| To evaluate effects of different deep cultivation approaches on the three-phase ratio of soil and root system structure of maize, the maize cultivar Xianyu 335 was used under three cultivation methods including deep-spin (TS) 35 cm, subsoiling (SS) 35 cm, and deep plowing (SF) 35 cm by comparing to shallow rotary tillage (CK) 15 cm, to examine the three-phase ratio of soil and maize root system structure. It turned out that by increasing the gaseous phase ratio and liquid phase ratio and decreasing the solid phase ratio, deep plowing increased the GSSI and decreased the STPSD, allowing the physical structure of soil in plow layer to reach an ideal state. SF could significantly improve the physical structure of soil in plow layer as deep as 20～60 cm, while SS could obviously improve the soil structure in soil layer as deep as 40～60 cm. The soil-improving effects of SS and SF were better than those of TS. Additionally, total length and surface area of roots in deep plowing were higher than those in the shallowly rotary tillage. There was obvious increment of biomass in the middle and lower root systems in soil and the biomass from fine roots with diameters between 0～0.5 mm was dominant. For distributions of corn roots with various lengths, root system with the diameter of 0～0.2 mm accounted for the most, while for distributions of roots with different surface areas, roots with the diameters between 0～0.33 mm are the majority. The gaseous phase of soil was significantly and positively correlated with the length and surface area of fine roots of corn root system, while liquid phase and solid phase showed significant and negative correlations with the length and surface area of fine roots of corn root system. Deep plowing could improve the physical structure of soil, decrease the density of soil, increase the water content, and simultaneously increase the weight of root trunk, length and surface area of roots. The proportion fine roots within the root system of corn accounting for became increased. Three phases of soil had certain correlations with the length and surface area of fine roots of corn root system. To some extent, high gaseous phase ratio would promote the growth of fine corn roots, while high solid ratio and liquid phase liquid would inhibit their growth. The three phases of soil co-influenced the growth of corn root system. |