| Summary: | 碩士 === 國立臺灣大學 === 農業化學研究所 === 89 === A vegetable (Lactuca sativa and Brassica chinensis) field experiment with three treatments: 1) nitrogen fertilizer (0, 261, 522 kg urea ha-1, and 15 ton org. fertilizer ha-1), 2) water management (adequate water amount and amount two times which), and 3) nitrification inhibitor (with and without dicyandiamide) was conducted to examine the effects of nitrogen fertilizes, water management, and nitrification inhibitor on nitrous oxide emission from a vegetable field soil (acid sandly soil) during the period from the autumn of 1999 to the summer of 2000. Fluxes of N2O were measured by a closed chamber method. The results showed that nitrous oxide emission increased with increasing nitrogen fertilizer rate ( for all four crops, p＜0.05 ) and decreased with using dicyandiamide ( for the fourth crop, p＜0.01 ) . The nitrous oxide emission were not affected by the vegetable species studied, and were not affected by the water management ( p > 0.05 ), but significantly correlated with soil moisture content by simple correlation analysis ( p＜0.001 ) and stepwise regression analysis ( p＜0.001 ) . Therefore, the suggested mitigation strategies of nitrous oxide emission from vegetable field soils were application of adequate amount of nitrogen fertilizer, irrigation of adequate amount of water (depending on soil texture, vegetable species, and precipitation), and application of adequate amount of nitrification inhibitor if necessary.
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