• KOREAN JOURNAL OF CROP SCIENCE
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• 제65권4호
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• pp.327-338
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• 2020

In recent years, the temperature of Korea has been rapidly increasing due to global warming. Over the past 40 years, the temperature of Korea has risen by about 1.26℃ compared to that in the early 1980s. By region, the west region of the Gangwon Province was the highest at 1.76℃ and the Jeonnam Province was the lowest at 0.96℃. As the temperature continues to rise, it is expected that the rice yield will decrease in the future using the current standard cultivation method. As a result of global warming, the periods in which rice cultivation could be possible in regions each year has increased compared those to the past, showing a wide variety from 110 days in Taebaek to 180 days in Busan and Gwangyang. In addition, the transplanting time was delayed by 3-5 days in all regions. The average annual yield of rice showed an increasing trend when we analyzed the average productivities of developed varieties for cooked rice since the 1980s, especially in the early 1990s, which showed a rapid increase in productivity. The relationship between the average temperature at the time of development and the rice yield was divided into the periods before and after 1996. The higher the average temperature, the lower the yield of the developed varieties until 1996. However, since 1996, the increase in the average temperature did not show a trend in the productivity of the developed varieties. The climate change adaptability of developed rice varieties was investigated by analyzing the results of growing crops nationwide from 1999 to 2016 and the change in the annual yields of developed varieties and recently developed varieties as basic data to investigate the growth status of the crops in the country. As a result of annual comparisons of the yields of Taebongbyeo (2000) and Ungwangbyeo (2004) developed in the early 2000s for Odaebyeo, which was developed in the 1980s, the annual yields were relatively higher in varieties in the 2000s despite the increase in temperature. The annual yields of Samgwangbyeo (2003) and Saenuribyeo (2007), which were recently developed as mid-late-type varieties, were higher than those of an earlier developed variety called Chucheongbyeo, which was developed in the 1970s. Despite the rapid increase in temperature, rice cultivation technology and variety development are well adapted to climate change. However, since the biological potential of rice could reach its limit, it is necessary to develop continuous response technology.

• Korean Journal of Soil Science and Fertilizer
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• 제37권3호
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• pp.156-164
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• 2004

This study was conducted to evaluate the effect of the application of green manure in the form of either green barley and Chinese milkvetch in reducing the amounts of N fertilizers and conventional fertilizers needed for paddy rice. Prior to rice transplanting, the green barley and Chinese milkvetch as a green manure produced respectively $668kg\;10a^{-1}$ and 3,492kg\;$10a^{-1}$ in fresh shoot weight basis. Calculated nitrogen content from harvested green manures was 3.9 and $17.8kg\;10a^{-1}$, respectively. Plant height and tiller number of rice increased when two kinds of green manure incorporated into soil. Above mentioned parameters also increased with increasing amounts of N fertilizers at both ear formation and heading stage of rice. Rice grain number was not affected by green manures treatment but increased when N fertilizers were applied. Although rice panicle and grain number increased with green manure treatments and fertilizer applications, whereas the percentage of ripened grain decreased. Chinese milkvetch with additional N fertilizer applications increased brown rice yield from 1 to 5% compared to rice yields in plots where non-green manure with the conventional amount of fertilizer application was applied. Rice treated with Chinese milkvetch and 30% of the conventional N fertilizer rate yielded the same as rice fertilized conventionally. During the rice growing season, $NH_4-N$ content of paddy soil was higher in green manures treatment than non-green manure one. Average $NH_4-N$ content in paddy soil drastically decreased after heading stage below $5.7mg\;kg^{-1}$ in non-green manure treated plots. While on the other, $NH_4-N$ content in soil slowly decreased in plots those were treated with green manures at harvesting stage, average $NH_4-N$ content was still greater than $5.5mg\;kg^{-1}$. Nitrogen content of rice shoot and brown rice seed was higher in green manure treatment.

• Korean Journal of Soil Science and Fertilizer
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• 제16권2호
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• pp.119-125
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• 1983

To find out problems and changing soil properties induced by leveling of paddy, a field survey was carried out with questionares to farmers of 68 project areas (990 farmers). The soil characteristics between natural soils and cut out sites was compared with soil samples taken from 37 project areas. More than 70 percents of farmers answered to the questionares expressed satisfaction on the paddy land leveling project; however, some farmers replied dissatisfaction that the arable land was decreased the soil productivity due to loss of surface soil or insufficient surface leveling, that the government support was insufficient and that transplanting of rice might be delayed due to retardation of the project. 1. The rate of cut out soils during the land leveling on plain terrain was about 15.3%, but the rates on gently sloped terrain (2-7% slopes) and sloped terrain (7-15% slopes) were relatively high showing 25.9% and 45%, respectively. 2. The deterioration of physical properties was clear in cut out site where the hardness and bulk density increased and the porosity and the rate of water stable aggregate decreased. 3. The degree of deterioration of physical properties on the Diluvial terrace was more severe than on plains or sloped alluvial fans and valleys. The decrease of available phosphorous and the content of organic matter in the cut out place due to land leveling were prominent. 4. The rice yield from cut site was decreased by 28% comparing with that from natural soils.

