Cover crops effect on farm benefits and nitrate leaching: Linking economic and environmental analysis

• Uncertainty analysis allowed evaluating the economic impact of cover crop strategies.
• Replacing fallow by cover crops increased yield of subsequent maize crop.
• Selling cover crops as forage created more economic benefits than fertilizer savings.
• Plotting NO3 leaching against economic benefit allowed scenario comparisons.
• Cover crops reduce NO3 leaching but farmer subsidies would be required in some cases.

Introducing cover crops (CC) interspersed with intensively fertilized crops in rotation has the potential to reduce nitrate leaching. This paper evaluates various strategies involving CC between maize and compares the economic and environmental results with respect to a typical maize–fallow rotation. The comparison is performed through stochastic (Monte-Carlo) simulation models of farms’ profits using probability distribution functions (pdfs) of yield and N fertilizer saving fitted with data collected from various field trials and pdfs of crop prices and the cost of fertilizer fitted from statistical sources. Stochastic dominance relationships are obtained to rank the most profitable strategies from a farm financial perspective. A two-criterion comparison scheme is proposed to rank alternative strategies based on farm profit and nitrate leaching levels, taking the baseline scenario as the maize–fallow rotation. The results show that when CC biomass is sold as forage instead of keeping it in the soil, greater profit and less leaching of nitrates are achieved than in the baseline scenario. While the fertilizer saving will be lower if CC is sold than if it is kept in the soil, the revenue obtained from the sale of the CC compensates for the reduced fertilizer savings. The results show that CC would perhaps provide a double dividend of greater profit and reduced nitrate leaching in intensive irrigated cropping systems in Mediterranean regions.