Effects of cultivation method and soil conditioner on soil water and salt distribution and watermelon yield in saline-alkali soil

Due to lack of suitable cultivation methods and soil conditioners for watermelon in saline-alkaline soil in the North Yinchuan Plain, it is necessary to investigate the effects of cultivation methods and soil conditioners on water and salt distribution and watermelon yields, therefore providing theoretical basis and technical support for watermelon cultivated in saline-alkaline soils. A field experiment including four treatments, namely, ridge planting with soil conditioner (LZST), flatten planting with soil conditioner (PZST), ridge planting without soil conditioner (LZCK), and flatten planting without soil conditioner (PZCK) was carried out to study the effects of cultivation methods and soil conditioners on the spatial and temporal distribution of soil water content, as well as watermelon yield and quality soil water content, salinity, and yield in saline-alkaline soils with the watermelon variety “Meidu 8424” as the test material. The results showed that compared with flatten planting, ridge planting obviously promoted the leaching efficiency of soil salts in the 0-20 cm soil layer, and changed the distribution characteristics of salts in the 0-40 cm layer. A zone with high water content, low salt content and low pH value was formed directly under the micro spray belt with ridge planting, while soil salt content and pH value were uniformly distributed in the upper 0-20 cm soil layer with flatten planting. Compared with PZST and PZCK treatments, soil salinity content and pH values were reduced at maturity period. Whether ridge planting or flatten planting, soil conditioner significantly increased watermelon yield by 23.60% and 19.99% compared with PZCK and LZCK treatments, respectively. It also increased rind and fruit hardness of watermelon. Compared with the PZCK treatment, soluble solids at perimeter, soluble sugars, ratio of sugar and acid, and lycopene of watermelon were increased by 38.40%, 20.57%, 71.78%, and 52.92%, respectively. Correlation analysis revealed that watermelon yield and quality indexes was significantly positively correlated with water content in the 0-20 cm soil layer, while significantly negatively correlated with soil pH and soil salt content. In conclusion, the cultivation method combined with soil conditioner significantly reduced the soil salinity content and pH value and promoted the growth, the yield and quality of watermelon, which was a suitable method for watermelon cultivation in saline and alkaline soils.