• Journal of Korean Society of Forest Science
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• v.90 no.3
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• pp.242-248
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• 2001

Changes in land-use can affect soil organic matter content and fertility. We compared total soil carbon and nitrogen concentrations, soil respiration, and nitrogen availability under three land-use types in central Korea; conversion of old rice field to natural willow-maple (Salix-Acer) forest, conversion of old field to artificial Korean pine (Pines koraiensis) forest, and indigenous oak (Quercus spp.) forest. After 20 years of fallow the area of rice field conversion to forest had higher soil carbon and nitrogen concentrations in the soil depth of 0-10cm and 10-20cm than the areas of field conversion to Korean pine forest and indigenous forest. In general, soil carbon and nitrogen concentrations decreased with soil depth. Organic matter accumulation as a balance of input and decomposition seemed to be higher in the soil of previous rice field, and carbon and nitrogen accumulation was largely confined to the topsoil. Soil respiration rates were greatest at the area of rice field conversion to forest, and appeared to be related to soil carbon and soil moisture. Soil nitrogen availability measured by the ion exchange resin bag method differed significantly among land-use types; soil inorganic nitrogen ($NH_4{^+}+NO_3{^-}$) and ammonium availability were highest in the soil under indigenous oak forest followed by conversion of old field to artificial Korean pine forest and conversion of old field to natural willow-maple forest.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.4
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• pp.209-213
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• 2006

This study was carried out to investigate the changes in soil chemical properties and yields of crops by rice-soybean rotation cropping system at silt loam soil. There were 4 rotation cropping systems; continuous rice cultivation, annual, biennial and triennial rotation of soybean and rice. There were little change in pH, organic matter, $Ca^{2+}$ and $K^+$ contents with decrease in available phosphate content in the continuous rice cropping. The cropping system of soybean-rice caused to increase in available $P_2O_5$, $K^+$ and $Ca^{2+}$ in the soil after harvest. Content of $NH_4-N$ in the soil also increased after the rotation of soybean than the continuous rice cropping in the soil during the rice growth period. These chemical change in the soil caused to increase rice growth in number of the panicles and the spikelet per square meter. The yield of rice was increased by the rotation with soybean, and was gradually increased in the triennial rotation of soybean and rice. But the yield of soybean was decreased in continuous cultivation for two or three years in the paddy field. It was recommended for annual rotation to prevent the yield of soybean from decrease.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.6
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• pp.473-477
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• 2001

Chinese milkvetch (Astragalus sinicus L.) has been traditionally used as a green manure supplying mineral N and organic matters to soil. In rice-Chinese milkvetch interrelay cropping system, three rice cultivating methods (no-till direct seeding, no-till transplanting, and tillage transplanting) were evaluated for stand reestablishment without reseeding Chinese milkvetch with two cropping times (May 25 and June 4) for two years. Chinese milkvetch incorporated was decomposed rapidly in the first week. Decomposition was fast in topsoil than in subsoil. Natural milkvetch reestablishment (NMR), following harvest of no-till-direct-sown rice was good enough to cover the paddy field in both cropping times, but rice yield of this method was lower than that of transplanted rice on paddy field without milkvetch cultivation. Even though good NMR was secured in no-till rice transplanting, the shoot of milkvetch should be removed before machine-transplanting of rice seedlings. NMR was better in rice cropping at the mid-ripening stage of milkvetch (June 4) than at the late-bloom stage (May 25). Rice yield was higher in tillage transplanting at the mid-ripening stage of milkvetch (June 4) than in the other rice cropping method.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.4
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• pp.378-385
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• 1985

In order to investigate the application effects of soil amendment on wetland rice soil field and laboratory experiment were conducted on ill drained paddy field on which rice straw, Compost, Lime and Silicate materlials such as wallostonite and fused phosphate were applied. 1. As compared with check plot, rice yield was increased by application of soil amendments significantly in all plots but rice straw one. 2. The effects of soil amendment on rice production were in the order of fused phosphate and N.K, addition > silicate material and N.K, addition=Compost > rice straw and lime plot. 3. The significant correlation was showed among the rice yield and the numbers of panicle and grain. 4. The application of the rice straw restrained the rice growth because of nitrogen defficiency in early stage but increased rice yield due to the number of panicle due to supplying nitrogens late stage. 5. The application of rice straw in wetland soil promoted to occur organic acids such as $PCO_2$ and $HCO_3$, and decreased tillering due to these organic acids occuring in early growth stage.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.343-343
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• 2017

