These two things make for quality alfalfa
|By Mike Rankin|
Much gets written and discussed about making high-quality alfalfa. In fact, there could be an entire volume of Encyclopedia Britannica dedicated to the topic.
If we were to list the factors involved in making quality alfalfa hay and haylage, where might we start?
I suspect the list would look different depending on who is asked. Though items numbered three through the end of the list might make for good debate, it seems to me that the two items topping the “Family Feud” survey board ought to be time of cutting (plant maturity) and leaf retention.
For me, it all starts with time of cutting because there’s nothing that can be done to improve the nutrient concentration of a late-cut crop; it can only be maintained or made worse. Most everyone understands the ramifications of cutting late from a forage quality perspective. We also know that cutting too early can result in a significant yield hit.
The more interesting but challenging key to great forage quality is leaf retention; it’s very close to plant maturity, and a factor that some people may even have in the top slot.
Why is leaf retention so important?
Consider this: Leaves have a neutral detergent fiber (NDF) value of 15 to 20 percent and a relative forage quality (RFQ) of about 550. Stems have an NDF value of 60 to 70 percent and an RFQ of only 70 to 80. Virtually all of the protein value of alfalfa is also in the leaves.
Standing alfalfa is, on average, about 50 percent leaves and 50 percent stems at the bud stage. In research studies and farm field determinations, the average decline in leaf content following a harvest is about 20 percent. However, the amount of leaf loss can be quite variable, ranging from a small percentage to over 40 percent of the total leaf content.
Many sources of leaf loss
The tricky thing about leaf loss is that it occurs at multiple production points. Fungal diseases can be responsible for significant leaf loss, especially within the canopy. It can also intensify as the crop matures, bringing us back to time of cutting as our first priority for high-quality alfalfa.
In cool, wet environments, foliar fungicide might provide an economic benefit when applied at earlier growth stages, though the forage quality response has been shown to be variable.
Leaf loss also occurs during cutting and conditioning. Flail-type conditioners work well for grass crops but act as large leaf strippers in alfalfa. Roll conditioners, either rubber or steel, are a much better option in alfalfa.
One practice that is not done often enough is to check the ground both before and after cutting to assess how much leaf loss is occurring before any swath or windrow manipulation even begins.
Once the crop is cut, leaf loss becomes a function of wilting crop moisture at the time of machine operations. This is why, all things being equal, haylage and baleage will be higher quality than dry hay as more leaves are conserved. This is not to say that dry hay can’t be exceptional quality, but tedding or raking when the crop is too dry can be an alfalfa leaf-loss disaster.
Small square and round balers hold the highest risk for leaf loss. In the arid West, moisture is often introduced back into the drying hay by baling at night or by some mechanical means such as a steamer. This is sometimes done at great expense but is evidence to the importance of leaf retention when forage quality drives the business.
Although there are many other factors that impact alfalfa quality, a focus on time of cutting and leaf retention will go a long way into accomplishing the ultimate goal. Weather can wreak havoc with even the best laid plans, but there are always things that can be done to get more leaves into the barn or silo.