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program, the same counties under the uniform policy are chosen to retire cropland. However, the
average rental payment is $88/acre, which is much lower than that of the uniform policy. The
uniform policy costs more than 65% compared to the least-cost land retirement program. Thus,
targeting will significantly reduce the total rental payments made to the farmers in achieving the
land retirement goal.
We also examine the implications of a policy that reduce the total water use by 10% with
the least-cost land retirement program in the region. This model minimizes the cost of the
program in terms of the total rental payments provided to the farmers in order to achieve the 10%
water-use reduction goal as compared to the baseline. The results indicate that 212,142 acres
need to be retired in order to achieve the 10% reduction in the total water use in the ESPA. The
average rental payment is found to be about $143/acre. These results indicate that increased
water-use reduction goal requires retiring more productive croplands out of production, which
leads to an increase in the rental payments.
To examine the cost-effectiveness of the least-cost land retirement program, we develop a
model to achieve the same water reduction provided with the least-cost land-restriction model.
This model maximizes the total returns in the region subject to the water-use reduction constraint
to determine the optimal cropping and rotation practices in the region. The model allows the
flexibility in achieving the water quantity goal by changing cropping and rotation practices and
allowing some land parcels to be idle. Under the least-cost land retirement model with the
100,000 cropland retirement target, the total water use in the ESPA decreases by 4.62%. With
this model, no land needs to be idle to achieve the water quantity goal. Changing cropping and
rotation practices in the region would allow achieving this goal with the least cost. The results
presented in Table 3 summarize the optimal aggregate cropping practices in 16 counties. As
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