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| Simulated rainfall effect on non-point source nitrogen output from fluvo aquic soil in the Huaihe River watershed, Henan Province, China |
| Received:May 18, 2021 |
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| KeyWord:farmland non-point source;nitrogen output;artificial rainfall;straw returning;Huaihe River watershed |
| Author Name | Affiliation | E-mail | | YUAN Yuan | School of Forestry, Henan Agricultural University, Zhengzhou 450002, China | | | YANG Haiyang | School of Forestry, Henan Agricultural University, Zhengzhou 450002, China | | | WANG Jiangyan | School of Forestry, Henan Agricultural University, Zhengzhou 450002, China | | | SHEN Chong | School of Forestry, Henan Agricultural University, Zhengzhou 450002, China | | | YANG Guoxin | School of Forestry, Henan Agricultural University, Zhengzhou 450002, China | | | WU Mingzuo | School of Forestry, Henan Agricultural University, Zhengzhou 450002, China | wumingzuo@henau.edu.cn |
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| Abstract: |
| To identify the effect of rainfall intensity and straw returning on nitrogen output, to provide a basis for quantifing and controlling farmland non point source nitrogen output in the Huaihe River watershed, and regional environment management, taking typical soil(fluvo aquic)with and without mixed straw in the Huaihe River watershed of Henan Province as study object, rainfall intensities of 0.5, 1.0, 1.5, 2.0, 2.5 mm·min-1, and 3.0 mm·min-1 were simulated to study surface runoff, sediment loss, and nitrogen loss. Cumulative runoff, sediment loss, nitrogen output, and the loss rate of each over a fixed interval increased with rainfall intensity. The nitrogen concentration in runoff changed rapidly during the first 20 minutes of rainfall, showing an early flush effect, then fluctuated, becoming relatively stable or slightly declining at the end. Its average concentration without admixed straw increased from a high concentration at a flow rate of 3.0 mm·min-1 to even higher at 2.0 mm·min-1. Nitrogen concentration was highest at a rainfall rate of 1.5 mm·min-1 in soil admixed with straw. The amount of nitrogen loss through sediment accounted for more than 98.25% of total loss, but was significantly reduced by mixing with straw(lowest loss rate was 65.12%). With straw returning, surface runoff and sediment loss could be reduced under low rainfall intensity(< 1.0 mm· min-1 and < 1.5 mm ·min-1 respectively), but sediment loss could be increased under high rainfall intensity. Nitrogen concentration with admixed straw was higher than that without, increasing cumulative nitrogen output. There were good correlations between cumulative runoff and sediment and nitrogen output. All correlation coefficients were above 0.900. Rainfall intensity and straw returning affected surface runoff, sediment, and nitrogen output. Rainfall intensity induced an obvious change in nitrogen output, with maxima at 1.0 mm · min-1 without admixed straw, and 1.5 mm·min-1 with admixed straw. Two important means for controlling farmland non-point source load include controlling nitrogen and sediment loss at early rainfall stages. |
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