• Magazine of the Korean Society of Agricultural Engineers
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• v.19 no.3
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• pp.4449-4461
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• 1977

Subsurface Drinage Problems arise from many causes. Flatland tends to be poorly drained, particularly where the subsoil permeability is low. There are many wet areas, however, where there is no evident connection between the area of seepage, or a high water table, and the topography of the site. High water tables may occur where the soil is either slowly or rapidly permeable, where the climate is either humid or arid, and where the land is either sloping or flat. This study is to bring light on subjects relating to increasing yield of crop and possibility of double crops a year in water logging paddy fields. Obtained results are briefly summarized as follows: 1. Effect of crop-yield in the plot A resulted 20.2 percent higher than the ordinary plot with yield of brown rice. 2. Possibility of double-crops a year is investigated. Effect of the barley production of the test plot resulted 168.2 percent higher than the other uplands near test plot with the yield of 1977 production and it is 3.8 percent higher compare with the yearly yields. 3. Decreasing depth of water level was measured 23.9mm per day and 14.3mm per day at the test plot and ordinary plot respectively and the amounts of subsurface drainage measured 30mm to 35mm per day. It is required that the relief well should be controled carefully and adequately. 4. Mean depth of ground water levl was measured 0.4∼0.5m regardless the width of corrugated pipe. It is significantly lowere than the ordinary plot(0.15∼0.20m) 5. The ground temperature of the test plot is higher 1 degree of centigarade or more than the ordinary plot and soil moisture content of the ordinary plot is higher 12.4∼27.8 percent than the plot reversely. There should be a relationship between rising of ground temperature and soil moisture.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.599-605
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• 2013

The effects of water-saving irrigation on the emissions of greenhouse gases and the prokaryotic communities in rice paddy soils were investigated through a field experiment. In the Water-Saving (WS) irrigation, the water layer was kept at 2~3 cm while it was kept at 6 cm in the Continuousiy Flooding (CF) irrigation. A plot was treated with Intermittently Drainage (ID) that is drained as fine cracks on the floor were seen after transplanting. GHGs emission amounts from WS plots were reduced by 78.1% compared to that from CF plot and by 70.7% compared to that from ID plot, meaning that WS could help contribute to mitigation of the greenhouse gas accumulation in the atmosphere.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.5
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• pp.153-162
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• 2001

A study was carried out to investigate the water balance and losses of nutrients at a paddy plot located at the southern Korea. The observed amount of precipitation, irrigation, runoff, evapotranspiration and percolation for the experimental paddy plot during cropping period were 1,030, 566, 701, 551. and 310 mm for 1999 and 1.214, 413, 710, 682, and 234 mm for 2000 year, respectively. The measured input quantities of N and P into the paddy field during cropping period were 122 to 140 kg N $ha^-1$ and 29 to 30 kg $P_2O_5$ kg $ha^-1$ by chemical fertilizer, 20 to 28 kg N $ha^-1$ and 0.35 to 0.36 kg P $ha^-1$ by precipitation, and 26 to 35 kg N $ha^-1$ and 0.57 to 0.72 kg P$ha^-1$ by irrigation water. respectively. The output amounts of N and P from paddy field were measured as follows. They were 48 to 52 kg N $ha^-1$ and 1.1 to 1.6 kg P $ha^-1$by runoff water, and 9 to 12 kg N $ha^-1$ and 0.04 to 0.05 kg $ha^-1$ by percolation water. When the runoff losses of nutrients were compared to applied chemical fertilizer. it was found that 34.3 % to 42.6 % of nitrogen lost via runoff while runoff losses of phosphorus account for 3.8 % to 5.3 % of the total applied amount. When the ratio was calculated between nutrients losses by percolation water and the applied of chemical fertilizer, two year results showed 6.4 % to 9.8 % for the nitrogen and 0.1% to 0.2% phosphorus, respectively.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.5
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• pp.41-54
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• 2018

