Effects Of Potassium Humate On Salt Leaching And Ions Leaching In Coastal Clayey Saline Soil

In this paper,aiming at the problems of low organic matter content,difficult salt leaching,high salt content and low crop yield of coastal clayey saline soil in the Yellow River Delta,through the combination of indoor soil column test and field experiment,the improvement of salt reduction and carbon increase of clayey saline soil was studied by using potassium humate.The indoor soil column experiment focused on the relationship between the potassium humate addition and the soil salinity and ion content,the adsorption quantity of salt and ion,the leaching quantity of salt and ion and the corresponding ion ratio;through the field experiment,the changes of salt content,Cl^-content and Na⁺content in different soil profiles after combined application of potassium humate fertilizer and the effects of potassium humate fertilizer on soil organic matter content and winter wheat yield were determined.The main research results are as follows:(1)Potassium humate can inhibit the soil salt adsorption,promote the soil salt leaching,and reduce the soil salt content.After salt and fresh water leaching,the soil salt content treated with potassium humate was significantly lower than that of the CK treatment,and the maximum decrease was 10.25%and 12.62%,respectively.Compared with the CK treatment,the quantity of soil salt adsorption decreased significantly after salt water leaching,with a maximum decrease of 67.59%,and the quantity of soil salt leaching increased significantly after freshwater leaching,with a maximum increase of 34.28%.(2)Compared with the CK treatment,the adsorption quantity of soil Cl^-and SO₄^2-in the potassium humate treatment after salt water leaching was significantly reduced,and the maximum decrease was 72.42%and 89.52%,respectively,and the maximum decrease of soil Cl^-and SO₄^2-ratio was 2.65%and 2.32%,respectively;after fresh water leaching,the quantity of soil Cl^-and SO₄^2-leaching in potassium humate treatment increased significantly,with the maximum increase of 27.43%and 41.22%respectively,and the maximum decrease of soil Cl^-and SO₄^2-ratio was 6.89%and 6.63%,respectively.(3)Compared with the CK treatment,the quantity of Na⁺adsorption in the soil treated with potassium humate after salt water leaching was significantly reduced,and the quantity of Na⁺leaching in the soil treated with potassium humate after fresh water leaching increased significantly.The soil Na⁺content and Na⁺ratio decreased significantly after twice leaching.The contents of soil Ca²⁺and Mg²⁺in potassium humate treatment after salt and fresh water leaching were higher than those in the CK treatment,and the proportion of soil Ca²⁺and Mg²⁺increased with the increase of potassium humate addition.(4)After applying potassium humate fertilizer in clayey saline soil in the field,the soil salt content,Na⁺content in the 0?60 cm soil layer and the Cl^-content in the 0?40 cm soil layer were significantly lower than those of the CK treatment,and the distribution of salt and main ions in soil profile was significantly improved.Compared with the CK treatment,the maximum decrease of soil salt content,Na⁺content and Cl^-content in the 0?20 cm was more than 10%.(5)After the clayey saline soil was combined with potassium humate fertilizer in the field,the soil organic matter content in the 0?40 cm soil layer increased significantly,and there was an obvious linear negative correlation between the soil organic matter content and the soil salt content in the 0?20 cm soil layer.(6)The yield of winter wheat was significantly increased after the application of potassium humate fertilizer in clayey saline soil in the field.Compared with the CK treatment,the maximum increase of winter wheat yield in 2020 and 2021 was 36.87%and 20.56%,respectively.A comprehensive comparison of the winter wheat yield of each treatment in2020 and 2021,when the field potassium humate fertilizer application rate was 1800 kg/hm~2,the yield increase effect of winter wheat was the best.