Untangling the Feedbacks of Soil Conservation Success: A Systems Investigation of Adoption, Targeting, and Efficacy.

High agricultural erosion rates, persisting despite a long history of conservation programs and large resource expenditure, expose entrenched, systemic competition for land management. We simulate dominant drivers of conservation adoption and erosion reduction through a combined analysis of physical, social, and economic incentives controlling conservation adoption using a system dynamics approach. The model evaluates the interplay between critical source areas and diffusion of innovation behaviors' response to conservation funding policy. The model was applied to Thorn Creek Watershed in the inland northwest dryland agricultural region known as the Palouse. The model is based on modeled 30-year averaged distributed erosion rates from 1975 to 2025. We simulated conservation adoption using nested Bass Diffusion models transferring land area between conventional and conservation tillage and the conservation reserve program (CRP). Adoption and funding parameters were calibrated to county level land management data for a baseline model simulation. Three policy tests were implemented to evaluate leveraging critical source area targeting and diffusion of innovation processes. Strong fit of baseline model behavior and theoretically consistent sensitivity analysis provided the foundation for assessing model scenarios. Current conservation efforts and considerable funds do provide consistently increasing adoption of conservation tillage, equilibrium in CRP and decreasing erosion rates. All three policy tests simulate improved conservation adoption and erosion reduction. In the short run, the targeting of CRP is highly effective but at a large and perpetual cost. This cost may be warranted on a small percent of the land area, but likely a smaller area than is under such programs today. Targeting reduced tillage adoption only on critical source areas produces the non-intuitive effect of limiting unpaid, diffusion type adoption, whereas increased funding to conservation tillage on all areas provides a compounding effect through word of mouth adoption. These policy scenarios provide evidence that funding self-perpetuating projects, aligning the positive feedback of producer decision making with conservation implementation efforts, provides greater efficacy at lower cost.