Yield Gains in Dry Beans in the U.S.

Dry edible bean (Phaseolus vulgaris L.) has been characterized as a nutritional powerhouse and is the most important grain legume in the human diet worldwide. The United States is among the top five producers worldwide with approximately 1 million ha grown annually. During the last 30 years, U.S. production has shifted geographically from the Northwest to the Great Plains and the Midwest. At least seven market classes are economically important.  An assessment of the yield gains during the last 30 years was conducted using three sources: i) USDA-NASS (on-farm yield); ii) Cooperative Dry Bean Nursery, (potential yield); iii) field trials of pinto and navy beans including both historic and modern cultivars across four locations (CO, MI, NE, and ND), and two years (2011 and 2012). On-farm yield across all market classes of dry bean grown in the U.S. showed a seed yield increase of 12.9 kg ha^-1 yr^-1 between 1909 and 2012. Pinto beans yield gains between 1981 and 2012 showed a positive trend for both on-farm yield and potential yield gains, ranging between 12.2 to 15.2 kg ha^-1 yr^-1 (on-farm and potential yield, respectively). Navy beans had yield gains between 18.5 and 25.9 kg ha^-1 yr^-1. Black beans show a more variable range in yield gains between the on-farm and potential yield (5.7 and 24.3 kg ha^-1 yr^-1, respectively). Kidney beans show a yield increase between 19.1 and 39.9 kg ha^-1 yr^-1. Yield gap between potential yield and on-farm yield was considerable for all market classes, but smaller for kidney beans. This observed yield gap suggests that improved on-farm agronomic practices could increase productivity. Genetic gain from selection in dry beans tested in common trials ranged between 13.9 to 17.4 kg ha^-1 yr^-1 for navy and pinto beans, respectively. These results are similar to the yield increases reported for soybean and wheat. The fact that similar gains were obtained from different data sources suggest that the results are robust and accurate. The results also suggest that yield increases have been linear since 1956 and dry edible bean has not reached a yield plateau in most market classes.