Yeong-Sang Jung

Suitability Classes for Italian Ryegrass (Lolium multiflorum Lam.) Using Soil and Climate Digital Database in Gangwon Province

As a part of establishing suitability classification for forage production, use of the national soil and climate database was attempted for Italian ryegrass (Lolium multiflorum Lam., IRG) in Gangwon Province. The soil data base were from Heugtoram of the National Academy of Agricultural Science, and the climate data base were from the National Center for Agro-Meteorology, respectively. Soil physical properties including soil texture, drainage, slope available depth and surface rock contents, and soil chemical properties including soil acidity and salinity, organic matter content were selected as soil factors. The crieria and weighting factors of these elements were scored. Climate factors including average daily minimum temperature, average temperature from March to May, the number of days of which average temperature was higher than 5 from September to December, the number of days of precipitation and its amount from October to May of the following year were selected, and criteria and weighting factors were scored. The electronic maps were developed with these scores using the national data base of soil and climate. Based on soil scores, the area of Goseong, Sogcho, Gangreung, and Samcheog in east coastal region with gentle slope were classified as the possible and/or the proper area for IRG cultivation in Gangwon Province. The lands with gentle or moderate slope of Cheolwon, Yanggu, Chuncheon, Hweongseong, Pyungchang and Jeongsun in west side slope of Taebaeg mountains were classified as the possible and/or proper area as well. Based on climate score, the east coastal area of Goseong, Sogcho, Yangyang, Gangreung and Samcheog could be classified as the possible or proper area. Most area located on west side of the Taebaeg mountains were classified as not suitable for IRG production. In scattered area in Chuncheon and Weonju, where the scores exceeded 60, the IRG cultivation should be carefully

Turfgrass Revegetation on Amended Sea Sand Dredged from the Yellow Sea

Abstract A field experiment was conducted to determine the optimal method for turfgrass revegetation at the new Incheon International Airport, Republic of Korea. The existing soil base was reclaimed sea sand dredged from the Yellow Sea. Ten different soil media main plots were created by treating the sand with combinations of mountain soil, chemical fertilizer [15–11–14 nitrogen–phosphorus–potassium (N–P–K)], peat moss, a wetting agent, pig manure, and composted pine bark. Subplots were established with five turfgrass treatments that included Zoysia japonica (ZJ), Z. sinica (ZS), Z. koreanna (ZK), cool‐season grass combination I (CSG I: Festuca arundinacea 30%, Poa pratensis 40%, and Lolium perenne 30%), and cool‐season grass combination II (CSG II: Festuca arundinacea 40%, L. perenne 20%, F. rubra 20%, and Puccinellia distans 20%). The highest percentage cover rate for all grass treatments occurred in sea sand treated with 5 cm of mountain soil plus 114 g m−2 of chemical fertilizer. Zoysia japonica had the highest percentage cover rates throughout the study. On 4 July 1998, the turfgrass cover ranking was ZJ (99.5% cover)>ZK (86.7%)>ZS (39.6%)>CSG II (33.3%), CSG I (33.1%). Zoysia japonica also showed the highest drought tolerance among turfgrass species on all soil bases. The treatment that included mountain soil plus chemical fertilizer reduced the pH, EC, alkalinity, and soluble sodium (Na+) by the exchange of calcium (Ca2+) for Na+. The amendment of sea sand with mountain soil and chemical fertilizer, followed by establishment to ZJ, was determined to be the best method of reclamation for the new airport.

SELECTION PROCEDURE FOR TURFGRASS IN NEW INCHEON INTERNATIONAL AIRPORT

The back-filled soil of the New Incheon International Airport in South Korea construction site was reclaimed with sea sand from the bottom of the sea and with sludge from along the bank of an inlet near Yongjong Island. The objective of this study was to investigate soil change to improve the soil properties where plant growth was limited by salts. The experiment was carried out from August 1993 to June 1997 to restore soil bases (SL, a base constructed using dredged sludge along the bank of an inlet; SD, a base constructed using dredged sea sand at the bottom of the sea; SDC, a base constructed using dredged sea sand at the bottom of the sea with 2 ton ha−1 calcium hydroxide; SDCD, a based constructed using dredged sea sand at the bottom of the sea with 2 ton ha−1 calcium hydroxide and with an established closed drainage system at 30 cm depth) and to select salt tolerance turfgrass species (Puccinella distans; Zoysia sinica; Zoysia japonica; CSG I, a combination of cool season grasses I with Festuca arundinacea 50% + Lolium perenne 30% + Agrotis alba 20% by weight; CSG II, a combination of cool season grasses II with Festuca arundinacea 50% + Festuca rubra 50% by weight) for a low maintenance area that included most of the open space of the airport site. In our study, soil salinity did not significantly affect the growth of turfgrass without irrigation in the dry season over the five years. The salinity decreased under 1 dS m−1 in 70 days on bases SD, SDC, and SDCD only with rainfall. Zoysia sinica and Zoysia japonica had a higher turfgrass coverage than Puccinella distans, CSG I and CSG II.

Decision of Available Soil Depth Based on Physical and Hydraulic Properties of Soils for Landscape Vegetation in Incheon International Airport

Decision of available soil depth based on soil physical and hydraulic properties for the 3 rd Landscape Vegetation Project in the Incheon International Airport was attempted. The soil samples were collected from the 8 sites at different depths, 0-20 and 20-60cm, for the three project fields, A, B, and C area. Physical and chemical properties including particle size distribution, organic matter content and electrical conductivity were analyzed. Hydrological properties including bulk density and water holding capacity at different water potential, -6 kPa, -10 kPa, -33 kPa, and -1500 kPa were calculated by SPAW model of Saxton and Rawls (2006), and air entry value was calculated by Campbell model (1985). Based on physical and hydrological limitation, feasibility and design criteria of soil depth for vegetation and landfill were recommended. Since the soil salinity of the soil in area A area was 19.18 dS m -1 in top soil and 22.27 dS m -1 in deep soil, respectively, landscape vegetation without amendment would not be possible on this area. Available soil depth required for vegetation was 2.51 m that would secure root zone water holding capacity, capillary fringe, and porosity. Available soil depth required for landscape vegetation of the B area soil was 1.51 m including capillary fringe 0.14 m and available depth for 10% porosity 1.35 m. The soils in this area were feasible for landscape vegetation. The soil in area C was feasible for bottom fill purpose only due to low water holding capacity.