Page 6 - การประเมินคุณภาพดินเพื่อการเพิ่มประสิทธิภาพการจัดการพื้นที่ ทางการเกษตรที่มีอัตราการชะล้างพังทลายสูงโดยใช้เทคนิคนิวเคลียร์ จังหวัดกาญจนบุรี Assessing soil quality and enhance crop productivity through agriculture management using nuclear techniques in the area of erosion in Kanchanaburi province.

ห้องสมุดกรมพัฒนาที่ดิน

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บทคัดยอภาษาอังกฤษ (Abstract-English)

The aims of this study was to assessment of soil quality for best practices and to study soil
redistribution with isotope technique by using Pb as a tracer. This study was conducted in Prangplae Sub-
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district, Sangkhla Buri District, Kanchanaburi Province. Factors included (1) Time of soil sampling (April, June,
and August); (2) Areas (General field crop, Perennial forest and rubber, and Field crop with soil conservation
practices) (3) Slope classes (Toeslope, Footslope, Backslope, Shoulder, and Summit); and (4) Soil depths (0-10
cm, 10-20 cm, and 20-30 cm)
For soil quality assessment, there were significant differences between factors and soil chemical
properties. To explain, the field crop with soil conservation practices maintained the greatest values in pH
(5.75), EC (0.040 dS/m), OM (3.09%), Mg (76.54 mg/kg), and Ca (1,436.06 mg/kg) following by the perennial
forest and rubber had values included pH (5.08), EC (0.016 dS/m), OM (3.05%), Mg (49.29 mg/kg), and Ca
(324.18 mg/kg); and the general field crop (5.06 for pH, 0.021 dS/m for EC, 2.41% for OM, 30.46 mg/kg for Mg,
and 292.64 mg/kg for Ca). Nevertheless, the amount of P and K were found to be the greatest values in the
perennial forest and rubber area (2.700 mg/kg for P, and 121.88 mg/kg for K); along with the general field
crop area (2.695 mg/kg for P, and 94.96 mg/kg for K), respectively. On the one hand, time period of soil
sampling and annual rainfall significantly affected the fluxs of soil chemical properties (EC, P, K, Ca, and Mg).
The annual rainfall in each soil samplings consist of 11 mm (April), 201.5 mm (June,), and 544.3 mm (August).
As a result, those chemical properties were sorted by time of soil sampling as followed : EC were equal to
0.032, 0.022, and 0.023 dS/m; P were equal to 3.801, 3.756, and 0.631 mg/kg; K were equal to 139.84, 105.67,
and 119.47 mg/kg; Ca were equal to 777.90, 644.95, and 677.36 mg/kg; and Mg were equal to 74.45, 39.97,
and 41.88 mg/kg, repectively. Furthermore, Topographic Position or Slope classes in each soil sampling time
significantly affected the changes of soilchemical properties. To explain, the values of EC, OM, and P could
differently ran off from upper areas to lower parts asccompared with those three areas because the general
field crop had the greatest values of EC, OM, and P on toeslope and footslope positions base on increasing
rates of rainfall. Also, the perennial forest and rubber and the field crop with soil conservation practices
contained the greatest values of EC, OM, and P on Backslope and Shoulderpositions. Moreover, annual
rainfall also affected infiltration rates of soil chemical properties, in brief, the greatest amounts of EC, OM, K,
Mg, and Ca were found within 0-10 cm depth of soil sampling in April. After that, they were infiltrated
through lower soil depth (10-20 cm) in June and August.
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Radioactivity levels of Pbex and soil redistribution rates (SRD) were significant differences in each
area, slope position, soil depth, and duration of soil sampling. To explain, concentrations of Pbex were
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25.11 Bq/kg for the general field crop, 24.08 Bq/kg for the Perennial forest and rubber, and 21.58 Bq/kg for
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the field crop with soil conservation practices. Additionally, Pbex were increase when entered to monsoon
season and were found in the greatest amounts on the soil surface. In SRD perspective, for the field crop
with soil conservation practices found a trend of mean SRD rates for soil deposition (8.649 t/ha/yr), as well
as, the perennial forest and rubber area also found mean SRD rates as soil deposition (2.992 t/ha/yr). On the
other hand, the general field crop tended to have SRD rates in a way of soil erosion (-1,830 t/ha/yr). Because
of land cover and soil conservation procedures the deposit areas in the field crop with soil conservation
practices and the perennial forest and rubber area were found at upper positions (Backslope to Summit).
However, the general field crop found soil erosive spots at lower positions, but soil sediment naturally
accumulated at the lowest position of this study.

Keywords : Soil quality, Soil and Water Conservation, Soil erosion, Isotope