• Applied Biological Chemistry
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• v.8
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• pp.65-73
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• 1967

For the study of method for salt elimination aimed at reforming tidal land into normal paddy fields in a short period with reduction of periods requiring for elimination of saline, CHP (a kind of Ca-hum ate), a soil conditioner made of peat as a main material was tried. In the pot experiment, effect on elimination of salt, improvement of physical-chemical characteristics and rice cultivation test were studied. The results of these tests are as follows: 1, CHP treatment somewhat improves aggregation state with some effect on aggregation. 2. CHP treatment is remarkably effective in permeability which increases with 1.0 percent treatment by three times in percolation rate, and by 4.5 times in volume of leached water respectively. 3. With the increase of CHP amounts, salt was eliminated in short period. When 80% of the total Na was leached in 1.0% CHP-A treated pot, control pot begins permeable. 4. CEC and phosphorous absorption capacity are not influenced by CHP treatment. 5. Growing state of rice is greatly influenced by rainfalls. Growth of rice in tidal land however are almost similar to those in normal paddy fields with layer amounts of CHP treatment. With salt content in the soils, saline hazard and numbers of ineffective stems, amounts of unmatured grain are increased. 6. With the treatment of CHP yields of rough rice were increased. With 0.5% CHP treatment the yields were similar to those of the normal paddy fields. With 1.0% CHP-A treatment, the yields were increased by 15 times more than those of none treated soil and by 25 percent more than normal paddy soils.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.1
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• pp.1598-1603
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• 1969

A field expeperiment has been conducted in order to explore possibilities of efficient and economical irrigation methods for the rice cultivation through which irrigation water may be saved and rice paddies may keep water for longer period of time, resulting in an increased yield of rice. Some of the major findings from the experimentation are summarized in the following. 1. There is slightly significant difference among experimental plots in the weight of rice straw. 2. The 9cm-lined plot proves to be the best in terms of the thickness. In this connection, however, it seems to by 3cm. 3. The wheat straw-lined plot is found superior in yield. However, this may be resulted in by the application of more fertilizer, and how long the plot could be durable may be problematic. Since every two or three years the straw-lining work has to be done, more labour may be required of the plot. 4. It would be inappropriate to expect any meaningful experimental results for the first year, since surface soil and deep soil are mixed up in the course of work. There is not observed any meaningful difference in the number of ears per stalk and in the number of grains per ear. However, in the lined plots, the number of tillers is slightly increased. 5. Irrigation has been applied by means of ordinary method after lining. When irrigation is applied at the interval of five to six days, irrigation water is saved by 44.9 per cent in the case of 9cm-lined plot, 39.7 per cent in the case of 6 cm-lined plot, and 36.3 percent in the case of 3 cm-lined plot. 6. An increased yields arenoted in the wheat straw-lined plot by 23.8 per cent, in the 9 cm-lined plot by 20.1 per cent, in the 3 cm-lined plot by 12 per cent. and in the case of vinyl-lined plot by 12.5 per cent. 7. The rate of maturity of grains is proved better, and the husking rate also found better(75%), that is, the quality of rice grains is improved.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.3
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• pp.183-193
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• 2020

This study was conducted to evaluate the effect of environment factors on the growth of autumn season cultivation of Kimchi cabbage using the big data in terms of public open data(weather, soil information, and growth of crop, etc.). The growth data and the environment data such as temperature, daylength, and rainfall from 2010 to 2019 were collected. As a result of composing the correlation matrix, the height and leaf number showed high correlation in growing degree days(GDDs) and daylength, and the yield showed negative correlation in growing degree days and the concentration of clay. GDDs and daylength explained about 89% and 84% of variation in height, respectively. These two environmental factors also explained about 85% and 79% of variation in leaf numbers, respectively. In contrast, the coefficient of determination was low for yield when GDDs and concentration of clay was used. The outcome of regional statistical analysis indicated that relationship between yield and sum of sand and silt were high in Haenam and Jindo areas. Hierarchical cluster analysis, which was performed to verify the association of yield, GDDs, and concentration of clay, showed that Haenam and Jindo were clustered together. Although GDDs and yield vary by year and region, and there are regions with similar concentration of clays, observation data are grouped as the result. These suggests that GDDs and soil texture are expected to be related to yield. The cluster analysis results can be used for further data analysis and agricultural policy establishment.

• Korean Journal of Environmental Agriculture
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• v.26 no.4
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• pp.306-312
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• 2007

