Growers and dairy producers require high-quality alfalfa forages, which makes timing of harvest critical. It's important to determine forage quality in the field to optimize harvest timing, especially in the spring. Alfalfa and alfalfa-grass stands mature at a quicker rate and lose nutritive quality faster during the spring growth cycle than during summer or fall growth. University of Wisconsin studies show that even a three- or four-day delay in harvest can make the difference between high-quality and average-quality silage. There are several tools available to growers and dairy producers for gauging the forage quality of alfalfa before harvest. The three most common methods are:
Growing Degree Units (GDU) typically used with first cutting. This method begins with identifying when plants break dormancy. GDU are not counted until the high daily temperature hits 41 degrees Fahrenheit for five consecutive days. Generally, 700 GDU are equivalent to bud stage, and 880 approximate first flower; however, growers should create targets for their unique environments.
Scissor clip helps identify changes in forage quality across both geography and time during spring alfalfa growth. Several state extension services share results of scissor-clip samples to enable growers to monitor alfalfa quality changes in nearby counties to help with harvest-timing decisions.
Predictive Equation for Alfalfa Quality (PEAQ) enables growers to determine the first harvest by monitoring plant height and maturity in the field. Plant height is an excellent indicator of staging harvest, because RFV and RFQ decrease as the plant height increases. PEAQ is the only staging method that works relatively well across all cuttings.
Once growers determine optimum harvest timing, several other management practices affect the quality of alfalfa silage, including cutting height, climate issues and alfalfa wilting and drying.
To learn more about alfalfa harvest best practices, visit The Silage Zone ® resource.
6.16.2015