There is a difference between ST and WRB in distinguishing the master horizon. When a pedologists investigate a soil profile, it is difficult to determine which classification method to choose including the master horizon, add a prefix, suffix, etc. to the horizon name. The suffix symbol for groundwater level uses 'g' for ST and 'l' or 'r' for WRB. The suffix symbol 'r' represents a strong reduction state, and 'l' is used in a state where oxidation is much progressed. However, in the real agricultural field, the groundwater level is lowered so that the oxidized part of the profile is classified based on < 2%, 2 -20%, > 20%. In addition, there are soils with a mottle quantity of 20 to 49%. ST classifies this as one like 'g', and WRB distinguishes it. However, since only the presence of a mottle is determined, a refinement is required.

No abstract

The soil which was confirmed by using auger with intervals of 200 m at a depth of 1 m in Agricultural tide land Section 5 had a somewhat poorly drainage and coarse loamy. The Gwangpo series has coarse loamy texture with a somewhat poorly drainage in Fluvio-marine plains, but confirmed soil had different characteristics with the Gwangpo series Our objective of in this study was to set a new soil series by comparing to the Gwangpo series. Both the Gwangpo and A-Gwangpo serieses showed the similar horizons (A, B and C horizons), texture (coarse loamy), and chemical properties. A somewhat poorly drainage in general Gwangpo series caused mainly grayish color and 2 -20% of the mottle's distribution (by oxidation) within 20 -50 cm depth. An our soils, the mottle's distribution was investigated by 2 -20% and 20 -49% in the Gwangpo and A-Gwangpo series, respectively. Gwangpo series is somewhat poorly drained and has a small amount of mottle (by oxidation) quantity, so it is used as a paddy field. But the A-Gwangpo series is estimated that it can be used as a field soil with an amount of 20 -49% of mottle (by oxidation) quantity.

Morphological characteristics provide a variety of important information for soils. Drainage class is also deternmined by the morphological characteristics such as soil color, which indicates the redox state of the soil. Soil color is usually measured with the Munsell color chart, which may not allow perfect conformity of results between surveyers. Quantitative approach, therefore, became more important to determine drainage class. In the quantification of the drainage class, we suggetsted following three factors as key points:ⅰ) earth color (hue, value, chroma), color due to rocks, and color due to redox are important factors, ⅱ) If there is a main color and mottles (color by reduction), the amount and degree of color by redox are important, ⅲ) When there is a groundwater level, the depth and the amount of the mottles (color by oxidation) are important determinants. Furthermore, not only the drainage class but also other characteristics should be quantified to create an Korean own classification system suitable for the characteristics of Korea.

Lay flat sprinkler hoses are widely use in S. Korea due to its reasonable price and flexibility. However, it applies a lot of water for a short time in a field that potentially causing unbalanced irrigation. In addition, there have been not many studies on characteristics such as irrigation uniformity. In this regards, the purpose of this study was to provide fundamental data for the design and operation of lay flat sprinkler by evaluating the irrigation uniformity and the watering pattern according to the change of water pressure. The most important characteristics for the uniformity were a pattern, number, and diameter of the holes on the lay flat sprinkler hoses. The amount of irrigation was different up to 2.3 times under the same (or about same) water pressure. Statistical uniformity (CV) of the sprinkler hose A, B, C showed good to fair, good, and fair respectively. Emission uniformity (EU) of the sprinkler hose A, B, and C classified good, excellent to good, and fair individually. The results of this study would be useful for proper water management by providing fundamental data such as water pressure level, spacing, and water management when installing lay flat sprinkler hoses in crop cultivating sites.