Marginal land and problem soil of Thailand
Sandy Soils with Hard Pans |
| These include sandy soils in which active amorphous material (organic matter and aluminum with or without iron) has been precipitated in the subhorizon. This is designated as the spodic horizon. Under c matter content. This in turn overlies a white or light gray, strongly leached, A2 horizon gradin natural vegetation; they usually develop a thick dark surface horizon that is relatively high in organiginto a dark brown or dark reddish brown illuvial horizon or spodic horizon which commonly occurs within 1 m from the soil surface. The thickness of the spodic horizon is variable but generally ranges from 20 to 50 cm. The underlying material consists mainly of brown sand or grayish brown sand with mottles in places. It should be noted that the degree of cementation in the spodic horizon may vary from weakly to strongly cemented. But on average, they are strongly cemented. |