우분퇴비 사용후 토양수분 조절에 따른 질소 및 탄소의 전환 = Mineralization of Cattle Manure Compost at Various Soil Moisture Content

다국어 초록 (Multilingual Abstract)

To investigate the transformation characteristics of nitrogen and carbon from cow manure compost amended in soil under different moisture conditions, dynamics of nitrogen and carbon were determined periodically for 15 weeks of aerobic incubation at room temperature during July∼November, 1996. Cow manure compost matured with mixing saw dust was amended with the 4 ratios (0, 2, 4, 6%(wt/wt)) in Ap horizon soil, which collected from green house in Yesan, Chungnam. Moisture was controlled with 0.2, 0.3, 0.4, and 0.5 of mass water content (θm) to air dried soil, and water loss was compensated at every sampling. During incubation, soil pH was decreased continuously, that was caused by hydrogen generated from nitrification of ammonium nitrogen. And pH became higher with inclining cow manure compost amendment and water treatment, that meaned the increase of mineralization of organic-N to NH₄^+-N. Total nitrogen was reduced with increasing water content, but total carbon showed the contrast tendency with that of nitrogen. Therefore, C/N ratio slightly decreased in the low water condition (θm 0.2) during incubation, but increased continuously in high water condition over θm 0.4. As a result, it was assumed that soil fertility is able to be reduced in the high water content over available water content. Nitrate transformation rate increased lasting in the low water content less than θm 0.3. Itdropped significantly in the first 2∼3 weeks of incubation over θm 0.4. In particular, nitrate was not detected in θm 0.5 of water content after the first 2∼3 weeks. In contrast, ammonium transformation was inclined with increasing water treatment. Nitrogen mineralization rate, which calculated with percentage ratio of (the sum of ex. NH₄^+-N and NO₃^--N)/total nitrogen, was continuously increased in the low water content of θm 0.2 and 0.3. But it saw the different patterns in high water content over θm 0.4 that was drastically declined in the initial stage and then gradually inclined . From the above results, nitrogen transformation patterns differentiated decisively in water content between θm 0.3 and 0.4 in soil. Thus, it is very important for the maintain of suitable soil water content to enhance fertility of soil amended with manure compost. However, excess treatment of manure compost might enhance the possibility of contamination of small watershed and ground water around agricultural area.