A method to account a detention in a rice paddy field in hydrologic modeling was tested at plot and watershed scales. Hydrologic Simulation Program - Fortran (HSPF) and its one of surface runoff modeling method, i.e Surface-Ftable, were used to simulate a inundated condition in a rice paddy culture for a study plot and basins in Saemangeum watershed. Surface-Ftable in HSPF defines surface runoff ratio with respect to surface water depth in a pervious land segment, which can be implemented to the feature of water management in a rice paddy field. A Surface-Ftable for paddy fields in Saemangeum watershed was developed based on the study paddy field monitoring data from 2013 to 2014, and was applied to Jeonju-chun and Jeongeup-chun basins which comprise 12% and 22% of paddy fields in the basins, respectively. Four gaging stations were used to calibrate and validate the watershed models for the period of 2009 and 2013. Model performed 7.13% and 9.68% in PBIAS, and 0.94 and 0.90 in monthly NSE during model calibrations at Jeonju and Jeongeup stations, respectively, while the models were validated its applicability at Hyoja and Gongpyung stations. The comparison of results with and without considering detention effect of paddy fields confirmed the validity of the Surface-Ftable method in modeling watersheds containing rice paddy fields.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.3
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• pp.214-220
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• 2007

The effects of soil percolation rate on $CH_4$ and $N_2O$ emissions were investigated from paddy fields with different drainage systems. Subsurface tile drainage plot of soil percolation rate $11.9mm\;d^{-1}$ and non-subsurface drainage plots of soil percolation rate $7.4mm\;d^{-1}$ and $6.9mm\;d^{-1}$ were designed. The effects of rice straw application were measured at each drainage plots. The subsurface tile drainage plot of soil percolation rate $11.9mm\;d^{-1}$ showed the lower emission amount both of $CH_4$ and $N_2O$ among treatments. In the subsurface tile drainage plot of $11.9mm\;d^{-1}$ percolation rate, 46% of $CH_4$ and 33% of $N_2O$ emission amounts were reduced in comparison of non-subsurface drainage plot of $6.9mm\;d^{-1}$ percolation rate. With rice straw application, the $CH_4$ emission amount was 2.1 times to that from no-applied plot, the $N_2O$ emission amount was not affected by rice straw application.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.2
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• pp.85-96
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• 2022

The study is aimed to investigate the features and socio-economic background of farmland consolidation project with medium-sized paddy plot at irrigation associations during the Japanese colonial period in Korea. Most of farmland consolidation works in the 1940s was composed of independent irrigation and drainage ditches along the short side of field plot. However, the number of farm roads at farmland consolidation zone was much smaller than number of irrigation ditches to decrease reduction in farmland area. The standard field plot was medium-sized (about 20-40 ares) in Korea but small-sized (about 10 ares) in Japan in this period. As the result of farmland consolidation works, the unit water requirement was increased to 0.0035 m³/s/ha, and the unit area drainage discharge was over 2.0 m³/s/km² in many cases. The farmland consolidation with medium-sized plot have been spread under the colonial landlord system, where major landlords occupied a large share of farmland and managed corporate farming to gain more benefit. The reasons for spread of farmland consolidation with medium-sized plot may be as follows: high net profit ratio, an increase in land price, and labor savings in rice farming. The farmland consolidation with medium-sized plot in the colonial period showed intermediate features between the farm consolidation with small-sized plot for an increase in land productivity in Japan and the farm consolidation with medium-sized plot for an increase in labor productivity after the 1960s.

• Korean Journal of Environmental Agriculture
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• v.20 no.2
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• pp.86-92
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• 2001

The current study was conducted to elucidate the optimum density of free-ranging ducks in a rice-duck farming system in terms of effects on duck behavior, and growth and yield of rice plants. Four paddy fields were used for this experiment, with 6, 9, 12 and 15 birds per plot, respectively. Ducklings at eight days of age were free ranged in experimental paddy plots (4.0 a each) on the 9th day after the transplantation of rice plants. Ducks were kept in the plot for seventy days, at which point rice plants reached the earing stage. Foraging, moving, working, resting, diving and pecking behaviors of the ducks were observed two times during the experimental period. Also, rice plant growth and yield according to the density of ducks per plot were examined. The foraging and moving behavior of free-ranging ducks in paddy fields for 12 hours during the daytime tended to be longer in the 12-bird plot, and working behavior was significantly (P<0.01) longer in the 12-bird plot than in the other three plots. The resting behavior was significantly (P<0.01) higher in the 9- and 15-bird plots than in the 12-bird plot. The frequency of moving behavior for 6 hours during the daytime in the 15-bird plot tended to be lower than that in the other three plots, but this difference was not significant. The amount of diving and pecking behavior in the 9-bird plot was significantly (P<0.05) higher than that in the other three plots, and the number of hills pecked tended to be higher with increasing of duck density. From thirty days after ducks were introduced to the paddy fields, the length of rice plants tended to be significantly (P<0.05) shorter in high free-ranging density plots as compared to low free-ranging density plots. The number of tillers per hill was not affected by the free-ranging density. The culm length of rice plants was significantly (P<0.05) shorter in the 12- and 15-bird plots than in the other two plots, however, the duck free-ranging density did not affect panicle length. The dry weight of the root of rice plants was increased with high free-ranging density, but there was no such increase in the top parts of the rice plants. The percent of rice plants badly damaged by free-ranging density tended to be lower in the order of 12-, 9-, 6- and 15-bird plots. The number of ears, ripening grains and crop yield per hill of rice plants in the 12-bird plot were significantly (P<0.05) higher than those of the other three plots. Therefore, the yield of each rice plant per 10 a was significantly increased in the 12-bird plot.

