The most important day in the life of an alfalfa stand is planting day. Proper establishment is critical to production of high quality alfalfa hay.
We recommend fall seeding. New Mexico Sate University and Texas A&M Extension suggest producers achieve at least six weeks of growth after germination before the average annual first killing frost (Oct. 16 at Clovis, Oct. 31 at Lubbock). Ten weeks is the maximum time needed. Planting earlier will increase irrigation costs and likelihood of weed problems.
Planting within these time frames allows the crown to establish and form more buds for spring growth and develop a modest supply of root carbohydrates to energize growth before a hard freeze.
Although producers occasionally inquire about it, we do not recommend spring seeding for virtually any reason in this region. Insects are worse on seedling alfalfa in the spring, sand is blowing (unless you have a good nurse crop like well-established oats), and weeds are more competitive. Furthermore, yield in the first year may drop by half or more compared to stands seeded the previous fall.
Sharon Cox, a crop consultant from Lamesa, Texas, says the risk is too high. “You might as well take that money and go gamble in Las Vegas; at least you’ll have more fun.”
A good start is critical.
Variety selection may be over-emphasized by producers and companies as only minimal differences are often observed among varieties in our regional New Mexico State alfalfa variety trials. Yet over the life of the stand these can add up for varieties that consistently yield well.
Until recently, producers typically targeted varietal choice based on Fall Dormancy scores. The lower the number, the more dormant and more winter hardy the variety. Some alfalfa breeders have broken the link between dormancy and winter hardiness, and as a result, some higher FD rated varieties can be seeded further north.
Use trial data
This will make FD less important regarding winter survival; still, most producers probably will continue to focus on FD ratings as well as regional adaptation to target alfalfa variety selection. All West Texas uses the NMSU variety trial data extensively and the Texas panhandle will also eye western Oklahoma results for appropriate varieties.
Less dormant varieties usually green up earlier in the spring and recover faster after harvest and grow later into the fall. Less dormant alfalfas should produce more forage per year, mostly due to a longer production season. These factors often permit additional harvests.
One consideration for extending stand life is fall harvest management. One might get by with a shorter harvest interval during the summer months when alfalfa tends to bloom quickly, but alfalfa needs a 6- to 7-week rest between the last harvest and the first fall temperature of 28 degrees, or between the last two harvests if one is scheduled near the anticipated average freeze date. This will allow the plants to store enough energy to survive the winter and regrow in the spring, which is critical regardless of FD category or variety.
The concern with less dormant varieties in this region is that they will continue to grow during the winter and with frequent freezes, root energy becomes depleted by springtime, resulting in stand loss. Infrequent freezes often simulate harvest interval and have less effect.
Producers should set aside concerns about seed cost and select several varieties with a broad cross section of Resistant (R) and Highly Resistant (HR) ratings. The National Alfalfa Alliance annual variety leaflet (available for download at http://www.alfalfa.org) reports insect and disease resistance ratings.
Other factors in varietal selection include a seed dealer you like, seed availability, and expected life of the stand (which is favored by more dormant alfalfas).
Ultimately seed cost does become a consideration, but with alfalfa you probably get what you pay for. Both Texas and New Mexico Extension staff recommend producers ensure that seed is recent seed and inoculated within the past year with nitrogen-fixing Rhizobium bacteria.
In addition, seed treated with a fungicide such as metalaxyl, can avert some seedling disease risk. Finally, certified seed helps provide safeguards for genetic purity, minimal weed seed contamination, good germination, etc. Any seed sample can always be submitted to the respective state’s department of agriculture for testing for growers interested in older varieties, commons, or other seed sources.
While poor variety selection restricts productivity, even with top management, be assured that poor management will reduce productivity by even the best variety. Proper establishment is the next factor paramount to a successful crop.
Local seeding rate preferences vary depending on location, seed cost, and producer objectives. Normally in the New Mexico High Plains and for Lubbock north we suggest 15 to 20 pounds of seed per acre. Below Lubbock, seeding rates increase 5 pounds per acre. Keep in mind, however, that poor seedbed conditions, seeding into cloddy, trashy soils, or using an airplane will require a higher seeding rate.
"Producers would be better off using recommended seeding rates on a properly prepared seedbed, which is described below."
First, soil test. But don’t get hung up on fertility recommendations as much as your lab’s determination of whether nutrient status ranges from very low to very high.
Nutrient removal by alfalfa is high. University research shows alfalfa hay harvest removes high levels of nutrients in each ton of forage: about 50 pounds of nitrogen (mostly supplied by Rhizobium bacteria nodulation on the roots), 12 to 14 pounds of phosphorus (P2O5) and 50 to 60 pounds of potassium (K2O) are removed in each ton of forage.
In New Mexico and West Texas producers should incorporate not only the first year’s phosphorus requirement but also the second. Surface applications are hard to get into the root zone in subsequent years. For establishment, if soil N levels are very low, apply 25 pounds or less per acre.
A firm seedbed is of utmost importance. As a rule of thumb, when you walk across a good seedbed for alfalfa your shoe heel shouldn’t sink into the soil more than three-eights of an inch. Otherwise, seed placement for optimum germination at depths of only half an inch (perhaps three-quarters to one inch for very sandy soils prone to drying quickly) is hard to achieve.
Although seedbeds with few clods and no trash are preferable, some producers use reduced tillage or leave some crop residue on the surface, which complicates alfalfa seeding but can be overcome with appropriate seeding equipment. Producers might increase seeding rate a few pounds per acre to reduce risk of poor seed to soil contact.
Targeting alfalfa production for high quality, something that can satisfy a dairy, requires planning and management. Instead of taking chances on the risks we know about for successful alfalfa establishment and production, we encourage producers to maximize opportunities to expand options with high quality alfalfa.
Alfalfa Resources on the Web:
New Mexico: http://cahe.nmsu.edu/pubs/research/agronomy/ and http://cahe.nmsu.edu/pubs/_a/