Timing the First Cutting of Alfalfa
Paul H. Craig, Extension Agent - Forage Crop Production, Pa
April 26, 2002
The timing of the first cut of alfalfa offers the greatest opportunity for economic gain or loss for any alfalfa producer. Properly timed, first cut sets the stage for future crop harvests and can significantly affect stand persistence. In addition, making first cut at optimum forage quality must be the goal of all forage producers. Dairy men and women know the importance of forage quality to profitability. Poor quality forages increase feed costs and limit production of high producing cows.
First cutting of alfalfa typically comprises 30 to 40% of the seasonal yield. For this reason alone, mistakes made at first harvest will have dramatic affects. Agronomists note that 2 factors determine the optimum time to harvest first cut. The first factor is the number of rain free days it takes to complete harvest. Forage producers must begin soon enough to allow for harvest to be completed prior to forage maturity that results in lowered forage quality.
The second factor that initiates spring harvest is the quality of the standing forage crop. Early harvest of alfalfa greatly improves quality factors but harvesting too early can reduce yields and reduce stand longevity. Many dairy producers intensely manage their alfalfa stands with frequent early harvests and up to 5 harvests yearly. These individuals plan on rotating alfalfa stands frequently, often after the third year of production. If longer lived stands are your goals then your stands must be managed differently.
Management of alfalfa and other perennial forages requires an understanding of the role of plant energy reserves. Energy reserves are important to perennial plants for winter survival and to initiate regrowth following harvest. High-energy reserves support quicker regrowth, which leads to higher yields. In alfalfa, these reserves are stored in taproots. In other legumes, the reserves may be found in low growing stems. In grasses, these reserves are found above ground in the
lowest 3 to 4 inches of individual tillers.
In springtime and immediately following harvest, the plants use energy reserves until sufficient growth is able to meet the needs of the developing plant. When this stage is reached the “extra” energy is directed to the plant reserve storage site for future use. Think of this like a bank account at payday. Storage reserves in alfalfa are usually at their lowest levels two weeks after harvest and at peak levels during bloom.
Agronomists recommend cutting alfalfa from the bud stage to early bloom in order to maximize plant reserves for stand longevity and still produce good alfalfa quality. Many dairy producers, managing alfalfa for higher quality and more cuttings will harvest alfalfa as soon as a few buds appear. These producers trade higher quality for long-term stand longevity. They ensure top production with optimum levels of soil pH, phosphorous and potassium. These individuals also monitor closely for alfalfa weevils and potato leafhoppers. Frequently, to ensure energy levels are higher, these producers will allow one summer cutting to reach the first bloom stage before taking a cutting.
The affect of intensely managing alfalfa on stand longevity depends on many factors including: variety, age of stand, fertility, insect pressure, weeds, soil moisture, growing conditions, the environment and cutting management. Spring growth has the highest tolerance to early cutting from a timing perspective. This factor allows dairy producers to manage first cutting a little more intensely in regards to stage of cutting. However, the timing of spring cuttings can affect stand
persistence from the standpoint that it sets up the cutting schedule for future cuts.
For new seedings, made in the fall, first cut should be made based on stand vigor. If plants are vigorous and well developed an early harvest, at bud stage, can safely be made. If plants are small and poorly developed, as many 2001 fall seeding are, it is best to wait until mid-bloom to begin.
First cut of spring seedings should be made 60 to 70 days after emergence (not planting). This will ensure high root reserves of the developing plant. Final cut of new spring seeding should be made prior to September 10 to ensure that the young stand is able to reach maximum energy reserves prior to winter dormancy. Fall harvest planning is a topic for a future article. For now, start planning for first cut. It will only be a short time away.
Additional information on cutting management of forages can be found on the web at:
http://www.cas.psu.edu/docs/casdept/agronomy/forage/forages.html
http://www.uwex.edu/ces/crops/alf1stcut.htm
http://www.uwex.edu/ces/forage/articles.htm#alfart
