Improving the Facility Soil by Combining Soil Amendment with Agronomic Measures

[Objectives] To study the remediation methods of secondary salinization and cadmium pollution in facility soil. [Methods] Two kinds of soil amendments, potassium fulvic acid and limestone powder, were selected to be applied alone or combined together to plant maize to carry out field experiments. Their effects on watermelon yield, watermelon cadmium content, soil available nitrogen, phosphorus, potassium and water-soluble salts were studied. [Results] The application of potassium fulvic acid, limestone powder and their combined application increased the yield and soluble solids of watermelon to different degrees. The contents of seven heavy metals including cadmium, copper, zinc, arsenic, lead, mercury and chromium in the watermelon of all treatments were all lower than the food safety limit stipulated in the national standard. During the harvest period of maize seedlings, all treatments could increase soil pH and decrease soil cadmium availability. In particular, 3 000 kg/ha of limestone powder and 1 500 kg/ha of potassium fulvic acid had the best effect on reducing soil available cadmium content. In reducing soil available cadmium content, there were significant differences between single application of amendment and combined application treatments. In addition, compared with the control CK, all treatments decreased soil available nitrogen, phosphorus, potassium and water-soluble salt content. [Conclusions] Potassium fulvic acid, limestone powder and their combined application can increase the yield of watermelon, and can significantly reduce the available cadmium, nitrogen, phosphorus, potassium and water-soluble salt content in the facility soil of maize cultivation.