As alfalfa comes out of dormancy in the spring, it’s important to evaluate stands for condition and yield potential. The earlier you make a determination, the more possibilities there are for remedial action. This stand assessment should occur in three parts:
1. Are individual plants alive? This assessment can begin as soon as the frost is out of the ground and continue until spring green-up occurs. The process is to dig a few plants 4" to 6" deep and look at the condition of the taproot. If the taproot is turgid (like a potato, the leftmost plant), it is alive and healthy. If the root is browned, dehydrated, and ropey (like the two plants on the right), it is dead or dying. This assessment can be repeated until green-up occurs and stand can be assessed on that basis.
2. Are plants injured? Alfalfa forms buds in the fall for spring growth. If these buds are killed the plant must form new buds in the spring, delaying growth and reducing yield. The three taller stems in the picture (above the line) are from buds formed in the fall and the shorter stems are from buds formed in the spring. The delayed, shorter growth will reduce yield of first cutting and then plants will recover. If you see this, consider management to reduce this in the future, such as adequate soil pH, fall application of potassium and more winter-hardy varieties.
Tall shoots from fall buds; short shoots from spring buds.
3. Are there thin spots in the field? A healthy stand should have 55 stems per sq. ft. Early assessments, before stems are visible, may need to assess based on plant count. A high-yielding alfalfa stand seeded last year should have 20 plants per sq. ft.; counts as low as 12 will produce good yield but result in shortened stand life. Stands seeded last spring or fall with less than 12 plants per sq. ft. should be disked and reseeded. A high-yielding alfalfa stand over 1-year-old should have at least 6 plants per sq. ft. If plant density is less than 6 plants per sq. ft., oats (2 bu. per acre) or Italian ryegrass (10 lbs. per acre) can be overseeded to increase yield this year. The stand should be turned over either immediately or at end of year.
Thin stand (left) vs. adequate stand (right)