Saturday, 15 July 2006

Influences of Soil Types and Slope Gradients for Nutrient Loss and Soil Erosion in Korean Highland.

Cholsoo Park, Gye-Jun Lee, Jeong-Tae Lee, Yong-Seon Zhang, and Yong-Ik Jin. National Institute of Highland Agriculture, RDA, Hoeng-gye, Doam, Pyeongchang, Gangweon, South Korea

Areas of the upland soil (740,000 ha) are about 7% of the total South Korean area and about 62% of the upland soils are located in the slopes higher than 7%. Due to this topographical distribution, most of the upland soils are vulnerable to severe erosion in Korean sloped highland. Highland upland in Pyeongchang of South Korea has been typically applied every two or three years with coarse saprolite, agricultural by-products and agrochemicals are inputted to raise vegetable production. Therefore, the influences of saprolite application on water quality in runoff and leachate should be monitored. A lysimeter experiment was conducted to evaluate the influence of different slopes and different soil types for Chinese cabbage cultivation on the soil loss, runoff and leachate water. The lysimeter with dimension of 2 m x 5 m x 1 m was installed in the experimental field of national institute of highland agriculture (NIHA, South Korea). Soil types of the lysimeter were coarse sandy loam and loam soil, and slope gradients were 5, 20, 35%. The precipitation was 1,609 mm during study period (2004. 5~10). Soil losses with different slopes on the loam soil were 10 Mg ha-1 in the 5% contour culture, 113 Mg ha-1 in the 20 percents contour culture and 142 Mg ha-1 in the 35% contour culture. On the sandy loam soil were 93, 238 and 474 Mg ha-1, respectively. Total nitrogen losses on the loam soil were 89, 109, 168 kg ha-1, and 115, 140, 182 kg ha-1 for the sandy loam soil, respectively. Soil loss was significantly correlated with slope steepness in order of 5, 20, and 35%. Soil losses for the sandy loam plots were higher about 3 times than for the loam soils. Tendency of nutrient losses were similar to soil loss.

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