The characteristics of soil macropores and water infiltration are closely connected to the growth of plant roots and their root zone environment. However, it is unclear how the root zone environment of oasis farmlands regulates the development of soil macropores and water flow in hyper-arid regions. The objective of this study was to investigate soil macropores and their effect on water flow under irrigated oasis farmlands using a combination of X-ray computed tomography (CT) and dye tracer. It was hypothesized that the integration of CT and dye tracer could clearly reveal preferential flow through biopores and large pores of oasis soils. A helical medical CT scanner was used to quantify more information about soil macropores in the root zone, along with an in situ single-ring dye infiltration experiment to reveal water flow in three different oasis farmlands (piedmont oasis farmland, marginal oasis farmland, and old oasis farmland). Soil macroporosity was 0.44% under crop rows, while soil macroporosity in the interrows was only 0.30% across the oasis farmlands. Biopores contributed 73% of the volume of the total macropores under crop rows. The stable infiltration rate in the interrows was 0.3 mm min⁻¹, which was significantly (p < 0.05) less than that under crop rows (0.7 mm min⁻¹). Water flow under crop rows were mainly transported in biopores and large pores. The contribution of macropores to preferential flow under crop rows was 4.8 times larger than interrows. The integration of CT and dye tracer was a more holistic technique, which adequately revealed that oases had preferential flow affected by biopores and large pores, resulting in higher solute and contaminant transport.

中文翻译：

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超干旱地区绿洲根区土壤大孔隙度与水流

土壤大孔隙和水分入渗特性与植物根系的生长及其根区环境密切相关。然而，目前尚不清楚绿洲农田的根区环境如何调节超干旱地区土壤大孔隙和水流的发育。本研究的目的是利用 X 射线计算机断层扫描 (CT) 和染料示踪剂的组合研究土壤大孔隙及其对灌溉绿洲农田下水流的影响。假设 CT 和染料示踪剂的结合可以清楚地揭示通过生物孔和绿洲土壤大孔隙的优先流动。螺旋医学 CT 扫描仪用于量化有关根区土壤大孔的更多信息，以及原位单环染料渗透实验，以揭示三个不同绿洲农田（山前绿洲农田、边缘绿洲农田和旧绿洲农田）的水流。作物行下土壤大孔隙率为 0.44%，而绿洲农田间行土壤大孔隙度仅为 0.30%。生物孔占作物行下总大孔体积的 73%。行间的稳定渗透率为 0.3 mm min^-1，显着（p  < 0.05）低于作物行（0.7 mm min ^-1）。作物行下的水流主要在生物孔和大孔隙中输送。大孔对作物行下优先流动的贡献是行间的 4.8 倍。CT和染料示踪剂的结合是一种更全面的技术，它充分揭示了绿洲具有受生物孔和大孔影响的优先流动，导致更高的溶质和污染物运输。