• The Journal of Natural Sciences
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• v.5 no.2
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• pp.49-62
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• 1992

This study was carried out to investigate the emergence, growth and yield components in rice inassoccation with Several cultivation methods direct sowing flooded paddy field(DSF), direct sowing by airplane(DSA), direct sowing in dry paddy field(DSD), 8days seedling planting(8DS), and 35days seedlingplanting(35DS). Also this study was attempeted to know the effects of calcium peroxide on germinationand early growth of rice under different soil conditions, seeding depth, application of organic matter,indirect sowing flooded paddy field.1. Rate of emergence was 73% in DSF, 70% in DSA, 62% in DSD, respectively, under the different cultivation method of rice in reclaimed paddy field.2. Degree of lodging in relation to cultivation was 5 at both DSF and DSA, 3 at DSD, 2 at both 8DS and 35DS respectively.3. Maximum tiller number was 568 per m2 at DSF and 527 at DSA. Heating was delayed for 4 days at DSF, 8 days at DSD and 2 days at 8DS as comparison with that at 35DS.4. Yield was higher 1% to 3% at DSF than that at DSA and DSD while decreased by 12% as compared with that of seedling planting.5. Total dry weight of seedling was decreased by 57% at 8DS, 60% at DSF 63% at DSD, respectively, under 0.3% of salinity. Ratio of decreasing in dry weight was higher with high salinity.6. The amount of O2 released was recorded highest to 2 to 3days after irrigatition, thereafter remaining constant to 10 days after irrigatition.7. The optimum coating amount of calcium peroxide for germination was a half of rice seed weight with 1 cm sowing depth and one-fold with 2-cm sowing depth when rice straw was not applied. With rice straw applied, on the other hand, the amount of peroxide was one-fold with 1-cm sowing depth. It was found that, under the condition of applied 600kg/10a, of 2-cm soil depth with rice straw calcium peroxide coating had no effect on emergence of rice seedling.8. In reclaimed paddy field, lodging degree was 7 with direct sowing by machine and 9 with direct sowing by hand.9. Yield was increased by 5% by applying rice straw with direct sowing by machine.

• Journal of Biosystems Engineering
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• v.31 no.1 s.114
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• pp.59-64
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• 2006

Application of herbicide for rice cropping is inevitable but notorious for its side effect of environmental pollution. Precision fanning will be one of important tools for the least input and sustainable fanning and could be achieved by implementation of the variable rating technology. If a device to detect weeds in rice field is available, herbicide could be applied only to the places where it is needed by the manner of the variable rating technology. The study was carried out to develop an algorithm of image processing to detect weeds in rice field using a machine vision system of multi-spectral digital images. A series of multi-spectral rice field picture of 560, 680 and 800 nm of center wavelengths were acquired from the 27th day to the 39th day after transplanting in the ineffective tillering stage of a rice growing period. A discrimination model to distinguish pixels of weeds from those of rice plant and weed image was developed. The model was proved as having accuracies of 83.6% and 58.9% for identifying the rice plant and the weed, respectively. The model was used in the algorithm to differentiate weed images from mingled images of rice plant and weed in a frame of rice field picture. The developed algorithm was tested with the acquired rice field pictures and resulted that 82.7%, 11.9% and 5.4% of weeds in the pictures were noted as the correctly detected, the undetected and the misclassified as rice, respectively, and 81.9% and 18.0% of rice plants in the pictures were marked as the correctly detected and the misclassified as weed, respectively.

• Research in Plant Disease
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• v.15 no.1
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• pp.41-45
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• 2009

In order to study a relationship between soil nutrients and rice brown spot occurrence, paddy field soils, rice grains and straws collected from different paddy fields with different disease degrees of brown spots were analyzed for inorganic nutrients. Brown spot was prevalent in the rice grown in nutrient-deficient soils, which is especially low in macronutrient elements (phosphoric acid, potassium, silicic acids) and micronurients (calcium, magnesium). The soil, however, was high in sodium while organic nutrients and pH level were similar to others. The rice straws with severe brown spot were low in inorganics such as ferrous, copper, T-N, and $P_{2}O_{5}$ while the rice grains with brown spot were low in ferrous, MgO, Zn, and Mn. In the analysis of field type and nitrogen level, the highest disease severity was found in sandy-type field soil, followed by salty-type field soil and disease severity decreased as application level of nitrogen fertilizer increased. As a summary, the most important factor for effective brown spot control in rice is maintenance of proper nutrients in sandy-type field and control of sodium level in salty-type field soil.

