Page 10 - การประเมินการชะล้างพังทลายของดินในพื้นที่เกษตรกรรมด้วย Cs137

ห้องสมุดกรมพัฒนาที่ดิน
(8)

ABSTRACT

A study on the evaluation of soil erosion in agricultural areas using Cs137 was
carried out in agricultural areas at Nakhonsawan province in Chaopraya watershed.

Soil samples were collected along eight transects. The study was composed of field
environment, Cecium137 activity, physico-chemical properties, soil redistribution rate

(SRD) using Mass Balance II model, and relationship between soil redistribution rate

and soil properties.

The result showed the Cs137 activities of all the soils studied are ranging

from Transect I > Transect H > Transect F > Transect E > Transect C > Transect B >
Transect D > Transect A, respectively. All soils had a rather fine texture such as

loam, silt loam, silty clay loam, clay loam, and sandy clay loam with the highest
content of silt (27.5-66.1% mean 45.8%) whereas the lowest clay content (16.3-

38.5% mean 25.1%). The soils in the transect A, Transect B, Transect C and Transect

D had the highest sand fraction compared to the others. However, the sand fraction
in all the soils were very fine sand size. Chemically, they had moderately alkaline

soil reaction (pH 8.0-8.4 mean 8.2), moderate to very high organic matter content

(1.7-4.5% mean 3.1%), , very low to very high content of available phosphorus (0.2-
227.4 mg/kg mean 39.4 mg/kg), very high quantities of potassium (158.2-539.2 mg/kg

mean 305 mg/kg), calcium content ranged from 6560 mg/kg to 12462 mg/kg (mean
9321 mg/kg) and magnesium content ranged from 73 mg/kg to 799 mg/kg (mean 212

mg/kg).

The soil redistribution rate calculated by Mass balance II model from CS137

revealed that the erosion point/deposit point of all the transect studied were

different. Most of the soils at each position were occurring on erosion rather than
deposition. The net soil erosion rate of all the transect studied were transect A >

Transect D > Transect B > Transect C > Transect E > Transect F > Transect H > Transect I.
The soil redistribution rate was a high positively linear significant to silt content

(r=0.66***) whereas negatively linear significant to the sand content(r=-0.66***). All

sizes of the sand fraction were significantly related to soil redistribution rate but not
the clay size particles.