The Value of Short Rotations with Intense Cutting Management
John Squire, PhD, CCA, Agronomist
Producers who raise quality alfalfa for dairy or beef know the value of a good crop of hay. Even those who raise alfalfa for horses know the value their customers place on the crop. They also know that in many cases the hay market for horses will give a higher price than dairy hay. This provides motivation to manage alfalfa in a way that yields the most return per acre. Therefore the intent of this article is to demonstrate the value of short rotation alfalfa and discuss a late fall harvest to boost yield as well as return per acre.
Since alfalfa is a perennial crop, people want to leave the stand in place for as long as possible to save the expense of planting something else. After all, if the field looks good and seems to be producing in an acceptable way, why replace it? Try turning the question around and asking why not replace it? Are you really better off with a four year old stand of alfalfa than planting something in its place? The answer, according to the Dr. Dan Undersander of the University of Wisconsin is no. You are financially better off rotating out of alfalfa after two full crop years. These cases refer to the establishment year as year zero and the first full crop year as year one.
Annual alfalfa yield has the largest impact on crop profitability on the positive side. In fact, profitability and alfalfa yield are so tightly related that best efforts should be made to maximize annual production. The challenge in keeping production at a maximum is a thinning stand as the years pass. Research from alfalfa variety trials conducted by universities indicates that average yield declines 10% in the third production year and 24% in the fourth year (these are well managed systems with competitive varieties). Consider an annual yield of 6 tons per acre and a value of $100 per ton. Just a 10% loss in yield translates to $60 per acre lost that year and a 24% loss means losing over $140 per acre a year!
The loss of $60 dollars per acre and the added nitrogen (even a bigger advantage as nitrogen prices are very high) to a following crop, make short rotations very attractive. In fact, as the alfalfa stand gets older/thinner there may be less nitrogen available to a following crop. The shorter rotation results in more acres being planted to alfalfa every year and more rotated from alfalfa to corn. The savings in insecticide costs to control corn rootworm following alfalfa can help cover the expense of seeding the alfalfa on other fields. This short rotation provides higher corn grain yields, reduces nitrogen expenses, brakes up disease cycles, and eliminates corn rootworm feeding in corn following alfalfa.
Don’t get caught in the snare of thinking that a field still looks good after three or four years and that you still get an acceptable yield. Remember, a 10% yield loss is not likely to be detected and a 20% loss may look like only a slight loss. Weeds start to invade older stands to reduce yield and quality. Even thought a stand may look good, that doesn’t mean the yield is at the level it should be.
You may say that seed companies just want to sell more seed so they promote short rotations. Yes, we want to sell seed, but we feel this is a service to the agriculture community and we believe these practices will increase grower profits. The way to improve profits with alfalfa is to maximize yield by: making good decisions in variety selection, soil inputs, harvest timing, pest management and crop rotation.
Another consideration to maximize the return from an alfalfa stand is to harvest a late fall crop. This can provide an added income if there is enough regrowth to make it worth the effort. The benefits of taking a late harvest include getting a little more yield that is normally of higher quality and which would normally be lost to the winter. If not harvested, the stalks from fall growth will reduce the value of the first crop hay. These dead shoots are undesirable because they have very poor quality and reduce overall quality. Research from the University of Minnesota indicated a Relative Forage Quality (relates to RFV) value of 99 for a crop with residue remaining from the fall, verses an RFQ of 169 without residue in the first crop. So the potential benefit is added yield of high quality feed and increased quality of first crop the following year since there are no dead stems from the fall.
The hazard of this type of approach is the risk of losing a stand due to stress and winter kill. In the past, some – if not many – have discouraged producers from taking a fall crop of alfalfa. The risk in taking a fall crop is that it will stress the plant so much that it reduces yield the following year and may ultimately kill the plant. If the fall cut is taken so late there is little or no regrowth, then the risk is reduced. In traveling the countryside there are various places where people take a fall harvest and others in the area don’t. There have been mixed results with this sort of management – hence the risk involved.
There are many factors affecting the risk of winter kill. These include soil moisture (at harvest and during the winter – dry soils are preferred), soil fertility, drainage, texture, snow cover, variety, stand age, diseases in the area, regrowth after cutting, and so on. Some may decide the risk is too great in killing the alfalfa and not take a fall cutting. One question to address when considering a fall harvest is the intention for a given alfalfa field. If it is an old stand and will be rotated anyhow, why not take a fall crop? On the other hand, young stands tend to be more resistant to winter kill, so the risk is lower with short rotations. In the event that the field of alfalfa does die, there is still the nitrogen credit that is available to a following crop or two.
The way to manage a field for a late fall cut is to allow about five or six weeks of growth from the last cut before taking a final crop. This is sometimes referred to as a 3 + 1 or 4 + 1 system, where the “+1” means a harvest taken late in the fall when other people would leave it in the field. The final crop is taken late enough in the fall that the alfalfa will not regrow after cutting. The early regrowth phase (1-2 wks after harvest) is the period that depletes the root reserves and predisposes the field to disease and death.
In the end, these approaches to alfalfa management can provide enhanced return per acre. But they are not without risk. This article has provided suggestions of reducing that risk or managing around it. We would even recommend using 9429, Awesome, or eXtreme alfalfa varieties as they were selected for very good winter hardiness and good disease tolerance. The point to remember is that these tools can enhance profitability. Short rotations can increase return per acre to a cropping system and proper cutting management, including a fall harvest, may be a strategy to consider. Remember, increased profits come from more intense management.
This article was written referring to:
Value of Short Rotations for Alfalfa Profitability. By Dr. Dan Undersander of the University of Wisconsin . Available at: http://www.uwex.edu/ces/forage/pubs/short_rotations_for_alfalfa.pdf
Influence of Fall Growth Management on Alfalfa Quality and Yield the Following Year. A report of a research/demonstration project near Lake City , MN . Involving Steve Drazkowski, Dr. Paul Peterson, and Jim Halgerson of the University of Minnesota .
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