• Korean Journal of Environmental Agriculture
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• v.24 no.2
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• pp.117-122
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• 2005

To find out reducing way of methane emission from a paddy field monitoring on the greenhouse gases emissions were carried out in the paddy soil with livestock compost and soil conditioner. The seasonal variations of methane emission were high at 36 days and 86 days after rice transplanting, on the other hand those of nitrous oxide emission were high at 64 days after that day. Methane emission by cow compost application, pig compost application and chicken compost application were 331, 282 and 294 kg $ha^{-1}$, respectively. Otherwise, nitrous oxide emissions by cow compost application, pig compost application and chicken compost application were 1.60, 1.78 and 1.78 kg $ha^{-1}$ respectively. The total emission rate of greenhouse gases equivalent to $CO_2$ emission rate (GWP) was 7,447 kg $ha^{-1}$ in cow compost application, 6,474 kg $ha^{-1}$ in pig compost application and 6,726 kg $ha^{-1}$ in chicken compost application. Methane emission by Ca, $SiO_2$ and artificial zeolite application were 373, 264, 239 kg $ha^{-1}$, respectively. The total emission rate of greenhouse gases equivalent to $CO_2$ emission rate (GWP) was 8,295 kg $ha^{-1}$ in Ca application 5,978 kg $ha^{-1}$ in $SiO_2$ application and 5,447 kg $ha^{-1}$ in artificial zeolite application.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.3
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• pp.289-295
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• 1988

An ordinary paddy variety Hwaseong and a high-yielding variety Samgang were taken under investigation to test the effect of top dressing of newly formulated three compound fertilizers on rice plants for at sprouting heads. The fertilizer formulate used were C. F. I (14-0-14; $NO_3-N$ and $NH_4-N$) and C. F. II (14-0-14; $NH_4-N$ only) and C. F. III (14-0-14 + OM 10%; $NO_3-N$ and $NH_4-N$). A field experiment was conducted on a plot of Gyuam series. The following results were obtained: 1. Effects of compound fertilizers at sprouting heads a. Hwaseong variety exhibited 5-10% yielding increases on the plots with application of 2nd compound fertilizer (I) and (II) compared to straight fertilizer of (I) and (III). Fertilization with 2nd and 3rd compound fertilizers gave the best result when they are done 15 days before heading. A yield increase of 3-5% was achieved when the fertilization was done 20 days before heading in the case of Samgang variety, but no beneficial effect was observed with an application 10 days before heading. b. Rate of barren grains was at the minimum in the compound fertilizer (II) plots of both Hwaseong and Samgang varieties. c. Content of $NO_3-N$ in soils and grain yield appeared to be positively correlated($r=0.618^*$) 2. Effects of heading fertilizers on artificially reduced conditions of soil a. No significant difference in Eh values were measured among reduced paddy soils. The compound fertilizer of (II) presented the best result in yield increases regardless of rice variety. b. Rate of barren grains in both varieties was observed at the minimum on the application of compound fertilizer of (II). c. No great difference of mineral contents was detected among plants from different treatments.

• Korean Journal of Agricultural Science
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• v.3 no.2
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• pp.145-151
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• 1976

This study was conducted to determine the effect of slaked lime and straw used on the soil pH in the flooded condition and yield of rice grown in AKIOCHI paddy field and their residual effects on the rice plants. The results obtained were summarized as follow: when lime and straw were applied, there was on the average 41% of yield increase over plots treated with three elements of chemical fertilizers. When lime plus straw were used, the growth rate at later stage of rice plant was prominent. Damage due to helminthosporium and blast were found less, the rate of lower-leaf death was low, and grain number, per head, filled grain ratio, and weight of rice grain were higher than control. When lime plus straw were used, higher amount of silicate, calcium, nitrogen and potassium was found in the plants at heading stage. The residual effects of lime plus straw were 20% in the first year, about 10% in the second year and 5% in the third year, respectively. Soil pH was affected by both straw and slaked lime, and it was fixed about 8 days after applying in the flooded condition. The following formulae was suggested from the results in the flooded conditions. $$pH=5.5293+8.6007X_1+2.7836X_2-{6.7422X_1}^2-{1.8522X_2}^2-7.000X_1X_2$$ ($X_1$=slaked lime, $X_2$=straw)

• Korean journal of applied entomology
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• v.50 no.2
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• pp.83-96
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• 2011

