Importance of National Crop Productivity in View of CO2 Balance

Crop production in a country is very crucial not only in a country's crop self-sufficiency, but also in carbon recycle. Crop can capture and store the emitted $CO_2$ by cereal food consumption. However, imported cereal food is not concerned in carbon recycle and this hinders the accurate estimation of carbon recycle. Korea imports major grain products including wheat, corn, soybean, and rice and about 90% of the grain composition consists of carbohydrate, protein and lipid. Carbon portions in carbohydrate, protein and lipid are 45, 53, and 77%, respectively. When the carbon portions are digested and converted into $CO_2$ completely, one ton of rice, wheat, corn, and soybean can release 1.51, 1.63, 1.56, and 1.56 tons of $CO_2$ to the atmopshere, respectively. Based on this premise, the evolved $CO_2$ calculated from imported grains for the last 4 years in Korea was over 21 MT of $CO_2$. This amount is equivalent to 4.8 billion US dollars in the conception of carbon tax. These results suggest that a decrease in a cereal import(i.e, an increase in a country's crop self-sufficiency) can lower $CO_2$ release to the atmosphere.

탄산가스 배출과 국내 작물 생산성의 중요성

우리나라에서 수입되는 곡물은 주로 밀, 옥수수, 콩 및 쌀이며 이들 곡물은 탄수화물, 단백질, 지질이 약 90%를 구성하고 있다. 탄수화물, 단백질 및 지질은 각각 45, 53, 77%가 탄소로 이루어져 있고 이들 곡물은 완전히 소화 이용되면 탄소부분은 전부 탄산가스로 산화 되어 대기 중에 방출된다. 따라서 쌀 1톤을 소비하면 탄산가스 1.51톤, 밀은 1톤을 소비하면 1.63톤, 옥수수와 콩은 1톤을 소비하면 1.56톤의 탄산가스를 방출하게 된다. 우리나라는 곡물 자급도가 26%밖에 되지 않아 지난 4년간 연평균 약 2,170만톤 이상의 탄산가스를 외국으로부터 수입하는 것과 같으며 이를 비용으로 계산하면 48억USD에 달한다.