• 한국토양비료학회지
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• 제44권1호
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• pp.48-52
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• 2011

The effect of soil water content on the transformation potential of N compounds derived from hydrolysis of urea applied in a reclaimed tidal soils which was saline-sodic was observed to evaluate nitrification rates of urea. Soil samples were collected from Moonpo series at the newly reclaimed area in Saemanguem. For the transformation potential of N compounds from urea (46% N), newly reclaimed tidal soils (RS) were amended with urea at the rates of 0, 10, and 20 kg $10a^{-1}$. With leachate obtained from the incubated RS in a leaching tube at $25^{\circ}C$, urea hydrolysis and nitrification were measured for a total of 30days. The cumulative amounts of $NO_3{^-}$-N in each of the four soils treated with urea was linear with time of incubation. Results showed that increase in pH occurred with increasing application rate of urea and volumetric water content due to hydrolysis of urea. The total N in the RS was decreased with incubation time, indicating that rates of urea hydrolysis was influenced by soil moisture conditions. Also, the cumulative amount of nitrate in RS gradually increased with increase in time of incubation.

• 한국토양비료학회지
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• 제44권5호
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• pp.745-751
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• 2011

In most agricultural soils, ammonium ($NH_4^+$) from fertilizer is quickly converted to nitrate ($NO_3^-$) by the process of nitrification which is crucial to the efficiency of N fertilizers and their impact on the environment. However, nitrification studies have been studied extensively in agricultural soils, not in a newly reclaimed tidal soil which show saline-sodic and high pH. Therefore, understanding the fate of nitrogen species transformed from urea introduced into reclaimed tidal soil is important for nutrient management and environmental quality. This paper reviewed studies regarding to transformation and fate of nitrogen sources such as urea under the circumstances of a reclaimed tidal soils located in a western coastal area.

• 한국토양비료학회지
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• 제47권4호
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• pp.254-261
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• 2014

The scientific information between microbial activities and chemical properties of reclaimed tidal soil is not enough to apply for reclamation projects. This study was conducted to investigate the relation between chemical properties and microbial activities of reclaimed tidal lands located at western coastal area (25 samples from Nampo, Ewon, Sukmoon and Shihwa sites). Most of the reclaimed soils showed chemical characteristics as salinity soil except Nampo site. The major component influenced the salinity of reclaimed soil was identified as a sodium from the relationship between EC and exchangeable cation. With an increase in EC of soil, the population of mesophilic bacteria decreases whereas halotolerant and halophilic bacteria increases. The population of mesophilic bacteria increased with an increase in both organic matter and dehydrogenase activity. However, the population of halotolerant and halophilic bacteria decreased with an increase in organic matter. Based on the relation between chemical property and microbial activity of reclaimed tidal soil, electrical conductivity and organic matter as chemical properties of soil, population of mesophilic bacteria, halotolerant and halophilic bacteria and dehydrogenase activity as microbial activities could be the major parameters for reclamation process.

• 한국토양비료학회지
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• 제48권4호
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• pp.262-270
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• 2015

The scientific information between microbial community and chemical properties of reclaimed tidal soil is not enough to understand the land reclamation process. This study was conducted to investigate the relation between chemical properties and microbial activities of soils from reclaimed tidal lands located at south-western coastal area (42 samples from Goheuong, Samsan, Bojun, Kunnae, Hwaong and Yeongsangang sites). Most of the reclaimed soils showed chemical characteristics as salinity soil based on EC. Only $Na^+$ in exchangeable cation was dependent on EC of reclaimed soil, whereas other cations such as $K^+$, $Ca^{2+}$, and $Mg^{2+}$ were independent on EC. The mesophilic bacteria decreased with an increase in EC of soil. Microbial population increased with soil organic content in the range of $0{\sim}10g\;kg^{-1}$ and dehydrogenase activity less than $100{\mu}g-TPF\;g^{-1}h^{-1}$. Microbial population of soils from reclaimed tidal lands was closely related to the microbial community containing hydrolytic enzyme activities of cellulase, amylase, protease, and lipase.