• Korean Journal of Soil Science and Fertilizer
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• 제28권4호
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• pp.301-305
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• 1995

This study was conducted to find out the changes of soil physical properties and rice growth by the different soil prepartion, such as direct seeding in dry or submerged condition, tillage or no-tillage, and transplanting the infant seedlings. Soil bulk density and hardness were higher in no-tillage plots than tillage plots, and in dry-seeding plots than submerged seeding plots. Permeability of no-tillage plot was increased 56% and water requirement was also increased 27% compare to the conventional transplanting condition. In no-tillage plot, the soil water contents were so rapidly decreased that easily changed to optimum condition for machinery working. The root growth of rice was inhibited as increasing the soil bulk density at early stage, bottom of culm in no-tillage submerged plot was located 0.9cm above the soil surface and the rice plant slightly lodged. The root distribution of surface layer was higher in no-tillage plot and the heading date was 2 days earlier in no-tillage plots than tillage plots, and 3 days earlier in dry seeding plot than submerged seeding plot. Rice yields of no-tillage plots were 5.55 M/T/ha and 5.16 M/T/ha for dry and submerged seeding respectively. These yields were lower about 12.1 % in dry seeding and 18.3% in submerged seeding compare with 6.31M/T/ha of transplanting plot. Rice yields were higher at dry seeding than submerged seeding in no-tillage condition, but in tillage condition, the rice yields were better at submerged seeding plot than dry one.

• Korean Journal of Environmental Agriculture
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• 제27권3호
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• pp.225-230
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• 2008

Objective of this study was to access the environmental impacts of the use of discharge water from municipal waste water treatment plant as alternative irrigation resources during drought season for rice cultivation. For the field experiments, it was observed that plant growth and yield characteristics at 20 days of alternative irrigation period with application of FAST (fertilizer application based on soil test) 50% were relatively the same as the control. For the surface water quality, it appeared that $EC_i$ (electrical conductivity of irrigation water) and SAR (sodium adsorption ratio) values of DMWT (discharge waters from municipal wastewater treatment plant) irrigation were twofold higher than those of ground water irrigation as the control regardless of fertilization levels. For the irrigation periods, there were not significantly difference between 10 and 20 days of treatments, but $EC_i$ and SAR values of surface water were highest at 30 days of irrigation periods at initial rice growing stages. Generally, $EC_i$ values of percolation water in all the treatments were gradually increasing until 30days after irrigation, and then decreasing to harvest stage. Overall, it might be considered that there was possibility to irrigate DMWT with application of FAST 50% for 20 days of drought periods at rice transplanting season. Furthermore, efficiency rate of alternative irrigation water for 20 days of drought period was 32.7% relative to the total annual irrigation water for rice cultivation.

• Korean Journal of Soil Science and Fertilizer
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• 제37권2호
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• pp.97-103
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• 2004

This study was performed to assess the influences of liquid pig manure (LPM) on the rice growth and nutrient behavior in soil under two different drainage comditions. Soils of paddy field were Jeonbuk and Gangseo series, and drainage conditions of the soils were imperfectly drained and moderate well drained, respectively, Application of LPM was based on nitrogen, and the treatments included 110 (LPM-N100%), 165 (LPM-N150%) and $220(LPM-N200%)kg\;N\;ha^{-1}$. In the LPM-N150% treatment, rice growth and yield were similar to the control treatment of conventional chemical fertilizer application. Rice yield of moderately well drainedfield were 3-11% higher than that of imperfectly drained field. Loss of nitrogen through $NH_3$ gas after application of LPM was higher in no plowing than in rotary plowing field. Losses of $NO_3-N$, $NH_4-N$, $SO_4$, Ca and K through runoff water were increased as the amount of LPM application increased. Losses of $NO_3-N$ and K through infiltration were higher in LPM-150% and LPM-N200% treatments compared to the chemical fertilizer treatment. Contents of $NO_3-N$ in infiltration water measured from trasplanting to tillering stage was higher at the moderately well drained condition than imperfectly drained condition. Contents of $P_2O_5$ and K in soil were accumulated by application of LPM compared to the chemical fertilizer plot.

