Evaluating Alfalfa Stands Part 1 - Using the Hay Square Method
Were you expecting more from your alfalfa yields? Is it time to renovate, start over, or move on? Typically, evaluating stands occurs in the spring, but evaluating this fall will give you a better idea going forward and allow more time for future options.
Evaluating stem/plant counts estimates the yield now. There are two options when evaluating your stand:
- by the number of plants per square foot (typically recommended for newer stands) and
- by the number of stems.
I would recommend evaluating by the total number of stems for established stands. University of Wisconsin research shows that stem count more accurately predicts yield compared to plant number. However, either method will give you more information when making management decisions.
The Hay Square Method
To determine the number of plants per square foot or stems, I would recommend using a hay square. Your hay square should measure 17 x 17 inches using a ½ inch PVC or you can use a circular hoop that is 19 inches in diameter. Pick 4 to 5 random areas in your field to sample, then count the plants or stems that would be harvested, typically anything over 6 inches, to determine your count. Divide those numbers by 2 to get stems or plants per square foot.
For established stands, having 4 to 5 healthy plants per square foot or 55 stems per square foot would indicate a productive and healthy stand. Stem counts below 55 show a significant decrease in dry matter production.
For stands less than a year old or spring planted alfalfa, you will see more plants per square foot compared to stems. Remember, a good rule of thumb is for every pound of seed per acre you would expect 3 to 5 plants per square foot. With that in mind, a seeding rate of 20 lbs per acre would have the potential for 60 to 100 plants per square foot. Typically, new alfalfa stands can have 22 to 30 plants per square foot, but will continue to thin out as the stand is established. This thinning out process will be evident by the end of the first year of production and some stands could have 15 to 8 plants per square foot. It is recommended to focus on stems and not number of plants at the end of the first year of production. As the alfalfa stand ages it will continue to branch out and produce more stems as the plants compete for space. After the first year of production, it is recommended to treat the stand like all other established stands.
Bottom line: Evaluate your established and newly seeded stands this fall to determine needs for spring and remember 4 to 5 plants and 55 stems per square foot are above maintenance levels for established stands. In newly seeded stands, having 15 to 8 plants and 35 to 55 stems per square foot will still leave you with a productive stand.
Additional Information on Alfalfa from Nebraska Extension: