耕作方式对岩溶区甘蔗地土壤优先流特征的影响

Tillage Pattern Effects on Characteristics of Soil Preferential Flow in Sugarcane Fields in the Karst Region

岩溶区特殊的岩性地质条件,使土壤优先流现象广泛发生。以广西岩溶区内的典型农地甘蔗地作为研究对象,利用野外染色示踪技术和图像解析方法,分别对传统耕作(CT)和粉垄耕作(SRT)方式下的田间土壤优先流特征进行分析,揭示耕作方式对岩溶区甘蔗地土壤优先流的发生及其空间发展变化的影响。结果表明:①在相同外部供水条件下,传统耕作甘蔗地优先流运动分化程度相对较高,多呈指状形式,且平均湿润锋下渗深度为43.19 cm,显著大于粉垄耕作(P<0.05),而粉垄耕作甘蔗地优先流以横向运动形式为主,表现为团块状湿润锋形式;②粉垄耕作甘蔗地土壤优先流发生时间显著滞后于传统耕作(P<0.05),是其1.67倍;③随土壤深度的增加,两种耕作方式下的甘蔗地土壤优先流发育程度总体呈现先增加后降低的变化趋势,但粉垄耕作甘蔗地优先流比(70.72%)和长度指数(527.12%)均显著小于传统耕作甘蔗地(P<0.05),且在土壤空间中对应的染色形态变异系数(1.19)是传统耕作的1.38倍,优先流发育程度显著低于传统耕作甘蔗地。粉垄耕作与传统耕作方式相比,在一定程度上降低了田间土壤优先流现象,改善了田间土层中的水肥状况。

The unique geological conditions lead to the soil preferential flow widely occurs in the karst region.Therefore,in this paper,the typical sugarcane fields in the karst region of Guangxi was taken as study objects,the methods of brilliant blue dye tracer technique and image analysis were used,and the characteristics of soil preferential flows in sugarcane fields were studied under the conventional tillage(CT)and smash-ridging tillage(SRT)in order to reveal the effects of tillage patterns on the occurrence and spatial development of soil preferential flow in sugarcane fields in the karst region.Results showed that:1)the differentiation degree of preferential flow movement was higher in CT sugarcane field under the same water supply condition.The motion morphology of wetting front in CT sugarcane field was finger form and reached at a depth of 43.19 cm,which was significantly deeper than that of SRT one(P<0.05).However,the wetting front of preferential flow in SRT sugarcane field was mainly blocky morphology which indicated a horizontal mobility pattern.2)The occurrence time of preferential flow in SRT sugarcane field was 1.67 times later than that of CT one(P<0.05).3)With the increase of soil depth,the preferential flow levels of two tillage patterns both increased first and then decreased.But the preferential flow fraction(70.72%)and length index(527.12%)of SRT sugarcane field were significantly lower than those of CT one(P<0.05).Meanwhile,the average of variation coefficient of the dyed area percentages in the whole soil profiles in SRT sugarcane field was 1.38 times higher than that of CT one.The degree of preferential flow in SRT sugarcane field was significantly lower than that of CT one.To a certain extent,compared with CT,SRT can reduce the phenomenon of preferential flow and preserve moisture and fertility in sugarcane field of karst region.