| Summary: | 碩士 === 國立臺灣大學 === 農業化學研究所 === 90 === The main aims of this study were to estimate the nitrous oxide emissions from livestock waste (cattle and hog manure) containing composts during composting and storage, and examine their affecting factors. At first, the influences of different sampling sites (top and half height of the compost heaps) and different sampling time intervals (10, 20 and 30 minutes) on the nitrous oxide emission were examined. Two composting plants were selected to estimate the nitrous oxide emission from livestock waste containing material during composting by a closed chamber method. And the nitrous oxide emission from two compost products of composting plant I during storage was also estimated by the same method. Their affecting factors analyzed and examined during composting and storage including the environmental factor (air temperature) and the basic properties of composts (moisture, compost temperature, bulk density, ammonium content, nitrate content, total nitrogen, total organic carbon, pH and ash content).
The results showed that there were no significant differences between the different sampling sites and the different time intervals. The cumulated emissions of nitrous oxide for four batches during composting in plant I (cattle manure) and II (pig manure) were 30、35、2.4、2.4 and 3.6、2.1、3.7、6.4 (g N2O-N Mg-1 compost), respectively. The composts of first two batches for plant I were added with a little of organic household waste to adjust the moisture of composts, and the nitrogen of the organic household waste added increased the emission of nitrous oxide. The emission factors of initial nitrogen of composts to nitrous oxide for plant I and II were 0.14、0.15、0.009、0.01% (the mean of last two batches was 0.01 + 0.001%) and 0.013、0.009、0.013、0.025% (the mean was 0.015 + 0.007%), respectively. The nitrous oxide emission during different periods of storage of 90 days and 50 days were 0.44 (0.39~0.49) and 0.21(0.16~0.26) (g N2O-N Mg-1 compost), respectively, and their emission factors were 0.002% and 0.0007%. The simple correlation analysis showed that the ammonium and nitrate content (P<5%), compost temperature (P<5%) and the pH of the composts (P < 5%) could significantly influence the emission fluxes of nitrous oxide in composting plant I, but no significant affecting factor was found in composting plant II. For the periods of storage of composts, the factors significantly influenced the nitrous oxide emission fluxes were the ammonium content (P < 0.1%), inorganic nitrogen content (NH4+-N + NO3--N) (P < 0.1%), the temperature of composts (P < 1%), the moisture of composts (P < 0.1%) and the air temperature (P < 1%). The forward stepwise regression analysis showed that the affecting factors could influence the nitrous oxide fluxes in composting plant I significantly in sequence were ammonium content, inorganic nitrogen content, the temperature of composts, the electrical conductivity of the composts and total nitrogen of the composts, but only the temperature of the composts could significantly influence the emission fluxes in composting plant II. For storage, the forward stepwise regression analysis showed the affecting factors could significantly influence the nitrous oxide emission fluxes was inorganic nitrogen content only. The results also showed that it could mitigate the nitrous oxide emission by properly adjusting the depth of the compost heaps and the temperature of composts during composting, but how to control needs further study. Besides, properly adjusting the temperature of the surrounding could mitigate the nitrous oxide emission during storage.
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