The Alfalfa Yield Gap: A Review of the Evidence

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 reports combine establishment-year and production-year harvests, which may inadvertently reduce yield expectations for production-year stands. However, some reported yields were unrealistically high, indicating a previously unreported problem with forage yield reports. 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 tons/acre are feasible under irrigation in the West and yields greater than 6 tons/acre are feasible under nonirrigated conditions in many states in the East. There is a yield gap of 2- to threefold between average and top-tier producers in most states. Bridging that gap should greatly improve farm profitability and availability of the product.