• Journal of Wetlands Research
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• v.11 no.1
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• pp.105-113
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• 2009

Heat energy exchange is very important processes in the coastal wetland ecosystems. We observed and analyzed the net radiation flux, the sensible heat flux, the latent heat flux and the soil heat flux, which are balanced in the heat energy balance, over a reclaimed land covered with reeds at Goheung, Jeonllanamdo where is horizontally plane. The atmospheric turbulence had been measured in order to estimate the heat transfer during 5 intensive observation periods (IOPs). It was considered that the soil consists of water, fine particles, and vegetation canopy that changes color and density according to the season. We examined the characteristics of the heat flux and the vegetation effect on the air temperature control. It was noted that the heat was transported mainly by latent heat flux in the summer season and the vegetation canopy decreased the daily temperature range due to the heat storage. The air temperature was lower at the IOPs site than near urban area. This showed that the coastal wetland covered with the vegetation control the thermal environment.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.955-960
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• 2012

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. The salinity significantly affects efficiency of N fertilizer in reclaimed tidal soil, and the soil pH may influence the conversion rate of ammonium to nitrate and ultimately affect nitrogen losses from the soil profile. Several results suggest that pH has important effects on recovery of fall-applied N in the spring if field conditions are favorable for leaching and denitrification except that effects of soil pH are not serious under unfavorable conditions for N loss by these mechanisms. Soil pH, therefore, deserves attention as an important factor in the newly reclaimed tidal soils with applying N. However, fate of N studies in a newly reclaimed tidal soils have been rarely studied, especially under the conditions of saline-sodic and high pH. Therefore, understanding the fate of nitrogen species transformed from urea treated into the reclaimed tidal soil is important for nutrient management and environmental quality. In this article, we reviewed yields of rice and fate of nitrogen with respect to the properties of reclaimed tidal soils.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.235-240
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• 2012

This study was conducted to find out the optimum cropping system for the stable production of forage crops in the newly reclaimed land located at Gwanghwal region of Saemangum reclaimed land in which the soil is sandy loam (Munpo series). There were two treatments of nitrogen fertilization 20% increment based on the standard fertilization of 150, $200kg\;ha^{-1}$. Whole crop barley as the winter crop sowed on 27 October. After the whole crop barley was harvested at the end of May. Corn and sorghum${\times}$sudangrass as the summer crop sowed at the early of June successively on the same field. Emergence rate the whole crop barley was high while the summer crops were low. Soil salinity was increased during cultivation of summer crops. However, corn and sorghum${\times}$sudangrass were not damaged by salt. Increase of nitrogen fertilization made the growth of cultivation crops good, stem and leaf tended to have a lot of the mineral nutrients at heading stage and silking stage. After experiment, among soil chemical properties pH, content of exchangeable sodium were decreased and content of organic matter, available phosphate were increased. Dry matter yield were showed whole crop barley $13,170kg\;ha^{-1}$ and sorghum${\times}$sudangrass $19,440kg\;ha^{-1}$ by increment of nitrogen fertilization. Therefore, to improve the product and nutrient balance of reclaimed saline land comprehensive soil management should be considered.

• Journal of Bio-Environment Control
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• v.24 no.4
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• pp.275-280
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• 2015

The objective of this study was to investigate the effect of drip irrigation level on soil salinity and growth of broccoli (Brassica oleracea L. var. italica) at the 'Saemangeum Reclaimed Tidal Land' from April to June, 2015. Drip irrigation was conducted at 1.5, 3.0 and $6.0mm{\cdot}day^{-1}$ level for reduction of resalinization in the plastic vinyl house using 10cm spacing drip irrigation tape. At harvesting stage, the average EC of surface soil was $10.9dS{\cdot}m^{-1}$ for $1.5mm{\cdot}day^{-1}$, $11.5dS{\cdot}m^{-1}$ for $3.0mm{\cdot}day^{-1}$ and $5.1dS{\cdot}m^{-1}$ for $6.0mm{\cdot}day^{-1}$ and was significantly reduced by 52~56% in $6.0mm{\cdot}day^{-1}$ treated plot compared to those in 1.5 and $3.0mm{\cdot}day^{-1}$ plots. The fresh bud weights of 1.5, 3.0 and $6.0mm{\cdot}day^{-1}$ treatment plots were 60.9, 129.1 and $371.3g{\cdot}plant^{-1}$, respectively. The estimated soil EC for 50% yield reduction was $7.6dS{\cdot}m^{-1}$ and the desalinization depth by drip irrigation was 30~40cm in soil profile. The total amount of drip irrigation water was estimated to be 422mm and the daily drip irrigation level was $6.0mm{\cdot}day^{-1}$ for the prevention of resalinization during the broccoli growing period at the 'Saemangeum Reclaimed Tidal Land'. Our results suggested that drip irrigation shows effectiveness on the lowering the soil salinity according to the drip irrigation quantity but it needs more research on this study because dynamics of salts in soil can vary with many factors such as soil physico-chemical properties and seasonal climate.

