• Korean Journal of Soil Science and Fertilizer
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• v.32 no.4
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• pp.344-356
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• 1999

A new and relatively simple equation for the soil water content-pressure head curve, ${\theta}$(h) is described in this paper. The particular form of the equation enables one to derive closed-form analytical expressions for the relative hydraulic conductivity, Kr, when substituted in the predictive conductivity models of Y. Mualem. Hopmans' equation is presented as an experimental method. The experienced method, $ET_a=K_sK_cET_o$ is introduced to estimate the actual evapotranspiration, $ET_a$(or $ET_c$). Using $ET_c$ and coil water data measured automatically in a weighing lusimeter, $K_s$ and $K_c$ values are estimated. Recently, FAO has introduced calculation procedures for the soil water(stress) coefficient, Ks in "Guidelines for computing crop water requirements".

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.3
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• pp.337-343
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• 2011

A particular empirical equation for rainfall kinetic energy is needed to compute rainfall erosivity, calculated by the annual sum of the product of total rainfall energy and maximum 30-min rainfall intensity. If rainfall kinetic energy equation was different, rainfall erosivity will be produced differently. However, the previous studies in Korea had little concern about rainfall kinetic energy equation and it was not clear which rainfall kinetic energy is suitable for Korea. The purpose of this study is to analyze and evaluate the difference of the rainfall erosivity based on different rainfall kinetic energy equations obtained from previous studies. This study introduced new rainfall erosivity factors based on rainfall kinetic energy equation of Noe and Kwon (1984) that is only regression model developed in Korea. Data of annual rainfall erosivity for 21 weather stations in 1980~1999 were used in this study. The result showed that rainfall erosivity factors by the previous equations had been about 10~20% overestimated than rainfall erosivity by Noe and Kwon (1984)'s equation in Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.635-643
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• 2016

Wine consumers desire to drink a high quality wine. For producing high quality wine, high quality soil is required. Conventionally, soil quality is assessed qualitatively. Using traditional laboratory methods, quantitative data can be obtained for management purpose, but it is time consuming and expensive. Therefore, new technology aims to address these limitations, namely portable X-Ray fluorescence spectrometers (pXRF). This instrument can be used directly in the field, requires no soil sample preparations, and can simultaneously measure a wide range of elements qualitatively that are useful for pedological studies. The chemical composition (Ca, Fe, Ti and Zr) of soils at Tallavera Grove vineyard in New South Wales, Australia, was studied using a pXRF. The analysis of the soil's elemental concentration (i.e. Ca and Fe) using pXRF supports management decisions. Measuring the soil's Ca concentration can be used to identify Ca-rich parent materials (limestone). The limestone indicates good soil conditions for vine production. Fe content was used to identify areas of texture-contrast soils or soil with accumulation of clays in the B horizon. In addition, a soil weathering index was calculated using elemental concentrations (i.e. Ti and Zr) to explore the history of soil formation for making decision of management. This index showed that the soil in the vineyard was affected by two processes: the deposition of materials from elsewhere (Aeolian transport or soil erosion) and mixing of materials from upslope.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.7
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• pp.1022-1028
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• 2005

The objectives of this study were to evaluate and compare the environmental load of two different concentrate feed supply systems to the Japanese domestic livestock industry using the Life-cycle Assessment (LCA) method. The current system was defined as that requiring 11.469 million tons of corn imported from the US by sea transport and supplied as concentrate feed to the Japanese domestic livestock industry. The new system proposed by Kaku et al. in 2004 was defined as where 802,830 tons of US imported corn would not be planted in US and would be replaced by barley planted in 278 thousand ha of Japanese domestic land left fallow for the past year. In this case, 909,000 tons of domestic harvest barley would have been supplied as concentrate feed to the Japanese domestic livestock industry in 2000. The activities taken into account within the two system boundaries were three stages: concentrate feed production, feed transportation and gas emission from the soil by chemical fertilizer. Finished compost was regarded as organic fertilizer and was put instead of chemical fertilizers within the system boundary. Adoption of this new concentrate feed supply system by the Japanese domestic livestock industry could reduce 78,462 tons $CO_2$-equivalents of global warming potential, 347 tons $SO_2$-equivalents of acidification potential, 54 tons $PO_4$-equivalents of eutrophication potential and 0.842 million GJ as energy consumption below 2,000 levels. This LCA study comparing two Japanese domestic livestock concentrate feed supply systems showed that the stage of feed transport contributed most to global warming and the stage of emission from the soil contributed most to acidification and eutrophication. The Japanese domestic livestock industry could participate in emissions trading with $CO_2$-equivalents reduced by shifting from some imported US corn as a concentrate feed to domestic barley planted in land left fallow. In that case the Japanese government could launch emissions trading in accordance with Kyoto Protocol in the future.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1286-1294
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• 2011

