Weon-Young Choi

Characteristics of Vegetation on Soils Having Different Salinity in Recently Reclaimed Saemangeumin Region of Korea

This study was conducted to survey vegetation changes and soil characteristics in Saemangeum new reclaimed tidal land. Soil salinity in border area to tidal land was 22.3 dS but showed 1.1~3.44 dS over the distance of 2 km from border line. The vascular plants in survey sites were recorded as total 26 taxa in 6 families. The frequency of species appearance of Aster tripolium, A. subulatus var. sandwicensis were highest by 61.5 and that of Phragmites communis, Puccinellia nipponica were 53.8. The almost vegetations occurred in the patch which range of soil salinity 14 dS were halophytes as Salicornia europaea, Suaeda asparagoides, S. japonica. As lowed soil salinity as 6.7 dS , mixed vegetation of halophytes with P. communis, P. nipponica, Carex pumila were occurred. Dominant species in the range of 3.0 dS area were A. subulatus var. sandwicensis, P. communis, Echinochloa spp., Zoysia sinica and Conyza canadensis. Biomass production was the highest in the area of dominant vegetation with P. communis, and mixed zone with P. communis and Aeschynomene indica are followed. The correlation between vegetation biomass and soil salinity, soil pH and dominance index of vegetation were negative. But that of vegetation biomass and soil organic content were positive.

Study on Forage Cropping System Adapted to Soil Characteristics in Reclaimed Tidal Land

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 and Gyehwa region of Saemangum reclaimed tide land from October, 2009 to October, 2011. Whole crop barley (WCB), Rye, Italyan-ryegrass (IRG) as winter crops and Corn, Sorghumsudangrass hybrid (SSH) as summer crops were cultivated. Soil chemical properties, nutrient uptake, feed value, growth and yield were examinated. The testing soil was showed saline alkali soil where the contents of organic matter, available phosphate and exchangeable calcium were very low, while exchangeable sodium and magnesium were higher. Changes of soil salinity during the growing season of forage crops were less than 0.2%, and the growth of forage crops was not affected by salt injury. Standing rates of winter crops were higher in the order of Rye, WCB, and IRG, while the dry matter yield of winter crops was higher in the order of IRG, Rye and WCB. The highest crude protein (CP) content was recorded in IRG, and total digestive nutrients (TDN) contents were increased in the order of WCB, IRG, and Rye. The TDN content was higher in corn, whereas other feed value was higher in SSH. The content of mineral nutrients on stem, leaf and grain in IRG, Corn were high. After experiment pH was lowed, contents of exchangeable magnesium, sodium and organic matter were decreased while contents of total nitrogen, available phosphate and exchangeable potassium, calcium were increased. Winer crops and summer crops after continually cultivating in cropping system, fresh matter yield increased, compared to WCB-Corn (74,740 kg ), IRG-SSH 10%, IRG-Corn 7%, Rye-SSH 6%, Rye-Corn and WCB-SSH 3%. Dry matter yield increased, compared to WCB-Corn (20,280 kg ), IRG-SSH 7%, Rye-SSH 6%, IRG-Corn/Rye-Corn/WCB-SSH 3%. The TDN yield increased, compared to WCB-Corn (13,830 kg ), IRG-SSH 2%, WCB-SSH and IRG-Corn 1%. Therefore, we suggest that the crop combination of IRG-SSH and WCB-SSH would be preferred for silage stable production.

Change of Vegetation Characteristics and Soil Chemical Properties at Saemangeum Reclaimed Land in Korea

This study was conducted to investigate changes of vegetation and soil characteristics to tidal land of Saemangeum reclaimed land from 2010 to 2012. Soil salinity was 0.16-22.3 dS m -1 in the first survey, while the three years later, it was decreased to 0.12-4.22 dS m -1 . Vegetations were classified as 6 families and 26 species but it was increased to 8 families and 31 species after three years. Numbers of average species in survey site were increased from 7.1 species to 10.6 species. Numbers of vegetation were increased at each survey sites except for survey site 7 : there was decreased halophyte according to decrease in the soil salinity. Biomass production was increased at low production site, and showed highest production in area of dominant vegetation as Phragmites communis. Simpsons dominance ratio(SDR) of main vegetation as Phragmites communis, Calamagrostis epigeios were increased but Suaeda maritima, Salicornia europaea, Puccinellia nipponica and Zoysia sinica were decreased.

Optimum Salinity Concentration and Nitrogen Fertilization for Salicornia herbaecea Growth in Reclaimed Land

