Practical Studies on Soil Conservation in Reclaimed Sloping Land : Establishment of Study Plots and Some Basic Soil Properties

In order to control soil erosion in reclaimed sloping lands among the mountains, first of all the important thing in case of the establishment of plot for repeating various experiments may be the interrelated uniformity of a study plot. The location of a study plot is inside of the development project area where there consists of most general and average slopes. 　Due to the interior study plot was on the same slope and soil property, each of the divided A. B, C, and D sub-plots was thought of having the same conditions, and the aim of this experiment was to estimate whether the sub-plots could be regarded as an uniformity or not from their soil characteristics. 　Soil samples were collected at the upper-, middle-, and lower points of four sub-plots and mixed together so as to evaluate their properties at large. The samples were analyzed to clarify such soil physical properties as specific gravity, porosity, soil structure, particle-size distribution, water retentivity (pF), erodibility, and so on. We then made clear of the general soil characteristics as well as investigated their uniformity among four sub-plots from these obtained results. 　The results obtained can be summarized as follows : l) The soil of study plot is an undeveloped structure, low in degree of aggregation which shows resistivity toward dispersion action, and low in porosity of supporting Permeability and water retentivity. The pF values also substantiate these results. 2) Distribution of particle sizes indicates the property peculiar to Masa soil consisting of the uniform mixture of gravel to clay particles. 3) The study soil showed erodibility resulting from its high ratios of dispersion and erosion. Therefore, it was clarified that some proper erosion control practices have to be devised for the use of soil in the future and for agricultural activities. 4) According to the foregoing results, the differences in soil physical properties were not found among four sub-plots, thus they could be regarded as the same experimental plot and be used for carrying the further experiment.