Methods Used to Identify Yield-Limiting Factors in Ohio.

From 1924 through 2013, soybean yield in Ohio increased at a rate of 0.37 bu/ac/yr with a state average of 49 bu/ac in 2013. However, the theoretical maximum soybean grain yield is estimated to be 335 bu/ac.  While the realization of the theoretical maximum yield is unlikely, the difference between theoretical and actual yield indicates that a great deal of yield potential is not achieved due to yield-limiting factors.  A process to identify soybean yield-limiting factors in Ohio with a team of farmers and Extension personnel was developed. The project uses farmer knowledge to identify sampling points in fields. Extension personnel collect soil, plant, and pest data throughout the growing season. Samples are sent to the Columbus campus of The Ohio State University for analysis. Upon completion of this multi-year project, multivariate statistics will be used to identify yield-limiting factors on a regional and statewide basis. Once yield-limiting factors are identified, Extension programming and field research will be developed to address the yield limitations.  Preliminary findings indicate soil fertility (low phosphorus and low soil pH) are limitations to soybean production in Ohio.