• Korean Journal of Organic Agriculture
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• v.26 no.4
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• pp.629-647
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• 2018

This study was carried out to investigate the economic value of organic rice production using gelatin chitin microorganisms in eco-friendly complex, Gongsan, Naju city. The soil condition of experiment paddy field was Jeonbuk series and silt loam with a slightly poor drainage. Except for the high effective silicate, the chemical characteristics of soils used were included in the optimum range of paddy soils in Korea. In growth, plant length, tiller number, ear number, and ear length were observed to be higher in conventional paddy fields than organic paddy fields. However, number of grain per panicle and grain filling ratio (%) were higher in organic paddy fields than conventional paddy fields. Incidences of diseases and insect pests were slightly higher in the organic paddy fields. Water weevil, sheath blight, rice leaf roller and rice blast were more occurred in organic paddy field. On the other hand, false smut was higher occurred in conventional paddy field. There was a significant negative correlation between rice sheath blight and rice leaf roller, and rice yield. In the milled rice quality, the quality of organically cultivated milled rices was lower by the increase of broken rice than that of conventionally cultivated milled rices. The quality and palatability of rice were higher in organic cultivation with decreasing of protein content. Net income of conventionally and organically cultivated rice was 360,000 won/10a and 610,000 won/10a, respectively. Premium net income of the organically cultivated rice was 68%.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.597-602
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• 2004

Field experimental study was performed to examine characteristics of nutrient export from paddy rice fields with irrigation practices. Experimental fields with surface-water and ground-water irrigation were monitored and analyzed during rice culture period. The water balance showed that outflow generally balanced the inflow showing that about half (58~68%) of total outflow was lost by surface drainage. Water and nutrient export are more in surface-water irrigation paddy than in ground-water irrigation paddy. The reasons might be more irrigation water available and easy to use in surface-water irrigation. If irrigation water reduced, it could result in reduction of nutrient export in paddy rice fields, which can save water and protect water quality. However, deviation from conventional standard practices might affect the rice yield and further investigations are necessary.

• Korean Journal of Agricultural Science
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• v.26 no.2
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• pp.70-76
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• 1999

Rice farming is not only the most important income resources of Korean farmers but also the roots of Korean traditional culture. Paddy fields have acted as an food supply base but also have contributed to the public multi-functions such as flood control, water conservation, controlling soil erosion, providing recreational and resting spaces, water purification, air cleaning, oxygen supply and air cooling and so on. The public multi-functions of paddy except rice production have not been evaluated before UR negotiation and starting WTO system. Under the drastic changes of rice economic settings as price decrease of rice and downward decrease of farm income, Korean and Japanese farmers might have lost their intention to grow rice in paddy fields without the direct payment system to compensate rice income decrease. To adapt the direct payment system, the total public value of multi-function of paddy should be identified in terms of money. According to the research results, the total value of multi-functional value of paddy in Korea were estimated 21,596thousand won which is higher than rice production value by 2.1 times. On the other hand the total value of Japanese paddy were amounted to 21,390 Yen which is more than that of Korea by 10times outstandingly. Likewise Japanese have evaluated the paddy field very important enterprise from the view point of food security and multi -functions of paddy to their socio-economic life and environmental sustainability in Japan.

• The Korean Journal of Pesticide Science
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• v.12 no.1
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• pp.74-81
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• 2008

To elucidate the exposure of pesticide in agricultural environment and to investigate distribution of pesticide in paddy fields. This experiment was carried out to clarify pesticide distribution in paddy fields applied with different formulations and growing stages. Initial dissipation rate of applied butachlor EW and oxadiazon EC before rice planting were more than 90% within 3 days in paddy fields. The distribution of a.i. in the pesticide formulations tested depended upon the elapsed time at each growing stage of rice plant after application. Most of pesticides applied within 15 days after transplanting of rice seedlings, more than 95%, were located in the surface water and soil regardless of pesticides; butachlor, thiobencarb and molinate GR. The distribution of iprobenfos GR, tricyclazole WP and phenthoate EC, after application 2 hours in middle growing stage (46 days after rice planting) were shown as 16.1, 48.9 and 38.9% in surface water, 83.6, 15.4 and 10.7% in soil, and 0.3, 35.7 and 50.4% in rice plants of paddy fields, respectively. Also tricyclazole WP and phenthoate EC, after application 2 hours in the late rice growing stage (90 days after rice planting) were distributed to 7.8 and 9.8% in surface water, and 21.7 and 5.1% in soil, and 70.5 and 85.1% in rice plants of paddy fields, respectively.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.479-484
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• 1999

Rice crop has relatively short growing season during the summer in Korea and, therefore, it is often difficult to acquire cloud-free imagery on time. This study was attempt to define the temporal characteristics of radar backscattering observed from satellite L-band SAR data on different growing stages of rice crop. Six scenes of multi-temporal JERS SAR data were obtained from the transplanting season to the harvesting month of October. Six layers of multi-temporal SAR data were registered on a common geographic coordinate system. Using topographic maps, field collected data, and Landsat TM data, several sample rice fields were delineated from the imagery and their relative radar backscatters were calculated by using a set of reference targets. The temporal pattern of radar backscattering was very distinctive by the growing stage of rice crop. It was also separable between two types of rice fields having different cultivation practices. Considering the temporal characteristics of radar backscattering observed from the study, it is obvious that a certain date of the growing season can be more effective to delineate the exact area of the cultivated rice crop field.

