BY: Clark Israelsen, a Cache County Extension agent specializing in agriculture.
Cache County has experienced an abundance of snow and rain in recent months. Happily, reservoirs are full to overflowing, snowpack continues to be deep, underground aquifers are recharging and there should be plenty of irrigation water for the hot months of summer.
This abundance of moisture has also created some difficulties. One discouraging problem is dead and declining alfalfa stands that have literally drowned from too much water. Certain fields with some degree of slope are just fine, but wherever there has been standing water, especially on heavier soils, much of the alfalfa is dead.
The question now is “what to do?”
When alfalfa stands decline to less than 5 plants per square foot, the decision must be made to either extend the life of the stand by over-seeding with annual forages like oats, beardless barley, triticale or ryegrass, or to remove the alfalfa stand and rotate to a new crop like corn or warm-season grass.
If a grower has no place to go with silage, they may consider inter-seeding perennial grasses like tall fescue, meadow brome, orchard grass or perennial ryegrass into declining stands of alfalfa. Perennial grass yields may be marginal the first year, but after establishment these grasses will yield quite well at first cutting and respectable later in the season. Over-seeding new alfalfa into existing alfalfa stands is usually not effective because mature alfalfa plants produce an autotoxin that inhibits the growth of new alfalfa seedlings.
Seedbed preparation is very important for successful establishment of any over-seeded crop in declining alfalfa stands, and seedbed conditions are seldom ideal. Usually, a minimum amount of tillage is required.
The objective of seedbed preparation is to break up the soil surface in the top 1 to 3 inches, with enough tillage to kill weeds, but with minimal damage to alfalfa crowns. Normally one pass with a spring-tooth harrow or a light discing is all that is necessary. If weed pressure is high or if the ground is hard, two passes may be required.
Prior to tillage, excessive weed growth can also be removed with herbicides. After seedbed preparation, planting can take place by broadcasting or drill seeding or using a no till seeder. The field may need to be rolled behind the planter to firm the seedbed, break clods, optimize soil-seed contact, and enhance germination.
Over-seeding can also be done using a conventional grain drill without seedbed preparation, provided the soil is sufficiently soft to allow penetration by the drill and to cover the seed.
Agronomists from the Universities of Minnesota and Wisconsin published an interesting paper identifying alternative forages to replace winter killed alfalfa. In their study they replaced declining alfalfa with corn silage, sudan grass, sorghum x sudan grass, hybrid pearl millet, foxtail millets, soybeans, Italian ryegrass, barley and peas, orchard grass and oats. Plots were planted in early to mid-May, early June and early July. Obviously, the cool-season plants responded best to early plantings while the warm-season plants did better with later plantings.
It was no surprise that corn silage provided the best tonnage and energy levels, even with later plantings. Sudan grass and sorghum x sudan grass also yielded quite well, but prussic acid poisoning was a concern, especially after frost.
The millets needed warm soils but provided outstanding yields within two months. Italian ryegrass was also quite impressive, with a dry matter yield of 6 tons and notable feed quality. Orchard grass yielded 3.7 tons per acre and oats produced 2.3 tons during their trials. Orchard grass had an advantage of being perennial, while all other entries were only annuals.
A recent article by Mike Rankin in Hay and Forage Grower magazine suggests a growing acceptance, even preference, to planting alfalfa-grass mixes instead of being “a pure alfalfa disciple.” The article says there are good reasons to feed a mixture of alfalfa and grass in both dairy and beef rations.
For dairy, this has been precipitated by feeding a higher percentage of corn silage in the rations. High levels of corn silage usually contain elevated levels of non-fiber carbohydrates (NFC) which are linked to higher incidences of lameness in cattle. Grasses have higher neutral detergent fiber (NDF) content than alfalfa, but they are also more digestible and more quickly digested. As such, Rankin contends they are a good fit for elevated NFC diets.
In the case of wintering beef cows, alfalfa hay has more than adequate protein, but may be limited by energy. A high-quality alfalfa-grass mix can help to moderate the protein consumption while adding a bit more total digestible nutrients.
Admittedly, selling a grass-alfalfa mixture can be more difficult because dairies have come to prefer pure alfalfa. Rankin also confesses that there can be a significant variation in forage quality from year to year and cutting to cutting in alfalfa-grass mixtures. This always makes for an ornery dairy nutritionist, but late-maturing varieties of orchard grass and improved tall fescue options have helped.
Grass will also grow in spots where the alfalfa has declined or died. This is certainly preferable to weeds invading bare spots. In mixed stands, weed control with herbicides becomes more complicated. For those who graze alfalfa fields in the fall, concerns of bloat are reduced when grass is inter-seeded with alfalfa.
Those who are really struggling with the idea of planting grass into alfalfa may consider another advantage. Knowing how we are often troubled by persistent storms, grass-alfalfa mixtures often dry more rapidly after cutting than pure alfalfa. As such, rain damage to the hay may be minimized. If it does get rained on, the mixture usually suffers less injury, both in the windrow and in the bale.
For Grass/Alfalfa/Corn seed and more, contact:
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