桂北喀斯特峰丛洼地橘园土壤入渗特征

广西(桂)是我国柑橘果园面积和喀斯特峰丛洼地分布最广的省份。目前,对广泛分布的喀斯特峰丛洼地橘园土壤的入渗特征还缺乏了解。为了更好的支撑喀斯特峰丛洼地柑橘产业与生态可持续发展,本文以桂林地区典型白云岩峰丛洼地小流域为研究对象。采用改进的表置式环式入渗仪结合染色(亮蓝)示踪方法开展土壤入渗试验,定量刻画了洼地和梯田橘园土壤基质入渗与优先流入渗特征。结果表明:(1)基质入渗是该地区橘园水分入渗的主要方式;(2)基质稳定入渗速率差异显著且表现为洼地橘园(91.60~145.75 mm/h)大于梯田橘园(35.02~44.78 mm/h),优先流稳定入渗速率差异同样显著且表现为洼地橘园(79.78~118.30 mm/h)大于梯田橘园(12.63~23.18 mm/h);(3)优先流入渗在空间上具有很强的变异性,土壤染色面积并不是随土层的深入而递减;(4)梯田染色深度(17.4 cm)显著小于洼地(25.5 cm),梯田染色区域主要集中在表层土壤,0~5 cm范围内的染色面积占总染色面积的61.23%,洼地相同范围内染色面积仅占38.95%;(5)梯田与洼地相比,优先流路径更少,优先流发育程度更低,潜在的增加了橘树对土壤水分的可利用量。本研究结果有助于了解喀斯特峰丛洼地橘园的水文过程,并为峰丛洼地橘园的土壤水分管理提供借鉴。

Soil infiltration characteristics of citrus orchards in the cluster depression of karst peaks in northern Guangxi

Citrus orchard and peak cluster depression landform are widely distributed in Guangxi province. At present, the characteristics of soil infiltration under the controlling of land use and landform are still unclear. In order to support the sustainable development between industrialization of citrus and ecology in the karst area, the field soil infiltration tests were carried out using the surface ring infiltration meters combined with the dyeing (bright blue) tracing method in a typical dolomite peak cluster depression watershed, Guilin. The characteristics of matrix flow and preferential flow in depressions and terraces in citrus orchard were defined quantitatively. The results showed that: 1) Matrix flow is the primary pattern for water infiltration. 2) The stable infiltration rate of matrix flow was significantly higher in depressions citrus orchard (91.60~145.75 mm/h) than that in the terraces citrus orchard (35.02~44.78 mm/h), while the preferential flow showed the same trend (depressions citrus orchard, 79.78~118.30 mm/h; terraces citrus orchard, 12.63~23.18 mm/h). 3) Preferential flow had strong spatial variability, and the stained area of decreases with soil depth with multiple peaks. 4) The dyeing depth in terraces citrus orchard (17.4 cm) was significantly smaller than that in depressions citrus orchard (25.5 cm). The dyeing area in 0~5 cm depth of terraces citrus orchard was up to 61.23%, while only 38.95% in depressions citrus orchard. 5) Soil profile in terraces citrus orchard presents fewer preferential flow paths and lower levels of preferential flow degree than that in depressions citrus orchard, which potentially increasing the utilization of soil water for orange trees. The results were helpful for understanding the hydrological process in orangery of karst cluster depressions, which was vital for providing reference to soil moisture management for the ecological sustainable development of citrus industrialization in karst area.