Soil Characteristics Derived from Limestone Between Agricultural and Forest Lands in Mae Tao Watershed, Mae Sot District, Tak Province

Abstract

The comparative study on soil characteristics derived from limestone in agricultural and forest areas at Mae Tao watershed, Mae Sot district, Tak province was carried out by digging six soil pits, three pits each in agricultural and forest lands with the size of 1.5 m in width and 1.0 m in depth. Soil samples were taken from six depths: 0-10, 10-20, 20-40, 40-60, 60-80 and 80-100 cm. The samples were later analyzed for physical and chemical properties. The physical properties of agricultural soils were nearly the same to forest soils. Within the plowed layer (20 cm), bulk density was relatively low with texture of clay loam and clay. Gravel contents were decreased in the old agricultural land. The soil reaction varied from neutral to strongly acid. Organic matter and carbon contents varied from moderate to high, but the nitrogen content was low. Concentrations of available P, exchangeable Ca and Mg were moderate while exchangeable K was high to very high. Amounts of organic matter, carbon and nitrogen as well as exchangeable Ca and Mg in the plowed layer were lower than forest soils which might be caused by loss of surface soils through soil erosion. The amounts of available P and exchangeable K within 20 cm soil depth were higher than forest soils which might be affected by fertilization.