Evaluating your alfalfa stand for maximum ROI

 By Steve Murty, Vita Plus, forage products specialist

The same questions arise several times every spring.  “Will my alfalfa stands survive another season?  Will there be enough forage this coming year?”  A proactive approach to answering these questions begins in late fall after you have filled the silos, pumped the pits and seeded cover crops.

Now is the right time to grab the spade and head to the alfalfa field to evaluate your alfalfa stand health.  Begin by evaluating your stand density either by plants or stems per square foot.  A stand of four to five plants or 55 stems per square foot will not be yield-limiting.  (Research done at the University of Wisconsin-Madison shows stems per square foot is a more accurate prediction of yield compared with plant count.)

If you have determined your stem count per square foot is satisfactory, dig deeper to remove several alfalfa crowns and tap roots from the soil.  Using a knife, split the crowns and tap roots to expose the center of the root, evaluating color, firmness and overall health.  UW-Madison experts have created a 0 to 5 scoring system to predict risk of winterkill.  Risk factors that contribute to winterkill include saturated soil conditions, plant heaving (freezing and thawing), mild melting and refreezing during the winter, poor snow cover, and lack of proper nutrition.

Reactive spring evaluation of winterkill should occur once alfalfa breaks dormancy and has 3 to 4 inches of top growth.  If you have determined the alfalfa stand will not be viable for another year of production, several alternative options can be considered.

Early-season interseeding of annual grass can be done with Italian ryegrass or spring cereals (oats, wheat, triticale, or barley).  Warm-season annuals suitable for planting after the first-cutting harvest are sudan grass, sorghums and millets.  Legumes – including clovers and trefoils – also can be added to the grass combinations to improve the quality yield.

Interseeding additional alfalfa into a mature stand of alfalfa is not recommended.  The mature plants produce allelopathic substances or biochemicals that influence the growth, survival, development and reproduction of other organisms, which are present in the soil until the crop is terminated.  A waiting period between termination and reseeding with alfalfa allows these biochemicals to leave your soil.  When the alfalfa stand is not salvageable, the best decision is to terminate and use the nitrogen credits the alfalfa plants have been adding to the soil profile.  Your failed alfalfa stand may have stored enough nitrogen during previous production years to supply adequate nitrogen needs for a following corn crop.  The amount of nitrogen left in the soil is variable due to the age of alfalfa stand and soil type.

Outlining your forage production goals will create the road map for a successful forage season.  The plan will help you navigate during times of severe winterkill in your alfalfa fields.  Building a sound forage plan developed with season long and fast forage solutions will compensate for poor stand surprises.