The Alfalfa Challenge
(En anglais seulement)
By: Kent Kammermeyer
Before reading this article, take a quick test by checking all that apply:
- I am a deer manager who won't settle for second best.
- I want to grow the Cadillac of deer forages.
- My friends call me meticulous, competitive, discriminating, and obsessed.
- I don't keep up with the Joneses. I am the Joneses.
- My thumb is extremely green.
- I have access to spraying and haying equipment.
- I have reasonably fertile, well-drained soils in fields larger than three acres.
If you checked several of the above, but especially the last three, you might be a candidate for growing alfalfa.
Alfalfa is among the Cadillacs of deer forages, but just as there are reasons why we don't all drive Cadillacs, there are reasons why every deer manager cannot successfully grow alfalfa - a long list of them. But the obstacles to success with alfalfa can be overcome if you know what you must accomplish when you set out, and if you have the resources to meet your goal. Consider the following, then decide for yourself if you are up for the alfalfa challenge.
Known as the "Queen of Forages," alfalfa is one of the most palatable and nutritious forage crops, and it also the oldest in cultivation - it originated in the Middle East and was first introduced into United States by colonists in 1736.
Alfalfa is rich in protein, with levels ranging from 20 to 30 percent depending on growth stage. It is also high in digestible energy, vitamins and minerals, and it has a very high yield potential, in the range of five to six tons of dry weight per acre, per year.
Alfalfa is a perennial legume that is erect-growing with many leafy stems arising from large crowns at the soil surface. A mature plant will have multiple stems which can reach the height of 24- to 36-inches tall. Stems are branched and slender and bear three leaflets. The flowers of most varieties grown in the South are normally some shade of purple. The plant's long taproot makes alfalfa drought tolerant.
Alfalfa is currently grown in most areas of the United States accounting for nearly 30 million acres of production, mostly for hay. Depending on variety, it is adapted to the entire United States, however it can be difficult to grow in the Deep South. For best production, it requires a well-drained soil with neutral pH (6.5 to 7.0) and good fertility. In particular, alfalfa needs lots of potassium.
Alfalfa is used primarily as a hay crop, although new grazing varieties are available that tolerate moderate grazing but should still be hayed as needed (see the inset on haying for more information). With careful management and selection of varieties, it can be used successfully as a strong perennial food plot for deer, remaining productive for three to five years. Stands have been known to persist for five years or more if adequately fertilized and cut at the proper stage of growth.
Alfalfa Variety Characteristics
The older varieties of alfalfa could not withstand heavy continuous grazing like you get from a high deer population grazing in small, isolated food plots. With the introduction of grazing-tolerant varieties, this has changed, and many small-field plantings of alfalfa for deer have been successful in recent years. For deer food plots, besides selecting a variety that was developed to resist heavy grazing, varieties of alfalfa are available with specific characteristics bred for fall dormancy, winter hardiness and resistance to insects and diseases. As a general rule, the greater the fall dormancy, the better the winter survival and overall persistence is going to be for any given variety. Weak winter hardiness can cause lower forage yield in spring and reduce the life of the stand by two or more years. However, dormant varieties have less vigor, less late summer and fall growth and lower forage yield potential than the less dormant types. Fall dormancy is important in the North but not generally in the South where winter low temperatures are more forgiving.
Regardless of variety, it is important to time the last fall cutting of alfalfa hay so that there will be about six inches of re-growth to establish a strong root system going into winter. Even so, if your deer graze it back to two or three inches in the fall, your stand is vulnerable to winter injury.
A snow cover of six inches or more protects alfalfa plants from severe cold. During winters without snow cover, soil temperatures can fall below 15° F, injuring or killing plants. Warm fall weather and midwinter thaws can cause alfalfa to break dormancy and have less resistance to freezing.
Selecting the right alfalfa variety can be bewildering. Hundreds of alfalfa varieties are rated on fall dormancy, winter survival and resistance to various diseases and insects. Go to www.alfalfa.org and click on "Variety Leaflet" for the 2005-2006 edition of ratings entitled Winter Survival, Fall Dormancy & Pest Resistance Ratings for Alfalfa Varieties. A few of the recommended grazing varieties that you will see in these ratings include: Alfagraze (north and central), Amerigraze 401 (north and central), Amerigraze 702 (southeast) and Amerigraze 701 (southwest). Better yet, consult your local county agricultural agent, seed dealer, or agronomist for even more grazing varieties that will do well in your area.