This study was conducted to investigate cropping system using paddy field in 152 cities and counties of Korea. Out of the 152 cities and counties, 106 regions responded(70%). The number of cultivated crops in 2 and 3 cropping system using paddy field was 48 crops. Among these, 35 crops were cultivated in winter and spring, 27 crops were cultivated in summer and fall. There were 33 crops in paddy field after cultivating rice. Among these, 11 crops were cultivated in spring and 26 crops were in fall-winter. There were 44 crops in paddy field without cultivating rice. Among these, 19 crops were cultivated in spring, 27 crops were in summer, 15 crops were in fall. Total cropping systems in Korea were 138 types, 2 cropping system were 119, among them outdoor crops were 77, using facility crops were 42, and 3 cropping system crops were 19. Cropping system of Jeonbuk province was 45 types and it was the most in Korea. Cropping systems of southern area were more various than those of middle-northern area in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.3
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• pp.213-219
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• 2013

A field study was conducted to understand nitrogen use efficiency of high yielding Japonica rice varieties under three levels of nitrogen fertilizer (90, 150 and 210 kg N $ha^{-1}$) in Iksan, Korea. Two high yielding rice varieties, Boramchan and Deuraechan, and an control variety, Dongjin2, were grown in fine silty paddy. Nitrogen use efficiencies (NUE) were 83.3, 56.3, and 41.2 in 90, 150, and 210 kg N $ha^{-1}$ fertilizer level, respectively. Total nitrogen uptake varied significantly among nitrogen levels and varieties. Variety Dongjin2 showed the highest nitrogen uptake efficiency (NUpE), while Boramchan and Deuraechan showed higher nitrogen utilization efficiency (NUtE). However, Nitrogen harvest index (NHI) was higher in Boramchan (0.58) than Deuraechan (0.57) and Dongjin2 (0.53). Rough rice yield showed linear relationship with total nitrogen uptake ($R^2$=0.72) within the range of nitrogen treatments. Boramchan produced significantly higher rough rice yield (8546 kg $ha^{-1}$) which mainly due to higher number of panicles per $m^2$ compared to Deuraechan (7714 kg $ha^{-1}$). Deuraechan showed higher number of spikelets per panicle, but showed lower yield due to lower number of panicle per $m^2$. Rice varieties showed different nitrogen uptake ability and NUE at different nitrogen level. Plant breeders and agronomist should take advantage of the significant variations and relationships among grain yield, NUpE, and NUE.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.3
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• pp.300-307
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• 2015

In order to develop optimum paddy-upland rotation system, we evaluated the 1st and the 2nd upland growth and yield characteristics of foxtail millet, proso millet, sorghum rotated from paddy field and rice rotated from upland in paddy-upland rotation. Average number of ears per hill was 3.3 in the 2nd upland cultivation. The value was greater by 1 ear as compared to 1st upland cultivation (2.2 ears per hill). In average yield per 10a, the 2nd upland cultivation showed 220.3 kg, 23% increased yield compared to the 1st upland cultivation (179 kg per 10a). In average number of ears per hill, the 2nd upland cultivation showed 8.3 ears, increased 4 ears compared to the 1st upland cultivation (4.2 ears per hill). In average yield per 10a, the 2nd upland cultivation showed 152.8 kg, 16.8% increased yield compared to the 1st upland cultivation (130.8 kg per 10a). In average days from seeding to heading of 5 sorghum varieties, there were no significant difference between the 1st (68.6 days) and the 2nd (67.4 days) upland cultivation rotated from paddy field. In the average number of grains per ears, the 2nd upland cultivation showed 2,931.6 grains per ear, 12% increased compared to the 1st upland cultivation (2,619.6 grains per ears). Average yield per 10a of sorghum in the 2nd upland cultivation showed 242.3 kg, 4.6% increased compared to the 1st upland cultivation (231.7 kg per 10a). In growth and yield characteristics of rice in paddy-upland rotation, culm length in paddy-upland-paddy plot showed 82.9 cm, 7.3 cm longer compared to the continuous rice paddy field (75.6 cm). Ear length was also 1 cm longer than that of the continuous rice paddy field. In average number of ears per hill, paddy-upland-paddy plot showed 25.0 ears, 4.3 ears more than that of the continuous rice paddy field (20.7 ears per hill). In average yield of rice per 10a, the paddy-upland-paddy rotation plot showed 526.8 kg, 9.8% higher yield compared to the continuous rice paddy field (479.9 kg per 10a).

