Seon-Woong Hwang

Application of Reduce Tillage with a Strip Tiller and its Effect on Soil Erosion Reduction in Chinese Cabbage Cultivation

Strip tiller equipment was developed to reduce soil erosion in the slope land for highland agricultural area. The equipment consisted of 4 rows strip tillage device and fertilizer applicator. The field was tilled in 10 cm width and in 10 cm depth by the equipment, of which tilled surface was 16.7% of full-width tillage. The working time and fuel consumption of the equipment were 3.8 hours ha -1 and 24.4 L ha -1 respectively, which were 59% and 74% less than those of the conventional tillage. Fertilizer efficiency of the equipment in cultivation of Chinese cabbage was 1.7, 1.6 and 1.5 times higher in nitrate, phosphorous and potassium respectively, than conventional tillage. When the equipment was used after covering of rye residue, the quantity of runoff was 49～67% lower than the conventional tillage. And the quantity of soil loss were 1.3 and 0.2 Mg ha -1 at right after and 30 days after planting of Chinese cabbage respectively, while 11.5 and 4.1 Mg ha -1 in conventional tillage. In conclusion, the strip tillage equipment developed in this study can be applicable to slope land, so that soil loss of 90% can be reduced.

Influence of Gravel Content and Nitrogen Application on Nitrogen Leaching by the Leachate and Chinese Cabbage Growth in Highland

Continuous monocropping of Chinese cabbage in Gangwon highland increased gravel and sand contents due to surface soil erosion. Nutrient leaching and Chinese cabbage growth were investigated with different treatments of gravel contents and nitrogen application levels by using Wagner pots. Gravel contents were 0, 10, 30, 50, 70, and 90%(w/w), nitrogen application levels were 60, 120, and 240 kg/ha, and manure compost application rate was 15 ton per hectare, respectively. Wagner pots were filled with loamy sand soil mixed with 5 cm-sized gravels. Fresh weight of Chinese cabbage was decreased as gravel contents in soil increased, and particularly severely decreased at 240 kg-N/ha. Yields of Chinese cabbage were remarkably decreased at the rate of 60 kg-N/ha with 30% gravel content and 120 kg-N/ha with 50% gravel content. Most of Chinese cabbages were severely wilted by heavy N application at the rate of 240 kg-N/ha in the middle of growth stages regardless of gravel contents, while about 50% of Chinese cabbage showed wilting symptom in the treatment of more than 50% of gravel contents and 120 kg-N/ha. N content in leachate increased as gravel content and N application increased. The relationship between gravel content and N contents showed linear regression: N in leachate = 0.014(gravel content) -0.039 (r = 0.961). Particularly, contents in leachates with more than 30% gravel content and 240 kg-N/ha ranged from . Chinese cabbage growth in loamy sand soil containing 30%, and 50% gravel contents could be adversely affected by N application at the rate of 240, and 120 kg-N/ha, respectively.