According to University of California Alfalfa and Forage Specialist Dan Putnam, ensuring a high enough quality for your alfalfa crop is certainly important. Yet, making sure that cutting meets your feed quantity needs—and overall economic returns for the animals that crop is feeding—is the highest priority.
“Cutting schedule is, overwhelmingly, the most powerful method under a grower’s control to manipulate forage quality, since both maturity and leaf percentage are impacted,” Putnam says. Yet, he adds, “If yield and stand persistence were not important, the earliest possible cutting dates would typically provide the highest quality forage, but these cutting intervals would rarely provide optimum economic returns.”
The dilemma of whether to cut for quality or yield is often referred to as the “yield-quality tradeoff.” The reason for this relationship is relatively simple, according to Putnam. There is a linear increase in yield as alfalfa matures from very early to very late growth stages. In contrast to yield, as alfalfa matures, there is a linear decline in forage quality (protein, relative feed value, relative forage quality or total digestible nutrients). “Leaf percentage declines, along with increased lignification of the stem, make late cuts a ‘double whammy’ that causes severe quality decline as the crop matures,” he says.
At the same time, later harvest schedules tend to improve stand persistence compared with cutting early. “Taking all harvests early is a sure recipe for stand loss,” Putnam adds. When stands decline (fewer plants per square foot), weeds begin to intrude, lowering the quality of subsequent harvests.
One Solution: A Staggered Approach
So, what to do? Rarely is there a single strategy that works for any one producer. That’s why Putnam recommends cutting schedules that target, during a given year, some harvests for quality and others for yield and stand life.
“A more integrated ‘staggered’ approach to harvest—balancing yield, quality, persistence and economics—promotes persistent higher hay quality,” he says. “Vary the interval and give fields a ‘rest’ at different times during the summer. Allow the plants to go to full yield, enabling them to deepen root systems, and crowd out weeds.”
That breather for a stand of alfalfa is, according to Putnam, vital both for its ability to produce in the short and long term. That’s because alternating the number of cuttings benefits the root and crown health, and therefore may also help maximize quality and yield later in the year and the next. Mixing strategies also assures a supply of both high- and medium-quality hay during the year, as well as the necessary tonnage for feeding goals.
Other Factors Affecting Time of Cutting
Seasonality and Temperature: The effectiveness of staggering harvests during the growing season to sustain alfalfa growth in the long term does have one caveat: Summer heat can stress growing plants, making it important to base a staggered harvest approach as much on attentiveness to weather conditions as on the calendar.
“Vary the interval and give fields a ‘rest’ at different times during the summer when producing top dairy quality is difficult to accomplish due to summer heat,” says Putnam. “This allows greater quantities of carbohydrates and nutrients to be translocated to the roots to replenish what we call ‘root reserves,’ which improves stand longevity and prepares for subsequent harvests.”
Time of Day … or Night: There is also a benefit to afternoon harvests due to the accumulation of soluble carbohydrates, or sugars. “Sugars contribute directly to TDN; thus, afternoon harvests may improve quality,” Putnam adds. Depending upon the rapidity of curing, this advantage may or may not be reflected in the final hay product.
Moisture: Another consideration is available moisture during baling, says Putnam. “Dew can provide much-needed softness and leaf retention.” That’s why, he says, “nearly all growers in the West bale at night or in early morning during summer months to maximize leaf retention.” It’s also important to bale when plant moisture levels themselves are right, allowing the crop to retain as much of its leaf content as possible while drying down before baling. The ultimate goal is to bale between 12 and 22% moisture. The exact time frame depends on the size of the bales, as larger bales are at greater risk of molds at higher moisture content.