This study was conducted to investigate the influence of natural degrading polymer film covering in rice paddies on the benthic macroinvertebrate community structure in Dangsu-dong, Suwon, Gyeonggi-do from May 2009 to September 2009. We compared 5 treatments: golden apple snail farming (GF), natural degrading polymer film + organic farming (NOF), natural degrading polymer film + chemical farming (NCF), conventional farming (CF), and no fertilization (NF) as the control. The total number of species was highest in NOF followed by GF, NF, NCF, and CF. The total number of individuals was highest in NOF followed by NCF, CF, NF, and GF. The Dominance index (DI) ranged from 0.43 to 0.95. The highest dominance index was in GF followed by NCF, NF=CF, and NOF. The species diversity index (H') for each experimental plot ranged from 0.49 to 2.93. The average species diversity index was highest in NOF followed by NF, GF, CF, and NCF. After the natural degrading polymer film covered the paddies, the benthic macroinvertebrates tended to recover, but leeches and aquatic beetles increased. Mollusca and Annelida, which are sensitive taxa, decreased in both species and individual numbers after the soil was covered with the natural degrading polymer film. The number of species tended to recover. However, the number of individuals continued to decrease.d, especially individuals. Since then, the number of species tended to recover. However, the number of individuals decreased.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.1
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• pp.8-14
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• 1996

Use of phosphate coated urea to decrease ammonia volatilization from directly seeded paddy under dryland condition at early stage was tested. Effect on urea hydrolysis was investigated through laboratory study comparing with use of thiourea, a urease inhibitor, under different water content. A field measurement of volitilized ammonia with phosphate-glycerol ammonia absorber was conducted for surface treated urea, phosphate coated urea, phosphate coated slow-release fertilizer and organic fertilizer. Through laboratory study, hydrolysis rate of phosphate coated urea at three days after treatment was lower than that of urea, however, the rate after one week was same. Thiourea addition retarted urea hydrolysis. By field measurement, ammonia volatilization was effectively reduced by use of phosphate coated urea.

• Journal of Korea Water Resources Association
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• v.50 no.10
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• pp.653-660
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• 2017

The SCS-CN (Soil Conservation Service-Curve Number) method has been practically applied for estimating the effective precipitation. The CN is used to be determined according to the land use condition based on the US standard. However, there are two distinctive differences between U.S. and Korean land use conditions: mountainous (forest) and rice paddy area that cover more than 70% of the Korean territory. The previous work proposed to use 79 for rice paddy area, regardless of the soil type. Because US SCS's goal was originally to increase crops, the SCS classification standard provides only for woods and there are no criteria to distinguish the wood and forest. To determine the CN for forest, alternatively the U.S. Forest Service criteria have been employed in practice considering hydrologic condition class. In this study, we investigated the change of the forest CN using the observed rainfall - runoff data within the target area. The results indicated that the CN for forest was suitable for HC=1, and the corresponding CNs were redetermined between 54 and 55.

• Korean Journal of Environmental Biology
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• v.34 no.3
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• pp.169-176
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• 2016

Although chemical fertilizers have a quick effect and broad applicability to agricultural fields, they have caused many problems like increasing soil acidity or decreasing soil organic matters. Environmental-friendly agriculture has been attempted in various ways such as organic agriculture, natural farming, low input and sustainable agriculture. The common interest of all environmental-friendly systems is to decrease burden to agricultural environment by low input of agricultural labor and materials. This study was conducted to estimate overwintering capacity and genetic distance among Chinese Milk Vetch (Astragalus sinicus, CMV) collections based on morphological characteristics and AFLP (Amplified fragment length polymorphism) analysis. Furthermore, the effect of CMV as green manure was observed in mix-cultured paddy fields with rice, sesame and sweet-potato. An another objective of this study was also to compare the pattern of weed occurrence in paddy fields with or without CMV and different rice transplanting times. The CMV collected from Paju district in central region of Korea was successively occurring through self-reseeding without artificial management. However, there was no noticeable difference in growth habit between Paju native CMV and introduced CMV from China which is currently used in farm fields. On the basis of multi-dimensional scaling and tree analyses, there are no significant difference of agricultural growth characteristics among Paju and chinese collections only excepting leaf angle and root length. The flowering time of Gurye collection was fast for 1 week as compared to other collections. AFLP that was commonly used for plant classfication, was applied to exam the genetic variation of CMV collections. Total 579 PCR products and 336 polymorphic fragments were generated using 8 primer pairs.

• Journal of Korean Society of Rural Planning
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• v.28 no.1
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• pp.17-26
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• 2022

