Determination of Nitrogen Balance of Agricultural Land among OECD Nutrient Balance Indexes

OCED 농업양분지표중 질소 균형지표 설정

To determine nitrogen balance (Input-Output) of Korea that was asked by Joint Working Party of the Committee for Agriculture and the Environment Policy Committee, OECD, nitrogen input and output were separately investigated as followings: nitrogen input included the amounts of chemical fertilizer consumption, cattle manure production, and biological nitrogen fixation in the national scale, and nitrogen output summed amounts withdrawn by crop and pasture harvesting, and crop residue removal, and lost by denitrification. In 1997, nitrogen balance of Korea was $158kg\;ha^{-1}$ and $211kg\;ha^{-1}$ on including and excluding denitrification loss, respectively. N balance excluded N loss by denitrification and N withdrawal by crop residues on nitrogen output was $250kg\;ha^{-1}$, which OECD asked to except two items from N balance determination because participants were not enough their data. Nitrogen balance was increased to 1.7~2.3 times in 1997 compared with 70 and $162kg\;ha^{-1}$ in 1985, which calculated on the condition of including denitrification and excluding denitrification and removal of crop residues in nitrogen output, respectively. This increase was caused mainly by increasing livestock manure production and chemical fertilizer consumption together with agricultural land area decrease. Nitrogen input was composed with 59% of chemical fertilizer. 42% of cattle manure and 5% of others in 1997, and output was with 73% of crop production, 23% of crop residue withdrawal and 4% of pasture production. Average nitrogen balance excluded N loss by denitrification and N withdrawals by crop residues in 1995~1997 calculated by OECD was $253kg\;ha^{-1}$, which was the second highest rank in OECD participants following $262kg\;ha^{-1}$ of Netherlands. Japanese N balance that has similar farming system with us was $135kg\;ha^{-1}$.

OECD농업/환경위원회 요청에 의하여 질소양분 균형지표 (Input-Output)설정을 위한 기초자료가 되는 비료소비량, 가축분생산량 생물적 질소고정량, 작물흡수량, 탈질량 및 작물부산물 회수량 등을 조사하였다. 질소균형지표는 1997기준, 탈질량을 포함할 경우와 포함하지 않을 때 각각 ha당 158kg, 211kg이었으나 OECD에서 요구하는 탈질량과 작물 부산물 회수량을 제외하는 경우는 250kg으로 산출되었다. 질소균형지표를 연도별로 비교해 보면 1985년 기준 $70{\sim}162kg\;ha^{-1}$에 비하여 1997년은 1.7~2.3배나 증가되었으며, 주요인은 가축분생산량 및 화학비료 소비량 증가와 경지면적 감소 때문이었다. 질소균형지표의 구성비율은 1997년을 기준으로 하여 질소의 Input에서 화학비료 59%, 가축분뇨 42%, 기타 5%이며 (가축분중 질소휘산량은 6%임), Output는 작물생산 73%, 부산물 회수량 23%, 목초생산 4%이였다. OECD사무국에서 검토한 자료(안)에 의하면 1995~1997년 기준 탈질량과 부산물회수를 통한 질소 질소제거량을 제외한 질소균형지표는 우리나라가 $253kg\;ha^{-1}$으로 네델란드의 $262kg\;ha^{-1}$ 다음으로 회원국중 두번째로 높으며, 일본은 $135kg\;ha^{-1}$이었다.