Compost And Returning In Situ Of Vegetable Wastes

As everyone knows, high moisture and nutrient content are the characteristics of vegetable waste. In recent years, the rapid development of vegetable industry, led to a sharp increase of vegetable planting area and output, and the output of vegetable wastes in the process of production, processing, transportation and storage increased dramatically, naturally. To reduce the waste of resources caused by improper disposal and environmental pollution, combined with the principle of near processing first, this study used composting and returning in situ, the two ways to deal with vegetable waste, and studied the agriculture and environmental effects of which. The conclusions were as follows:(1) After all treatments being mixed, the aerobic compost is conducted through aeration oxygen-supply and the physicochemical properties and material changes in the compos ting process have been monitored. The results show that: adding cattle dung has a greater impact on the process of vegetable waste composting than adding chicken manure, where, the germination indexes(GI) LDM and PDM adding cattle dung are respectively 7.10% and 3.44% higher than those of LCM and PCM in adding chicken manure; after the composting the C/N of all treatments are lower than their initial values and reach a significant level(P <0.01), among them, C/N of LDM and PDM decrease to the greatest extent, which are 52.84% and 53% respectively; in the whole composting process, the quantity of ammonia volatilization in treatments adding chicken manure(LCM and PCM) is significantly higher than that of adding cattle dung(LDM and PDM). On the whole, adding cattle dung can better promote the decomposing process in vegetable waste composting and reduce nitrogen loss than adding chicken manure under conditions in this experiment.(2)It was found that, adding SP improved the average temperature during the compost, the S10 treatment had the highest average temperature of 51.90℃, and significantly accelerated the harmless of compost process and consumption of carbon and nitrogen in high temperature period. At the end of the composting, adding SP had no significant effect on C/N of composting process, however, it decreased p H and improved the EC of the compost, the EC value of the treatments of S10, S15, S20 and S25 were significantly higher than CK. The GI of S5, S10, S15 and S20 were 105.61%, 99.47%, 95.22% a nd 96.65% respectively, which were significantly higher than CK(P<0.01). Adding SP significantly reduced the nitrogen loss rate of composting(P = 0.0008), the lowest of which was S5, only 23.94%. SP additives in vegetable waste composting decreased the ammonia volatilization,and greenhouse gas emissions significantly. SP additives reduced total N H3 emission by 4.04% to 16.66%. Compared with the control,the total greenhouse gas emissions(CO2-eq) of five treatments with SP additive were decreased by 10.18% to 20.78%.The NH3 emission during the process of vegetable waste made a greater contribution to the greenhouse effect in the four different gases. The amount of NH3(CO2-eq) from every treatment were from 59.90~81.58 kg?t-1, which accounted for 69%~77% in the four kind of gases. It is concluded that SP as a cheap phosphorus fertilizer can be used as an additive in vegetable waste composting to reduce the NH3 and greenhouse gas emissions and improve the value of compost as fertilizer.Under this experimental co ndition, the feasible addition amount of SP could be about 2.05% ~ 8.21% of raw materials of dry weight.(3)When ventilation rate was 15min/8h, the average temperature was 47.29 ℃, significantly higher than the other treatments(P<0.01). At the end of the compost, when ventilation rate was 15min/2h, GI value was the lowest, at 80.48%, significantly lower than the value when the ventilation rate was 15min/8h(P<0.01). The nitrogen loss rate of vegetable waste mixed with straw and urea compo st increased by 17.67%, than that just adding straw, and reached significant level(P=0.02), and which was significantly reduced when ventilation frequency was 15min/8h, only 34.01%(P=0.03).(4)The concentration of 5% lime slurry reduced microbial quantity 92.36%, significantly, which can be a suitable concentration for disinfectant 1, but lime slurry was not suitable for application in large numbers in alkaline soil in the north of China. Disinfectant 2 had better inhibition of microbial growth, 1% concentration of disinfectant 2 reduced the number of bacteria and actinomycetes was 83.33% and 65.13% respectively, than CK, and reached significant level, therefore, can use 1% concentration of disinfectant 2 to deal with vegetable wastes. Spraying and soaking, the two ways of the use of disinfectant 2 impacted on the number of microorganisms had no significant difference from the high pressure steam sterilization treatment, meanwhile, spraying was easyer and cost lower, which should be the way of disinfectant 2 used, in the actual production.(5)Pepper phytophthora disease control effects of XD2, XD3 and ZY3 were 100%, when on November 22 nd. The plant height, stem diameter and SPAD value of XD3 were significantly higher than these of ZY3 by 3.76%, 10.95% and 3.76% respectively, disinfectant XD can promote the growth of pepper better. At the end of the study, disinfectant XD showed up a good control to pepper phytophthora disease, and the treatment of XD3 was best, 100%; Disinfectant ZY had certain control effect, and ZY3 keep more than 70% control effect for 16 days, if increase topdressing frequency, the control effect will be much better.(6)Returning in situ had no significant effect on the first crop of lettuce yield, but the second crop had significant difference: sprayed disinfectant increased the yield 3.75% higher than No sprayed, the yield of returning treatment increased 5.90% than CK, there were no significant difference among the returning treatments. After the first time of the vegetable waste returning, there were no significant effects on soil fertility. After second returning, there were significant effects on soil organic matter content, the treatments of C, D and E were higher 18.70% than CK, and reached significant level each. The first time vegetable waste returning had no significant influence on CO2 and CH4 emissions during the lettuce growth season, but average N2 O emission flux of C and D were higher than CK of 38.53% and 46.75% respectively, and reached the significant level. After the first time returning, there were no significant difference between the contribution of every treatments to the greenhouse effect; after the second returning, the CO2 and N2 O emission flux increased significantly, but no significant change in CH4 emission flux, the contribution of vegetable waste returning to the total greenhouse effect were significantly higher than CK(P=0.01), and increased generally with the amount of returning increasing. The highest total CO2 emission equivalent was E, which was 2.45 times of CK.