• Journal of Biosystems Engineering
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• v.21 no.3
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• pp.343-356
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• 1996

The plot geometry of the paddy land is directly related to the performance of machines, especially those having a large size and high speed. The study was to investigate the optimum plot geometry from the standpoint of mechanization. A simulator, Field-Plot-Structure-Evaluation-System(FPSES) was developed for evaluation of the field performance of machines according to the plot geometry. The efficiency and capacity of different sizes of machinery used for rice farming functions were analyzed for a various combination of plot geometry, which could be used as reference for the land reclamation planning and mechanization programming. It is shown that the plot size of about two hectares having a length of 200m and width of loom may be optimum, considering the efficiency and capacity of large sized machinery available currently and in near future.

• Journal of the Korean Professional Engineers Association
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• v.1 no.1
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• pp.18-25
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• 1968

Higher yield in rice paddies is greatly dependent on adequately balanced and timely supply of water. A majority of rice paddy in Korea is generally irrigated by rainfall, but in many cases it has to be supplemented by artificial irrigation for optimum rice culture. Although the water requirement of rice plant is for higher Than that of athec crops, submerged condition of rice paddy is not Necessarily required. The moisture requirement of rice plant varies with its growing stages, and it is possible to increase the irrigation efficiency through reduction of water loss due to percolation in rice paddies. An experimental plots were set up by means of sandomized block design with three duplication; (a) All time submerged, (b) Economically controlled, and (c) Extremely controlled. Three different irrigation periods Were (a) Initial sage, (b) Inter-stage, and (c) Yast stage. The topsoil of the three plots were excavated to the depth of 30 cm and then compacted with clay of 6 cm thickness. There after, they were piled up with the excavated top soils, leveled and cored with clay of 6 cm thickness around footpath in order to prevent leakage. The results obtained from the experiments are as follows, 1. There is no difference among the three experiments plots in terms of physical and chemical conditions, soil properties, and other characteristics. 2. Culm length and ear length are not affected by different irrigation methods. 3. There is no difference in the mature rate and 1, 000 grain weight of rice for the three plots. 4. The control plot which was irrigated every three days shows an increased yield over the all the time submerged plot by 17.8 percent. 5. The clay lined plot whose water holding capacity was held 5 days long, needs only to be irrigated every 7 days. 6. The clay lined plot shows an increased yield over the untreated plot ; over all-the-time submerged plot by 18 percent ; extremely controlled plot by 18 percent, and economically controlled plot by 33 percent. 7. It may be saved in water requirement about one Thirds.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.6
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• pp.403-408
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• 2006

Fluvio-marine paddy soils in Korea consist of high silt content and have the hardpan located below 20~30 cm from surface soil. This properties cause poor rice rhizosphere conditions such as low permeability and porosity, high bulk density and hardness. The aims of this study was to investigate the effect of popped rice hulls compost(PRHC) on soil fertility changes in the Fluvio-marine plain paddy soils. Total nitrogen content and nitrogen mineralization rate of PRHC were 1.17 and 33.5, respectively, and its C/N ratio was 35.4. Application of PRHC increased the content of organic matter and exchangeable potassium and improved the bulk density and porosity. The content of $NH_4-N$ in soil was high in the PRHC plot until maximum tillering stage. An uptake amount of fertilized nitrogen was greater in standard fertilization plot at early growth stage, however, it was greater more in PRHC plots at the ripening period than in standard fertilization plot. Among the PRHC treated plots, uptake amount was the greatest in 50% PRHC plot during the all growth period. Nitrogen efficiencies were higher in PRHC plot during the all growth period. Rice yields in all PRHC plots were lower than in standard fertilization, however, the yield of 40% PRHC plot was similar with that of standard.