Effects Of Different Doses Of Vermicompost Substitute For Mineral Fertilizer On Soil Communities And Crop Growth

In intensive agriculture,the accumulation and improper use of organic waste has caused many environmental problems.In recent years,with the increasing attention to food,environment and soil quality,the use of bio-regulation to achieve environmental protection and sustainable development of agriculture has received widespread attention through the application of environment-friendly and renewable resources.Vermicompost is a by-product of effective disposal of organic waste by earthworm,and is a high-quality organic fertilizer which can improve soil quality and crop growth.At present,most of the research focuses on the impact of vermicompost on soil nutrients and ignored soil biological properties.This study carried out three vegetables(pepper,tomato,spinach)rotation under greenhouse conditions.Based on the principle of nutrient equalization,five doses of vermicompost were set to substitute fertilizer,including 0 t ha-1(mineral fertilizer only),5 t ha-1 vermicompost + mineral fertilizer,10 t ha-1 vermicompost + mineral fertilizer,20 t ha-1 vermicompost + mineral fertilizer,40 t ha-1 vermicompost + mineral fertilizer.Which was aimed to systematically study the effect of different doses of vermicompost substitute fertilizer on soil nutrients,microbial activity,enzyme activity,nematode community,crop growth and quality.The results are as follows:(1)Compared with no vermicompost,the application of different doses of vermicompost improved soil physical and chemical properties.Increasing of the application doses of the vermicompost enhanced gradually soil water-retaining capacity,improved gradually soil acidification,and increased the content of soil available phosphorus and potassium.(2)Compared with no vermicompost,the increasing of the application doses of the vermicompost improved significantly soil microbiological properties,and increased gradually the content of microbial biomass carbon and nitrogen in the three seasons.In the pepper and tomato season,the soil enzyme activities(AG,BG)involved in carbon cycling increased with the increase of the doses of vermicompost,but the other enzyme activities involved in carbon and nitrogen cycling in the two seasons reached a higher doses under the treatments of 10 t ha-1 and 20 t ha-1 vermicompost.The soil enzyme activity also increased with lower doses of the vermicompost application and then decreased with higher doses of the vermicompost application in spinach season.(3)Compared with no vermicompost,regardless of vegetable type,the soil nematode abundance reached the highest with the application of 10 t ha-1 of vermicompost,while no longer promoted after the increase in the doses of vermicompost.Among them,the abundance of herbivores decreased while omnivorous-predators gradually increased with the increase of the doses of vermicompost.The abundance of microbivores reached the highest under the treatment of 10 t ha-1 vermicompost.The maturity index and enrichment index also increased while the herbivores maturity index decreased with the application doses of the vermicompost.(4)Compared with no vermicompost,application of vermicompost increased the yields of pepper,tomato and spinach.When the doses of vermicompost was 20 t ha-1,the yield of the three season crops reached the highest and increased by 8.5%,66.4%and 76.6%,respectively.But the application doses of 40 t ha-1 no longer promoted the crop yield.The quality of the crops,including protein,soluble sugar and vitamin C,was improved when the doses falls between 20 and 40 t ha-1 vermicompost.The crop NPK uptake was higher under 10 t ha-1 vermicompost treatment.