| Research Abstract |
In1996, study site was selected from several types of land use to investigate geomorphlogical and morphological properties of the soils. Soil samples were collected there. Water samples were also collected from the surrounding area. Items for soil analysis were as follows ; Physical : texture, three phase distribution, saturated hydraulic conductivity, Chemical : exchangeable cations (Ca, Mg, Na, and K), exchangeable Al and H,cation exchange capacity, available phosphorus, total carbon and nitrogen, pH (H_2O and KCl), Charge : zero point of charge, sigmap, Mineralogy : Tamm and DCB extractable oxides and hydroxides, clay mineralogy. Soil hardness and hydraulic conductivity were measured in the field on May, September, and December in 1996.
In 1997, we had conducted monitoring in grassland in view of microorganisms, soil solution composition, pH and EC.We measured soil hardness and collected fresh soils on June, September, December in 1997. Actinomycetes and fungi were counted using dilute plate method. On the other hand, we evaluated the low molecular weight organic acids with air dried soils. Comparing older grassland with younger grassland and natural forest, we found that (1) the old grassland had a little water-soluble nutrients, (2) showed no difference between surface and subsurface soils, and (3) had stable soil condition to circulate nutrients and water within the depth of 5 to 20cm.
|
