• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.3
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• pp.75-85
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• 2021

This study evaluated variations in the paddy rice water demand based on the continuous changing in rice transplanting period and ponding depth at the four study paddy fields, which represent typical rice producing regions in Korea. Total 7 scenarios on rice transplanting periods were applied while minimum ponding depth of 0 and 20 mm were applied in accordance with maximum ponding depth ranging from 40 mm to 100 mm with 20 mm interval. The weather data from 2013 to 2019 was also considered. The results indicated that the highest rice water demand occurred at high temperature and low rainfall region. Increased rice transplanting periods showed higher rice water demand. The rice water demand for 51 transplanting days closely matched with the actual irrigation water supply. In case of ponding depth, the results showed that the minimum ponding depth had a proportional relationship with rice water demand, while maximum ponding depth showed the contrary results. Minimum ponding depth had a greater impact on rice water demand than the maximum ponding depth. Therefore, these results suggest that increasing the rice transplanting period, which reflects the current practice is desirable for a reliable estimation of rice water demand.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.564-571
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• 2016

As the amount of rice straw collected increases, green manure crops are used to provide the needed organic matter. However, as green manure crops generate methane in the process of decomposition, we tested with different tillage depths in order to reduce the emission. The atmosphere temperature of the chamber was $25{\sim}40^{\circ}C$ during the examination of methane and soil temperature was $2{\sim}10^{\circ}C$ lower than air temperature. The redox potential (Eh) of the soil drastically fell right before irrigated transplanting and showed -300~-400 mV during the cultivating period of rice (7~106 days after transplant). When hairy vetch was incorporated to soil and the field was not irrigated, the generation of methane did not occur from 12 to 4 days before transplanting rice and started after irrigation. Regarding the pattern of methane generation during the cultivation of rice, methane was generated 7 days after transplanting, reached the pinnacle at by 63~74 days after transplanting, rapidly decreased after 86~94 days past transplanting and stopped after 106 days past transplanting. When tested by different soil types, methane emission gradually increased in loam and clay loam during early transplant, whereas it sharply increased in sandy loam. The total amount of methane emitted was highest in sandy loam, followed by loam and clay loam. In all three soil types, methane emission significantly reduced when tillage depth was 20 cm compared to 10 cm. The rice growths and yield were not affected by tillage depth. Therefore, reduction of methane emission could be achieved when application hairy vetch to the soil with tillage depth of 20 cm in paddy soil.

• Korean Journal of Weed Science
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• v.14 no.2
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• pp.101-106
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• 1994

Factors affecting phytotoxicity of dithiopyr in rice such as transplanting depth, seedling age, soil texure were examined and mechanism of phytotoxicity in rice was also determined by absorption study of $^{14}C$-dithiopyr in rice seedlings under above conditions. Rice injury was occurred in shallow transplanting depth, young rice seedlings and sandy soil conditions. Higher amount of dithiopyr was absorbed in rice at shallow transplanting depth and sandy soil conditions which may related to phytotoxicity of dithiopyr.

• Journal of Biosystems Engineering
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• v.5 no.1
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• pp.58-65
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• 1980

Sinkage differences between the wheels of a transplanter which are caused by the different hard pan of fields and land preparation affect the field performance of a rice transplanter. In this experiment the relationships between the sinkage differences of the wheels of a transplanter and the planting distance, planting angle, planting depth and deviation from a straight transplanting line were investigated. The objective of this experiment was to obtain some basic informations for the effective use of the rice transplanter . The results of this experiment are as follows. 1. Transplanting distance became shorter as the sinkage differences increased. This effect was greater on the side of the transplanter with a shallower sinkage. 2. The depth of transplanting increased as the differences in the depth of sinkage increase for the side with the deeper sinkage. An opposite trend was observed for the side with shallower sinkage. 3. The angle of transplanted seedlings from the vertical portion increased slightly as the sinkage differences increased. The variation in results were greater from the side of the transplanter with deeper sinkage than with shallower sinkage. 5. The best postures of planted seedling were found when the water depth was 3 cm for the side of transplanter with deeper sinkage and 4 cm for the shallower sinkage side. The relationships between the postures of planted seedling and water depth. , or $y=67.62 + 10.69x-1.76x^2$ for the side of transplanter with deeper sinkage and $y=66.64+11.62x-1.50x^2$ for the side with shallower sinkage, were found from this experiment.

• ALGAE
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• v.20 no.2
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• pp.151-155
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• 2005

To obtain basic data, we investigated the effect of blade length on transplants, the transplanting method of Laminaria japonica for creating L. japonica resources and the number of transplanting plates with surviving L. japonica. The survival rate of L. japonica, blade length of transplants and drag force of transplanting plates were also researched. The number of transplanting plates with surviving L. japonica, the survival rate and blade length of 20 cm long-initial transplants were greater than those of 1.5, 5 and 10 cm long-initial transplants in an outdoor aquarium. At the depth of 4 m in the coastal waters, the number of transplanting plates with surviving transplants, the survival rate and the blade length of 30 cm long-initial transplants were higher than those of 10 and 20 cm longinitial transplants. The drag force is calculated by cording up sporophytes of L. japonica into the transplanting plates under water. The drag force in the case of a 2.18 kg-weight transplanting plate and in a current speed of 0.5 m${\cdot}s^{-1}$ for considering stability of the plate was 631.50 g to a concrete substratum on the seabed, 703.92 g to a shingle substratum, 788.00 g to a sand substratum, and 1018.30 g to a silt substratum. If we consider the stability and economic efficiency of the transplanting plate, the proper weight of the plate per one individual of 18.11 cm in blade width and 190.20 cm in total blade length is regarded as 508.2 g when it is calculated with the concrete substratum that shows the lowest drag force.