• Korean Journal of Soil Science and Fertilizer
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• 제5권1호
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• pp.25-32
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• 1972

The effects of limestone and wollastonite on an acid sulfate soil were studied. In addition, the effect of wollastonite was analyzed in terms of those due to calcium and to silica in the paddy field and in the laboratory with equivalent amounts of lime and wollastonite on a calcium basis. 1. Lime and wollastonite as liming materials were equally effective in neutralizing the soil acidity. 2. Lime, however was more reactive, raising the pH up to neutralization point in three days under waterlogged conditions at $25^{\circ}C$, in the lab study, and introduced alkali damage to transplanted rice seedlings showing marked restrictions of tillering in the field even though lime was applied two weeks before transplanting. On the other hand, wollastonite reacted very slowly, taking one week to two weeks to reach neutralization even when thoroughly mixed, and did not restrict the tillering. 3. Both lime and wollastonite effectively reduced the toxic aluminium in soil as well as in the soil solution but not always in the case of ferrous iron. However the reduction effect of the toxic substances in the experimental field was not so great as expected, because typical toxic symptoms were mild only. 4. Lime considerably increased the availability of silica in soil resulting in an increase of silica content in straw. Wollastonite released extra available silica itself resulting in a greater uptake of silica. 5. Increase of silica uptake by these materials was effective in reducing rate of infection of neck blast and resulted in higher rate of ripening, and in turn increased the paddy yield. 6. Application of either one significantly diminished the effect of the other. 7. Wollastonite markedly increased tillering in the early growing stage, but decreased the rate of effective tillers finally, resulting in about the same number of ears per hill at harvesting. 8. These liming materials appear to increase the number of grains per panicle slightly.

• Korean Journal of Environmental Agriculture
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• 제8권2호
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• pp.128-135
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• 1989

To find the effects of solar energy into the rice canopy and its balance on the rice plant growth, a Tongil type rice, Raekyeong and a japonica rice, Koganebare were used with four levels of nitrogen fertilizer application, 6, 10, 14, and 18kg $l0a^{-1}$ in Chigugo, Japan. The micrometerosological data, the solar radiation and absorbed solar radiation by the rice plants, and leaf area index on cardinal growth stage of the rice community were measured. The results are as follows : Raekyeong showed increased LAI by increased nitrogen fertilizer application rates, and larger LAI than Koganebear. 1. There was no difference in total dry weight till 20 days after transplanting regardless of nitrogen levels in the same variety, after that, however, Raekyeong showed higher dry matter productions for the same durations than Koganebare. 2. In early growth stage of transplanting rice, reflection ratio of solar radiation above the crop canogy was about 6%, however, it was increased up to 20% by the increased LAI at heading date. 3. In high levels of nitrogen application plots, LAI were increased so that values were decreased. 4. Relationship between the amount of absorbed radiation by plants and its dry matter production was linearly significant. Higher levels of nitrogen application produced higher dry matter in Raekyeong, however, in lower level, the dry matter production pattern was almost similar between both rice cultivars.

• Korean Journal of Soil Science and Fertilizer
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• 제30권2호
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• pp.108-113
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• 1997

A field experiment was conducted to evaluate effect of phosphate coated slow release fertilizer on the directly seeded rice. Odae byeo was seeded by drill under dry condition. The soil was a sandy clay loam soil located in the Experimental Farm of the Kangweon National University, Chuncheon, Kangweon-Do. The yield of rice from the urea applicated directly seeded field was 84.9% of the yield from the transplanted field, and showed no difference between split application treatments. The yield from the phosphate coated slow release fertilizer was the highest showing 110.7% of the yield from the urea application. The yield from the polymer coated slow release fertilizer was 90.4%. The yield from the organic fertilizer 400kg/10a treatment was 81.8% and was 94.8% from the organic fertilizer 600kg/10a treatment. In 1996 experiment, the yield from the phosphate coated slow release fertilizer was higher than the yield from the transplanted field. The $NO_3-N$ and $NH_4-N$ concentrations in soil solution at the depth of 15cm revealed that nitrogen leaching was the highest from the urea N40-0-30-30 treatment, and the lowest from the phosphate coated slow release fertilizer. The phosphorus concentration showed similar pattern. Therefore, use of phosphate coated slow release fertilizer increased rice yield and decreased loss of nitrogen and phosphorus loss.

• Korean Journal of Weed Science
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• 제30권4호
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• pp.361-370
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• 2010

This study was carried out to establish the analytical method of MCPA residue in brown rice and rice straw by HPLC/UVD. When MCPA was extracted from sample under the pH 3.6 by adding acetone 200 mL and 1N-HCl 100 mL, the extraction efficiency was high by 87%. And purification efficiency was high by 83% when 5 mL of 1% methanol/acetonitrile was eluated by the florisil Sep-pak cartridge column. From spiking of $0.1{\mu}g\;mL^{-1}$ and $0.25{\mu}g\;mL^{-1}$ of MCPA to control sample, respectively, average recovery rate of MCPA in brown rice was 96.0% and 94.9% and that in rice straw was 92.5% and 88.2%, respectively. Precision of experiment was very high by relative standard deviation of 1.5% to 5.7%. In brown rice and rice straw treated with bentazone+MCPA (11+1.2%) of 30 kg and 60 kg per ha at 30 days after rice transplanting, respectively, maximum residue limit was under $0.05{\mu}g\;mL^{-1}$ of the recommended rate of Korean Food and Drug Administration. From the above results, the analytical procedure of MCPA in plants such as hydrolysis, saponification and derivatization were ommited, and retention time was faster and recovery rate was higher than the existed results of HPLC/UVD. Therefore, these results were greatly improved and seemed to be usefully applied for residue analysis of MCPA in plants.