• The Plant Pathology Journal
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• v.18 no.1
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• pp.43-49
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• 2002

Direct effects of atmospheric ozone on conidia of the rice blast pathogen, Magnaporthe grisea, were investigated to evaluate ozone-induced effects on infection potential of the rice blast fungus. Acute ozone exposure (200 nl $1^{-1}$, 8 h $day^{-1}$3 days) during sporulation significantly affected conidial morphology, appressorium formation, and disease development on rice loaves. Ozone caused reduction in conidial size and change in conidial shape. Relative cytoplasmic volume of lipids and vacuoles were increased in ozone-exposed conidia. Inhibition of appressorium formation and simultaneous increase in endogenous levee of polyamines were found in ozone-exposed conidia. The inverse relationship between appressorium formation and level of polyamines implies that ozone-mediated increase in intracellular level of polyamines may inhibit appressorium formation in rice blast fungus. Furthermore, rice plants inoculated with ozone-fumigated conidia exhibited less severe disease development than those with unfumigated conidia. This result suggests that the anti-conidial consequence of acute ozone will eventually weaken the rice blasts potential for multiple infection cycle. This further suggests that consequently, rice blast can be transformed from an explosive disease to one that has limited epidemiological potential in the field.

• Journal of Biosystems Engineering
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• v.31 no.2 s.115
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• pp.88-94
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• 2006

The market of rice transplanter has already been changed for riding and to be turned large size of chassis. Because an automation is rapidly expanded, It is strongly need to analyze a mechanism and develop a hydraulic circuit. In this study, we analyzed the mechanism of working equipment of rice transplanter for riding and developed hydraulic circuits. We proposed the operating mechanism of rice transplanter for riding through the mechanistic analysis of working equipment. And the simulation and experiment were performed. In order to up and down the working equipment of rice transplanter for riding, we designed the mechanism which was installed hydraulic circuit and hydraulic cylinder, and it was manufactured. The pressure of developed hydraulic circuit was set by 800 $N/cm^2$. In the field testing, the hydraulic response presented at 50 msec in the maximum driving velocity, 0.8 m/sec of rice transplanter for riding, and it was well performed. The results of experiments showed the system characteristics sufficient to use as the hydraulic mechanism for a rice transplanter for riding.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.2
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• pp.179-185
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• 2006

The Ministry of Agriculture and Forestry announced in 2001 that the overall amount of paddy land set aside for rice will be cut down by 12% by 2005, decreasing from 1.08 million to 953,000 hectares. When evaluating the value of paddy rice systems, the multi-function of paddy systems in the monsoon climate is vital importance. The main functions of paddy rice systems are to conserve biodiversity and maintain sustainability. Some crucial environmental benefits of the paddy rice systems include: flood prevention, recharge of water resources, water purification, soil erosion and landslide prevention, soil purification, landscape preservation and air purification. The paddy rice systems in Korea, which are more diverse than upland crop systems, are known to be composed of 14 orders, 36 families and 134 species. The sustain ability of paddy rice production systems can never be overestimated. Rice is part of the culture and even the heart of spiritual life in the area under the monsoon climate. Therefore paddy rice systems should be preserved with the highest priority being the enhancement of the systems' multi-function. As an outlook to future research, the need of joint and interdisciplinary research projects between economists and natural scientists at inland as well as international levels were emphasized in establishing the development of counter-measure logic through actual proofed analysis.