To investigate the effect of N fertigation on the growth, yield, and water and nitrogen use efficiencies during tomato cultivation, seedlings were transplanted in a sandy loam soil under plastic film house condition. 0, 88, 132, 176, $220\;kg\;ha^{-1}$ N rates, which correspond to 0 (NF0), 40 (NF40), 60 (NF60), 80 (NF80), 100% (NF100) N level of soil test-based N fertilization, were injected weekly through drip irrigation system for 15 weeks in N fertigation system, and the control (conventional N treatment) was installed for comparison. Herein, nitrogen was applied by top-dressing with 60% as a basal and 40% as additional fertilizer. There was little different in stem diameter growth among N fertigation treatments, but plant height and dry matter increased with increasing N fertigation rates as well as in N conventional treatment. Tomato yield was increased with increasing the number of marketable fruits in N fertigation treatments, and the fruit yield was maximized in NF 80 treatment ($176\;kg\;ha^{-1}$ N supply or $96.6\;mg\;L^{-1}$ N injection). Dry matter productivity and nitrogen uptake amount were significantly increased with increasing N fertigation rates. The ratio of fruits to the dry weight of whole plant was decreased with increasing N fertigation rates, but this ratio was $2.6{\sim}5.3%$ higher in N fertigation treatments than in the control. In addition, the ratios of nitrogen distributed toward fruits in N fertigation treatments were $3.7{\sim}21.7%$ higher than that of control. The apparent N recovery percentages showed significantly higher values as $71.8{\sim}102.3%$ in N fertigation treatments, compared to 45% in N conventional treatment. Water use efficiency was significantly increased by fertigation system with the maximum $361\;kg/ha\;cm^{-1}$ in NF 80, which is comparable to $324\;kg/ha\;cm^{-1}$ of the conventional treatment. Conclusively, N fertigation system was effective on increasing tomato productivity and nutrient efficiency as well as 20% reduction of N fertilization level.

• Korean Journal of Plant Resources
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• v.15 no.1
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• pp.50-56
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• 2002

This study was carried out to optimize the fertigation method using fermented swine liquid manure for the growth of two western vegetables, broccoli and celery. Plants were grown in a rain-shelter house and fertilized with a range of dilutions(efflux 5 dilution=Ef. 5, efflux 10 dilution=Ef. 10, efflux 25 dilution=Ef. 25, and efflux 50 dilution=Ef. 50) of the liquid manure or with conventional application of N : P$_2$O$\_$5/ : K$_2$O = 200 : 70 : 500kg/ha for broccoli, 250 : 210 : 240 kg/ha for celery as controls. After harvest, soil pH and K content decreased after using a high concentration of the liquid manure, Ef. 5, than after treatment with weaker concentrations at Ef. 25 and Ef. 50. On the other hand, soil electrical conductivity, content of P$_2$O$\_$5/, organic matter, total nitrogen, and NO$_3$-N at Ef. 5 increased as concentration of swine liquid manure increased. After harvest, available P$_2$O$\_$5/ in plant tissue did not differ significantly between any of the treatments. In broccoli, the lower concentration (Ef. 50) of swine liquid manure increased flowering over the other treatments, perhaps because the level of absorption into the plants is higher with lower concentration. The amounts of K and Ca in plant tissue were greatest after Ef. 25 and Ef. 50 treatments. Plant growth was best at Ef. 50 in broccoli, head height, head width, and head weight were the best with Ef. 25 and Ef. 50 treatments after harvest. In celery, leaf length was greater after Ef. 25 and Ef. 50 treatments than any other treatments. Total yield of celery of Ef. 25 and Ef. 50 treatments was twice that of conventional cultivation. On the other hand, yield severely decreased after application of high-concentration treatment at Ef. 5. In conclusion, fertigation of swine liquid manure, diluted in the range of Ef. 25 to Ef. 50, could improve yield and quality in broccoli and celery.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.344-352
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• 2019

Drought stress caused by global climate change is a serious problem for rice cultivation. Increasingly frequent abnormal weather occurrences could include severe drought, which could cause water stress to rice during the seedling stage. This experiment was conducted to clarify the effects of drought during the seedling period on yield and quality of rice. Drought conditions were created in a rain shelter house facility. The drought treatment was conducted at 3, 10, and 20 days after transplanting. Soil water content was measured by a soil moisture sensor during the whole growth stage. In this study, we have chosen 3 rice cultivars which are widely cultivated in Korea: 'Haedamssal' (Early maturing), 'Samkwang' (Medium maturing), and 'Saenuri' (Mid-late maturing). The decrease in yield due to drought treatment was most severe 3 days after transplanting because of the decrease in the number of effective tillers. The decrease in grain quality due to drought treatment was also most severe 3 days after transplanting because of the increased protein content and hardness of the grains. The cultivar 'Haedamssal' was the most severely damaged by water stress, resulting in about a 30% yield loss. Drought conditions diminished the early vigorous growth period and days to heading in early-maturing cultivars. The results show that drought stress affects yield components immediately after transplanting, which is a decisive factor in reducing yield and grain quality. This study can be used as basic data to calculate damage compensation for drought damage on actual rice farms.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.4
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• pp.162-173
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• 2009

