Converting Alfalfa Development Measurements from Mean Stage by Count to Mean Stage by Weight

Mean stage by weight (MSW) precisely quantifies the stage of development in alfalfa (Medicago sativa L.), and it is an established basis for predicting alfalfa quality. Mean stage by count (MSC) eliminates oven drying of separated subsamples as a part of the process of determining the mean stage, but MSC should not be used on samples with a mixture of mature herbage and young regrowth. Conversion of MSC to MSW allows stage comparisons across experiments and use of published quality prediction equations based on MSW without recalibration for MSC. Using field data from central New York State, MSW was accurately estimated from MSC by the equation MSW = 0.456 + 1.153‐MSC (n = 569; r2 = 0.982; RMSE = 0.311). Over the midrange of MSC values (2.0‐5.0), which correspond to stages when most management decisions should be made, the simplified procedure appears to be as accurate as direct measurements of MSW.