• Korean Journal of Weed Science
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• v.10 no.4
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• pp.261-268
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• 1990

Various herbicides were applied to the young rice seedling from which endosperm were removed and their effects were determined at 40 days after transplanting. Generally, growth was retarded, but the number of tillers was not effected. Application of bensulfuron and pretilachlor showed slight growth inhibition compared to dimepiperate and pyrazolate. Injury due to herbicide application was dependent on the transplanting depth. Injury was severe when pretilachlor and pyrazolate were applied to rice transplanted 0 and 4cm deep, respectively. However, bensulfuron showed much injury regardless of transplanting depths with the tendency of general growth retardation. Dimepiperate was fairly safe at all transplanting depths. The application of herbicides at 3 and 6 DAT showed higher injury than that at g and 12 DAT. The degree of injury was severe when pretilachlor and bensulfuron were applied.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.662-668
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• 2016

No-tillage dry-seeding of rice can offer potential benefits by reducing time and labor cost compared with conventional tillage practices. This study was conducted to investigate the effects of no-tillage dry-seeding on rice growth and soil hardness in comparison with other rice cultivation methods, machine transplanting and wet-hill-seeding on puddled paddy. The seedling stand fell within optimum range for both no-till dry-seeding and wet-hill-seeding on puddled paddy. Plant height, number of tillers and SPAD values in no-tillage dry-seeding cultivation were higher than those observed in other methods. There were no significant differences in grain yield of rice among three cultivation methods. The quality characteristics of milled rice grown in no-tillage dry-seeding were similar to those grown in other cultivation methods. Soil hardness in top 10 cm depth was significantly higher in no-tillage dry-seeding than other cultivation methods, while soil hardness below 10 cm depth was highest in machine transplanting cultivation. Results indicate that no-tillage dry-seeding practice is comparable to conventional tillage system in terms of seedling establishment, growth, yield and grain quality.

• ALGAE
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• v.20 no.4
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• pp.379-388
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• 2005

Seagrass bed is an important component in coastal and estuarine ecosystems, providing food and shelter to a wide variety of fauna. Recently, seagrass coverage has declined significantly due to anthropogenic influences such as reclamation, dredging, and eutrophication and consequently, necessity of seagrass habitat restoration is rising. Transplantation experiments with Zostera marina using TERFS, staple method, and shell method have been conducted at Dadae Bay, Kosung Bay and Jindong Bay on the south coast of Korea to select an optimal transplanting method for restoration of Z. marina habitat. Three experimental sites located at the vicinity of natural Z. marina beds with an average water depth of about 4m. Z. marina plants, which were collected from donor bed in Koje Bay were also transplanted at 7 different time from October 2003 to July 2004 to find appropriate transplanting time. Density of Z. marina was monitored monthly at both transplanted areas and natural beds. Transplantation using the staple method showed the highest survival rate of transplant. Shell method was also an effective transplanting method at muddy areas in Kosung Bay and Jindong Bay, but not suitable at sandy areas in Dadae Bay. These results suggest that sediment composition of transplanting areas should be considered for the selection of the optimal transplanting method. Z. marina transplanted during fall usually showed the highest survival rate, while most Z. marina plants transplanted in summer died due to high lethal temperature during this period.

• Korean Journal of Weed Science
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• v.11 no.3
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• pp.174-177
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• 1991

This study was conducted to determine the influence of dithiopyr on growth of transplanted rice with different transplanting depths and the amount of $^{14}C$-dithiopyr adsorpted in the root and shoot of rice plants under paddy soil conditions. The growth rate of transplanted rice was lower in 0 and 0.25cm of transplanting depths with exposed basal stem than in 1 and 2cm of the depths in control plot. In the growth of transplanted rice treated with dithiopyr, plant hight and dry weight were significantly inhibited in 0 and 0.25cm depth plots but not affected.in 0.5, 1, 2 and 4cm depth plots, and roop length were influenced in 0, 0.25 and 4cm depth plots but not in 0.5, 1 and 2cm depth plots. The amount of ratioactivity in shoot and root of rice plants as affected by $^{14}C$-dithiopyr were the highest in 0 and 0.25cm depth plots and decreased in over 0.5cm depth plots. However the extent in amount of distributed radioactivity in the plants among the different transplanting depths was narrow gradually with the growth of plants. Therefore, injury of transplanted rice by dithiopyr is little in over 0.5cm transplanting depth with burried basal stem and the inhibition on rice plants with extreme shallow transplanting such as 0 and 0.25cm depths should be due to more adsorption of dithiopyr.

• Journal of Biosystems Engineering
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• v.35 no.1
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• pp.37-45
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• 2010

Since SRC (Short-term Rotation Coppice) such as poplar and willow can be harvested in three years, they are known to be a potential forest biomass as fuel for a power plant. The production system including transplanting and harvesting is, however, necessary to be mechanized because such a biomass should be handled in a massive volumetric size. A pull-type stem-cutting transplanter was developed in the research as the first step to realize the production of SRC. A needle-like transplanting device pushes a stem-cutting into the prepared soil bed by a pneumatic cylinder, and another device firms soil around a stem-cutting transplanted. Since this is an intermittent operation, it was necessary to develop a zero horizontal velocity mechanism which enabled only the transplanting needle part to continue a zero horizontal movement relative to the ground during the transplanting operation even when the tractor kept moving forward. The 2-row transplanter can transplant stem-cuttings at the rate of 6.5 seconds per row without missing a single attempt. The planting depth and distance were well maintained and controlled. Their CVs were between 2.1~3.4% and 0.87~1.7% for the depth and the distance, respectively. Although, the transplanted stem-cuttings tended to lean outward from the back-view and forward from the side view, they were planted within the range of $3^{\circ}$ from the upright position.