秸秆覆盖对岩溶区稻田土壤优先路径特征的影响

Effect of Straw Mulching on Characteristics of Preferential Flow Paths of Paddy Soils in Karst Area

为探究秸秆覆盖对桂北岩溶区水稻田土壤优先路径的影响,采用野外染色示踪方法,结合图像形态学解析技术与空间统计分析方法,研究桂北岩溶区秸秆覆盖与非覆盖条件下水稻田优先路径及其空间分布特征。结果表明:随土壤深度的增加,秸秆覆盖条件下的水稻田土壤染色形态呈表层整体分散分布向深层团块状零散分布形态转变,而非秸秆覆盖条件下的土壤染色形态以聚集枝状裂隙为主向两侧团块状分布形态转变,且秸秆覆盖的水稻田平均总染色面积比(18.23%)仅是非秸秆覆盖的0.75倍,二者之间差异显著(P<0.05)。秸秆覆盖条件下水稻田的平均优先路径总数量(6323)仅是非秸秆覆盖条件下的0.81倍,二者优先路径数量均随土壤深度的增加而降低,但覆盖条件下水稻田的优先路径数量下降最快,以4.48倍速减小,其优先路径的平均复杂度为2.11,而非覆盖条件下水稻田优先路径平均复杂度为2.15,二者之间差异性显著(P<0.05),非秸秆覆盖下的水稻田优先路径复杂扭曲程度更高,秸秆覆盖措施影响水稻田优先路径。秸秆覆盖措施提高了田间土壤含水量,加快了土壤表层水流运动状态,但降低了深层土壤中优先流的发育程度,减少了田间水肥深层渗漏,在一定程度上可提高作物耕作层中的水肥利用率。

In order to explore the effect of straw mulching on the preferential flow paths of paddy field in the Karst area of northern Guangxi,the method of field staining and tracerombined with image morphological analysis and spatial statistical analysis used to study the priority path and spatial distribution characteristics of straw mulching and non-mulching paddy fields in north karst area of Guangxi.The result show that with the increase of soil depth,the soil staining morphology of paddy fields under the condition of straw mulching changes from surface scattered distribution to deep dyeing form crumb scattered distribution.However,the staining morphology mainly changes from cluster dendritic fissures to lumpy distribution on both sides of the non-straw mulching conditions in the paddy field,and the average total dyeing area ratio of straw mulching paddy field(18.23%)is only 0.75 times higher than the non-cover conditions paddy field with significant difference(P<0.05).The average total number of preferential flow paths of straw mulching(6323)is only 0.81 times higher than that under the condition of non-straw mulching in the paddy field.The number of preferential flow paths of both conditions decrease with soil depth.But the number of preferential flow paths for paddy fields under the condition of straw mulching faster at the speed of 4.48 times.The average complexity of preferential flow paths under the condition of straw mulching is 2.11,while the average complexity of preferential flow paths is 2.15 in the paddy field under non-straw mulching conditions,and the difference between the two is significant(P<0.05).In other words,the non-straw mulching preferential flow paths has a higher degree of distortion,which is reflected in the spatial distribution state of more concentrated path,and measures of straw mulching affect the pre-ferential flow paths of paddy field.Straw mulching measures increase the field soil moisture content,speed up the surface water flow movement of the soil the development of preferential flow paths in deep soil and the deep leakage of field water and fertilizer are reduced improve the utilization rate of water and fertilizer in crop ploughing layer to some extent.