Influences Of Vermicompost As A Substitute For Chemical Fertilizer On Soil Properties,Yield And Quality Of Vegetables

Currently,the long-term excessive application of chemical fertilizer and inappropriate disposal of livestock manure and crop straw have caused a waste of resources and environmental pollutions in China.Partial substitute of chemical fertilizer with organic amendments particularly vermicompost could not only positively reply to government’s call on reduction of chemical fertilizer and pesticide,but also could promote crop yield and quality and consequently satisfy the requirements of food security.A field experiment was conducted with a rotation of pepper-tomato-spinach each year in a greenhouse.Different treatments including chemical fertilizer only and four gradients of vermicompost substituting chemical fertilizer with(5 t/ha,10 t/ha,20 t/ha and 40 t/ha)following the principle of equivalent nutrient(N,P and K)input was set up with four replicates in the year of 2015.Soil and vegetable plants were collected at the harvest stage of pepper,tomato or spinach in the year of 2016 to investigate the effects of vermicompost as a partial substitute of chemical fertilizer on soil properties,vegetable yield and quality.The main results are as follows:(1)Compared with chemical fertilizer only,vermicompost substitution significantly increased soil moisture and pH regardless of the pepper,tomato or spinach(P<0.05).Soil available phosphorus and potassium significantly declined with the increasing substitute dose of vermicompost at the harvest stage of pepper and tomato ’(P<0.05),which help reduce the leachate of nutrients.The reverse was true at the harvest stage of spinach.The more substitute dose of vermicompost,the higher available phosphorus and potassium in soils,suggesting that the residual nutrients were higher for organic amendment.(2)Enzyme activities involved in C and N cycling significantly enhanced in soils with vermicompost supplement compared to those with chemical fertilizer only(P<0.05).There was no significant difference among treatments for the enzyme activities involved in P cycling at the harvest stage of pepper.(3)Compared to the treatment of chemical fertilizer,partially substituting chemical fertilizer with vermicompost could significantly increase the vegetable yield with the largest increment being 27.7%and 32.0%for pepper and spinach,respectively(P<0.05).(4)Vermicompost amended at the doses of 20 t/ha and 40 t/ha could significantly promote the contents of free amino acids,vitamin C flavonoids and total phenols(i.e.improvement of the antioxidant capacity of the pepper),and reduce the nitrate content of the spinach leaves(P<0.05).Moreover,vermicompost amendment could enhance the pepper uptake of the elements of Fe,Mn and Ca(P<0.05).In conclusion,vermicompost substituting chemical fertilizer could promote vegetable yield and quality,and improved soil physicochemical properties.Particularly,vermicompost amendment accelerated the soil carbon and nutrient cycling,which suggested more attentions should be paid on the function of soil community and mechanism of vermicompost in future agricultural management research.Our results provide theoretical basis for reducing the doses of chemical fertilizer via vermicompost substitution,in order to develop recycle and sustainable agriculture.