Never underestimate the value of a good soil testing program, Lang said. “This costs a fraction relative to its benefits.”
For alfalfa, soil test at least two years ahead of seeding to determine soil pH and apply lime as recommended at least a year before seeding. For P and K, follow soil test recommendations. Don’t over-fertilize due to cost, but don’t skimp on recommended rates due to profit potential.
“In Iowa, we have seen large yield responses to sulfur,” Lang said. “However, the soil test is not a reliable indicator for this nutrient.”
He recommended about 15 pounds per acre of sulfur in the seeding year and double that rate for each production year. A plant analysis can help determine if a field is deficient in sulfur.
Lang advised to take the same care in selecting alfalfa varieties as with corn hybrids. Choose those yielding in the top 5 to 10 percent of variety trials that include the winter survival ratings appropriate for your region and high disease resistance ratings necessary for your field conditions.
“For alfalfa, this usually means high resistance for all common root and stem diseases,” Lang said.
Cutting height has an impact on both yield and quality of harvest. Lang recommended a cutting height of 2 to 3 inches for alfalfa (inches above the soil), but no shorter than 4 inches for grasses. Alfalfa regrows its most robust, higher yielding shoots from the crown of the plant, and alfalfa stores its regrowth reserves in the crown and upper taproot. While cutting this short also reduces forage quality a little, Lang said the improved yield potential from cutting low maximizes milk per acre. However, he noted, most grasses store regrowth reserves in the lower stem, and cutting too short hurts the regrowth potential.
Can a short rotation provide more profit? Yield of a “well managed” four-cut system is maximized in the first and second years following the seeding year, said Lang. Typically, year three’s yield declines to about 85 percent when compared with the first two years’ yields. The fourth year often drops to about 70 percent of the first two years.
Rotating after two full years of production may provide other economic benefits such as a higher frequency of nitrogen credits to the corn rotation, higher corn grain and silage yields (following alfalfa versus corn), and a higher frequency of corn rootworm control, reduced corn leaf disease issues compared with continuous corn and reduced potential for developing herbicide resistant weeds.
Lang recommended doing a stand count at the end of the stand’s second year, when the plants are about 8 to 10 inches. If there are 55 or more stems per square foot, chances are high the field will yield near 100 percent the next growing season. If there are 46 to 47 stems per square foot, yield will be about 85 percent, and less than 40 stems will result in a 65-percent yield.
Harvesting methods can also have a large impact on quality and quantity of alfalfa.
Flail or impeller type conditioners were development for grass production, not alfalfa. They tend to have a 2 to 3 percent higher dry-matter loss versus rollers for conditioning alfalfa.
A wide swath maximizes drying time, Lang said. A 12-foot cutting width laid in a 9-foot swath instead of a 6-foot swath will have a 35 percent faster drying time. A wider swath can reach 65-percent moisture in five to eight hours, allowing haylage harvest in a day and reaching dry hay conditions at least half a day faster. This reduces dry matter loss in the field and improves forage quality.
If you do not have a haybine that can provide a wide swath, a tedder could follow the haybine. This adds some dry matter loss and increases wheel traffic on a field, but it can reduce dry-down time of a hay crop by as much as half a day.
Wheel traffic should be minimized as much as possible. Use equipment only large enough to do the task, Lang advised. Mergers can be advantageous in reducing overall traffic where harvest equipment can handle the larger volume windows. If you need to drive on fields for manure application or other purposes, do it as soon as possible after harvest. When a field is driven on two days after harvest, the wheel tracks generally cost about 13-percent yield. Tracks made five days after harvest generally cost about 28-percent yield.
(Source – http://www.farms.com/news/alfalfa-quality-and-quantity-8-factors-in-your-control-91091.aspx)