Effect Of Continuous Application Of Vermicompost On Availability Of Potassium In Soil In Greenhouse

In order to determine the effect of vermicompost on soil potassium activation,soil potassium supply capacity,crop yield and quality,using cucumber as the test material,a long-term experiment to replace fertilizer with different amounts of vermicompost in greenhouse,compare with equal straw,100% fertilizer,75%fertilizer and no fertilizer.To study the effect of different amount of vermicompost on potassium content,ability of soil potassium supply,plant potassium absorption,cucumber yield,quality,and soil microorganism,The main findings are as follows:（1）25% vermicompost or straw instead of fertilizer can increase the content of soil slowly available potassium,available potassium,but 25% vermicompost instead of fertilizer can improve the soil potassium better than 25% straw instead of fertilizer.The total potassium content of soil increase first and then decrease with the increase of soil layer,the slowly available potassium and available potassium decrease rapidly in 0-10 cm,10-20 cm,20-30 cm soil depth and there is no obvious downward trend below30 cm soil depth.However,only 25%vermicompost instead of fertilizer has higher potassium content than 100% fertilizer in30-40 cm,40-50 cm,50-60 cmsoil depth.（2）The application of vermicompost and straw can not only improve the ability of soil to supply potassium,but also improve the effectiveness of potassium.AR0 K of 25%vermicompost instead of fertilizer higher than10×10-3（mol·L–1）1/2,it shows that potassium ions are mainly adsorbed on the clay mineral surface,which is beneficial to plant absorption.25%vermicompost instead of fertilizer,50% vermicompost instead of fertilizer,100%vermicompost instead of fertilizer,25% straw instead of fertilizer can increase the potassium supply capacity of soil,25% vermicompost instead of fertilizer of them increase the most,is0.50cmol·kg^-1.The-ΔG of all treatments are all between8.36 k J·mol^–1and14.64 k J·mol^–1,indicating that there is no potassium or calcium deficiency in the soil.（3）Vermicompost or straw can improve the richness,uniformity,diversity and coverage of soil microorganisms,the 100% of the treatment of vermicompost is the best.The relative abundance of Bacillus in 100% straw instead of fertilizer is the highest（8.46%）.Therelative abundance of Bacillus in 25% vermicompost instead of fertilizer is higher than 50%or 100% vermicompost instead of fertilizer and also higher than 25% straw instead of fertilizer.（4）The application of vermicompost can increase the amount of potassium absorbed by plants,and 25% vermicompost instead of fertilizer compared with 50% vermicompost instead of fertilizer,100% vermicompost instead of fertilizer increase by 7.43%,19.25%.The yield of cucumber was significantly increase by 25% vermicompost instead of fertilizer,it higher than 100% fertilizer treatment about 18.44%,and 0.82% higher than 25% straw instead of fertilizer.25% vermicompost or straw instead of fertilizer also can improve the quality.The effect of vermicompost on VC content,soluble solids content is better than that of straw.To sum up,the application of vermicompost or straw instead of some fertilizer can increase the content of available potassium and slowly available potassium in soil,but 25% of the replacement better than 50%,only 25% vermicompost instead of fertilizer has higher potassium content in30-40 cm,40-50 cm,50-60 cmsoil depth.At the same time,the application of vermicompost or straw has a positive effect on the regulation of potassium in deep soil and the improvement of soil potassium supply ability,the main performance is to improve the equilibrium activity ratio of soil potassium and the capacity of potassium supply,among which the improvement effect of vermicompost on soil potassium supply ability is better than that of straw.25% vermicompost or straw instead of fertilizer can increase cucumber yield and improve cucumber quality.Although 100% vermicompost instead of fertilizer has the best effect in improving soil microbial diversity,100% straw instead of fertilizer can significantly increase the relative abundance of dominant genus in soil,both treatments can significantly reduce the soil potassium content and cucumber yield.