• Korean Journal of Soil Science and Fertilizer
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• v.51 no.2
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• pp.101-110
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• 2018

There is an increasing concern over arsenic (As) contamination in rice since Codex Committee on Contaminants in Food (CCCF) discuss on maximum levels for As in rice in 2010. This study was conducted to reduce As concentration in rice by soil amendment treatments in paddy field soils contaminated by As. The selected four amendments were poultry manure, agri-lime, steel slag, and gypsum with the addition of 3% or 5% (w/w) on a dry basis. The As reduction effect could not be verified, as a result of the pot test by adding poultry manure to the paddy soil around the mine located in Yesan. Among the agri-lime treated rice cultivated pots, the As concentration increased up to 32.1%. On the other hand, the content of As in the sample pots treated with steel slag and gypsum decreased by 65.4% and 63.4%, respectively. On the basis of the results of these pot experiments, the field test was carried out in the As polluted rice field around the mine located in Yesan, and when the four amendments were treated, the As content in the brown rice reduced in all the amendment treatments compared with the control plot. The As reduction in brown rice of the amendment was confirmed to be higher efficiency by the order of gypsum > steel slag > poultry manure > agri-lime. As a result of pot experiments using paddy soil around the mine located in Seosan, As stabilization efficiency in rice and As reduction effect could not be determined by comparison to the control. From the rice cultivated from agri-lime treated pot, As concentration increased by 15.8% in rice. On the other hand, the As content of the pots treated with steel slag and gypsum decreased by 39.1% and 60.2%, respectively. In conclusion, distinguished As reducing effectiveness could be expected by soil amendment treatments for rice cultivation.

• Korean Journal of Environmental Agriculture
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• v.32 no.1
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• pp.17-23
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• 2013

BACKGROUND: Today, environmentally friendly farming has become an important feature of agricultural policy. It promotes or sustains farming systems which protect and enhance the environment. This study was conducted to compare benthic invertebrate communities in an organic and a conventional paddy field in South Korea. METHODS AND RESULTS: Benthic invertebrates were collected at 11 regions of a rice paddy from June to August, 2009, 2010 and 2011. These comparisons undertaken using a community assessment approaches such as the number of individuals and species and community composition. Generally, the larger number of individuals and species of benthic invertebrates was observed in an organic paddy than in a conventional paddy field. Organic paddy fields could supported the wider range of species and abundance in aquatic invertebrates comparing to conventional paddy fields. Carrying capacity to support larger numbers of invertebrates also tends to be higher in organic paddy than in conventional paddy field. Specially, organic farming regions surrounded by forests were high quality habitat for benthic invertebrates than other surrounded regions such as grassland. CONCLUSION(S): We concluded that organic farming was more advantaged to benthic invertebrates than conventional farming. In order to improve biodiversity in rice paddy field, farming regimes without agricultural chemicals are recommended. The effect of organic management on biodiversity and abundance of benthic invertebrates could be maximized across highland farmland.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.3
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• pp.382-390
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• 1995

To compare the rice yield and grain quality characteristics between mature(MPF) and reclaimed paddy field(RPF), grain yield and its components, some physicochemical properties of rice grain and palatability of cooked rice were investigated for Dongjinbyeo grown at three different locations of mature and reclaimed paddy field, respectively, in south western part of Korea. Variation of culm length in mature paddy area was larger than that in reclaimed saline area. Panicle number per m$^2$ in RPF was more then that in MPF but grain number per m$^2$, filled grain ratio and 1, 000-grain weight in RPF were lower than those in MPT. Average yield of milled rice in RPF was 12% lower than that in MPF (5.l1t /ha). Daejeon showed the highest yielding among MPF and Yeongam reveald the highest grain production among RPF. RPF rices had slightly higher carbohydrate content and alkali digestibility but lower protein, fat and amylose content compared with MPF rices. RPF rices also exhibited higher mineral contents, Mg/K ratio, peak and hot viscosity compared with MPF rices. RPF rice showed slightly poor apparent grain quality but a little better eating quality of cooked rice compared with MPF rice.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.570-573
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• 2004

