April's Ag Advice By April Borders Winter has been very mild for us and that is both good and bad. It has certainly been nice not having to fight the snow but the lack of snow can cause problems for some of our crops like winter wheat and alfalfa. Snow cover helps protect the alfalfa plants from prevailing air temperatures and weather fluctuations that cause frost heaving.
Winter injury will show up when spring growth begins. The plants may be dead, resulting in thinning of the stand or they may be weakened as a result of partial injury. Check for winter damage early (about mid-April), then make a final assessment when plants reach a height of 4 to 6 inches, which could be as late as mid-May. Six to 10 healthy plants, not stems, per square foot will provide satisfactory yields in pure alfalfa stands, while three to five plants are adequate for mixtures with cool-season grasses.
Do not take the first cutting from an injured alfalfa stand until mid-bloom or later, depending on the degree of injury. This allows the plants time to recover from winter-related injuries and store carbohydrate reserves in the roots. The forage will be lower in quality, but yields will be higher and stand vigor will be regained. A normal cutting schedule, based on optimum maturity stage can then be resumed.
Soil fertility, especially P and K levels, are critical for recovery of winter injured stands. Soil fertility is also important in maintaining and producing a top-quality alfalfa crop. Although some things, like weather, cannot be controlled, many other critical components need to be carefully managed. As the demand for high-quality hay increases, a closer look at the role of proper nutrition is needed.
This is no substitute for maintaining an adequate plant nutrient supply for production of high-yielding and high-quality alfalfa. Alfalfa production removes large amounts of nutrients from the soil that must eventually be replaced to remain sustainable. About 15 pounds of P2O5 are removed in each ton of hay. Since phosphorus has many essential roles in alfalfa, both yield and quality are reduced when this nutrient is limited.
Soils vary in their ability to supply phosphorus and nutrient deficiency symptoms in alfalfa are hard to detect before the deficiency becomes quite severe. Therefore, soil testing is the best way of predicting the potentially available nutrient supply. It is generally best that phosphorus be applied prior to establishing the crop, since an adequate supply of phosphorus is critical for rapid stand development and a strong root system. For established stands, surface applications are a good way to meet plant needs.
Many sources of fertilizer phosphorus are successfully used for alfalfa production, including both solid and liquid forms. The selection of a specific phosphorus fertilizer is generally based on local availability, ease of application and the cost per unit of nutrient. Failure to monitor and replace the nutrients removed in harvested hay will lead to losses of yield, plant stand and profit.
If you have an alfalfa field that is starting to lose stand and production ability after cutting because the field is too old, you can turn that land into high producing pasture if needed. This is a great time to interseed grasses, and maybe some other legumes, into your thinning alfalfa. You'll be able to extend the life of your alfalfa field by several years while providing excellent grazing.
The most common grasses interseeded into alfalfa are orchard grass and smooth brome, but other grasses, like endophyte-free tall fescue, meadow brome, wheatgrass and creeping foxtail also can be used. In addition, other legumes like red clover can be seeded for short-term pasture and birdsfoot trefoil can be used in you plan to graze the pasture more than three years. This will add diversity to your animal's diet and help assure good legume growth for several more years.
You must get these new seedlings off to an early start, so be sure to interseed as soon as soils thaw and conditions allow tractor and drills to operate properly. If your alfalfa still is relatively thick and vigorous, take an early hay cutting, probably during the first week of May, well before buds form. This will allow sunlight to continue to reach new seedlings below the alfalfa. Then use your good judgment regarding competition from the existing alfalfa for subsequent hay cuts. By mid to late summer you should be able to start rotational grazing.
Interseeding grass into existing alfalfa takes timely haying and planting, but both land and livestock will improve with your efforts.
For more information contact the Clay County Extension Office at 677-7111.