The 2018 drought has placed pressure on many forage systems and highlighted the need for more resilient forage production. Lucerne a very deep rooting and drought tolerant legume and has been a minor crop in the UK for many years. However in dry seasons on the right soils it comes into its own, producing good yields of high quality forage at a competitive cost.
Historically, many growers have perceived that the problems surrounding soil type establishment and ensiling have outweighed the advantages of a drought resistant low nitrogen requiring perennial crop. Like most legumes, Lucerne performs best on alkaline soils with a pH above 6.5 and it does not tolerate water logging especially during the winter so free draining soils are important. Lucerne is slow to establish and takes up to 12 months and for this reason is best under sown under a cover crop of spring barley. Planting a companion crop of Timothy or a small leaved clover will help to provide full ground cover.
Mistakenly some growers think that as a legume Lucerne has a low fertiliser requirement, whilst this is true for nitrogen, Lucerne has a high need for phosphate and potassium, removing approximately 3.3 Kg P, 10 Kg K, 5 kg Ca and 1.3 kg of Sulphur for each tonne of Dry Matter. For recommendations see table below:
Under organic management, application of farm yard manure and slurry should be applied when the crop is dormant with FYM best applied in the autumn. Establishment is probably the single most important factor if the crop is to reach full potential for up to 5 years. Many growers have tried to establish this like a grass in the early autumn only for the plant to fail to germinate until the following spring. Under sowing under a spring cereal has proved successful as long as the cover crop is not too thick and reducing the seed rate by at least 25% is recommended.
As a legume, Lucerne needs to work with the correct nitrogen fixing bacteria which are not native to the UK and therefore if Lucerne has not been grown before the seed needs inoculating either by the seed supplier or at the point of drilling.
The quality of Lucerne silage in terms of energy is always significantly lower than rye grasses although protein levels are considerably higher and often averaging in excess of 19% with no nitrogen fertiliser.
Ensuring good fermentation is critical as the crop has lower sugars than ryegrasses. Good clamp management is critical as is ensuring that the crop has a dry matter of at least 28%. One problem often quoted is that with small quantities being grown ensuring that a consistent diet can be fed is often impossible. With the advent of woven top silage sheets and fewer tyres on silage clamps it is now not such a difficult task to unsheet a clamp and ensure that the Lucerne is ensiled in layers. Alternatively, Lucerne can be baled but care needs to be taken to ensure that the stems do not puncture the silage wrap.
Many farmers are afraid to graze Lucerne because of fears of bloat. This can be overcome as long as grazing is delayed until at least 20% of the crop is in flower, and there are now a number of European bred varieties that are suitable for grazing.
Post-harvest management is critical if the crop is to survive for more than 2 or 3 years and this requires the crop to replenish the root system. For this reason the crop needs to reach full flower at least once in the growing season.
Compared to short term conventional leys Lucerne works out at up to 10% more expensive but has lower annual capital invested due to lower fertiliser requirement.
Contact William at firstname.lastname@example.org or your local FCG office for more information on Lucerne.