Soil Physicochemical Properties in Mining Areas and Plantation Forest for Land Reclamation of Ban Pu Lignite Mine, Li District, Lamphun Province

Abstract

Soil properties of Ban Pu Lignite Mine were studied at three sites: natural forest, mine pit and plantation forest, by making 7 soil pits and collecting samples along soil profiles at 0-5, 5-10, 20-40, 40-60, 60-80 and 80-100 cm depth. Analysis of physicochemical properties of soil samples was taken in the laboratory. The physical properties varied greatly with sites and soil depths, and not suitable for plant growth. The soils were the weatherd rocks, gravels and fragmented rocks or clays. Bluk density was moderately, moderately low and low caused by the type of material and rock gravel. Soil texture were sandy loam or loamy sand or clay loam. Soil reaction in natural forest was almost neutral whereas those soils of bare site and plantation forest at the bottom of mine pit were extremely acid. In contrast, the soil reaction of upper area of mine pit was neutral. In areas of plantation forest 1 and 2, the reaction varied greatly along soil depths: neutral, slightly acid and very strongly acid, while that of plantation forest 3 was ultra acid almost soil depth. Organic matter, carbon and nitrogen contents were low in soils of both mining areas and natural forest; however, some layers of subsoils contained the higher contents than surface soils as similar as variations of available phosphorus, extractable potassium, calcium and magnesium. These caused by the dumping weatherd rocks, gravels and fragmented rocks or subsoils on the surface soils.