ผลของรูปแบบการใช้ที่ดินและสภาพภูมิประเทศต่อสมบัติบางประการที่สำคัญทางกายภาพและเคมีของดิน บริเวณลุ่มน้ำทุ่งใหญ่ จังหวัดสงขลา

Abstract

A study of the effects of different land use patterns and topography on some physical and chemical properties of soils and soil fertility status assessment in Thung Yai watershed, Hat Yai district, Songkhla province. Goal is a guideline to manage the land resources for create sustainable benefits in the future. The survey was conducted and selected areas (in Thung Yai watershed) with different land use patterns and related topography. Data sources are soil survey report and soil map of Songkhla province and field survey in the study area by researchers themselves. Thung Yai watershed has 6 major land use patterns which related to the topography (%slop) are, (1) The para rubber plantation area with slop range 0-8% (2) The para rubber plantation area with slop range 8-16% (3) The para rubber agroforest area with slop range 8-16% (4) The para rubber agroforest area with slop range 16-30% (5) The orchard plantation area with slop range 16-30% and (6) The forest area with slop range >30%. Soil sampling was taken at 2 the depth ranges, were the topsoil (0-15 cm) and the subsoil (15-30 cm), which disturbed and undisturbed soil sampling (all forms of land use and topography). All soil samples were analyzed for some important chemical and physical properties in the soil and plant laboratory. The soil information obtained was used to evaluate soil fertility status under different land use and management in different topography. The result show that soil texture of all topsoils were sandy lom (all forms of land use and topography), and subsoil were sandy loam to sandy clay when the slop increases. The topsoil of para rubber plantation area with slop range 0- 8% was highest total bulk density, but lowest soil porosity and satuated hydraulic conductivity. While, the topsoil of forest area with slop range >30% was lowest total bulk density, but highest soil porosity and satuated hydraulic conductivity. The changes of some chemical properties of soil samples (at 0-30 cm) of all forms of land use and topography indicated that soil pH varied from strongly acid to very strongly acid (5.45-5.03, soil:water = 1:5), soil EC as 3.34- 19.50 μs/cm, OM as 3.44-21.16%, total N as 0.60-1.37 g/kg, available P as 1.20-5.40 mg/kg, exchangeable K as 66.30-152.10 cmol/kg, available S as 0.43-1.69 mg/kg, CEC as 3.16-12.63 cmol/kg and %BS as 7.95-36.20. The soil fertility status assessment in Thung Yai watershed showed that the para rubber plantation area with slop range 8-16% was low level. While, the soil fertility status evaluated moderately level were the para rubber plantation area with slop range 0-8%, the para rubber agroforest area with slop range 8-16% and 16-30%, the orchard plantation area with slop range 16-30% and the forest area with slop range >30%.