Crop goals key to determining lucerne harvest schedule
Date: 20 November 2017
When scheduling your lucerne harvest, it is important to first determine what the yield, quality and persistence goals are for your crop.
When harvesting for high quality, the first cut should be taken early in the season when the plants are around 30-40 cm in height. Leave a 7-10 cm residual after cutting to encourage a fast growth.
The remainder of the cuts should be taken at the 30-40 cm height, up until the longest day; this is generally 35-45 days. After the longest day we need to let the crop flower to around 50% flower once.
Once the flowering cut is removed for hay or low-quality feed we can go back to the 35-45 day cutting interval and 30-40 cm height guide to maintain high quality and high yield cuts.
Targeting a lower height at cutting will result in high quality lucerne, but yields will be lower and harvest costs will increase. However, if we harvest higher than around 40 cm, quality will be reduced. This is because the proportion of leaves decreases, and the stem increases in lignin and other fibrous constituents (cellulose and hemicellulose).
To enable maximum persistence, it is important we let the crop mature to 50% flower once a year, around January/early February. At this time radiation levels are high, along with day temperatures, so the crop will flower very quickly and will be shorter in height. This is to allow the lucerne to build up its carbohydrate root reserves for winter and the subsequent spring production.
If you are aiming for both optimum yield and quality, the cuts before the longest day (in the spring) must be timely. During this time forage quality changes quickly as and short delays can negatively impact quality.
It is recommended that cutting takes place from late morning to mid-afternoon, as leaf sugar and starch concentrates are slightly higher than any other time of the day.
Cutting fresh lucerne at the optimal stage of maturity and feeding it directly to your animals year-round would supply the highest quality and most palatable feed possible.
However, fluctuations in seasonal growth and plant maturity, as well as changing animal feed requirements, means it may be necessary to harvest and store the lucerne crop to maximise quality and quantity.
There are also a few benefits of harvesting lucerne for silage as opposed to hay: these include lower field losses when harvested as silage; less leaf loss, resulting in more nutrients for feeding; consistent forage quality; and greater ability to harvest the crop at ideal maturity as less rain-free weather is required for silage.
Overall, to make the most of your lucerne harvest, an early harvest followed by a short cutting yield gives a high yield of quality forage.