Now in Korea, halophytes such as Salicornia herbacea and Spergularia marina are being cultivated as new income crops in southwestern coastal regions. So basis studies on halophytes’ growth characteristics is needed for developing a standard cultural practices of them. This study was carried out to investigate on cultivation of Salicornia herbacea, representative halophytes at new reclaimed land. First, in order to examine the characteristics of Salicornia herbacea germination by salinity (NaCl concentration 0 ~ 3%), germination tests were carried out. At the low-temperature 10C, germination of Salicornia herbacea was slow but lasted for 15 days at all salinities, and final germination rates were of 78 ~ 90%. At higher than 20C, maximum germination rate was showed within four days. Germination inhibition by salt was showed at NaCl concentration 3% and 30C. The second, to investigate on the growth characteristics of Salicornia herbacea by nitrogen fertilization, port experiments were conducted at the greenhouse. Salicornia herbacea’s buds began to be found after five days after sowing. Salicornia herbacea growth such as plant height, number of braches, etc. increased with increasing nitrogen fertilization. In order to investigate the growth characteristics by salinities, cultivation test of Salicornia herbacea was conducted in nutriculture with different salinities. In the plot without NaCl, the growth of Salicornia herbacea was very low, and it began to wither within one month. In plots with NaCl, the growth of Salicornia herbacea was well until concentrations of NaCl 500mM, and optimum NaCl concentration was 200mM for growth of Salicornia herbacea. Field verification experiments about the effect of nitrogen fertilization on transplanted Salicornia herbacea were conducted at the Saemangeum reclaimed land in Korea. There was a tendency to increase number of branches and plant length with increasing nitrogen fertilization. Amount of P2O5 and mineral element such as CaO, Na2O, K2O and MgO tended to increase with increasing nitrogen fertilization. However, there was no statistically significant difference.

Effects of Nitrogen Fertilization Increment on Forage Crops Cultivation in Saemangum Reclaimed Land

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, . 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 sorghumsudangrass 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 sorghumsudangrass 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 and sorghumsudangrass by increment of nitrogen fertilization. Therefore, to improve the product and nutrient balance of reclaimed saline land comprehensive soil management should be considered.

Establishment on Fertilizer Recommendation and Soil Characteristics of Rice Paddy with Environment-friendly Cultivation

Environment-friendly agriculture (EFA) are aimed to reduce use of chemical inputs as possible the recycling of resources and the environment while preserving the local resources in the long term to ensure a constant productivity and profitability for producing safe food. This study was conducted to investigate characteristics on soil environment at paddy field of environment-friendly agriculture regions (EFARs) in Honam area. Survey point of EFARs Chungnam, Jeonbuk and Jeonnam, rice bran farming method in two districts, rice bran + snail farming method in eight districts, snail farming method in five districts and ducks farming method in three districts a total of 18 districts were selected. Annual of farming method, friendly-environment certification, amount of applied fertilizer, and history of cultivation to the farm household were surveyed. The content of available phosphate and silicate among the soil chemical properties in EFA paddy field were a little lower than optimum level, and those of agricultural methods fertilized with rice bran were a little lower than those of others. Hardness among the soil physical properties in EFA paddy field were a little lower than conventional practices, and that of agricultural methods fertilized with rice bran were a little lower than those of others. We showed fertilizer recommendation dose about soil nutritional shortages according to fertilization prescriptions index by crops.

Effect of Sesbania Incorporation as Nitrogen Source on Growth and Yield of Whole Crop Barley and Reduction of N Fertilizer in Saemangeum Reclaimed Tidal Land

It is known that the poor soil fertility of newly reclaimed saline soils is due to the lack of organic matter and available mineral nutrients for crop production. The effect of green manuring with Sesbania aculeata in combination with five rates of urea-N treatments (N0. N25, N50, N75, N100) on the productivity of a subsequent whole-crop barley and the fertility of the reclaimed saline soil in Saemangeum was evaluated in the field during 2013-2014 growing season. Sesbania was grown during summer season (June to October). The amount of Sesbania incorporated was 16.2 Mg ha -1 . Sesbania contributed to 393 kg N ha -1 to the soils when ploughed down and incorporated before whole-crop barley cultivated. The performances of whole-crop barley following sesbania incorporation were significantly affected by a combination of Sesbania manuring and different N rates. The N fertilizer equivalence without N fertilizer following Sesbania was 42.6% (63.9 kgN ha -1 ), compared with N100(150 kg N ha -1 ) in fallow soils. The whole-crop barley yield responded to N fertilizer rates in both sesbaniaamended and fallow soil. The yield response to nitrogen rates in fallow soil was linear (Y=0.0586X+3.3011, R 2 =0.9534), whereas that in sesbania-amended soils was quadratic (Y= -0.001X 2 +0.1322X+5.7143, R 2 =0.9576). The yield of whole-crop barley in sesbania-amended with increasing N rates was increased up to SN75 (115 kgN) 10.3 Mg ha -1 . Apparent N recovery (ANR) of whole-crop barely showed decreased with sesbania plus increasing rates of N fertilizer. Despite higher yield with sesbania manuring plus increasing N rates, the contributions of N from Sesbania with increasing N rates to whole-crop barley were decreased, whereas those from fertilizer increment due to excessively mineralized Nitrogen. Considering yield, ANR, N contribution from Sesbania and nitrogen fertilizer, the optimum N rate was N50 rate following sesbania incorporation.

Nitrogen Fertilization on the Growth of Rape (Brassica napus L.) in Newly Reclaimed Land in Korea

This study was conducted to find out the optimum nitrogen application rate for the stable production of rape in the newly reclaimed land located at Gangwhal region of Saemangum reclaimed land in which the soil is sandy loam (Munpo series). There were five treatments of nitrogen fertilization from zero to 60% increment based on the standard fertilization of . The growth of rape (Sunmang) was not affected by salt content while soil salinity was increased at blossoming season of rape. Compared to yield of standard fertilization the yield and the content of oleic acid of rape were increased by 4~26% with the increasing additional nitrogen fertilizer. The results obtained from the growth and yield of rape in this study indicated that it was possible to cultivate rape in a newly reclaimed land if soil salinity was kept below .