How to assess spring Stands of Alfalfa
Key Numbers to assess right now.
Factsheet to bring to the field during assessment.
Marvin Hall, Forage Specialist
Unfortunately, “taking out” or saving and alfalfa stand is not always an easy decision. But with the current price of corn I think that decision will be on the minds of many Pennsylvania farmers. Recent research can help in assessing the productivity and profitability of a questionable alfalfa stand.
The magic number of plants, that traditionally indicated when it was time to rotate out of alfalfa, has been 4–5 plants per square foot. However, depending on fertility and weed invasion, alfalfa stands with 5 plants per square foot can yield as much as a stand with 10 or 15 plants per square foot. The correlation between plants per square foot and yield is very low since individual alfalfa plants respond to decreasing stand density by producing more stems. An increase in stems per plant compensates for fewer plants and maintains the yield.
A better indicator, than the number of plants, of the productivity of an alfalfa stand is the number of stems per square foot. Fields with 55 or more stem per square foot produce maximum yields. As the stem number declines below 55 per square foot yields begin to decline. Once stem numbers falls below 40 per square foot alfalfa fields begin to loose profitability and should be rotated out of alfalfa.