This paper reviews the future directions and perspectives on the soil environmental researches in the 21 century. Previously, the principal emphasis of soil environmental researches had put on the enhancement of food and fiber productions. Beside the basic function of soil, however, the societal needs on soil resources in the 21st century have demands for several environmental and social challenges, occurring regionally or globally. Typical global issues with which soil science should deal include food security with increasing agronomic production to meet the exploding world population growth, adaptation and mitigation of climate change, increase of the carbon sequestration, supply of the biomass and bioenergy, securing the water resource and quality, protection of environmental pollution, enhancing the biodiversity and ecosystem health, and developing the sustainable farming/cropping system that improve the use efficiency of water and agricultural resources. These challenges can be solved through the sustainable crop production intensification (SCPI) or plant welfare concept in which soil plays a key role in solving the abovementioned global issues. Through implementation of either concept, soil science can fulfill the goal of the modern agriculture which is the sustainable production of crops while maintaining or enhancing the ecosystem function, quality and health. Therefore, directions of the future soil environmental researches should lie on valuing soil as an ecosystem services, translating research across both temporal and spatial scales, sharing and using data already available for other purposes, incorporating existing and new technologies from other disciplines, collaborating across discipline, and translating soil research into information for stakeholders and end users. Through the outcomes of these approaches, soil can enhance the productivity from the same confined land, increase profitability, conserve natural resource, reduce the negative impact on environment, enhance human nutrition and health, and enhance natural capital and the flow of ecosystem services. Soil is the central dogma, final frontier and new engine for the era of sustainability development in the $21^{st}$ century and thus soil environmental researches should be carried according to this main theme.

• Journal of Korean Society of Forest Science
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• v.96 no.6
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• pp.693-698
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• 2007

We have only one type of forest fertilizer involved a composition ratio of 12:16:4% (N:P:K). It is required to develop new fertilization ratios which are suitable to soil environmental conditions and seedling growth characteristics. This study was carried out to determine change of seedlings growth on different fertilizer composition ratios. Two coniferous seedlings (2-year old Pinus densiflora Sieb. et Zucc., 2-year old Larix leptolepis Gordon) and two deciduous seedlings (2-year old Quercus acutissima Carruth., 1-year old Betula platyphylla var. japonica Hara) were planted in pots (about 30 l) and the seedling growth responses after composition ratio treatments (N:P:K, 2:2:1, 3:4:1, 3:8:1, 6:4:1, 3:4:2, control) with 30g fertilizer were measured for three-year study period. Growth of height and root collar diameter of two coniferous seedlings was highest in 3:8:1 ratio compared with other fertilizer composition treatments or control, while there was not significantly different among fertilizer composition ratios except for 2:2:1 and 3:4:1 ratios. Height growth of two deciduous seedlings was highest in 3:8:1 ratio compared with other fertilizer composition treatments or control, while growth of root collar diameter showed the highest values in 6:4:1 ratio. The results indicated that the growth of four tree seedling types were better in 3:8:1 or 6:4:1 ratios than in 2:2:1 or 3:4:1 ratios.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.462-469
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• 1982

