Study On Mechanism Of Food Waste Compost Improving Facility Barrier Soil

Food waste is an ideal material for producing organic compost because of its higher content of organic matter,less harmful substances and more nutrients.Making food waste into organic fertilizer by aerobic composting can not only reduce the waste,but also promote the recycling of resources.On the other hand,facility agriculture has been popularized in many large cities with less land and more people because of its high land use rate and crop yield.However,due to the properties of high temperature and humidity,lack of rainwater leaching and excessive use of chemical fertilizer,facility obstacles such as soil borne disease,heavy metal pollution and salinization are very easy to affect crop growth.The organic compost made from food waste has great potential in improving facility barrier soil.However,compared with the materials of traditional organic compost,food waste has the properties of high salt and oil.After being produced into compost,its unique physicochemical properties and the impact on soil microbial community are still unknown.In addition,as a common soil conditioner,whether the combined use of biochar and food waste compost can better improve facility barrier soil remains to be studied.Therefore,pot experiments in the facility greenhouse were conducted to explore（1）combined improvement of food waste compost and microbial agents on soil borne disease;（2）combined improvement of food waste compost and biochar on heavy metal pollution in facilities;（3）combined improvement of food waste compost and biochar on facility salinized soil.Besides,theoretical basis and technical guidance will also be provided for the resource utilization of food waste and the improvement of facility barrier soil.The main research conclusions are as follows:1)Compared with biochar and chemical fertilizer,the combined use of food waste compost and microbial agents could significantly improve the soil borne disease.It significantly reduced the abundance of Plasmodiophora brassicae（clubroot pathogen）by 78%,and decreased the incidence rate of clubroot by 44%（P < 0.05）.Microbial community analysis showed that compared with traditional fertilizers,food waste compost could provide more probiotics（Lysobacter,Streptomyces,Dongia,Bacillus,Zopfiella and Rhizophlytis）,which interacted with probiotics in the added microbial agent to strengthen each other’s colonization ability in barrier soil and produced antagonistic effect against pathogens.Mantel test and canonical correspondence analysis showed that alkali hydrolyzable nitrogen had the greatest impact on microbial community.Food waste compost could better improve soil available nutrients（especially nitrogen）than chemical fertilizer and biochar,significantly increasing alkali hydrolyzable nitrogen by 26.7%（P < 0.05）.This promotion avoided the decline in yield caused by the competition between microorganisms in microbial agents and crops for scarce nutrients.2)Food waste compost could reduce soil available cadmium better than straw compost and chemical fertilizer,so as to reduce the absorption of cadmium by crops.When food waste compost and biochar were mixed at a certain proportion,it could further improve the improvement effect of heavy metal contaminated soil.When the proportion was 50%,the improvement effect was the best,significantly reducing 63.16%plant cadmium,33.04% soil total cadmium and 26.32% soil available cadmium（P <0.05）.Network analysis showed that soil organic matter and microbial diversity were the two factors most closely related to cadmium.They were also significantly negatively correlated with three kinds of cadmium.The food waste compost biochar combined treatment with 50% biochar proportion had a better effect on these two factors,significantly increasing 32.71% organic matter and 77.04% Chao1 index respectively（P < 0.05）.In addition,compared with straw compost,food waste compost contained more salt,which could reduce the concentration of cadmium through ion exchange.Therefore,under the same proportion of biochar,the improvement effect of food waste compost biochar combined treatment on heavy metal contaminated soil was better than that of straw compost biochar combined treatment.3)When food waste compost and biochar were mixed at the proportion of 50%,the yield of crops could be increased by as much as 450.98%,which was much higher than that when used alone（54.9%）.The better improvement effect could be attributed to that the treatment significantly increased the soil cation exchange capacity by 5.06%and organic matter by 204.35%（P < 0.05）,thus reducing the alkalinity from 10.11% to5.51%,and the sodium adsorption ratio from 16.74 to 11.47.The improvement of these soil indicators further reduced the salinization level.In addition,compared with straw compost,probiotics in food waste compost were more suitable to play a role in facility salinized soil because they were in a high salt environment for a long time.The addition of biochar also increased the abundance of probiotics such as Streptomyces,Pseudomonas and Nocardioides,which further improved the soil microbial community structure,so as to promote the soil quality.In summary,this study revealed that food waste compost could better improve the physicochemical properties and microbial communities of facility barrier soil than traditional fertilizers.By optimizing the proportion of food waste compost and biochar,the improvement of three kinds of facility barrier soils: soil borne disease,heavy metal pollution and salinization was realized,and the crop yield was also increased.This conclusion helps to provide a theoretical basis for the resource application of food waste on facility agriculture.