Studies On Effect Of Different Additives On Composting Of Fresh Cow Dung And Fertilization Efficiency

Manure composting and field experiments were conducted for this thesis to investigate the effects of organic nitrogen, 2 microbial agents and their combinations on dynamics of some physical, chemical, biological parameters and changes in microorganisms community during the process of composting for fresh cow dung under aerobic and high-temperature conditions. Meanwhile, effects of the composting products from different treatments were also studied through field application. There were 6 treatments for composting experiment: without any addictive agent (T₁), microbial agent E₁ (T₂), microbial agent E₂ (T₃), organic nitrogen (T₄), combination of the organic nitrogen and microbial agent E₁ (T₅), combination of the organic nitrogen and microbial agent E₂ (T₆). Three treatments for the field experiment included: chemical fertilizers (F₁), composting products with addition of the organic nitrogen (F₂), and composting products with addition of the microbial agents (F₃). Majos findings of these studies are as follows.1. Inoculation of microbial agents brought the peak of high temperature forward by 2d to 3d, with 3d extension of high-temperature period. Higher maximum temperature and more days of temperature higher than 50℃, through which requirements of harmless could be fulfilled. Water content declined gradually during compositing process and eventually became stable at about 38%. Water content was an important factor to differentiate aerobic or anaerobic conditions for manure composting as excess water would have made the condition anaerobic. After completion of compost, pH values of final products from different treatments varied between 7-8.2. Inoculation of microbial agents increased the decomposition of total organic carbon during composting; the effect of E₂ was comparatively superior to E₁, while addition of the organic nitrogen did not significantly influence the speed of decomposition. However, on basis of inoculation of either microbial agent E₁ or E₂ combined with the organic nitrogen, the decomposition of total organic carbon was further accelerated. In comparison to materials before composting, T₁, T₂, T₃, T₄, T₅ and T₆ showed 69.0%, 89.4%, 94.5%, 56.8%, 86.9%, 81.6% increased contents of humic acid in final composting products respectively3. Addition of organic nitrogen remarkably reduced the biological availability of Cu and Zn, which may decline their toxicity as the compost products were applied to the field.4. As for the population of microorganisms, the quantity of bacterium maintained was largest, followed by autonomics and fungus was the smallest throughout the process of composting. Treatments with inoculation of microbial agents resulted in greater total quantity of different microorganisms than treatments without inoculation.5. Results of field experiment showed that F₂ achieved the best effect on improving the quality of the vegetable product, which relatively reduced nitrate contents by 63.7% and increased contents of vitamin C by 19.2% respectively in comparison with F₃. F₁ resulted in the highest yield, with up to 22.7% incease over F₃.