中国农业科学 ›› 2021, Vol. 54 ›› Issue (1): 140-151.doi: 10.3864/j.issn.0578-1752.2021.01.010

• 土壤肥料·节水灌溉·农业生态环境 • 上一篇    下一篇

雨强和地下孔(裂)隙度对喀斯特坡耕地养分流失的影响

姚一文(),戴全厚(),甘艺贤,高儒学,严友进,王玉红   

  1. 贵州大学林学院,贵阳550025
  • 收稿日期:2020-04-20 接受日期:2020-09-02 出版日期:2021-01-01 发布日期:2021-01-13
  • 通讯作者: 戴全厚
  • 作者简介:姚一文,E-mail: 2101029397@qq.com
  • 基金资助:
    国家自然科学基金项目(41671275);国家重点研发计划课题(2016YFC0502604);贵州省高层次创新型人才项目(黔科合平台人才[2018]5641);贵州省重大专项(黔科合重大专项字[2016]3022号);贵州省科技计划项目(黔科合平台人才[2017]5788);贵州省一流学科建设项目(GNYL[2017]007)

Effects of Rainfall Intensity and Underground Hole (Fracture) Gap on Nutrient Loss in Karst Sloping Farmland

YAO YiWen(),DAI QuanHou(),GAN YiXian,GAO RuXue,YAN YouJin,WANG YuHong   

  1. College of Forestry, Guizhou University, Guiyang 550025
  • Received:2020-04-20 Accepted:2020-09-02 Online:2021-01-01 Published:2021-01-13
  • Contact: QuanHou DAI

摘要:

【目的】研究不同降雨强度和地下孔(裂)隙下,喀斯特区坡耕地表和地下土壤养分流失途径及流失规律,为喀斯特坡耕地土壤养分流失控制和农业面源污染防治提供理论依据。【方法】以喀斯特区坡度为15°的坡耕地为研究对象,通过模拟其地表形态和地下孔(裂)隙特征,设置不同雨强(30、50、70、90 mm·h-1)和地下孔(裂)隙度(1%、3%、5%)交叉试验共36场降雨,探索喀斯特坡耕地地表和地下养分流失特征。【结果】(1)雨强对喀斯特区坡耕地产流产沙影响显著(P<0.05),地表、地下产流产沙量随雨强增大而增加,其产流产沙从地下过渡到地上的临界雨强可能在30—50 mm·h-1;随地下孔(裂)隙度增大,地下产流产沙量增加,地表呈相反的规律。(2)喀斯特坡耕地径流养分主要通过地表流失,小雨强下通过地下孔(裂)隙流失;径流中全氮(TN)、全磷(TP)、全钾(TK)流失量和流失模数均随雨强增大而上升,雨强对各径流养分流失浓度影响不明显。地表养分流失量和流失模数随地下孔(裂)隙度增加而下降,地下反之。地下孔(裂)隙度的增加使地下径流养分流失占比逐渐增加。(3)养分会通过附着于泥沙流失,其中以地表泥沙流失为主。地表、地下各泥沙养分平均流失浓度、流失量和流失模数均随降雨强度增大而增加,其中TK流失平均浓度和流失量在不同雨强下显著高于TN和TP。同雨强下,地表泥沙各养分平均流失浓度、流失量和流失模数随孔(裂)隙度增加呈减小趋势,地下反之,但流失量从地表为主到地表与地下二者并重。(4)相关性分析表明,降雨强度与径流和泥沙流失量均呈现显著正相关关系,雨强对各养分径流的影响高于泥沙,地表径流受雨强影响最大。地下孔(裂)隙度对泥沙养分流失量的影响高于径流,而泥沙养分中地下泥沙养分流失量受其影响较大。【结论】喀斯特坡耕地养分主要通过地表流失,但地下孔(裂)隙对养分流失的影响不容忽视。在坡耕地养分流失防治上,地表通过增加植被覆盖度和添加枯落物等方式减缓坡耕地产流产沙量,地下通过植被根系固定土壤,防止养分通过孔(裂)隙向地下渗漏进而达到减少坡耕地土壤养分流失。

关键词: 养分流失, 雨强, 地下孔隙度, 径流, 泥沙, 喀斯特坡耕地

Abstract:

【Objective】 The ways and laws of soil nutrient loss and surface loss in slope farmland in karst area under different rainfall intensities and underground holes (fissures) were studied in order to provide a theoretical basis for the control of soil nutrient loss and agricultural non-point source pollution control in karst slope farmland. 【Method】 Taking the slope farmland with a slope of 15° in the karst area as the research object, the surface morphology and underground pore (fissures) characteristics of karst slope farmland were simulated under different rain intensities (30, 50, 70, and 90 mm·h-1) and underground pore (fissures) gap degrees (1%, 3%, and 5%), with a total of 36 rainfalls in the cross-test, in order to explore the characteristics of surface and underground nutrient loss. 【Result】 (1)Rain intensity had a significant effect on runoff and sediment production on slope farmland in karst area (P<0.05). Surface and underground runoff and sediment production increased with the increase of rain intensity, and its critical rain intensity might be between 30 and 50 mm·h-1, when the runoff and sediment production were from the underground to the ground; with the increase of the underground pore (fissures) gap, the amount of underground runoff and sand production increased, and the surface was in the opposite pattern. (2)The loss of runoff nutrients in karst slope farmland was mainly through the surface form, which was through the form of underground pores (fissures) under the light rain intensity; the loss and modulus of TN, TP and TK in runoff increased with the increase of rain intensity, and the effect of rain intensity on the nutrient loss concentration of each runoff was not obvious. In addition, the amount of nutrient loss and the loss modulus of the ground surface decreased with the increase of the underground pore (fissures) gap, and vice versa and the increase of underground pore (fissures) gap made the proportion of underground runoff nutrient loss gradually increase. (3)Nutrients would be lost through the form of attachment to the sediment, of which the surface sediment was mainly lost. The average loss concentration, loss amount and loss modulus of each sediment nutrient on the surface and underground increased with the increase of rainfall intensity, and the average concentration and loss amount of TK loss were significantly higher than TN and TP under different rainfall intensities. Under the same rain intensity, the average loss concentration, loss amount and loss modulus of surface nutrients showed a decreasing trend with the increase of pore (fissures) porosity, and the opposite was underground, but the loss amount was mainly from the surface to the surface and underground. Both were equally important. (4)Correlation analysis showed that rainfall intensity had a significant positive correlation with runoff and sediment loss. The impact of rain intensity on nutrient runoff was higher than sediment, and surface runoff was most affected by rain intensity. The effect of underground pore (fissures) gap on the loss of sediment nutrients was higher than that of runoff. Among the sediment nutrients, the loss of underground sediment nutrients was greatly affected by it. 【Conclusion】The surface was the main form of nutrient loss in karst slope farmland, and the effect of underground pores (fissures) on nutrient loss could not be ignored. In the prevention and control of nutrient loss on slope farmland, the surface could slow down the runoff and sediment yield of slope farmland by increasing vegetation coverage and adding litter, etc. The underground soil was fixed by the roots of the vegetation, thus reducing the leakage of nutrients to the underground through the fissure, thereby reducing the soil nutrient loss of the slope farmland.

Key words: nutrient loss, rainfall intensity, underground fissure porosity, runoff, sediment, karst slope farmland