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Title: The alfalfa yield gap: A review of the evidence

Author
item Russelle, Michael

Submitted to: Forage and Grazinglands
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2013
Publication Date: 8/26/2013
Publication URL: http://handle.nal.usda.gov/10113/57502
Citation: Russelle, M.P. 2013. The alfalfa yield gap: A review of the evidence. Forage and Grazinglands. DOI: 10.1094/FG2013-0002-RV.

Interpretive Summary: Farmers, crop insurance providers, and policymakers need to know what the feasible yield level is for crops that are grown in the US. These yield levels have been well established for many crops, but a comprehensive analysis has not been done for alfalfa, the most widely grown forage crop and the first legume being considered as a bioenergy feedstock source. This research summarized four lines of evidence, from small plot research trials to whole-farm statistical reports. The best managers in most of the US states produce two to three times more alfalfa per acre than the average in those states. While we still must determine what is limiting alfalfa yield on most of our farms, it is clear that there is great potential to increase the production of this valuable crop.

Technical Abstract: Knowledge of feasibly attainable crop yields is needed for many purposes, from field-scale management to national policy decisions. For alfalfa (Medicago sativa L.), the most widely used estimates of yield in the US are whole-farm reports from the National Agriculture Statistics Service, which are based on the farmer’s estimates of total production. These estimates combine establishment-year and production-year harvests, which may inadvertently reduce yield expectations for production-year stands. This article presents new summaries of information from the small-plot to the whole-farm scale, which support the conclusion that dry hay yields (13% moisture) greater than 8 t/acre are feasible under irrigation in the West and yields greater than 6 t/acre are feasible under nonirrigated conditions in many states in the East. Therefore, there is a yield gap of 2- to 3-fold between average and top-tier producers in most states. In the process of reviewing the Census of Agriculture data, it was apparent that some reported yields were unrealistically high, which indicates the need for improved survey questions and independent, on-farm validation.