秸秆覆盖对土壤水分和侵蚀的影响研究进展

(中国农业大学 土地科学与技术学院, 北京 100193)

秸秆覆盖; 水土流失; 水分入渗; 水分蒸发

Research Process on the Effects of Straw Mulch on Soil Moisture and Soil Erosion
LIU Yanqing, WANG Jilei, LI Zizhong

(College of Land Science and Technology, China Agricultural University, Beijing 100193, China)

straw mulch; soil erosion; soil water infiltration; soil water evaporation

备注

随着我国经济的发展,我国农业生产力得到很大的提高,但水资源短缺、耕地退化仍是干旱半干旱区农业生产的主要限制因子。坡耕地作为土壤侵蚀多发地,土地生产力受到土壤侵蚀的严重威胁,秸秆覆盖可在一定程度上抑制土壤水分蒸发,增加地表糙度、促进水分入渗,从而提高土壤含水量; 防止外营力与地表土壤颗粒直接相互作用,抑制土壤侵蚀的发生,同时也可提高土壤有机质含量,改善土地生产力。为更加有效地利用水资源、防治土壤侵蚀,保护生态安全,推进生态文明建设,我国学者开展了一系列研究,涉及到农田水分利用效率及土壤侵蚀在秸秆(覆盖方式、度或量)、降雨和地形等因素综合影响下的响应,并取得了可观成果。秸秆覆盖量在3~10 t/hm2时,可减少土壤无效蒸发20%~90%,此后增加覆盖量抑制蒸发的效果不太显著。秸秆覆盖虽然在一定条件下会阻隔降雨入渗,但也会抑制潜水蒸发和返盐,最终表现为提高了土壤含水量和作物水分利用效率。秸秆带状覆盖在发挥“保土增墒”作用同时又降低了对播种、出苗带来的不利影响,大量研究认为30%~60%的秸秆覆盖度并结合高留茬可减少水土流失60%~90%,也有研究认为在强雨强条件下(≥100 mm/h),秸秆覆盖于坡度较陡或犁底层存在的耕地,会加剧侵蚀。通过总结秸秆覆盖措施对土壤水和土壤侵蚀影响的研究成果,认为目前秸秆覆盖措施的研究较为全面和深入,但还有待更进一步研究的地方:秸秆覆盖对土壤水分运动和土壤侵蚀影响效果及机理的定量化研究; 秸秆覆盖技术规程的制修定; 秸秆覆盖及播种等相关机械研制及改进; 秸秆覆盖措施的区域适用性及评价; 作物生长模型、水土流失模型中秸秆覆盖参数的确定及校验。
With the development of China's economy, agricultural productivity in China has also been greatly improved. However, water shortage and cultivated land degradation are still the main limiting factor for agricultural production in both arid and semi-arid regions. Sloping land with frequent soil erosion is seriously threatened by soil erosion. Straw mulch, to some extent, can inhibit soil water evaporation, increase surface roughness, promote water infiltration, and thus improve soil water content; meanwhile, straw mulch can prevent direct interaction between external forces and surface soil particles, reduce the occurrence of soil erosion, and improve soil organic matter content and thus improve soil productivity. In order to make more effective use of water resources, prevent and control soil erosion, protect ecological security, and promote ecological civilization construction, Chinese scholars have carried out a series of studies involving the influence and mechanism of different straw mulch methods, straw mulch degree and straw mulch amount on farmland water use efficiency and soil erosion, and have achieved considerable results. When the application of straw mulch is about 3~10 t/hm2, the soil ineffective evaporation could be reduced by about 20%~90%. After that, the effect of increasing the straw mulch on evaporation inhibition was not significant. Although straw mulch may prevent rainfall infiltration under certain conditions, it can also inhibit underwater evaporation and salt rehydration, and finally improve soil water content and water use efficiency. Straw strip mulch, which prevents soil erosion, reduces the negative influence of it on seeding and germinating. A lot of researches suggest that 30%~60% of straw coverage and high stubble can significantly reduce water loss and soil erosion by 60%~90%. Some studies also suggest that under the circumatance of high rainfall intensity(≥100 mm/h), straw mulching on farmland with steep slope or plough layer will increase soil erosion. This paper summarizes the results of predecessors' study on soil water and soil erosion, and concludes that the current straw mulching measures are comprehensive and in-depth research, but there still have some areas to be further studied: quantitative research on the effect and mechanism of straw mulch on soil water movement and soil erosion; definitional revision of straw mulch technical regulations; development of straw mulch and seeding machinery; regional applicability and evaluation of straw mulch measures; determination and calibration of straw mulch parameters in crop growth model and soil erosion model.