• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.6
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• pp.125-130
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• 2015

Field study was carried out to assess the effect of automatic inlet and filtration outlet to reduce non-point source discharge and save agricultural irrigation water from paddy. The comparison of control and treated plots showed that irrigation water was saved up to 58 mm and discharge water was reduced up to 110 mm. The filtration outlet improved the discharge water quality for SS, COD, TN and TP up to 60.1 %, 0.1 %, 4.5 %, and 26.0 %, respectively. Overall, the findings of this study indicated that non-point source pollution discharged from paddy fields where automatic inlet and filtration outlet were installed could be reduced 266.3 kg/ha/yr in SS, 10.3 kg/ha/yr in COD, 1.22 kg/ha/yr in TN, and 0.10 kg/ha/yr in TP, respectively. This clearly showed that the automatic inlet and filtration outlet are effective management method for saving of agricultural water and protecting water environment.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.5
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• pp.369-382
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• 2017

Accurate and optimal water supply to cereal crop is critical in growing stalks and producing maximum yields. Recently, upland crops are cultivated in paddy field soils to reduce overproduced rice in Korea. In order to increase productivity of cereal crops in paddy fields which have poor percolation and drainage properties, it is necessary to fully understand crop response to excessive soil water condition and management of soil drainage system in paddy field. The objectives of this study were to investigate effects of excessive soil water to sesame growth and to quantify stress response using groundwater levels. Two cultivars of sesame were selected to investigate; Gunbak and Areum. These sesames were planted in paddy fields located in Miryang, Gyeongnam with different soil drainage levels and drainage systems. The experiment site was divided into two plots by drainage class; very poorly and somewhat poorly drained. Two different drainage systems were applied to alleviate excessive soil water in each plot: open ditch and pipe drainage system. Soil water contents and groundwater levels were measured every hour during growing season. Pipe drainage system was significantly effective to alleviate wet injury for sesame in paddy fields. Pipe drainage system decreased average soil moisture content and groundwater level during sesame cultivation. This resulted in greater yield and lignan contetns in sesame seeds than ones from open ditch system. Comparison between two cultivars, Gunbak had greater decrease in growth and yield by excessive soil water and high groundwater level than Areum. Seed components (lignan) showed decrease in seeds as soil water increased. When soil moisture content was greater than 40%, lignan content tended to decrease than ones from less soil moisture content. Based on these results, pipe drainage system would be more effective to reduce wet injury to sesame and increase lignan component in paddy field cultivation.

• Journal of Korean Society of Rural Planning
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• v.18 no.3
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• pp.103-110
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• 2012

This study aims to find out the geographical distribution, the physical structure and characteristic of Gudle-jang Paddy-field in Cheongsando. On the basis of this study, the potential value and the assignment for the preservation of Gudle-jang Paddy-field were suggested. Gudle-jang Paddy-field is centrally distributed to Cheongsando and has various features as follows. First, it has the Ondol structure which is used Gudle-jang. Second, it has an irrigation canal which has functions of the tank and the prevention of cold-weather damage as well as the irrigation and drainage canal. The values of Gudle-jang Paddy-field are as follows; 1) It is the peculiar and inherent agricultural structure which is only found in Cheongsando. 2) It is the structure that the agricultural civil engineering and the agricultural water management technique of traditional methode are applied. 3) It has the worths of the traditional culture of Korea. 4) It is the important resource creating superb rural landscape of the region. In spite of these values of Gudle-jang Paddy-field, there were little efforts to preserve it. From now on, it is needed to form of sympathy about the value of Gudle-jang Paddy-field and to make efforts for preservation of it. Also the institutional and political strategy should be provided to preserve and manage Gudle-jang Paddy-field.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.385-388
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• 2002

We investigated net outflow load and unit load of pollutants from a paddy fields area in dry year 2001. Amount of irrigation water in 2001 was about 61-63% of that in previous years 1999 and 2000 due to drought. The net outflow load and unit load of pollutants in 2001 were negative, showing that paddy fields acts as sink of pollutants due to function of water quality purification. The relationship between unit load of pollutants and net surface outflow (= surface outflow - irrigation water) showed positive correlation. The results showed that abatement of surface outflow by appropriate water management contribute to reduce surface outflow load from paddy fields.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.7
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• pp.53-63
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• 2002

