Soil Moisture Distribution Characteristics of Cotton Fields under Wheat and Cotton Cropping System

Sun Julong; Liu Shuai; Hu Qixing; Bai Zhigang; Li Xiaofei; Cui Aihua; Li Yabing

doi:10.14083/j.issn.1001-4942.2024.11.007

Abstract：To clarify the distribution characteristics of soil moisture in cotton fields under different plant-ing modes,three planting modes of wheat-cotton intercropping,direct-seeding cotton after wheat harvest,and monoculture cotton were selected in the long-term positioning test in field.The spatial grid method was used to measure the soil moisture in cotton fields during the whole growth period,in order to explore the influence of different planting modes on soil moisture distribution and try to determine the water requirement characteristics of cotton in various growth periods.The results showed that the spatial distribution of soil moisture had a cer-tain spatial heterogeneity,which was specifically manifested in:the determination coefficient of soil moisture semi-variance analysis at different growth stages of cotton under different planting modes were all above 0.92,and the best fitting model was Gaussian model;when the ratio of partial abutment value to abutment value(C/Sill)was above 0.75,the spatial distribution of soil moisture had a strong autocorrelation;the spatial vari-ation range of soil moisture under the three planting modes was larger than the actual sampling interval of 20 cm indicating the spatial variation characteristics of soil moisture.According to the spatial distribution of soil moisture,it was found that the influence of direct-seeding cotton after wheat harvest on soil moisture in cotton fields was mainly concentrated in the 10～50-cm soil layer.In the wheat-cotton intercropping pattern,the soil moisture was obviously affected by the wheat-cotton symbiosis period,and the impact could reach to the 70-cm soil layer due to the roots growing deeper.In summary,the double cropping system of wheat and cotton changed the temporal and spatial distribution of soil moisture in cotton fields,and soil moisture consumption was one of the important factors that determined the spatial differences.In this study,the law of soil moisture movement during the whole growth period of cotton in the double cropping pattern was explored by using the spatial grid method to sample and quantify soil moisture,and using the geostatistics to analyze the spatial het-erogeneity,which could provide theoretical supports for rational use of water resources in cotton fields and in-telligent irrigation in double cropping pattern.