Since 1962, varietal development and dissemination for summer upland crops have been actively initiated by the Crop Experiment Station, Office of Rural Development, Suweon, Korea. The major breeding objectives of soybeans have been to develop varieties which are early maturing, disease resistant, and adaptable to late planting for after-barley cropping. Development of eleven new soybean varieties including Hwangkeumkong, Jangyeobkong, Danyeobkong, and Kwangkyo has greatly increased the soybean yield throughout country. For com, after development of Hwangok #2, a synthetic, in early 1960's, nine corn hybrids-single crosses, double-crosses, and three-way crosses-such as Jecheon-ok, Hoengseong-ok, Kwangok, Suweon #19, etc., have been disseminated mainly to Kangweon province, a major corn producing area in Korea, and drew up the yield over 4 tons per hectare. The major breeding objectives of sweet potato have been to develop varieties which have high starch content and root yield. Hwangmi, Hongmi, and Shinmi are three sweet potato varieties developed and disseminated by the Crop Experiment Station, Office of Rural Development and are grown most widely in Korea. Most of researches on cultural practices of upland crops have begun on a full scale from early 1960's. In soybeans, for example, no fertilizer but for barley was applied although the effects of phosphate and potassium fertilizers were great on soybeans in after-barley soybean croppings. The effects of heavy application of phosphate and calcium fertilizers on soybeans in newly reclaimed soils were recognized. Recently a mixed fertilizer for soybean (N; 40, P:70, K:60 kg/㏊) was developed and sold for soybean growers. The optimum planting densities of 220, 000 plants/ha in full-season cropping and 330, 000 pts/ha in after-barley cropping of soybeans were known from repeated experiments. For higher yield, a means of cultural practices such as transplanting-pinching, direct planting-pinching, and hilling-up, etc., were developed along with barley-stubble planting with no tillage and integrated herbicide application for labour savings. For sweet potato, cultural practices for planting date, harvesting date, fertilizer, and planting density were fully established. For early marketing, a technique of vinyl-mulching on sweet potato has also fully developed. For com, planting density of 37, 000 pts/ha in early 1960's has been changed to 55, 000 pts/ha for grain production and 67, 000 pts/ha for silage. The amounts of fertilizers have also been changed from 120-120-120kg/ha (N-P-K) in early 1960s to 180-150-150 kg/ha. These increases in number of plants per unit area and fertilizer levels have resulted in greater production for both grain and silage. At the same time, the production techniques of F1 seeds have also improved.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.5
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• pp.280-289
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• 2003

The purpose of this study was to establish a model for recommendable application level of nitrogen fertilizer based on soil testing for summer chinese cabbage in highland. A field experiment was carried out with various nitrogen application levels in sand loamy soil with and without poultry manure compost. The application level of N in poultry manure compost plot was found to be $291kg\;ha^{-1}$ for maximum yield of chinese cabbage, and it was 87% of the required N application level, $335kg\;ha^{-1}$, for maximum yield of chinese cabbage in nonmanure plot. In the treatment of poultry manure, approximately $174kg\;ha^{-1}$ of N was required to obtain the same yield of chinese cabbage as the maximum yield obtained in the treatments without poultry manure application. Therefore, with poultry manure application, N application level can be reduced by 40%. Using these results, a new equation for N recommendation for chinese cabbage in highland soil was proposed. With the average organic matter content of $33g\;kg^{-1}$ in highland field, the application levels of N for chinese cabbage were in the range of $215-129kg\;ha^{-1}$, which means that 32.8-59.7% of current application amount of N fertilizer can be reduced.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.1
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• pp.61-68
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• 1996

Hehage production, botanical composition and soil chemical characteristics were investigated Ween new pastures and old pastures during grazing seasons from May 1993 to October 1994, to find out the condition of pastures grazed by horses on Chdu. Dry matter yields between new pastures and old pastures were 8,757kglha and 7,486kglha respectively. Plant heights of new pastures were 17.4cm. compared with those of old pastures of 12.lcm. The botanical composition of new pastures was composed of grasses about 402, legumes 7~14%, others 18-30% and dead materials 18~ 25%. whiie there were grasses 12%, legumes 3~7%, others 65% and dead materials 15% in old pastures. The contents of crude protein, phosphoms and sodium were lower in old pastures(l3.30, 0.24 and 0.10% respectively) than those in new pastures(l5.47, 0.28 and 0.14% respectively). There was no difference in ADF, NDF, Ca, Mg and K content between the 2 kinds of pastures. The chemical characteristics of the 2 kinds of pastures was shown to be similar, except available phosphorus, comparing 8.18ppm in old pastures with 84.43ppm in new pastures. Although the herbage yield and the soil characteristics of old pastures were lower than those of new pastures, we suppose that the old pastures would be improved, if taken good care of by methods such as oversowing and sometimes applying fertilizer.

• Korean journal of applied entomology
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• v.15 no.1 s.26
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• pp.39-46
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• 1976

As the technology of rice production in Korea has rapidly developed and progressed over the last few years, many problems in rice production have been solved. But with the introduction of new genetic material, the increased use of pesticides, higher fertilizer rates and closer plantings, new problems are beginning to emerge. The brown plant hopper outbreak in 1975 resulted to a great extent from some of the changes in management practices. Some rice diseases and nutritional problems that have existed in Korea but have not been considered of serious consequence, are now becoming increasingly severe and possibly as limiting as the hopper outbreak in 1975. Other diseases and nutritional problems are completely new and their cause and significance have not yet been adequately defined. In this discussion there is no Intention to state, nor is there evidence to support a statement, that any of these problems are going to be limiting factors in the future production of rice on the Korean peninsula. Rather this is an attempt to bring together some of the current field problems in Korean rice so that they can be discussed and where necessary receive suitable consideration for research and control.