Globally quantified the value of water used for irrigation: on average it is equal to 0.23 dollars per cubic meter, but varies according to the type of crop, its price and location.
This is demonstrated by the high-resolution global hydrological models developed by researchers at the Politecnico di Milano, who conducted the study together with colleagues from the University of California at Berkeley.
The results, published in the journal of the American Academy of Sciences (PNAS), will help investors in the agri-food sector interested in buying land and the right to water associated with it, but also farmers and rural communities who negotiate the sale. of their land or water rights and concessions.
"The evaluation of water is difficult because this natural resource is rarely traded and, therefore, its value cannot be determined by a market price", explains Maria Cristina Rulli of the Politecnico di Milano, who coordinated the study with Paolo D 'Odoric of Berkeley.
To make estimates, the researchers took into consideration the 16 main crops in each site in the world where they are currently present, calculating the value of the water needed for their cultivation.
With reference to the four main crops (wheat, corn, rice, soybeans), which represent about 60% of global food production, it is clear that the value of water for the production of corn, soybeans and rice is everywhere higher than that of wheat: this is due to the combined effect of differences in the price of crops and the efficiency in the use of water by the crops themselves.
The data also shows that the value of water for maize and rice is substantially higher in East Asia than in other regions of the world.
Finally, the global analysis highlights that the current spatial location of crops is not such as to maximize the value of water.
