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| Nitrogen emission of farmland at village level: A case study of Xinan Village, Zhengding County, China |
| Received:November 20, 2019 |
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| KeyWord:planting system;farmland nitrogen;spatio-temporal variation;influencing factor |
| Author Name | Affiliation | E-mail | | CHEN Shuai | College of Resources and Environment Sciences, Hebei Agricultural University, Baoding 071000, China | | | XIN Si-ying | College of Resources and Environment Sciences, Hebei Agricultural University, Baoding 071000, China | | | TONG Bing-xin | College of Resources and Environment Sciences, Hebei Agricultural University, Baoding 071000, China | | | Lü Min-juan | College of Resources and Environment Sciences, Hebei Agricultural University, Baoding 071000, China | | | JI Qing-kai | College of Resources and Environment Sciences, Hebei Agricultural University, Baoding 071000, China | | | MA Wen-qi | College of Resources and Environment Sciences, Hebei Agricultural University, Baoding 071000, China | | | WEI Jing | College of Resources and Environment Sciences, Hebei Agricultural University, Baoding 071000, China | weijing_199@163.com |
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| Abstract: |
| A case study was conducted in Xinan Village, Zhengding County, Hebei Province to reveal the characteristics of nitrogen emissions at the village level. It was based on sampling analyses and field investigations of crop management by farmers. Crop yield and other characteristics were also considered over two rotation cycles from 2016 to 2018. The NUFER-Farm model system was used to study the spatial and temporal characteristics of nitrogen emissions from Xinan village and their correlation with crop types, nitrogen input levels, frequency of irrigation, and soil texture. The results showed that total nitrogen(TN)emission and nitrous oxide(N2O)emissions per unit area of farmland were not significantly different over the two rotation cycles. In contrast, the nitrogen losses caused by nitrate-nitrogen leaching and ammonia volatilization were significantly different. Compared with the first rotation cycle, the nitrate-nitrogen leaching and ammonia volatilization per unit area of farmland in the second rotation cycle increased by 60.1% and decreased by 13.8%, respectively; these significant differences were attributed to meteorological conditions and crop types. In terms of season, the TN emissions per unit area of farmland was significantly greater in autumn-winter-spring than in summer throughout the two years. The difference in the nitrogen emissions between adjacent fields in the village was large, and there was no clear spatial distribution law. However, considering the village as a whole, there were certain patterns in the spatial distribution of the nitrogen emissions in different directions. The average TN emission rate in the northwest, northeast, southeast, and southwest were 66.8, 60.2, 59.6 kg N·hm-2, and 52.3 kg N·hm-2, respectively; the nitrogen losses in the southwest were significantly lower than those in other directions. The nitrogen emissions of farmlands at village level were significantly affected by crop type, nitrogen input level, frequency of irrigation, and soil texture. The average TN emission rate of local main crops presented significant differences; for example, the values for winter wheat, summer maize, and soybean were 40.5, 28.5 kg N·hm-2, and 5.3 kg N·hm-2, respectively. The nitrogen emissions presented an increasing trend with a high nitrogen fertilizer input and irrigation frequency over the two crop rotation systems. The soil texture of the farmland also had a great influence on the nitrogen emissions. The nitrogen emission rate of sand, sandy loam, and loam soil were 78.2, 60.4 kg N·hm-2, and 51.0 kg N·hm-2, respectively. In short, nitrogen emissions at the village level displayed a large temporal and spatial variation and were affected mainly by crop types, soil conditions, and management measures. Therefore, measures to reduce the nitrogen emissions at this level should be applied to optimize nitrogen fertilization irrigation, and distribution of crops. |
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