Phosphorous and potassium, on the other hand, are mined products and production is often located close to natural reserves which are concentrated in few countries. Therefore, the market for nitrogen is assumed to approach perfect market conditions, whereas some degree of market imperfection could be imagined in phosphorous and potassium markets. As the degree of market imperfection is unknown, an ad-hoc sensitivity analyses is performed to see the impacts of the simulated policies on intermediate input use.