• Korean Journal of Environmental Agriculture
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• v.28 no.1
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• pp.25-31
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• 2009

The effect of application of gypsum (G), popped rice hulls (PRH), and zeolite (Z) in exchangeable cations concentrations of reclaimed tideland soil in Kyehwado was investigated for 3 years from 2004 to 2006 in a pot experiment with bermuda grass (Cynodon dactylon). Treatments with three soil conditioner and with three applications were established with three replications; G1 (1,550 kg $10a^{-1}$), G2 (3,100), and G3 (6,200) for gypsum, H1 (1,000), H2 (2,000), and H3 (3,000) for PRH, and HZ1 (200), HZ2 (400), and HZ3 (800) for co-application of zeolite with PRH at the 1,500 kg $10a^{-1}$. At 60, 90, 120 days after treatment (DAT), exchangeable cations ($K^+$, $Na^+$, $Mg^{2+}$, and $Ca^{2+}$) were analyzed Gypsum application significantly decreased $k^+$, $Na^+$, $Mg^{2+}$ in the soil probably due to exchange and subsequent leaching of these cations by $Ca^{2+}$ from the gypsum applied. Overall, $K^+$ concentration was gradually decreased by continuous application of soil conditioners and was in the order of 2004>2005>2006 regardless of the kinds and application rate of soil conditioners. Comparing $K^+$ concentrations among the soil conditioners in the same year, its concentration was in the order of gypsum$Na^+$ concentration; i.e. $Na^+$ concentration was in the order of gypsum$\ll$PRH$Mg^{2+}$ also showed a similar pattern to $Na^+$. Gypsum application significantly increased $Ca^{2+}$ concentration and in the gypsum treated soil $Ca^{2+}$ concentration increased with years.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.2
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• pp.204-207
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• 2007

This study was conducted to suggest proper water management practices after and before broadcasting of rice seed on flooded paddy surface at reclaimed saline soil with two different saline levels in Gyehwado Substation of Honam Agricultural Research Institute (HARI) NICS, RDA for two years from 2004 to 2005. The stable seedling stand in low saline soil of 0.1% salinity was obtained by one time of water exchange after soil rotary Whereas in medium saline soilof 0.3% salinity, three times of water exchange was required for the stable seedling stand. Milled rice yield was not affected by frequency of water exchange in low saline soil, while it decreased sharply in one and two times of water exchange compared with three times of water exchange in medium saline soil. Irrigation water immediately after direct seeding increased the number of seeding stand in low saline soil. With the increase in the interval of water exchange after direct seeding, the milled rice yield decreased. Although the continuous water flowing showed the most number of seedling stand and was increased milled rice yield compared with the others interval of water exchange in medium saline soil, the number of seedling stand and milled rice wasn't significantly different up to exchange of two days interval compared with the continuous water flowing.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.3
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• pp.269-274
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• 1987

A laboratory experiment was conducted to find out the effect of inoculation with plant growth of associative $N_2$-fixing bacteria on the combination of eight different rice seedling with seven different associative $N_2$-fixing bacteria in which were isolated and identified from grasses and rice in saline and reclaimed saline paddy soil. Those were examined in N-free axenic culture medium. The result of this experiment exemplified the contribution of associative $N_2$-fixing bacteria to their host plant were varied much by the combination of rice cultivars and bacterial strains. Acetylene reduction ($N_2$-fixation) activity seems to be more variable with respect to the combination of rice cultivars and bacterial strains. The relationship between acetylene reduction activity and rice performance such as dry matter weight, plant height, root length, and number of root were statistically insignificant. However, in comparision with the control, the dry matter yield of Annapuruna was increased by inoculation of all the seven bacteria strains. Among the seven rice cultivars, the average acetylene reducing activity was the highest in Annapuruna, and Shingwang, and the lowest in IR-8 inoculated with Pseudomonas sp H8. Among the seven bacterial strains the highest acetylene reducing activity was obtained by the combination of Shingwang with Pseudomonas sp H8.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.3
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• pp.305-309
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• 1983

To know the effect of desaltation in the reclaimed tidal fields on the succession of vegetation and on the root hair formation of paddy rice, reclaimed fields in Kang Hwa Island, Nam-Yang Bay and Ke-Hwa Island were investigated during summer crop season in 1982. The obtained results can be summarized as followings. l) In the highly salty and water logged areas of reclaimed tidal fields, the first dominating species of higher plant were observed to be Salicornia herbacea L. and Suaeda japonica Makino. With the continued desaltation, Chemopodium virgatum Thumb. occurred in the vegetation. After this transition, the dominating species were composed of Scirpus maitimus L. and Phragmites communis Trin. At the S. maitimus and P. communis dominating salinity level, rice cultivation was safe from the salt damage. 2) In the water logged area, Artemisia capillaria Thunb. and Aster tripolium L. took the place of dominating species after S. herbacea and S. japonica. At this salinity level, graminaceous weeds began to immigrate. 3) In dry areas, Suaeda asparagoides Makino and Suaeda maritima were the first appearing dominant species. Atriplex subcordata Kitakawa was also observed in sucy dry areas, but colony formation was not observed. 4) Plants immigrated slowly into dry areas from the already vegetated water logged areas with the continuation of desaltation. 5) The high soil salinity level affected the root hair formation of rice by reducing both the rate of root hair formation and the length of root hairs.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.79-82
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• 2003

This study was performed in order to analyze the changes of electrical conductivity during the growing period in Saemangum reclaimed tidal lands soils. According to USDA Salinity Laboratory classification system of salt affected soils, the reclaimed tidal land soils used in this study were saline-sodic soils. As the results obtained from analying the changes of electrical conductivity(EC) during the growing period in reclaimed tidal land soils, EC of irrigation water and soils were no difference among the fertilization quanity, fertilization method and fertilization times.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.54-65
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• 2000

This study was performed to analyze the changes of electrical conductivity with increasement of water requirements for desalinization in reclaimed tidelands and to obtain the basic data for developing prediction techniques of desalinization to be applicable in the beginning of tideland reclamation. Two different desalinization experiments were conducted through the leaching method by subsurface drainage and the rinsing method by surface darainage, using the samples of silt soil and silt loam soil collected in 5 units of tideland reclamation projects. Regression equations were obtained in order to investigate the changes of electrical conductivity during the desalinization of reclaimed tidelands and to estimate water requirements for desalinization.