Objective of this study was to investigate residual the levels of heavy metals in rice grain and soils of “Top-Rice” and common rice cultivation areas from 2005 to 2007. Soil and rice grain samples were taken from 33 “Top-rice” areas and neighboring paddies, and analyzed for the elements using ICP-OES and ICP-TOF-MS after acid digestion. A concentration of arsenic in paddy soil was 1.33 mg/kg which was below 1/5-1/11 fold of the threshold levels (concern: 4 mg/kg, action: 10 mg/kg), and paddy soil was 0.06 mg/kg of Cd (cadmium) being below 1/25-1/67 fold of the limits (concern: 1.5 mg/kg, action: 4 mg/kg). A level of Cu (copper) in paddy soil was 4.57 mg/kg which was below 1/11-1/27 fold of the threshold levels (concern: 50 mg/kg, action: 125 mg/kg), and Pb (lead) concentration in paddy soil was found to be a 4.68 mg/kg. In addition, Hg (mercury) concentration in paddy soil was to be a 0.03 mg/ kg, which was below 1/131-1/328 fold of the threshold levels (concern: 4 mg/kg, action: 10 mg/kg). The average concentrations of As, Cd, Cu, Pb and Hg in the polished rice samples were 0.037, 0.043, 0.280, 0.048 and 0.002 mg/kg, respectively. These levels are lower than those of other countries in rice grains. Assuming the rice consumption of 205.7 g/day by total dietary supplements in Korea, the amount of total weekly metal intake of As, Cd, Cu, Pb and Hg by polished rice were estimated to be 0.0892, 1.035, 6.712, 1.161 and 0.054 μg/kg body weigh/week, respectively. The PTWI(%) of As, Cd, Cu, Pb and Hg were 5.95 (inorganic arsenic), 0.26 (total arsenic), 14.79, 0.19, 4.65 and 1.07% estimated to be 0.0892, 1.035, 6.712, 1.161 and 0.054 μg/kg body weigh/week, respectively. In conclusion, it was appeared that the heavy metals contamination in the brown and polished rice should not be worried in Korea.

본 시험은 중부지역 답리작에서 파종시기를 달리하여 이탈리안 라이그라스(Italian ryegrass, IRG, Lolium multiflorum), 총체보리(barley, Hordeum vulgare), 호밀(rye, Secale cereale)을 재배할 경우 생육특성, 수량 및 사료가치에 미치는 영향을 구명하기 위하여 2004년부터 2005년까지 2년간 축산과학원(수원) 포장에서 시험을 실시하였다. 생육특성 및 숙기는 조기 파종(9월 26일)구에서 관

본 연구에서는 팽연화왕겨를 이용한 토마토 양액재배시 높은 근권 pH를 적정 수준으로 유지학 위해 공급배양액의 pH를 낮추는 방안과 배지 내에 pH 3.0∼4.0 수준의 sphagnum peatmoss를 혼합하는 두 가지 방법을 시도하였다. 급액 pH를 낮추는 방법은 근권 pH의 경시적 변화가 매우 커서 뿌리에 장해가 있는 것으로 판단되며, 유의성은 없으나 수량이 약간 감소하는 경향을 보였다. Spagnunm peatmoss를 혼합하는 방법은 10%(v/v) 혼합처리에서 안정적인 pH 수준이 생육 전기간에 걸쳐 유지되었으며 수분 특성 개선 등의 부수적인 효과가 있어 유의성 있는 증수 효과를 보여 팽연화왕결르 이용한 양액재배시 높은 근권 pH의 문제는 sphagnum peatmoss를 10%(v/v) 혼합하는 처리로 해결할 수 있을 것으로 판단되었다.

Rice culture in Korea has a long history ranging over two thousand years. In the agriculture economy of pre-mordern Korea, however, its importantce was not as great as generally assumed. In fact, rice culture reached full development only after the 1920s when the Japanese colonial government carried out its drive to increase rice production in the Korea peninsula. It was not until the mid-1930s that rice became the staple in Korean diet. This can be attributed to two factors : (1) a mountainous topography that provides little irrigated fields and (2) a climate characterized by droughts in spring and heavy precipitation in summer. The present paper attempts to answer some of these questions. Specifically it will focus on these : Did the development of rice culture actually result in population growth? What are the salient features of agricultural develdpment and population grow in traditional Korea? Does the case of Korea conform the prevailing generalization about the agriculture in East Asia? I have discussed the development of rice culture and population growth in the Chosn dynasty, focusing on the relation between the rapid spread of transplanting and the rapid growth of population from the seventeenth to the nineteenth century. Here are my conclusions. (1) The spread of transplanting and other technological innovationsc contributed to the rapid growth of population in this period. However, we should also note that the impact of rice culture on population growth was rather limited, for rice culture was not the mainstay of agricultural economy in pre-modern Korea. Indeed we should consider the influence of dry field cropsn population growth. Nevertheless, it is obvious that the proliferation of rice culture was a factor crucial to population growth and regional concentration. (2) How should we characterize the spread of rice culture in the whole period? Evidently rice culture spread from less then 20% of cultivated fields in the fifteenth century to about 36% of them in the early twentieth century. Although rice as a single crop outweighed other crops, rice culture was more then counter-balanced by dry field crops as a whole, due to Korea's unique climate and geography. Thus what we have here in not a typical case of competition between rice culture and day field culture. Besides, the spread of rice culture in the seventeenth and eighteenth centuries accomplished by technological innovations that overcame severe springtime drought, rather than extensive irrigation. Althougt irrigarion facilities did proliferate to some extent, this was achieved by local landlords and peasants rather than the state. This fact contradicts the classical thesis that the productivity of rice culture increased through the state management of irrigation and that this in turn determined the type of society. (3) We should further study other aspects of the transition from the stable population and production struture in the fifteenth and sixteenth centuries to the rapid population growth and excessive density of population thereafter. We should note that there were continuing efforts to reclaim the land in order to solve the severe shortage of land. Changes also took place in the agricultural production relations. The increase in land producrivity developed tenancy based on rent in kind, and this in turn increased the independence of tenants from their landlords. There were changes in family relations-such as the shift to primogeniture as an effort to prevent progressive division of property among multiplying offspring. The rapid population growth also produced a great mass of propertyless farm laborers. These changes had much to do with the disintegration of traditional social institutions and political structure toward the end of the Chosn dynasty.