Runoff, sediments and nutrient losses were studied under different patterns of paddy field management: (1) fall and spring plowing (Plowing)i (2) fall plowing for half of plot and spring plowing (Semi-plowing); (3) no-till for fall and spring plowing (Un-plowing) during the non-cropping period in the southern Korea for two years. The runoff amount and initial abstract were significantly affected by plowing practices. Un-plowing plot showed the highest runoff amount among treatments. The concentrations of sediment from Plowing plot were much higher than those from Un-plowing plot, especially after (all plowing. Sediment losses from Plowing plot were 25% more than those from Un-plowing plot. There was significant difference in nutrient losses via runoff water and sediment according to plowing practice. Two-year average of losses of N from paddy field during non-cropping period were 9.42 kg ha$\^$-1/, 8.17kg ha$\^$-1/, and 7.76 kg ha$\^$-l/ for Un-plowing, Semi-plowing, and Plowing plot, respectively, while losses of P were 0.64 kg ha$\^$-1/, 0.58 kg ha$\^$-1/, and 0.58 kg ha$\^$-1/ for each tillage system. Losses of total-N, ammonia-N, nitrate-N, Total-P from Un-plowing plot was larger than those from Plowing and Semi-plowing plots during study period.

• Journal of Korean Society of Rural Planning
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• v.24 no.4
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• pp.99-119
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• 2018

Unit load factor, which is used for the quantification of non-point pollution in watersheds, has the limitation that it does not reflect spatial characteristics of soil, topography and temporal change due to the interannual or seasonal variability of precipitation. Therefore, we developed the method to estimate a watershed-scale non-point pollutant load using seasonal forecast data that forecast changes of precipitation up to 6 months from present time for watershed-scale water quality management. To establish a preemptive countermeasure against non-point pollution sources, it is possible to consider the unstructured management plan which is possible over several months timescale. Notably, it is possible to apply various management methods such as control of sowing and irrigation timing, control of irrigation through water management, and control of fertilizer through fertilization management. In this study, APEX-Paddy model, which can consider the farming method in field scale, was applied to evaluate the applicability of seasonal forecast data. It was confirmed that the rainfall amount during the growing season is an essential factor in the non-point pollution pollutant load. The APEX-Paddy model for quantifying non-point pollution according to various farming methods in paddy fields simulated similarly the annual variation tendency of TN and TP pollutant loads in rice paddies but showed a tendency to underestimate load quantitatively.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.1
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• pp.1-16
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• 2020

The APEX model has been developed for assessing agricultural management efforts and their effects on soil and water at the field scale as well as more complex multi-subarea landscapes, whole farms, and watersheds. Recently, a key component of APEX application, named APEX-Paddy, has been modified for simulating water quality by considering paddy rice management practices. In this study, the performance of the APEX-Paddy model was evaluated using field data at Iksan experimental paddy sites in Korea. The discharge and pollutant load data during 2013 and 2014 were used to both manually and automatically calibrate the model. The APEX auto-calibration tool (APEX-CUTE 4.1) was used for model calibration and sensitivity analysis. Results indicate that APEX-Paddy reasonably performs in predicting runoff discharge rate and nitrogen yield. However, sediment and phosphorus yield is not correctly predicted due to the limitation of model schemes. With APEX-Paddy, the performance in reproducing the discharge and nitrogen yield is found to be a satisfactory level after manual calibration. The manually calibrated model performed better than the automatically calibrated model in nearly all comparisons. For runoff, manual calibration reduced PBIAS while R² and NSE values of the automatically calibrated model were the same as the manual calibration. For T-N, NSE and PBIAS were reduced when using manual calibration, whereas R² value was the same as manual calibration. The limitation of the APEX-Paddy model for predicting sediment, as well as the phosphorous yield, was discussed in this study.

