한국유기농업학회지 Vol.23 No.4 (p.875-886)

유기농경지 밭 토양의 물리화학적 특성

Physico-Chemical Properties of Organically Cultivated Upland Soils
키워드 :
chemical property,organic farming,organic matter,soil,physical property

초록

The upland soils (56 samples) from organic farms in Gyeonggi-do (12 sites), Gangwon-do (8 sites), Chungcheong-do (14 sites), Gyeongsang-do (4 sites), Jeollado (18 sites) in Korea were collected and their physical and chemical properties were analyzed by RDA’s methods. In the results of physical property, the bulk density of soils averaged 1.14 Mg m-3 (surface soil), 1.38 Mg m-3 (subsoil), respectively. The porosity of them was 57%, 48%. Organically managed soil’s (OS) bulk density was lower than conventional soil’s but OS’s porosity was a little higher than conventionally managed soil in surface soil. The depth of plough layer in organically managed soils was 21.2 cm indicating that the organic farming had good effect on soil physical property. In the results of chemical property, the surface soil pH was 6.9 and the contents of organic matter (OM) was 26 g kg-1, available phosphate (Avail. P2O5) was 554 mg kg-1, exchangeable calcium (Exch. Ca) was 8.9 cmolc kg-1, exchangeable potassium (Exch. K) was 0.89 cmolc kg-1, exchangeable magnesium (Exch. Mg) was 2.0 cmolc kg-1. The subsoil pH was 6.8 and the contents of OM was 21 g kg-1, avail. P2O5 was 491 mg kg-1, exch. Ca was 7.9 cmolc kg-1, exch. K was 0.68 cmolc kg-1, exch. Mg was 1.8 cmolc kg-1. The nutrient accumulation emerged in organic farming. Compared to the optimum nutrient range for the conventional upland soils, the exceed rate of pH, OM, available phosphate, and exchangeable Ca, K, and Mg was 79, 52, 64, 84, 66% and 55%, respectively, which mainly resulted from the over-application of lime materials or livestock manure compost. With these results it is suggested thatorganic farm need to reduce the use of inputs, which make soil alkalification or nutrient accumulation. More study on effects of inputs on lowering soil pH from alkalification could help organically managed soil to be improved.