2.3. Slope model experiment
An experiment was conducted using a slope model to
confirm the effectiveness of a weed cover in reducing soil
and nutrient losses. Dimension of the slope model was
0.50 m wide, 0.20 m deep, and 2.00 m long, and it was set
at 8-. According the soil particle size distribution as shown
in Table 1, the soil texture was light clay, as is the soil in
Pang Prarachatan village. The nitrogen and phosphorus
concentrations were 3327 and 376 mgIkg1, respectively,
which are higher than their concentrations in the soils in
Pang Prarachatan village. The soil was compacted, and
then weeds were allowed to grow naturally. The dry
density of the soil is shown in Table 2. Setaria viridis (L.)
Beauv. was the dominant weed in the model slope plot, as
shown in Table 3. The weeds were cut and left on the
surface.