Model I results also indicate that the variables for installation timing of conservation
structures installed on 2005 corn fields in the study area were not statistically significant.
Therefore, accounting for structural practice installation timing likely does not impact estimated
model parameters.11
Model II, which includes additional socio-environmental variables in the estimated
conservation-practice adoption model, demonstrates results quite similar to those found with Model
I (table 3). First, Model II results also demonstrate the stronger statistical case that conservation
program non-participants give to adoption of infield and perimeter-field conservation structural
practices, while for program participants, program incentives appear to be needed to encourage the
adoption of perimeter-field structural practices. Model II results also demonstrate the robustness of
cost-function parameter coefficients, and that producers likely do account for more than just
economic factors when making field-level acreage allocation decisions. For 2005 corn producers
(in the study area) variables for farm cropland acres, use of crop rotations on the field, and whether
surface drainage structures are present on the field are the more important socio-environmental
factors with respect to whether producers allocate corn field acres to different conservation
structures. However, whether gully erosion was present on the field and whether the corn field was
located next to a water body, intermittent stream, or wetland are additional site-specific
environmental attributes also relatively important to producers when making field-acreage
allocation decisions, i.e., when deciding on the adoption of conservation structural practices.
The relatively strong significance of four of the additional socio-environmental parameter
estimates likely suggests that farm size (as measured by farm cropland acres), as well as the field-
specific environmental attribute identifying surface drainage structures on the field positively
influence corn-field size, i.e., the corn-producing acres for the field. On the other-hand, field
11 Model estimation without the installation-timing variables did not impact the model’s estimated parameters, i.e.,
18