Agricultural crop production is most simply a product of the land under cultivation and the yield per hectare of land. We can compute also the global sum (WAPRO). The determination of yield is, however, rather more complex.
Agricultural yield is determined in a Cobb-Douglas type production function, the inputs to which are agricultural capital, labor, and technical change, modified by the efficiencies of capital and labor. Unlike the Cobb-Douglas function in the economic model, this one is subject to a saturation factor that is computed internally to the model - investments in increasing yield are subject to diminishing rather than constant returns to scale. Moreover, the increase in atmospheric carbon dioxide can, if the user sets appropriate parameters, affect agricultural yields. Finally, the user can rely on a yield multiplier to increase or decrease yield patterns.