Information on the expected geographical shift of suitable zones for growing crops under future climate is a starting point of adaptation planning in agriculture and is attracting much concern from policy makers as well as researchers. Few practical schemes have been developed, however, because of the difficulty in implementing the site-selection concept at an analytical level. In this study, we suggest site-selection criteria for quality Fuji apple production and integrate geospatial data and information available in public domains (e.g., digital elevation model, digital soil maps, digital climate maps, and predictive models for agroclimate and fruit quality) to implement this concept on a GIS platform. Primary criterion for selecting sites suitable for Fuji apple production includes land cover, topography, and soil texture. When the primary criterion is satisfied, climatic conditions such as the length of frost free season, freezing risk during the overwintering period, and the late frost risk in spring are tested as the secondary criterion. Finally, the third criterion checks for fruit quality such as color and shape. Land attributes related to these factors in each criterion were implemented in ArcGIS environment as relevant raster layers for spatial analysis, and retrieval procedures were automated by writing programs compatible with ArcGIS. This scheme was applied to the A1B projected climates for South Korea in the future normal years (2011-2040, 2041-2070, and 2071-2100) as well as the current climate condition observed in 1971-2000 for selecting the sites suitable for quality Fuji apple production in each period. Results showed that this scheme can figure out the geographical shift of suitable zones at landscape scales as well as the latitudinal shift of northern limit for cultivation at national or regional scales.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.2
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• pp.143-152
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• 2008

In order to share the understanding agricultural multifunctionality with people, we carried out quantification and monetary evaluation for controlling flood and fostering water resources function in paddy and upland farming in Korea. The amount of water controlling flood and fostering water resources function in paddy farming was much greater than that in upland. The quantification of flood control function could be estimated by sum of the height of dike and water infiltrated during the flooding periods in paddy farming, and water excepting runoff water from precipitation at flooding time in upland farming. As results of estimation of flood control function, the amounts of water controlling flood have been evaluated as $294mm\;year^{-1}$ in paddy farming and $72.6mm\;year^{-1}$ upland farming, and was calculated 3.71 billion MT on a nation basis in 2006. When it was carried out monetary estimation as the cost of dam construction and the depreciation expense by using replacement cost method, flood control functions in paddy and upland were evaluated as 44,338.9 and 7,221.5 billion won, respectively. Comparing with previous reports, monetary value was analyzed much to increase because of rising price cost recently. Fostering water resource functions were also quantified in paddy and upland farming as the amount of water keeping and infiltrating water during the cultivation. In the basis of estimation model, it was showed that paddy and upland farming had been estimated to have $414.28mm\;year^{-1}$, $18.7mm\;year^{-1}$, respectively. They were also calculated to 4.49 and 0.137 billion MT on a nation basis in 2006, respectively. The economic values of fostering water resources function in paddy and upland farming were also estimated to 1,769.4 and 52.8 billion won, respectively, as replacing the amount of water to the cost of drinking water in 2006. There were differences by much to the amounts of controlling flood function and fostering water resource between paddy and upland farming. It means that paddy farming more play an important role in environment than upland farming in Korea.

• Korean Journal of Weed Science
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• v.31 no.1
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• pp.34-40
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• 2011

Cover crop can be used to suppress weeds by competition for light and nutrient. Objective of this study was to evaluate the effectiveness of legume cover crops on change of weed community in no-till corn cultivation. Two legume cover crops, hairy vetch and crimson clover were grown in the field, and succeeding corn was sown on 4 May, 2010. The distribution of weed was surveyed at 15 April, 1 June, and 20 August. At 15 April, the weed biomass in hairy vetch field was higher than in crimson clover field. The dominant weeds were Capsella bursa-pastoris L. and Stellaria aquatica L. in hairy vetch and crimson clover fields, respectively. At vegetative stage of corn, occurred weeds in hairy vetch and crimson clover fields were four and six species, respectively, while the weed was occurred with nine species in conventional. Also the dry weight of weed was decreased by 82 and 75% in hairy vetch and crimson clover fields compared to conventional. On the other hand, after harvest of corn, occurred weed in hairy vetch, crimson clover and conventional was five, four and five species, respectively. Dry weight percentage of occurred weed in conventional was 23.5%, and the value was higher than 13.8 and 14.7% in hairy vetch and crimson clover fields, respectively. Stellaria aquatica L. as winter annual weed only occurred in cover crop field during corn growing season. It is these possibilities that low soil temperature and light interception by soil cover of legume cover crop.

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.268-277
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• 2014

This study assessed microbiological hazards at postharvest stage of dropwort farms (A, B, C, D, E, F, G, H, I) located in 4 different areas in Korea. The samples were assessed for sanitary indication bacteria (total aerobic bacteria, coliform, and Escherichia coli) and pathogenic bacteria (Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus). Total aerobic bacteria and coliform in 9 dropwort farms were detected at the levels of 0~7.00 and 0~4.25 log CFU/g, mL, of $100cm^2$. In particular, microbial contamination in worker's hand showed higher than cultivation environment factors. Escherichia coli was detected in several farms of soil, irrigation water, washing water and worker's hand and also, dropwort in these farms was contaminated with E. coli (positive reaction). In case of pathogenic bacteria, B. cereus was detected at the highest levels in soil. S. aureus was detected qualitatively from only one sample of dropwort washed by water. E. coli O157:H7 and L. monocytogenes were not detected. Although dropwort pass through 2 process (trimming and washing), the microbial contamination was not differ significantly before and after which indicates that current washing system was not effect on reduction of microorganism. From these results, the postharvest environment and workers have been considered as cross-contamination factors. Thus, processing equipments and personal hygiene should be managed to reduce the microbial contamination of dropwort. Accordingly management system such as good agricultural practices (GAP) criteria is needed for the safety of dropwort