We proposed a new system to collect hyperspectral data using a general cargo crane. The system has advantageous characteristics for precise data collection and analysis. In order to evaluate the validity, we performed the system on actual rice paddy field and analyzed the observed data. On the process, we could successfully extract the pure vegetation spectrum with high stability. The data taken by the system are useful for detail analysis among fields. In future development, it can be used for obtaining the grand truth for calibrating satellite or aerial hyperspectral images.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.7
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• pp.14-24
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• 2002

The effect of reclaimed water irrigation on paddy rice culture was evaluated by pilot study at the experimental field of Konkuk University in Seoul, Korea. The sewage was treated by constructed wetland system, and its effluent was used as irrigation water for four treatments and one control plots with three replications. Irrigation of reclaimed water onto paddy rice cultures did not adversely affect the growth and yield of rice. Instead, experimental rice plots of reclaimed water irrigation displayed about 10 to 50% more yield on average than controls. This implies that reclaimed water irrigation might be beneficial rather than harmful to rice culture as long as the sewage is treated adequately and used properly. The amount of irrigation water had little effect on experimental rice cultures, but its strength was important. The strength of treated sewage was not a limiting factor in this study, and no lodging was observed even with a relatively high nitrogen concentration (up to 160mg/L). In general the paddy soil was not affected by reclaimed water irrigation. However, there was an indication that continuous irrigation with high strength of reclaimed water might cause salt accumulation in the soil. Supplemental use of reclaimed water with existing sources of irrigation water is recommended rather than irrigation with a single source of reclaimed water. Overall, the results demonstrated that reclaimed water could be reused as a supplemental source of irrigation water for paddy rice culture without causing adverse effects as long as it is properly managed. For full-scale application, further investigation should be done on environmental risks, tolerable water quality, and fraction of supplemental irrigation.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1043-1048
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• 2012

We have researched the changes of paddy soil properties and rice yield by several different methods to treated with liquid pig manure(LPM). In the execution of this experiment, rice was cultivated to full maturity at a paddy field in Jeollabuk-do in 2011. Field experiment was designed with surface application on dry field condition+jet hose spray(Tr. 1), surface application on dry field condition+incorporation with irrigation water(Tr. 2), surface application on dry field condition+application device of fertilizer through irrigation(Tr. 3), submerged application on irrigated field condition+jet hose spray(Tr. 4), submerged application on irrigated field condition+incorporation with irrigation water(Tr. 5) and submerged application on irrigated field condition+application device of fertilizer through irrigation(Tr. 6) plot. Total N, P, K contents in used LPM were 0.44%, 0.07% and 0.14%, respectively. After the experiment, soil properties were not significant difference both several treated plots. But $NO_3$ and $NH_4$ contents at incorporation with irrigation water plots in paddy soil were higher than other plots. The yield was 602 kg $10a^{-1}$ in Tr. 2 plot compared Tr. 6 plot, which showed a value of 9.6% higher.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.310-317
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• 2016

This study aimed to evaluate the nutrient load balance from rice paddy fields with different topographies, alluvial plain and local valley. Continuous monitoring from May to September, 2013 was conducted for water quantification and qualification from alluvial plain in Yeoju region (32 ha) and local valley in Jincheon region (24 ha). The discharge rates of T-N from the alluvial plain were 57.2, 5.84, 22.7, and $5.20kg\;ha^{-1}$ for irrigation, precipitation, drainage, and percolation, respectively. In case of local valley, T-N loads were 34.6, 4.73, 21.1, and $4.15kg\;ha^{-1}$ for irrigation, precipitation, drainage, and percolation, respectively. In contrary, the T-P loads from the alluvial plain were 2.23, 2.22, 2.54, and $0.41kg\;ha^{-1}$ for irrigation, precipitation, drainage, and percolation, respectively. In case of local valley, T-P loads were 1.44, 1.57, 1.82, and $0.34kg\;ha^{-1}$ for irrigation, precipitation, drainage, and percolation, respectively. The nutrient contents in drainage water were influenced by the amount of waters, rainfall, and surface drainage water. The Pearson correlation analysis showed that rainfall was significantly correlated with nutrient loads from July to August due to the amount of runoff in local valley paddy field, and irrigation was related with nutrient loads of drainage from July to August. This study showed that paddy rice farming in alluvial plain and local valley might be beneficial to water quality protection.