 19.83 mg·L-1, and 0.02 to 55.4 mg·L-1 for Zengcheng, Qingyuan and Gaozhou region, respectively. The corresponding total nitrogen(TN) concentrations were from 0.33 to 36.51 mg·L-1, 0.46 to 21.01 mg·L-1, and 0.49 to 61.96 mg·L-1. Nitrogen application increased the concentrations of NH4+-N and TN in runoff water from paddy fields, both exceeding the grade V(2.0 mg·L-1) of the national surface water quality standards within 10 days after nitrogen application, implying that nitrogen runoff during this period would impose potential risks to the water environment. Although nitrogen fertilization affected NO3--N concentrations in the runoff water, it was less than 10 mg·L-1 in all three experimental regions. The nitrate concentrations in the runoff met the fifth grade(grade V) of national surface water quality standards. Annual loads of nitrogen runoff in Zengcheng, Qingyuan and Gaozhou regions were from 24.31 to 53.68 kg·hm-2, 8.71 to 23.76 kg·hm-2 and 13.32 to 88.16 kg·hm-2, respectively, and the corresponding runoff coefficients were from 1.4% to 3.9%, 0.1% to 5.5% and 0.9% to 21.6%. Approximately 53% to 86% of nitrogen runoff loads were observed in the early rice season, which was directly related to the local rainfall distribution. |
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