Do More Alfalfa Cuttings Yield More Income?
Researchers from the upper mid-West suggest more income will be available by harvesting four times per year rather than three times, and that more frequent timely cutting will increase forage quality. This increased forage quality will be translated into increased milk production. They do acknowledge that alfalfa stands probably will not always last as long with a 4-cut system. Stand life may be one, two or three years compared with four or five years when only three harvests are taken. Consider the economic implications of varying stand life in Tables 1 and 2.
| Stand Duration (years) | Breakeven Yield (*) (av. for each yr -- ton per acre) | ||
|---|---|---|---|
| $80/ton | $100/ton | $120/ton | |
| 1 | 5.3 | 4.2 | 3.5 |
| 2 | 4.1 | 3.3 | 2.7 |
| 3 | 3.7 | 3.0 | 2.5 |
| 4 | 3.5 | 2.8 | 2.3 |
| 5 | 3.4 | 2.7 | 2.3 |
* - Based on $185/ac prorated establishment cost, and $235/ac annual operating/ownership cost.
Farmers can manage alfalfa for maximum persistence or high quality. Both will influence fall management. For maximum persistence alfalfa should be cut between first flower and 25% flowering. This will average 35 to 45 days between cuttings, so in Massachusetts only 3 cuts will be possible. The first cutting will likely occur in early to mid-June. Yield will be greatest under this management, but quality will be reduced.
| Stand Duration (years) | Profit (in dollars) at Yield Levels (*) | |||
|---|---|---|---|---|
| 3 ton/acre | 4 ton/acre | 5 ton/acre | 6 ton/acre | |
| 1 | -120 | -20 | 80 | 180 |
| 2 | -30 | 70 | 170 | 270 |
| 3 | 0 | 100 | 200 | 300 |
| 4 | 20 | 120 | 220 | 320 |
| 5 | 30 | 130 | 230 | 330 |
For high quality the first cutting should be taken at the late bud stage before the first visible flower. Remaining cuttings should be taken at mid to late bud stage. For alfalfa, the neutral detergent fiber (NDF) should be 40% or less at approximately the late bud stage. This means the first cutting should occur during late May. In some years, buds may not be visible before alfalfa has reached 40% NDF. In such years, if there are no buds by the end of May, alfalfa will likely reach 40% NDF by the first week of June in the valleys and the second week of June in the hills.
For highest quality, the second cutting should be taken 28 to 33 days after the first, and the third and fourth 30 to 35 days after the previous cuts respectively. Ideally, harvest of all alfalfa should occur within a 3 to 4 day period at each cutting. Delaying the harvest of the third cutting will not lower quality of the alfalfa forage as much as it would for the first and second cuttings, but it might prevent a fourth cut without increased risk of winter injury.
Allowing alfalfa to build energy reserves before winter is an important aspect of winter survival and stand persistence. After the third or fourth harvest, there should be a non-harvest period of 4 to 6 weeks prior to the first killing frost. In Massachusetts this would mean the third or fourth harvest should be taken by mid to late August, leaving sufficient time for recovery prior to a killing frost and winter dormancy. This relationship to fall management has been shown to be associated with the level of total non-structural carbohydrates (TNC - sugars and starches) in alfalfa roots and crowns. Root TNC provides energy for plant survival during the dormant season, early spring growth, and regrowth after each harvest. Thus in most years in a 4-cut system it has been suggested that the fourth harvest only be taken after the killing frost.
If the length of the regrowth period following the third harvest is more than 45 to 50 days since the last harvest, a fourth cut might be taken without much increased risk, and without the need for a further 4 to 6 week regrowth period prior to the killing frost. Research at the University of Massachusetts farm showed taking the fourth harvest 6 weeks after the third harvest but before a killing frost had little or no adverse effects on alfalfa regrowth in spring for the first two years of such fall management compared to taking the fourth harvest after the killing frost. However, in the third growing season, there was more stand thinning, remaining plants were less vigorous, and forage yields were reduced compared to a 3-cut management system. Yield for the 4-cut system was less in the spring and throughout the next season. After three years of fall management, 4-cut systems averaged 38.2% weeds compared to 7.6% in the 3-cut system.
Harvesting a late fall cutting will increase tonnage for the season and maybe profitable where winter kill risk potential is low. That is good snow cover and moderate winter temperatures. Both are unpredictable environmental variables. In winters without snow cover, soil temperatures can fall below 15ºF, injuring or killing plants. It is the both severity and duration of the low temperatures that influences alfalfa plant mortality. Tables 1 and 2 were developed with the assistance of Kent Fleming, formerly a Farm Management Specialist for UMass Extension.
While cost values and profits have been generalized and may slightly overestimate operating costs for lower yields and your operating costs, they do show that high yield is the most important factor influencing profit. Many of the costs associated with hay production are fixed. Once yield is high enough to offset total costs, a high percentage of additional yield will be profit. Certainly lengthening the stand life after 2 or 3 years adds much less to profit than maintaining a high yield.
Do more alfalfa cuttings yield more income? They can if timely management results in higher quality forage being fed. High yields need to be maintained. When stand density and vigor deteriorates and yield begins to fall away, rotating the field through a corn crop to capture nitrogen may be the best solution. Maintaining highly productive stands for just 3 years may be the realistic goal for many farmers. For others longer stand duration may lessen the frequency of stone picking.
When considering the last harvest of the season, if the decision is to maintain the alfalfa for another year, then a longer stubble needs to be left to collect protecting snow especially if no further growth is expected. Often the amount of forage available to be harvested after a killing frost may be hardly worth collecting.
Stephen J. Herbert
Dept. of Plant and Soil Sciences
University of Massachusetts Amherst
Crops, Dairy, Livestock News. Vol. 2:2, Summer 1997
