• Korean Journal of Organic Agriculture
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• v.19 no.4
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• pp.463-474
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• 2011

The objectives of this study were to establish of resource cycling agricultural system focused on farmer's organization. Case is selected as the farming corporation for the regional agriculture considering the amount of sowing by-products and livestock by-products generated. As a result, generation of fertilizer ingredient depend on feces and urine of Korean native cattle is estimated nitrogen 7.7 ton, phosphoric acid 2.9 ton, and potassium 4.9 ton. On the other hand, generation of fertilizer ingredient demand in cultivated acreage is estimated nitrogen 42.4 ton, phosphoric acid 14.3 ton, and potassium 17.0 ton. Therefore, optimum livestock numbers is estimated 1,867 cattle and it means 1,468 cattle can be raise additionally. In order to complete the resource cycling agricultural system, it should be establish nutrient management system at all of organization level and achieve improvements in regional resource supply. Both economic value of organic fertilizer and the resource cycling system linked market system is considered to develop resource cycling level.

• Korean Journal of Agricultural Science
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• v.42 no.4
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• pp.431-437
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• 2015

Recently, assessment of nitrogen balance has been required for environmental agriculture. Nutrient management using organic matters in farmlands has been strongly required as a means of extending resource-cycling agriculture and reduction of nitrogen balance. Organic matters-derived nutrients and soil-available nitrogen should be necessarily considered to manage nutrient balance in soil-plant system. In this study, we reviewed the amount of N supply according to types of organic matter such as livestock compost and green manure in arable land. In case of applied livestock compost in soil, nitrogen mineralization was influenced by nitrogen amount of livestock manure and mixed materials. And nitrogen mineralization of green manure in arable land was influenced by types of crop and return period of green manure because of change of C/N ratio. Also, nitrogen supply by organic matter in arable land can be changed by environmental factors such as temperature, moisture in soil. Therefore, nitrogen supply according to C/N ratio of organic matter and analysis method for estimation of soil nitrogen supply availability should be evaluated to set up the nutrient management model.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.149-160
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• 2007

KoFlux Gwangneung Supersite comprises complex topography and diverse vegetation types (and structures), which necessitate complementary multi-disciplinary measurements to understand energy and matter exchange. Here, we report the results of this ongoing research with special focuses on carbon/water budgets in Gwangneung forest, implications of inter-dependency between water and carbon cycles, and the importance of hydrology in carbon cycling under monsoon climate. Comprehensive biometric and chamber measurements indicated the mean annual net ecosystem productivity (NEP) of this forest to be ${\sim}2.6\;t\;C\;ha^{-1}y^{-1}$. In conjunction with the tower flux measurement, the preliminary carbon budget suggests the Gwangneung forest to be an important sink for atmospheric $CO_2$. The catchment scale water budget indicated that $30\sim40%$ of annual precipitation was apportioned to evapotranspiration (ET). The growing season average of the water use efficiency (WUE), determined from leaf carbon isotope ratios of representative tree species, was about $12{\mu}mol\;CO_2/mmol\;H_2O$ with noticeable seasonal variations. Such information on ET and WUE can be used to constrain the catchment scale carbon uptake. Inter-annual variations in tree ring growth and soil respiration rates correlated with the magnitude and the pattern of precipitation during the growing season, which requires further investigation of the effect of a monsoon climate on the catchment carbon cycle. Additionally, we examine whether structural and functional units exist in this catchment by characterizing the spatial heterogeneity of the study site, which will provide the linkage between different spatial and temporal scale measurements.