Soil Requirements and Seedbed Preparation
Alfalfa is a heavy user of plant nutrients. Careful pre-planning is very important in establishing alfalfa, and it should go without saying that a soil test is the first step. Applications of fertilizer and lime should be based on annual soil-test results.
A pH of 6.5 to 7.0 is necessary - slightly over 7.0 is even better. Alfalfa does not tolerate acid soils below a pH of 6.2, especially in the seedling stage. Adding a ton of lime per acre to the amount recommended by the soil test ensures neutral pH and can add a year or more to the lime longevity before re-application is needed. Apply lime six to 12 months in advance and incorporate to six inches depth by disking. Phosphorus (P) levels should be at 90 units per acre and potassium (K) levels at 250 units per acre split over at least two applications per year. K should be applied after the first hay-cutting in spring and after the last cutting in late summer to ensure a continuous supply to the plants.
Sulfur, if called for in soil-test recommendations, and boron should be broadcast and incorporated prior to seeding.
Since alfalfa is a legume, nitrogen (N) application is not necessary but, if applied at planting, should not exceed 40 lbs./acre. Never apply N on established alfalfa stands.
Alfalfa requires a deep, permeable soil with an adequate moisture supply. It is sensitive to poor drainage and compacted soil conditions that restrict root growth. A good seedbed for alfalfa is finely pulverized, leveled, and firmed to the seedling depth. Perfect planting conditions also include ample soil moisture from about two inches of rain just prior to seeding, if you can time everything right. This will ensure good seed germination and plant establishment. When possible, use a pre-emergent incorporated grass herbicide such as Eptam. When incorporated at three- to four-inches deep it will keep most grass competition under control.
Planting Date and Seeding
Most alfalfa seeding in the United States occurs from August to October or March to April. Northern ranges usually require sowing in August or April, while Southern plantings do better in September or March. In spring, plant near the average date of the last frost. Fall plantings tend to be more weed free and should be planted at least six weeks before the date of the average first freeze.
All alfalfa seed should be inoculated immediately prior to seeding or purchased pre-inoculated. Inoculated seed should be kept reasonably cool until planted.
For best seedling survival, drill seeds approximately ¼-inch deep. Seedling emergence is greatly reduced when seeds are planted deeper than ¾ of an inch. If you broadcast the seed, cultipack the soil after broadcasting. A firm seedbed is critically important for establishing alfalfa and prevents heaving during freezing and thawing conditions.
Seeding rates are 15 to 20 lbs./acre for drilling and 20 to 25 lbs./acre when broadcasting. Mixing with small grains is not recommended because of competition in the early seeding stage. Alfalfa can be mixed with red or ladino clover at reduced rates (5 lbs./acre of clover to 15 lbs./acre of alfalfa) but this practice is not recommended, again because of competition in the early stage, with alfalfa generally being more sensitive than the clovers.
Insects, Diseases and Weeds
More than 20 diseases can be serious problems for alfalfa in the United States. These include fungal and bacterial wilts, anthracnose, leaf spots, crown and root rots, viruses, and nematodes. Resistant varieties are available for most of the diseases and nematodes listed. The document mentioned earlier from www.alfalfa.org covers disease resistance.
There are also a number of insect pests on alfalfa in the United States. These include the alfalfa weevil, clover leaf weevil, blister beetles, several aphids, potato leaf hoppers and the alfalfa plant bug. Depending upon the severity of the infestation, chemical control of insects may be necessary to maintain a healthy, productive stand.
Weeds can also be a serious problem with alfalfa, especially in spring planted stands. In all plantings, preparing a smooth, firm, weed-free seedbed is essential. Use of pre-emergent chemicals (see above) may be necessary. Watch for warm-season weed competition in the spring and treat accordingly as needed with post-emergent selective chemicals. Chemical selection depends heavily on the offending weed species, as each has different vulnerability to the selected chemical and some chemicals can seriously weaken alfalfa stands.
Here again, when it comes to identifying and combating diseases, insects and weeds in alfalfa, seek advice from your local Extension agent.
Each year after planting, follow fresh soil-test results in re-applying P and K and control weeds and insect pests such as the alfalfa weevil as needed. You will need to cut and remove hay (near 50 percent bloom stage and before most of new crown growth reaches bloom height) down to three inches tall as needed in late spring and summer when growth exceeds the deer herd's ability to graze the growth down to three or four inches.
