While things are muddy with hints of green in northern Ohio, we are hearing from colleagues in central and southern Ohio that spring is definitely here and bringing things to life, including pasture grasses and hayfields. After green-up happens in your part of the world, it’s the ideal time to be scouting hayfields and pastures for winter damage, legume crown health, heaving of the root systems, and pesky winter annual weeds. Over the next few weeks, it may be necessary to rescout fields as they receive additional frost freeze events and ponding rain fall.
Depending on where you are located and what type of forage fields you have, winter damage may be one of the most significant reasons to be scouting for now. In northern Ohio, where we do not have a lot of grass hayfields or pastures, but alfalfa fields are plentiful. This is yet another year for major concern. There was never a period of more than 5 to 6 days where the ground was frozen in most of the state, and the same can be said for snow cover. Both of these things can be good for an alfalfa field if they last. But when they do not and leave behind standing water, or provide for constant freeze-thaw cycles throughout the winter, alfalfa and other legumes can suffer and even die. Recent walks in some alfalfa fields in north-central Ohio have revealed just what we are concerned about...heaving of the crown and root system, which can lead to disease, less stems and lower yield, and eventual crown die-off. In some cases, as we saw in the spring of 2020, and again last year, when warmer temperatures occur sporadically in February and March, followed by short freezes, the roots will heave enough to expose the taproot and many plants will not even survive into April and May. Remember, alfalfa suffers from cumulative stress loads – once it is stressed in some way, its yield potential and life expectancy goes down permanently, and those stresses add up over the life of the stand. So be sure to get down to ground level when scouting and observe those alfalfa crowns to see if field renovation with grasses may be necessary, or if there may even be enough die-off to warrant crop rotation and an alternative forage plan for 2023.
If you do observe significant heaving, but crown health seems to be intact, or at least the plant will attempt to produce enough stems to offer a profitable tonnage, adjustments on the hay mower may be in order before first cutting. Cutting too low on heaved crowns can not only damage the crown and slow regrowth but can also damage the root system, often causing immediate death and no second cutting. Growers should certainly be looking at how many healthy crowns and/or stems per square foot are visible in alfalfa fields to make a decision on whether or not to keep that stand. Most forage specialists and researchers commonly use 55 and 40 as key numbers when assessing stem counts. This means a good stand of alfalfa has 55 or more healthy stems per square foot, and yield potential is still at or near 100%. When a field falls between 40 and 55 stems per square foot, yield is still acceptable and considered economically viable, but counts below 40 indicate that the stand should be rotated to another crop and a new field prepared. At 40 stems per square foot you can expect about an 80% yield, and when counts fall to 30 stems, yield declines to 60% of the maximum dry matter yield. Additional factors such as taproot health, asymmetrical growth out of a crown, or discolored crowns should also be considered along with stem count when assessing a field. When doing your stem count, don’t count the stems on crowns that are unlikely to survive first cutting, such as stems that have heaved more than 2 inches out of the ground. When reviewing crown health, the charts below can help you rate crowns (Undersander et al., 2011). A healthy stand will have less than 30% of crowns rating 3 or 4 and no crowns in the count rating 5, which are dead plants.
After you have completed your stand assessment and if renovations are needed to meet your forage needs, begin lining up seed now. Marginal stands can be improved with grasses and clovers for a couple more years of forage production. If stands are poor, there are many options for summer annual forages to meet your forage needs. Some of them are easier to make as dry hay, such as Teff grass, Italian ryegrass, or Berseem clover. Summer annual cereal grain forage such as oats, spring triticale, or spring barley are other forage options that could possibly be made as dry hay but may be easier to harvest as silage or baleage. Spring seeding new alfalfa fields is an additional option if planted with a companion crop, which can result in forage this year and a full stand ready for maximum yield next year. Higher-yielding options such as sorghum, sudangrass, sorghum-sudan, or corn silage can also be planted with higher yields achieved with May plantings than June plantings with all of these crops.
Undersander, D., C. Grau, D. Cosgrove, J. Doll, and N. Martin. 2011. Alfalfa Stand Assessment: Is this stand good enough to keep? University of Wisconsin-Madison, Accessed March 30, 2023, https://fyi.extension.wisc.edu/forage/alfalfa-stand-assessment-is-this-stand-good-enough-to-keep/