Structural change in US crop yield growth

Crop yield growth is a key parameter in determining the future of agriculture—whether it can simultaneously meet our traditional demands and new demand derived from renewable energy production and climate change mitigation. At the same time, there is concern that crop yield growth has slowed down with changes in societal investment patterns and climate or environmental change. In this paper we investigate crop yield growth in the US for the past 70 years and develop the best possible estimates of likely future growth rates for 8 key crops, including corn, soybean, wheat, etc. We find that all crops investigated except for soybean have experienced slowdowns during the period of late 1960s to early 1980s. The reductions in crop yield growth rates are significant—most of the post-break growth rates are found to be lower than the pre-break growth rates by 50% or more. Furthermore, a linear growth model and an exponential growth model fit the post-break data equally well for corn and some other crops. This result suggests that long-term policy assessments would benefit from the inclusion of an optimistic scenario using the estimated exponential growth rates and a more pessimistic scenario in which the linear crop yield growth rates are used.