亚表层有机培肥调控盐渍土孔隙结构与水盐运移机制

为探明亚表层有机培肥结合地膜覆盖对土壤孔隙结构及其水盐运移的调控机制,以内蒙古河套灌区典型盐渍土为研究对象,设置了地表不覆膜(CK)、地膜每年覆盖(PM)和亚表层单次有机培肥+地膜每年覆盖(OMP)3个处理,3年后采用X射线CT扫描和图像处理技术获取了部分亚表层(15 ～21 cm)与深层(35 ～41 cm)土壤孔隙...

Effects of Pore Structure and Water-Salt Movement for Saline Soil under Subsurface Organic Amendment

Plastic film mulching is one of the widely adopted agronomic measures in the northwest of China,and subsurface(10~30 cm)organic amendment is an important soil improvement and fertilization technique to quickly realize the efficient use of salinized farmland.However,it is still not clear of the effects of combinations of plastic film mulching and subsurface organic amendment on the soil pore structure and watersalt movement.The field experiment with three treatments was conducted:with(PM)and without(CK)plastic film mulching yearly,as well as the combination of subsurface organic amendment once with plastic film mulching yearly(OMP),in a typical saline soil in the Hetao Irrigation District of Inner Mongolia.Pore structures of subsurface(15~21 cm)and deep(35~41 cm)soil layers were measured by X-ray computed tomography and image processing,water and salt contents within soil profiles were measured in three years after the applications simultaneously,and then the effects of soil pore structure on watersalt movement were analyzed.The results showed that there was no significant difference(P>0.05)in macroporosity(greater than 30μm)between PM and CK in subsurface soil layer.However,the macroporosity in deep soil layer of PM was decreased by 0.48 percentage points than that of CK(P<0.05).Compared with CK,the macroporosity of OMP was boosted by 11.95 percentage points and 0.75 percentage points in subsurface and deep soil layers(P<0.05),respectively.The porosity of each equivalent pore size and the pore connectivity were also improved significantly with OMP than that with CK.Compared with CK and PM,the water contents in 0~40 cm soil layers with OMP were significantly increased by 12.02%and 6.33%,and its total salt contents were significantly reduced by 16.22%and 13.21%(P<0.05)after spring irrigation,respectively.In addition,the water contents in 0~40 cm soil layers with OMP were decreased by 40.69%and 35.77%after harvest,and its salt accumulation rate was reduced by 12.22 percentage points and 11.56 percentage points respectively(P<0.05),compared with CK and PM.It was worth noting that the macroporosity,soil pore connectivity,and watersalt content were significantly related(P<0.05).Increasing the porosity of equivalent diameter(less than 1500μm)significantly improved the soil water retention ability,and fortifying the porosity of equivalent diameter(less than 500μm)promoted the salt leaching after spring irrigation.Therefore,subsurface organic amendment combined with plastic film mulching could optimize the soil physical structure and enhance the regulation ability to regulate water and salt contents in saline soil.