As we approach alfalfa harvesting season, it’s important to walk fields to determine how the crop is progressing. Ultimately, harvest timing can be critical to achieving high-quality alfalfa that delivers optimal performance for our livestock.
The following checklist can help lead you to a successful harvest:
- Weather: Unfortunately, weather is something we cannot control. However, weather can have a significant impact on forage quality.
- Temperature: Forages are typically of higher quality when growing conditions are cooler. Increased temperatures can have several detrimental effects, including decreased stem diameter, accelerated rate of maturity, increased lignification, decreased digestibility, decreased plant height, decreased leaf:stem ratio and increased protein content.
- Rain: Forecasted rainfall can be a challenge during harvest. Make sure you’re fully prepared for first-cutting alfalfa so you can take advantage of a good weather window and avoid delays. Delaying harvest increases plant maturity, thus decreasing forage quality. Rainfall on cut alfalfa will decrease forage yield and quality through leaching, respiration and leaf loss.
- Time of day at harvest: It is known that plants accumulate soluble carbohydrates during the daylight; therefore, long sunny days will increase the sugar and starch content of plants. After a sunny day, the sugar content of alfalfa will be the highest in late afternoon and lowest in the morning. Therefore, cutting alfalfa in the afternoon can help to minimize sugar loss prior to harvesting. Cutting during the afternoon will likely increase drying time by nearly 18 hours when compared to morning-cut alfalfa. Depending on the number of acres that you will be harvesting, cutting alfalfa in the afternoon is not always a logistical possibility. Some researchers argue that the increased sugar content is not worth the potential exposure to delayed drying and increased weather risk.
- Reduce ash content: Higher-than-normal ash levels can be a result of picking up additional ash from soil during mowing, wilting, windrowing and chopping. Raising the cutter height can greatly reduce ash content and further increase dry matter digestibility. It is also important to ensure push tractors and delivery trucks are not contaminating the pile with any soil or manure. Increased ash content significantly increases the risk of additional Clostridia spores in the haylage, further creating the opportunity for undesirable fermentation.
- Cutting height: For pure alfalfa stands, cutting at 2.5 to 3 inches is advised. To prevent shortened stand life in mixed stands, this should be increased to 3 to 4 inches if the stand includes brome grass, orchard grass or timothy.
- Drying time: Forage sugar content will decrease due to plant respiration in the field during wilting. Therefore, a rapid wilting process can improve the amount of forage sugar content. One way to decrease drying time is to cut alfalfa in wide swaths, thus increasing the surface area exposed to the sun. If the alfalfa is going to be ensiled, the additional sugar will aid in a more desirable fermentation process.
- Optimal dry matter:
- Haylage: 40–45 percent dry matter
- Dry Hay: 82–88 percent dry matter
- Balage: 45–55 percent dry matter
Emphasizing the aforementioned critical control points can greatly enhance yield, fermentation and preservation of higher-quality alfalfa haylage throughout the 2018 alfalfa harvest season.
Important safety message: Varying weather patterns can cause narrow windows of alfalfa harvest opportunity. This greatly increasing the likelihood of stress, fatigue and a general disregard for your surroundings. Remember to keep yourself and team members rested and hydrated to ensure clear thinking and decision-making is taking place.
Brouk, M. 2018. Harvest and Storage Management. Presented at the Hubbard Dairy Forage Focus Meeting. May 1 and 2, 2018. Bloomington, MN
Linn, J. and M. Raeth-Knight. 2009. Ace Alfalfa Harvesting. Minnesota Dairy Extension Forage Update. https://www.extension.umn.edu/agriculture/dairy/forages/ace-alfalfa-harvesting/