The two sensitivity analyses show that the increasing crop yields generated by
the use of soil conservation practices encouraged agents to adopt these practices
more than when reducing labor requirements. When maize yields under the soil
conservation practices increased to 150 % of the baseline, the area under leucaena
hedges expanded to 285.6 ha, with an adoption rate of 100 % (Table 10.6), whilst
when the labor requirement dropped to 10 % of the baseline, this accounted for
27.58 ha and an adoption rate of 63 % (Table 10.7). It can be concluded that the
prospect of lower crop yields was the major constraint on farmers adopting soil
conservation practices.
10.6.4 Payment Policy
The use of soil conservation practices reduced the quantity of soil loss but also
caused a decline in farm incomes due to lower crop yields, so farmers needed to be
encouraged to conserve the soil and thus sustain their livelihoods over the longer
term. This section assesses the policies used to support farmers in applying soil
conservation practices, the idea being that a policy would support farmers by
paying them for the area under such techniques.
Under the calibrated model, this payment was introduced as a variable in the
decision-making model – linked to the adoption of soil conservation practices.
In addition to the baseline, simulations were run for six payment scenarios. The
results of the payment scenarios are presented in Table 10.8, showing substantially
higher soil conservation adoption than in the baseline. Compared to grass strips and
grass barriers, there was a faster uptake for leucaena hedges, because growing
maize with leucaena hedges was more profitable than the other options, due to the
higher maize yields produced. Applying grass strips to the maize fields generated
more profit than when using grass barriers, and so more agents adopted this
technique. At a level of three million VND ha
À1 , the adoption rates for leucaena
hedges, grass strips and grass barriers were 100 %, 90 % and 69 % respectively. The
area under maize using grass barriers and grass strips was 2.12 and 44.57 ha
respectively, while when using leucaena hedges it was 270.88 ha.
Table 10.8 shows that the conservation area was considerably larger when the
payment was increased from 2 to 3 million VND ha
À1 . Above 3 million VND ha
À1 ,
the conservation area expanded at a slower rate.
In the model, agents received a specific amount of payment in cash for the area
under soil conservation; agents applying soil conservation practices over a larger
area thus receiving higher payments. This implies a positive relationship between
the amount of cash received, the area under soil conservation and the reduction in
soil losses. In terms of the relationship between payments and the reduction in soil
losses, the costs incurred when reducing soil erosion could be derived from the total
payments divided by the quantity of soil-loss reduction for each agent. The last row
in Table 10.8 shows the costs needed to reduce soil loss. For a payment of 3 million
VND per ha, the cost of reducing soil loss was 201,000 VND Mg
À1 year
À1 and the
410
C. Marohn et al.
the use of soil conservation practices encouraged agents to adopt these practices
more than when reducing labor requirements. When maize yields under the soil
conservation practices increased to 150 % of the baseline, the area under leucaena
hedges expanded to 285.6 ha, with an adoption rate of 100 % (Table 10.6), whilst
when the labor requirement dropped to 10 % of the baseline, this accounted for
27.58 ha and an adoption rate of 63 % (Table 10.7). It can be concluded that the
prospect of lower crop yields was the major constraint on farmers adopting soil
conservation practices.
10.6.4 Payment Policy
The use of soil conservation practices reduced the quantity of soil loss but also
caused a decline in farm incomes due to lower crop yields, so farmers needed to be
encouraged to conserve the soil and thus sustain their livelihoods over the longer
term. This section assesses the policies used to support farmers in applying soil
conservation practices, the idea being that a policy would support farmers by
paying them for the area under such techniques.
Under the calibrated model, this payment was introduced as a variable in the
decision-making model – linked to the adoption of soil conservation practices.
In addition to the baseline, simulations were run for six payment scenarios. The
results of the payment scenarios are presented in Table 10.8, showing substantially
higher soil conservation adoption than in the baseline. Compared to grass strips and
grass barriers, there was a faster uptake for leucaena hedges, because growing
maize with leucaena hedges was more profitable than the other options, due to the
higher maize yields produced. Applying grass strips to the maize fields generated
more profit than when using grass barriers, and so more agents adopted this
technique. At a level of three million VND ha
À1 , the adoption rates for leucaena
hedges, grass strips and grass barriers were 100 %, 90 % and 69 % respectively. The
area under maize using grass barriers and grass strips was 2.12 and 44.57 ha
respectively, while when using leucaena hedges it was 270.88 ha.
Table 10.8 shows that the conservation area was considerably larger when the
payment was increased from 2 to 3 million VND ha
À1 . Above 3 million VND ha
À1 ,
the conservation area expanded at a slower rate.
In the model, agents received a specific amount of payment in cash for the area
under soil conservation; agents applying soil conservation practices over a larger
area thus receiving higher payments. This implies a positive relationship between
the amount of cash received, the area under soil conservation and the reduction in
soil losses. In terms of the relationship between payments and the reduction in soil
losses, the costs incurred when reducing soil erosion could be derived from the total
payments divided by the quantity of soil-loss reduction for each agent. The last row
in Table 10.8 shows the costs needed to reduce soil loss. For a payment of 3 million
VND per ha, the cost of reducing soil loss was 201,000 VND Mg
À1 year
À1 and the
410
C. Marohn et al.