Rescuing Alfalfa

Regardless of how hard we try, alfalfa stands do thin with time. Why? They thin because of poor soil selection and use, insects, diseases, fertility stress, and poor and hay, silage and grazing management decisions are some of the major reasons stands of alfalfa do thin over time.

When Stands Drop to This Level, it is Time for Action!

When an alfalfa stand gets off to a poor start, it is possible to reseed or thicken a stand in the following planting season. However, after the field has gone through at least one production year, the malady known as autotoxicity (an allelopathy) infects and kills the new seedlings as they emerge. The infection is ‘born’ in the old alfalfa plant residue (leaves, stems and roots). The ‘disease’ effects not only the establishment but also ‘hangs on’ and continues to infect the plants that do survive at the cost of yield and stand reduction. This is the problem when professionals tell you that you cannot successfully follow alfalfa immediately with alfalfa and have a successful alfalfa planting. Once an area is infected and the stand is in shambles, the field should be planted to a row crop for at least one year before returning to alfalfa. When water erosion is not a problem, two years out of alfalfa is better than one year.

New Seedings:
You can thicken an alfalfa stand that is one season old most of the time. Should you have an unacceptable establishment in a fall seeding for instance, a seeding the following spring should be fine. If you should miss on a spring seeding, a fall planting will work as well. But if you try to stretch the re-plant to a year or more, forget it. Rather you should go to a row crop if the land is suitable for at least one crop year (two is better) to eliminate the malady.

If you should decide to thicken the new stand, be sure to drill the seed at ¼ to ½ inch depth. A no-till drill is the best equipment, but watch the depth! These drills are heavy and are adapted to seeding grasses and legumes even in un-tilled and grass sods. Use the original seeding rate. Spot seeding rarely works since spot harvests are hard if not impossible to time for best forage quality and plant survival. However if you should decide to spot seed harvest the first crop later than normal to allow the newer plants time to become well established.

Older alfalfa stands:
The first action should be to check the soil pH and levels of phosphate and potash. There is no substitute for current soil tests and solid advice in the form of recommendations from a qualified professional to correct deficits if they exist.

 Keep in mind that older fields need to be handled quite differently than younger fields. Walk the field and about every 50-100 steps, stop and look down between you shoes and count the plants and record your number. Do this in at least 20 places in the field. If your average is 10-14 plants in those areas, the stand is great and get ready for a fantastic forage harvest this year. If on the other hand the plant count is less 10-14, go to our web site and pull up the publication entitled, “Evaluating & Managing Established Alfalfa Stands” from our website or call and ask for one at 1-800-873-2532. Take those numbers you wrote down on your walk and go through the publication and decide what measures you can take.
 

You will note in the publication when the stands are thinning, we have suggested that you drill adapted cool season grasses into the alfalfa stands to replace weeds. Red clover also works where it is adapted and can help to extend the life of the field for hay for another year or two. The grass will usually survive much longer. Again, should you decide to keep the field for another season or two, don’t’ forget to lime and fertilize as needed.

When should you plow alfalfa and go to another crop? For many farmers, it is a matter of a set crop rotation system. For others it’s a matter of yields, accessibility, etc. My rule of thumb has always been when the annual hay yield is less than four tons per acre, plow it under and plant the field to a row crop. Not only will you rid the soil of the autotoxicity malady, you will be able to ‘harvest’ the nitrogen and the organic matter that the alfalfa has produced. The corn crop will be a dandy and the fertilizer nitrogen cost will reduced considerably.