With spring temperatures stretching across much of the U.S., alfalfa has broken dormancy in many areas, making it an optimal time for growers to evaluate stand density and yield potential. Experts at Pioneer Hi-Bred, a DuPont business, provide methods for determining yield potential, including plant density and stem count processes.

As alfalfa plants start to green, growers should plan to evaluate for yield potential and, where needed, consider stand termination. Plant density, a form of evaluating stand growth, is one method for determining quality. When counting plants per square foot, growers should take a random 1-foot square and count the number of plants (crowns) that are alive and healthy. Take four to five counts for every 10 acres. Calculate the field average and use the chart below for determining quality.

Stand age
(years)

Plant density (plants/sq ft)

Good

Marginal

Poor

1

15+

10-11

<10< />

2

10+

8-10

<8< />

3

8+

6-8

<6< />

4

5+

4-5

<4< />

 The second option, the stem count method, is the most reliable but needs to be conducted several weeks after initial green-up.

          1.  Check stands when the alfalfa plants are 4 to 6 inches tall.
          2.  Randomly select four to five 1-foot-square sites for every five to 10 acres.
          3.  Count the number of stems per square foot.

If an alfalfa field averages more than 55 stems per square foot, it has top yield potential. Some losses may incur with 40 to 55 stems per square foot. If the stem count is below 40 stems per square foot, the grower should consider replacing the stand.

If stand density is questionable, growers should consider turning the crop under early or after the first cutting. Alfalfa supplies a great deal of nitrogen to the soil. Growers should look to plant an alternative crop, such as corn, to utilize the N (nitrogen) credit.

Source: Pioneer Hi-Bred, a DuPont business