Effects Of Wheat Cover Crop And Potassium Reduction On Yield Of Cucumber And Nutrient Absorption

In recent years,with the expansion of the planting area of faculty vegetable,the scale of faculty vegetable industry system has gradually become bigger.However,it has become a growing obstacle to continuous cropping.Long continuous cultivation can make the effectiveness of soil nutrient imbalance,soil ecological environment deterioration,causing loss of sustainable land use,which affect the crops quality and yield.Therefore,how to improve the nutrient cycling capacity,maintain the health of the soil ecosystem,and improve the quality and yield of crops are import ant issues in the development of the facility vegetable industry under the premise of “double reduction”.In this study,no wheat cover crop was used as a control,wheat cover crop,wheat cover crop with normal potassium and wheat cover crop with potassium reduction were set up for treatments.This experiment was carried out for two years to study the effects of wheat cover crop on soil nutrient and nutrient absorption of plant.This study simulated wheat straw and root decomposition under wheat cover crop to explore the effect of wheat residue decomposition on plant concentration and soil microbial community and clarify the effect of wheat cover crop on nutrient cycling.The main results were as follows:1.Compared with no wheat cover crop,wheat cover crop with normal potassium and wheat cover crop with potassium reduction didn't affect cucumber yield significantly,but reduced the nitrate content of cucumber fruit in 2018 spring.In addition,the content of ammonium nitrogen in spring 30 d,available phosphorus in spring 50 d,available potassium in spring 50 d and available silicon in spring 70 d in the soil decreased significantly,but the concentration of nitrogen in spring 50 d,phosphorus in spring 50 d and potassium in spring 70 d in cucumber plant in creased significantly.Compared with noromal potassium,potassium reduction decreased soil available calcium content.2.During decomposition of 150-170 d,the potassium content of wheat straw and root decreased,but the soil available potassium content in creased;during decomposition of 170-200 d,the nitrogen and magnesium content of wheat straw and root decreased greatly,but the soil available magnesium content increased,and the plant nitrogen concentration increased;during decomposition of 170-220 d,the calcium content of wheat straw and root was reduced,but the available calcium content of the soil increased.Compared with noromal potassium,potassium reduction didn't affect wheat residue decomposition.3.Compared with no wheat cover crop,wheat straw and root decomposition in wheat cover crop increased the absolute abundance of bacteria,bacillus and pseudomonas at 240 th d of decomposition.Compared with wheat root,the decomposition of wheat straw increased the absolute abundance of bacteria,bacillus at 220 th d of decomposition.The decomposition of wheat residues changed the structure of soil bacteria and fungi.The decomposing of wheat residues increased the relative abundance of Bacillus and Pseudomonas.Bacillus and Pseudomonas participated in multiple nutrient cycles,and their increase was beneficial for nutrient cycling.Compared with noromal potassium,potassium reduction increased the relative and absolute abundance of Bacillus.In summary,the cover crop changed soil nutrients content,and promoted the absorption of nitrogen,phosphorus and potassium.Among them wheat residue decomposition provided nitrogen,promoted the absorption of more nitrogen for following crop.The decomposing of wheat resid ues changed the soil microbial community structure and composition,increased the quantity of soil bacterial and beneficial microorganisms,changed the biological environment of the soil,and promoted plant growth and development.Reduction potassium not o nly ensured the yield,but also improved the quality of cucumber fruit.At the same time,reduction potassium didn't affect the absorption of nitrogen,phosphorus and potassium by cucumber.