Measuring the relative importance of different agricultural inputs to global and regional crop yield growth since 1975

Background: : We identify the agricultural inputs that drove the growth in global and regional crop yields from 1975 to the mid-2000s.  Methods: : We compare and contrast the inputs that drove yield change as identified by econometrically estimated yield functions and decision trees that use yield change as the class attribute.  Results: : We find that improvements in agricultural science and management, increased fertilizer use, and changes in crop mix around the world explained most of the gain in global crop yields, although the yield impacts of input use varied across the latitudinal gradient. Climate change over this time period caused yields to be only slightly lower than they would have been otherwise. In some cases, cropland extensification had as much of a negative impact on global and regional yields as climate change.  Conclusions: : To maintain the momentum in yield growth across the globe 1) the transfer of agricultural chemicals and investment in agricultural science and management in the tropics must increase rapidly and 2) international trade in agricultural products must expand significantly.