---

Simulation data from the Erosion Productivity Impact Calculator Model (EPIC) and enterprise budget elaborated from the Oklahoma State University Budget Generator were used to study the long-term onsite and offsite effects of soil erosion on wheat production in Garfield County, Oklahoma. A discrete dynamic economic model was used to determine the private and social optimum rate of nitrogen application and choice of reduced tillage systems under different assumptions of market prices of wheat and nitrogen, cost of erosion and nitrogen loss, and discount rate.It was found that optimal tillage system was different from private versus social choice.

---

Kolado Bocoum PhD,graduated,in agricultural économist from Oklahoma State University (USA)in 2000. He is currently working for the West African Economic and Monetary Union (UEMOA). Before, he worked for the Government of Mali and the Inter State Committee against Drought in the Sahel (CILSS).

---