Roundup Ready Alfalfa
Several varieties of Roundup Ready Alfalfa from several different companies have recently been approved by the EPA for sale and growth in the United States. Roundup (glyphosate) is a broad-spectrum herbicide that kills a wide range of plants. It is not normally applied directly to crops. The Roundup Ready technology incorporates genetic resistance to glyphosate into crop plants by inserting a single bacterial gene that modifies an enzyme essential for plant growth. Monsanto has used this technology to develop several Roundup Ready crops, including cotton, soybeans, and corn.
Roundup Ready technology will enable the development of new weed control strategies for alfalfa. Specifically, these new varieties will allow glyphosate to be applied over the top of the entire crop to control a wide spectrum of annual and perennial weeds commonly found in alfalfa (always refer to the herbicide label for the full spectrum of weeds controlled and application guidelines). Several of these weeds, especially perennials, are difficult to control using conventional herbicides or non-herbicide weed-control methods. Although scientists at Monsanto and Forage Genetics International have developed the technology, Roundup Ready alfalfa varieties will be marketed broadly by a wide range of seed companies. Important characteristics, such as genetic resistance to insects and diseases and yield potential, remain important criteria for selecting a variety. The Roundup Ready trait enables a unique weed control program to be used in alfalfa. You should be prepared to spray for weeds multiple times during the growing season.
Your seed dealer should have access to Roundup Ready varieties by the spring 2006 growing season. Be prepared to pay a premium price for this seed! You may have to plan on spraying high rates per acre multiple times per year depending on weed species, weather and stand density.
Why You Need to Hay or Mow Alfalfa
New growth is the nature of the highly productive alfalfa plant. Haying at the half-bloom stage (when half of the plants have begun to bloom) takes out mature growth as it moves past the nutritious vegetative stage and into flowering and seed production. Haying serves to rejuvenate the stand, setting it back to nutritious, young growth again. It encourages new crown growth as it discourages fungal diseases that often occur on old crown growth. Haying also removes a potentially thick mulch that smothers new growth, provides a medium for diseases and adds nitrogen (N) to the soil, which shortens the life of the alfalfa stand and fuels weed competition.
Mowing (especially with a mulching mower) is a poor substitute for haying but is still much better than doing nothing. Mowing removes old crown growth and rejuvenates the stand but still drops the dead mulch back on top of the new growth, reducing the life of the stand. Mowing instead of haying may reduce the longevity of alfalfa stands to a maximum of three years instead of five or six. Not cutting the stand at all reduces longevity even more.
Summary and Comments
Alfalfa is not a panacea or a miracle plant. It is dormant from November to April in most of the United States and is therefore a poor choice by itself for cool-season forage. Small grains, clovers and brassicas do better in this period. Alfalfa is expensive and somewhat difficult to establish. It requires careful management, including strict attention to pH and fertility, especially potassium, chemical spraying for insect or weed control, and removal of excess growth for hay, if possible.
Despite all this, alfalfa can be worth the effort in the right program. Alfalfa is an excellent forage plant for deer. It is highly productive, palatable, nutritious and persistent. Well-managed alfalfa stands can be highly productive for five or more years. If you haven't gathered this already, alfalfa is a good choice for the deer manager with good farming equipment, including sprayers, and plenty of farming experience.
I would not recommend planting more than 50 percent of available food plot acres in alfalfa and would not plant it in fields smaller than three acres in size. Plant the remainder of your acreage in a bona fide cool-season mixture such as clover/small grain mixes. Monitor alfalfa stands closely, and aggressively treat for weeds, insects or diseases as needed. Once again, do not skimp on potassium fertilizer!
One final piece of advice - put your local agricultural Extension agent on speed dial. Invite him or her over for Sunday dinner at least twice per month from April through October as you carefully and methodically pick his or her brain for alfalfa maintenance tips.
Consider yourself informed about alfalfa and the extensive planning and care that go into a successful crop. Still think you qualify as a potential alfalfa farmer? Go for it!
About the Author: Kent Kammermeyer is a senior technical advisor to QDMA who recently retired after 30 years as a wildlife biologist with Georgia Department of Natural Resources. Kent served as the Georgia White-tailed Deer Committee chairman for more than 20 years, and he has published more than 250 popular articles on deer management and food plots. In 2005, Kent was honored with the Career Achievement Award from the Southeast Deer Study Group, becoming the eighth person to receive the award.