• Korean Journal of Remote Sensing
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• v.28 no.6
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• pp.653-660
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• 2012

This study classified paddy fields according to rice varieties and monitored temporal changes in rice growth using SAR backscatter coefficients (${\sigma}^{\circ}$). A growing period time-series of backscatter coefficients was set up for nine fine-beam mode RADARSAT-1 SAR images from April to October 2005. The images were compared with field-measured rice growth parameters such as leaf area index (LAI), plant height, fresh and dry biomass, and water content in grain and plants for 45 parcels in Dangjin-gun, Chungnam Province, South Korea. The average backscatter coefficients for early-maturing rice varieties (13 parcels) ranged from -18.17 dB to -6.06 dB and were lower than those for medium-late maturing rice varieties during most of the growing season. Both crops showed the highest backscatter coefficient values at the heading stage (late July) for early-maturing rice, and the difference was greatest before harvest for early-maturing rice. The temporal difference in backscatter coefficients between rice varieties may play a key role in identifying early-maturing rice fields. On the other hand, comparisons with field-measured parameters of rice growth showed that backscatter coefficients decreased or remained on a plateau after the heading stage, even though the growth of the rice canopy had advanced.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.132-139
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• 2010

To manage the effluent nutrients amounts from rice paddy fields using free range ducks or rice bran, we evaluated the effects of a purifying paddy field which is no fertilizer, no pesticides, and dense rice seedling having a concept of constructed wetland. The experimental paddy field was located at downstream in the watershed of ducks using rice culture area in Milyang. The purifying paddy of land design were treated with seeding method, and vegetation type. As land design, direct seeding on plane, and direct seeding on high-ridge field in 2007. Planting rice only, and planting rice with water hyacinth were treated as vegetation type in purifying paddy in 2008. The purifying paddy fields were effective to reduce amount of T-N and T-P contents in effluent to 33.2~45.3%, and 53.1~55.4%, respectively. The direct seeding on high-ridge treatment, having long residence time of effluent water was more effective than plane plot as T-N 0.29 $g^{-1}m^{-2}d^{-1}$, and T-P 0.031 $g^{-1}m^{-2}d^{-1}$. The planting rice with water hyacinth treatment was effective than planting rice only as T-N 0.23 $g^{-1}m^{-2}d^{-1}$, and T-P 0.049 $g^{-1}m^{-2}d^{-1}$. The optimum area of purifying paddy field to treats all effluent were found out 3.2~4.7% of rice culture area using free range ducks, and rice bran at upper stream.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.1
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• pp.38-43
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• 1999

Over 2,000 ha of rice fields in the western and southern coastal region of Korea were flooded with sea water during the spring tide, on August 19-21, 1997, and the rice plant at heading stage was injured. The field surveys were undertaken at the sea water flooded paddy fields in Chonbuk Province, to identify the injury symptoms and rice yield damage subjected to different flooding condition and desalinization methods. Five days after sea water flooding at heading stage, the flag leaves of rice plants flooded with 30 ㎝ deep sea water withered from the tip, the withering progressed to the lower leaves in deeper flooding. The spikelets were spotted black and discolored from the tip at 50 ㎝ deep flooded rice, and some panicles changed to white at 80 ㎝ deep flooded rice. Most of the rice leaves submerged completely for an hour were withered and most of panicles changed to white. The milled rice yield, percentage of ripened grain, and 1000 grain weight of flooded rice decreased with deeper flooding water, higher water salinity and longer flooding time. Even under the same flooding conditions, the damage of rice yield varied with the growth stage: heading stage>dough stage>booting stage. Rice yield damage was less in the fields on the upper riverside than those of the fields on the estuary and seaside, because of lower water salinity. In a flooded field, the rice yield damages were reduced as the distance increased from the levees where the sea water inflowed and increased as the distance increased from the fresh water irrigation gate. The desalinization treatments consisting of frequent exchange of irrigation water and spraying with fresh water soon after flooding effectively reduced the rice yield damage.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.1-8
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• 2011

BACKGROUND: With increasing public awareness to environment-friendly agriculture, many efforts have been run to develop organic farming technologies in Korea as of late 90s. The objective of this study was to investigate the effects of different organic farming practices on soil chemical properties and water quality in paddy fields. METHODS AND RESULTS: Total nitrogen (TN) and total phosphorus (TP) were monitored for a two-year period (2006 to 2007) from the study organic paddy fields located in Wan-ju, Jeonbuk Province in Korea. TN and TP of organic paddy water were gradually increased for 2~3 weeks after organic manure application and then gradually decreased afterward. The overall variation of TP in the paddy fields was much greater than that of TN. The phosphorus content in organic paddy field appeared to increase with the organic farming period. CONCLUSION(s): This indicates that long-term organic farming is likely to cause phosphorus accumulation in soils and increase vulnerability to rainfall runoff. Thus, appropriate phosphorus management needs to be implemented, particularly, to reduce excessive phosphorus supply owing to nitrogen-based determination of organic manure application amount.

• Journal of Astronomy and Space Sciences
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• v.29 no.4
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• pp.407-411
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• 2012

Space-borne remote sensing is an effective and inexpensive way to identify crop fields and detect the crop condition. We examined the multi-temporal spectral characteristics of rice fields in South Korea to detect their phenological development and condition. These rice fields are compact, small-scale parcels of land. For the analysis, moderate resolution imaging spectroradiometer (MODIS) and RapidEye images acquired in 2011 were used. The annual spectral tendencies of different crop types could be detected using MODIS data because of its high temporal resolution, despite its relatively low spatial resolution. A comparison between MODIS and RapidEye showed that the spectral characteristics changed with the spatial resolution. The vegetation index (VI) derived from MODIS revealed more moderate values among different land-cover types than the index derived from RapidEye. Additionally, an analysis of various VIs using RapidEye satellite data showed that the VI adopting the red edge band reflected crop conditions better than the traditionally used normalized difference VI.