Salt movement of seasonal freezing-thawing soil under autumn irrigation condition

In view of severe salt accumulation in Hetao irrigation district, Inner Mongolia, during spring, salt movement of seasonal freezing-thawing soil after autumn irrigation was analyzed based on field experiment. Results showed that soil salt only leached to deeper layers in a short time after autumn irrigation, and they were mainly discharged from field during early freezing period. Influenced by both freezing and discharging process, salt movement was complex and resulted in little salt storage change of frozen layer during the freezing period, while the main process of salt accumulation happened in the thawing period. After the whole experiment period, salt storage in the layer of 0-100cm and 0-150 cm both increased, which indicated that the autumn irrigation did not accomplish leaching salt absolutely. It was also found that good drainage conditions inhibit salt upflowing in some degree, which presented significantly during the freezing process.