Environmental Friendly Fertilization And Runoff N/P Emission Reduction Technology In Vegetable Fields

Due to its large amount of irrigation,large amount of fertilizer,and low nitrogen fertilizer utilization,vegetable planting industry makes agricultural non-point source pollution more serious.This paper focuses on vegetable cultivation bases in the Tiaoxi River Basin,and mainly includes environmental protection fertilization techniques,nitrogen and phosphorus loss because of rain,and theri emission reduction and reuse technology.The research results will provide reference for the timely and appropriate selection of efficient and environmentally friendly fertilization methods for vegetable planting,also provide super support and engineering demonstration for the prevention and control of vegetable diffused pollution.The main findings are as follows:(1)The loss of nitrogen from different fertilization treatments in vegetable fields was concentrated within one month after the application of base fertilizer,accounting for 78.84-87.75%.The loss morphology was dominated by nitrate nitrogen;the phosphorus loss was linked to rainfall,and the granular phosphorus was the most.In high-fertility plots,the enhanced site-specific nutrient management technology(ESSNM)can significantly reduce the amount of fertilization compared to conventional fertilization(FF).The total nitrogen and total phosphorus loss during the entire planting season was reduced by 38.44 and 1.9 kg/hm2,respectively.The total nitrogen and total phosphorus reduction rate reached 67.9%and 40.1%,respectively.The runoff coefficients of total nitrogen and total phosphorus in the ESSNM were 3.37%and 0.66%,and in the FF treatments were 7.09%and 0.53%,respectively.The adsorption of DON and PN by biomass charcoal can reduce runoff nitrogen loss.The moderate fertilization resulted in the increase of soil microbial diversity and the increase of proteobacterial phytophthora.The application of biofertilizer and chicken manure combined with chicken manure treatment was more conducive to soil nitrogen metabolism,which was reflected in the increase in nitrogen fixation and assimilation genes related to N metabolism.However,due to the increase of dissolved organic nitrogen(DON),the loss of runoff nitrogen increases.The combination of biomass charcoal and biological bacterial fertilizer can reduce nitrogen loss to some extent.(2)The total nitrogen concentration in runoff drainage at the beginning of rainfall in open-air vegetable fields is not the highest.Generally,the concentration of total nitrogen in runoff is higher in the later period of rainfall,or the total nitrogen concentration of runoff peaks in heavy rain and light rain after the rain.The total phosphorus concentration in runoff drainage is related to rainfall intensity.The concentration of total phosphorus in the runoff during the initial period of light rain and moderate rain is relatively high,and during the little rain after heavy rain it is also high.In general,nitrogen and phosphorus concentrations in runoff were not significantly associated with turbidity,EC,and turbidity.Based on the EwE model ecological stability study of ecological ponds,the ratio of primary productivity to total respiration of the ecological pond is 7.36,which is much larger than index 1 of the mature ecosystem.The ecological pond is eutrophic and unstable,so it is not appropriate to directly used for receiving runoff drainage from vegetables.Time-choosing drainage technology was used to collect and eliminate the drainage of vegetable land.Total nitrogen and total phosphorus were lost in the growing season of open field vegetable crops were 4.71 and 0.16 kg/hm2,respectively.Nitrogen and phosphorus were reused 1.16,0.02kg/hm2,the removal rates of nitrogen and phosphorus can reach 50%when overloaded biological purification system runs in the May-October period.The discharge of nitrogen and phosphorus are 2.08 and 0.11kg/hm2,respectively;the total nitrogen and total phosphorus of runoff vegetables are reduced by 56%and 31%,respectively.(3)The concentration of nitrogen and phosphorus in greenhouse vegetable fluctuated more,the total nitrogen concentration was 4.17-70.14mg/L,the total phosphorus concentration was 0.61-13.01mg/L,and the time of lateral water leakage was 45-60 minutes.Stop the irrigation and stop the side osmosis after 45-60 minutes.Irrigate for 2 to 4.5 hours in summer and 0.5 hours in winter.Each time the amount of irrigation water is 7.5-28.5mm,the amount of lateral water seepage is about 20-40%of the amount of irrigation water.Time-choosing drainage technology was used to collect and eliminate the drainage of vegetable land.The annual amounts of N and P in the tail water of greenhouse vegetables were 25.68 and 2.86 kg/hm2,respectively.The annual cumulative use of nitrogen in the runoff fractionation system was 23.48 kg/hm2,phosphorus 2.64kg/hm2,total nitrogen and total phosphorus reduction of 91%and 92%,respectively.After the overload purification system is stable,the removal rates of nitrogen and phosphorus can reach 50%.After the demonstration project was in normal operation,the overall total nitrogen and total phosphorus in the greenhouse vegetable were reduced by 92%and 93%,respectively.