• Agribusiness and Information Management
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• v.9 no.1
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• pp.7-17
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• 2017

Agricultural water management has gained enormous attention in the developing world to alleviate poverty, reduce hunger and conserve ecosystems in small-scale production systems of resource-poor farmers. The story of food security in the $21^{st}$ century in India is likely t o be closely linked to the story of water security. Today, the water resource is under severe threat. The past experiences in India in general and in Andhra Pradesh in particular, indicated inappropriate management of irrigation has led to severe problems like excessive water depletion, reduction in water quality, water logging, salinization, marked reduction in the annual discharge of some of the rivers, lowering of ground water tables due to pumping at unsustainable rates, intrusion of salt water in some coastal areas etc. Considering the importance of irrigation water resource efficiency, Krishna Western Delta (KWD) of Andhra Pradesh was purposively selected for this in depth study, as the farming community in this area are severely affected due to severe soil salinity and water logging problems and hence, adoption of different water saving crop production technologies deserve special mention. It is quite disappointing that, canals, tube wells and filter points and other wells could not contribute much to the irrigated area in KWD. Due to less contribution from these sources, the net area irrigated also showed declining growth at a rate of -6.15 per cent. Regarding paddy production, both SRI and semi-dry cultivation technologies involves less irrigation cost (Rs. 2475.21/ha and Rs. 3248.15/ha respectively) when compared to transplanted technology (Rs. 4321.58/ha). The share of irrigation cost in Total Operational Cost (TOC) was highest for transplanted technology of paddy (11.06%) followed by semi-dry technology (10.85%) and SRI technology (6.21%). The increased yield and declined cost of cultivation of paddy in SRI and semi-dry production technologies respectively were mainly responsible for the low cost of production of paddy in SRI (Rs. 495.22/qtl) and semi-dry (Rs. 532.81/qtl) technologies over transplanted technology (Rs. 574.93/qtl). This clearly indicates that, by less water usage, paddy returns can be boosted by adopting SRI and semi-dry production technologies. Both the system-level and field-level interventions should be addressed to solve the issues/problems of water management. The enabling environment, institutional roles and functions and management instruments are posing favourable picture for executing the water management interventions in the State of Andhra Pradesh in general and in KWD in particular. This facilitates the farming community to harvest good crop per unit of water resource used in the production programme. To achieve better results, the Farmers' Organizations, Water Users Associations, Department of Irrigation etc., will have to aim at improving productivity per unit of water drop used and this must be supported through system-wide enhancement of water delivery systems and decision support tools to assist farmers in optimizing the allocation of limited water among crops, selection of crops based on farming situations, and adoption of appropriate alternative crops in drought years.

• Environmental Engineering Research
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• v.15 no.2
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• pp.123-126
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• 2010

Modeling non-point pollution across multiple scales has become an important environmental issue. As a more representative and practical approach in quantifying and qualifying surface water, a modular neural network (MNN) was implemented in this study. Two different site-scales ($1.5\;{\times}\;10^5$ and $1.62\;{\times}\;10^6\;m^2$) with the same plants, soils, and paddy field management practices, were selected. Hydrologic data (rainfall, irrigation and surface discharge) and water quality data (time-series nutrient loadings) were continuously monitored and then used for the verification of MNN performance. Correlation coefficients (R) for the results predicted from the networks versus measured values were within the range of 0.41 to 0.95. The small block could be extrapolated to the large field for the rainfall-surface drainage process. Nutrient prediction produced less favorable results due to the complex phenomena of nutrients in the drainage water. However, the feasibility of using MNN to generate improved prediction accuracy was demonstrated if more hydrologic and environmental data are provided. The study findings confirmed the estimation accuracy of the upscaling from a small-segment block to large-scale paddy field, thereby contributing to the establishment of water quality management for sustainable agriculture.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.461-464
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• 2002

This study is to application the TANK modle for Ponding depth and discharge, T-N, T-P simulation from paddy field area. Simulation coefficient of correlation for Ponding depth and discharge, T-N, T-P were 0.89, 0.60, 0.99, 0.91 respectively. advanced purposes are development of agriculture runoff character modeling and application of best management practice with this study model.