It is necessary to prepare a stable production base in advance for a change in the global grain market, and it is required to prepare comprehensive countermeasures such as securing technical skills and cultivation technology. Therefore, Korea, which relies on imports of major grains other than rice, could be exposed to a food crisis at any time unless the self-sufficiency rate of grains is improved. In order to respond to this new food crisis, it is necessary to find ways to efficiently utilize rice fields to increase the domestic grain self-sufficiency rate. From this point of view, interest and demand for the generalization of farmland that can be used as paddy fields and returned to paddy fields are increasing, and related research is also being continuously performed. In order to select a multipurpose farmland project site, this study extracted farmland containing 10% or more purchased and stockpiled farmland through spatial analysis (buffer, dissolve, intersect, etc.), and finally presented areas subject to multipurpose farmland projects. The target site for the multipurpose farmland project was finally selected by integrating data onto a point-by-point basis so that the current status of farmland purchased and stockpiled, Farm Manager Registration Records, and the Korean Soil Information System data (drainage classes, surface soil texture, field-suitability classification, etc.) can be used in combination. There are 175 areas where the multipurpose farmland is possible. Incheon 2, Gyeongbuk 40, Gangwon 2, Chungbuk 7, Chungnam 48, Jeonbuk 34, Jeonnam 19, Gyeongbuk 15, Gyeongnam 8. Chungcheongnam-do has the most target site for the multipurpose farmland project, and Gangwon-do is the least. It is expected to contribute to new commercialization and business expansion by deriving business areas by identifying the scale of the farmland multipurpose farmland project using Farm Manger Registration Records and spatial data.

• Korean Journal of Soil Science and Fertilizer
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• v.3 no.1
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• pp.23-28
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• 1970

The effect of wollastonite and manganese dioxide on the growth of rice on an acid sulfate soil were investigated in pot experiment. 1. Since aluminum content in the leachate of soil was reduced with increasing the pH and these chemical changes in the leachate were more pronounced by applying wollastonite, aluminum toxicity in flooded paddy rice was overcome by applying wollastonite, or flooding. 2. Poor growth of rice with iron toxicity-like symptoms on the untreated acid sulfate soil may be caused by excess iron and sulfur. Plants applied wollastonite, however, grew normally and did not show any symptoms. Iron and sulfur contents in the plant was reduced by applying wollastonite. 3. Because of the iron content in the both leachate and plant can be lowered by applying wollastonite, iron-toxicity was averted by applying the wollastonite. 4. Application of manganese dioxide in combination with wollastonite did not counteracted iron content in the plant as compared with the wollastonite treatment. 5. The application of wollastonite increased the dry weight of straw and grain yield. Manganese dioxide with wollastonite caused the increase of number of spickelets per panicles and ripened grains as compared with wollastonite. 6. From these results it can be concluded that the major cause of the poor growth of rice on acid sulfate soil is iron toxicity and the Fe-toxicity can be reduced by application of wollastonite.

• Korean Journal of Remote Sensing
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• v.33 no.6_1
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• pp.931-946
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• 2017

The purpose of this study is to observe and analyze soil moisture conditions with high resolution and to evaluate its application feasibility to agriculture. For this purpose, we used three Landsat-8 OLI (Operational Land Imager)/TIRS (Thermal Infrared Sensor) optical and thermal infrared satellite images taken from May to June 2015, 2016, and 2017, including the rural areas of Jeollabuk-do, where 46% of agricultural areas are located. The soil moisture conditions at each date in the study area can be effectively obtained through the SPI (Standardized Precipitation Index)3 drought index, and each image has near normal, moderately wet, and moderately dry soil moisture conditions. The temperature vegetation dryness index (TVDI) was calculated to observe the soil moisture status from the Landsat-8 OLI/TIRS images with different soil moisture conditions and to compare and analyze the soil moisture conditions obtained from the SPI3 drought index. TVDI is estimated from the relationship between LST (Land Surface Temperature) and NDVI (Normalized Difference Vegetation Index) calculated from Landsat-8 OLI/TIRS satellite images. The maximum/minimum values of LST according to NDVI are extracted from the distribution of pixels in the feature space of LST-NDVI, and the Dry/Wet edges of LST according to NDVI can be determined by linear regression analysis. The TVDI value is obtained by calculating the ratio of the LST value between the two edges. We classified the relative soil moisture conditions from the TVDI values into five stages: very wet, wet, normal, dry, and very dry and compared to the soil moisture conditions obtained from SPI3. Due to the rice-planing season from May to June, 62% of the whole images were classified as wet and very wet due to paddy field areas which are the largest proportions in the image. Also, the pixels classified as normal were analyzed because of the influence of the field area in the image. The TVDI classification results for the whole image roughly corresponded to the SPI3 soil moisture condition, but they did not correspond to the subdivision results which are very dry, wet, and very wet. In addition, after extracting and classifying agricultural areas of paddy field and field, the paddy field area did not correspond to the SPI3 drought index in the very dry, normal and very wet classification results, and the field area did not correspond to the SPI3 drought index in the normal classification. This is considered to be a problem in Dry/Wet edge estimation due to outlier such as extremely dry bare soil and very wet paddy field area, water, cloud and mountain topography effects (shadow). However, in the agricultural area, especially the field area, in May to June, it was possible to effectively observe the soil moisture conditions as a subdivision. It is expected that the application of this method will be possible by observing the temporal and spatial changes of the soil moisture status in the agricultural area using the optical satellite with high spatial resolution and forecasting the agricultural production.