• 한국초지조사료학회지
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• 제10권2호
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• pp.77-83
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• 1990

A three year's field experiment was carried out on newly reclaimed tidal saline soils to evaluate the salt tolerance and growht characteristics, and their relationship to dry matter production and nutrient quality of main selected pasture species. Nine temperate grasses (14 varieties) and two forage crops (sorghum and pearl millet) were grown under different mulching treatments with medium sand and red-yellow soils (fine loamy materials of Typic Hapludults) from 1986 to 1988. Tall wheatgrass, tall fescue, reed canarygrass and alfalfa showed a good tolerance to soil salinity, especially tall wheatgrass (cv. Alkar) produced 19.6 ton/ha dry matter yield annualy under mulching treatment with medium sand depth in lcm. Pearl millet (cv. Gahi-3) was also evaluated as a salt tolerable forage species. Under salt stress in newly reclaimed tidal lands, plant showed a decrease in the assimirable leaf area (LA) as well as specific leaf area (SP. LA) and a low leaf weight ratio(LWR), and it resulted in a low concentration of crude protein and low digestible dry matter contents. Absorption of macro and micro elements in the plant on tidal lands was increased markedly.

• 한국토양비료학회지
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• 제45권6호
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• pp.1222-1229
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• 2012

간척지토양은 일반적으로 매우 높은 염농도를 가지고 있으며 염고농도의 염 특히, 높은 $Na^+$ 농도는 점토의 분산을 일으키고 토양의 공극을 감소시켜 토양의 공기와 수분의 유통을 악화시키고 고농도의 염은 생리적가뭄(physiological drought)의 한 가지 형태인 낮은 수분퍼텐셜을 발생시켜서 수분과 양분의 흡수를 어렵게 한다. 따라서 간척지를 효율적으로 활용하기 위해서는 간척지 토양에 대한 제염이 선행되어야 한다. 이러한 제염 효과를 증진시키기 위해서는 상기에서 살펴본 바와 같이 물리성 개선을 통하여 토양의 화학성을 개선시켜야 한다. 본 조사를 기준으로한 간척지토양 개선은 물리성 중 물질의 이동을 용이하게 하는 심층토 내 토양압밀층 개선이 우선되어야 할 것으로 판단한다. 그리고 높은 지하수위에 의한 모세관상승에 동반한 재염화를 방지하기 위한 토양관리방안이 필요하다. 따라서 최종적으로 간척지의 효과적 재염 (Resalization)방지와 제염(Desalinazation) 방안에 대한 토질역학적 측면에서 연구가 추진되어야 한다.

• 한국토양비료학회지
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• 제46권2호
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• pp.129-135
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• 2013

This study was conducted to investigate the soil characteristics of newly reclaimed tidal land and the effect of green manure crops on soil properties. Summer green manure crops such as sesbania (Sesbania grandiflora), barnyard grass (Echinochloa spp.) and sorghum${\times}$sudangrass hybrid (Sorghum bicolor L.) were cultivated at Hwaong, Ewon, Saemangeum and Yongsangang area. Soil pH of reclaimed tidal land was relatively high, but organic matter and available phosphorus contents were lower compared to the optimum range for common upland crops. Soil nutrient contents were unbalanced for upland crop growth. Yield of green manure crops had a wide spatial variation. Nitrogen content in green manure crops was the greater in Sesbania and it was estimated that major nutrient ($N-P_2O_5-K_2O$) supply amount were 150-40-370, 220-50-170 and 140-50-250 $kg\;ha^{-1}$ from sorghum${\times}$sudangrass hybrid, sesbania and barnyard grass, respectively. Based on these results, desalination is required to grow the upland crops at newly reclaimed tidal lands and management practices are necessary to reduce the salt damage by resalinization during the growing seasons. To improve the productivity and increase the nutrient utilization rate, soil physicochemical properties need to be improved to the level for upland crops by application of organic matter and fertilizer.

