Effect Of Continuous Fertilizer Reduction On Cucumber Growth And Soil In Solar Greenhouse With Long Season Cultivation

Cucumber is the second largest vegetable crop in solar greenhouse in China.Long-term excessive application of chemical fertilizer not only leads to serious facility soil obstacles,affecting yield and quality,but also brings potential environmental pollution problems,which has become the bottleneck of green and sustainable development of facility vegetables in China.For this reason,China has put forward policies such as "reduction of fertilizer and pesticide application" and "zero increase of fertilizer and pesticide application",but the effect of continuous reduction of fertilizer application on vegetables and soil in solar greenhouse is not clear.Therefore,in this paper,’Jin Lvxing’(grafted seedling)was used as the test material,and conventional fertilization was used as the control(T100).Four treatments,namely 20%(T80),30%(T70),40%(T60)and 50%(T50)of chemical fertilizer,were set.From 2017 to 2020,the effects of chemical fertilizer reduction for three consecutive years and three cropping times on the growth,yield,quality and soil fertility of cucumber in the long winter season in solar greenhouse were carried out,in order to clarify the effects of chemical fertilizer reduction for three consecutive years,and provide theoretical and technical guidance for scientific fertilization and green production of cucumber in solar greenhouse.The main research results are as follows:(1)Plant growth,fruit yield and quality: With the increase of chemical fertilizer application amount,the number of leaves,total biomass and yield of cucumber all showed a trend of first increasing and then decreasing.The number of leaves,total biomass and yield of cucumber in the third crop T70 treated with chemical fertilizer reduction were the highest,reaching 82.6 leaves/plant,294.0g/ plant and 6.3kg/ plant,respectively,which were significantly increased by 15.3%,6.13% and 5.6%compared with T100 treatment,respectively.Fertilizer reduction treatment had no significant effect on plant height,stem diameter and fruit quality of cucumber.(2)Changes of soil surface nutrients: with the increase of chemical fertilizer reduction,the contents of alkali-hydrolyzable nitrogen,available phosphorus and available potassium in soil surface decreased gradually.The contents of total nitrogen,total phosphorus and total potassium in soil surface decreased with the increase of chemical fertilizer application.However,the contents of total nitrogen,total phosphorus and total potassium in the soil increased gradually with the increase of crop times.(3)Changes of soil nutrients in deep layer: with the deepening of soil depth,the contents of alkali-hydrolyzable nitrogen,total nitrogen,available phosphorus and total phosphorus in the soil gradually decreased,but the EC value and the contents of available potassium and total potassium did not decrease accordingly,indicating that the leaching phenomenon of salt,available potassium and total potassium in the soil was serious.(4)Nutrient utilization and balance: with the increase of chemical fertilizer reduction,the total nitrogen,phosphorus and potassium uptake of cucumber plants showed a trend of first increasing and then decreasing.The total uptake of N,P and K in the third crop T70 treated with chemical fertilizer reduction was the highest,reaching 5.17g/ plant,8.44g/ plant and 9.98g/ plant,respectively.With the increase of chemical fertilizer application amount,the fertilizer use efficiency,partial productivity and agronomic use efficiency of N,P and K also showed a trend of first increasing and then decreasing.In the third crop of chemical fertilizer reduction,T70 treatment of N,P and K fertilizer utilization was the highest,while T60 treatment of N,P and K partial productivity and agronomic utilization were the highest.The soil residual and leaching loss of N,P and K decreased with the increase of chemical fertilizer application.(5)Comprehensive evaluation: According to the principal component analysis of the measurement results,the ranking of comprehensive evaluation scores of each treatment is: T70>T80>T100>T60>T50.Overall,T70 treatment(30% less fertilizer)was the best fertilization plan.