Organic and conventional production systems: Corn and soybean yield trends 1990-2010.

Over the past two decades agronomists have used steady to positive yield trends as evidence of a sustainable cropping system (Jenkinson, 1991; Singh and Jones, 2002; and Bundy et al., 2011). However, some writers have suggested modern agriculture is predisposed to, unsustainable negative yield trends because it relies on large machinery, manufactured pesticides, and commercial fertilizer, which they claim have an adverse effect on soil health. On the other hand, the recent advances in agricultural biotechnology may be accelerating yield increases, especially in the major crops such as corn, which may lead to a widening advantage for conventional cropping systems relative to organic systems. Hence in long-term crop trials it is important to not only determine mean yields that tell what has happened on average, but also examine any yield trends that give more insight into the sustainability of the systems. In a previous paper we reported on the mean crop yields from the WICST (Posner et al., 2008); in this paper we update those mean yields for corn and soybeans, determine if any crop yield trends occurred and if they did, were there any negative trends and were there differences among cropping systems - especially between conventional and organic systems.

Authors: Jon Baldock, Janet Hedtcke, Joshua Posner