Abstract: Based on the combination of dye tracer and radar detection technology, the spatial distribution patterns and influencing factors of soil priority flow in sugarcane fields under ridge tillage and no-tillage treatments in Guangxi were examined by morphological analysis of dye image, interpretation of radar image information, and Logistic regression analysis. The results showed that soil dielectric constant and radar profile image amplitude showed a trend of first increasing and then decreasing with soil depth, and that the dielectric constant was significantly different among soil depths (P<0.05). Under no-tillage, the soil layer of 20-50 cm had a range of amplitude variation, with a variation range between -0.3×10⁶ and 0.3×10⁶, which indicated that water moved vertically. The fluctuation of electromagnetic wave amplitude in ridge-cultivated sugarcane fields was concentrated in the soil layer of 0-20 cm, and the preferential flow was mostly lateral movement. The change value between the peak and the nadir was 0.27 under ridge tillage, which was smaller than that under no-tillage (0.34) (P<0.05). Saturated hydraulic conductivity and organic matter content were the main factors affecting the development of preferential flow under radar detection. Radar detection can quantitatively characterize the spatial distribution of preferential flow in the soil. Ridge tillage can reduce the rapid migration of soil water in sugarcane fields to a certain extent, and enhance water retention and storage conditions in the fields.

Key words: farming method, preferential flow, spatial variation coefficient, electromagnetic wave amplitude.