• 미생물학회지
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• 제8권1호
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• pp.13-20
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• 1970

Chenges in respiration of the soils collected from the reclaimed tidal soil in Chogi-ri, Kanghwa Island and treated with organic matters are presented. The measurement of the respiration for the smaples, which were incubated for 0,2,4 and 5 weeks, were carried out by using Warburg's respirometer. While the respirations of the samples added by organic matters were increased 6.7 - 28.0 times compared with that 0 week during the incubation in case of 5-year soil, the respiration in case of 3-year soil were increased 3.3-11.8 times. Thus, the effect of adding organic matters on the respiration of the experimented soils, as this indicates, was much higher for the soil of 5-year area than that of 30-year area. And for the organic matters Salicornia was most effective and then Suaeda and Oryzae. The samples treated with Salicornia and Suaeda showed their highest respiration rate at the 4th week, but the one with Oryzae was measured to increase progressively during 5 weeks experimented. Regarding the salinity, content of organic matters and number of bacteria, in each intact soil experimented, 5-year soil samples had much poor habitat then 30-year soil for the activity of soil microorganisms, but according to the result mentioned above, it is firmly believed that the addition of organic matters on the saline soil is one of the best means to change the reclaimed tidal land into arable land with less time duration.

• 한국관개배수논문집
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• 제18권1호
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• pp.4-17
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• 2011

The standard design methodology was suggested to construct wetland system for reducing non-point source pollution from Saemangeum reclaimed paddy land. To set for the design flow and concentrations, runoff and water quality survey were conducted during the irrigation period in 2008 at Gyehwa reclaimed paddy land located at near Saemangeum lake. It is rational that 1ha is the optimum constructed wetland size. To meet this size, the moderate drainage area of reclaimed paddy field was 50ha under the conditions that rainfall is 30mm, average runoff coefficient is 0.83, and runoff capture ratio is 0.6. At these condition, the runoff volume from 50ha was 10,520 $m^3/d$ including base flow during irrigation period. To select the optimum wetland system, several case studies were conducted by focusing on the tidal reclaimed land areas having wetland systems in Seokmun. Pond-Wetland system was selected as the standard model because of showing the highest reduction efficiency. Single variable regression equation were delivered to estimate effluent water concentrations from the designed wetland by using long-term monitoring data from the Seokmun experiment site. The effluent concentration from the designed wetland using these equation were showed moderately range.

• 농업과학연구
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• 제27권2호
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• pp.141-157
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• 2000

This study is aimed at identifying the socio-economic value of the total area of 23,500ha of paddy field which will be reclaimed in year 2003. In Korea, tidal land reclamation projects has been carried out not only for paddy field expansion to meet national food security but also for national land expansion to cope with the shortage of land supply in implementing urbanization and industrialization. As of end of 1999, 75,738ha of tidal land reclamation, 48.3%, out of 156,666ha has been carried out in Korea. In spite of continuous implementation of tidal land reclamation, 48.3%, out of 156,666ha has been carried out in Korea. In spite of continuous implementation of tidal land reclamation projects, the appraisal of the national land expansion value has not been made even though the severe competitiveness of land use in economic development. Agricultural land about 20,000 - 30,000ha per year has been converted to urban and industrial land and the converted areas have been produced higher added value than that of the farm land. Accordingly, farm land expansion equivalent to the converted area have to be reclaimed to cope with the food shortage and security in the future. In relation to the study, demand and supply of rice, the staple food of Korean, has been projected up to year 2025. The study results are as follows: 1. Under the assumption of continuing the present tendencies of rice consumption, population increase, farming practices and farm land conversion, paddy area requirement to meet self sufficiency of rice were forecasted as 136,950ha in 2015, 193,460ha in 2020 and 218,482ha in 2025 respectively. 2. The average converted price of paddy per pyeong in Kimje city, Puna Gun and Gunsan city was estimated at 241,150won and average farm land price was amounted to 63,760won. The differential rent was estimated at 177,400won per pyeong which was used as a criteria for valuation of national land expansion effect of the tidal land reclaimed by Saemangeum project. The total land rent of 23,250ha expanded by tidal land reclamation was amounted to 12,361 billion won. Annual expected value of the expanded national land was estimated at 988.9 billion won considering 8% of annual discount rate in Korea. 3. Tidal land resource for paddy area development is limited comparing with the future requirement of paddy area to cope with self sufficiency of rice consumption. Accordingly farm land conversion to urban and industrial land should be regulated and protected in the sense of sustainable development in the future.