Abstract:Abstract: Soil pore structure plays an important role in the ways of soil water movement in both topsoil and subsoil, and has a close relationship with soil surface runoff and permeability. Soil pore structure has evident spatial characteristics which includes soil porosity, pore number, pore radius, spore size distribution, circularity, morphological and quantitative characteristics, and the distribution of pore space, correlations between connectivity, and spatial pore distribution. In recent years, CT scanning has been introduced to study the characteristics of soil pores. CT image is applied to research the soil pore distribution, the density of soil spatial distribution and size, soil porosity, pore surface fractal dimension, the spatial distribution of soil moisture, and the unsaturated hydraulic conductivity of soil properties. Meanwhile, CT scanning has accurately revealed the number, size, and location of macro pores (>1 mm in diameter). No-tillage, straw mulching, application of organic fertilizer and superabsorbent polymers (SAP) can increase soil organic matter content, improve soil structure, increase soil fertility and soil porosity, and thus decrease soil bulk density and promote crop growth. However, further study will be needed to study the impact of different measures on the soil pore number, size, and distribution of soil pores in the soil profile. Therefore, in order to investigate the effect of different improvement measures for soil structure, such as straw mulching, no-tillage, application of organic fertilizer and super absorbent polymers, on the characteristics of soil pores and its distribution in different soil layer, CT scanning was used to quantitatively analyze soil pore numbers, soil porosity, and distribution of soil pores in different soil profiles. The results showed that the numbers of soil total pores, macro pores, and 0.13-1.0 mm pores were significantly increased in different soil improving treatments in contrast to CK treatment, and the porosity and circularity were improved. The optimal soil improvement measures occurred in treatments that applied organic fertilizer and no-tillage, and then were followed by the treatments of applying SAP and straw mulching, CK treatment was the lowest. In addition, soil field capacity and the amount of water stable aggregate of >0.25 mm were significantly improved in different soil structure improvement measures, however, soil bulk density was decreased in each treatment. The optimal soil improvement measures were also found in treatments that applied organic fertilizer and no-tillage, compared with treatment CK, soil water capacity was increased by 15.9% and 16.4% in treatment applications of organic fertilizer and no-tillage, respectively. In addition, corresponding soil bulk density was decreased by 6.8% and 8.8%, respectively. The correlation analysis among different soil pore indexes showed that these significantly or extremely significantly positive correlations were found between the field soil water capacity, and soil bulk density and the amount of water-stable aggregate of >0.25 mm and soil total porosity and macro porosity. However, soil bulk density and soil total porosity and macro porosity and pore cycle rate were submitted to a significantly negative correlation.