Lucerne management

 

1. Establishing a new field

Choice of variety
It is important to choose a good, reliable variety which enables you to produce high quality yields for a  period of 3 - 4 years. Many lucerne varieties are offered very cheaply to the market but are often what are  known as “ecotypes”. Ecotype varieties, also known as “Italian types”, have limited adaptability to areas  outside their original growing area which makes such varieties less persistent. Therefore, an ecotype variety  will last for fewer years on a field compared with Barenbrug varieties. Seed quality is a second point for  attention because in general the seed quality (purity and germination) can be much lower. Moreover, cheap  ecotype lucerne often contains harmful weeds such as Cuscuta which kills the Lucerne in the field.


Please note that Barenbrug lucerne seeds are produced under strict control and certification and are free of   these harmful weeds.

 

Soil type and requirements
Fields selected for growing lucerne should meet the following requirements:

  • Possibility of deep rooting; no disturbance in the subsoil.
  • Well drained.
  • The pH-KCl on sandy soils: minimum 5.5.
  • The pH-KCl on clay soils: minimum 6.0.
  • No lucerne grown on the field in the last 4 years.
  • Low weed pressure.


Sowing
Lucerne is grateful for soils with good soil structure. Compressed soils need to be loosened first. Before sowing, the top soil should be flat and fine. The soil preparations for sowing lucerne are similar to those for sugar beets.

 

Sowing period Seed rate Sowing depth Row distance

From: mid-March - end of April*

Until: end of August*

25 - 30 kg/ha 1 - 2 cm 8 - 12.5 cm**

 

This might vary depending on the area of usage.
** On fields with low weed pressure, a larger row distance can be used up to 22 cm. In this case the weeds  can be controlled (mechanically) by harrowing.

 

Sowing period

  • After sowing in springtime, up to two cuts can be harvested in the sowing year.
  • Look out for snail damage if sowing in August (particularly after winter wheat).


Seed rate

  • To increase the yield of the first cut and to improve the control of weeds during establishment of the  lucerne (on clay soils), it can be mixed with Trifolium alexandrinum (25 - 30 kg lucerne + 5 kg Trifolium  alexandrinum).
  • If you intend to control weeds mechanically, it is better to increase the seed rate by an extra 5 kg of  lucerne per hectare.

 

Row distance

  • If you expect problems with weeds, use a narrow row distance.
  • Using larger row distances enables you to use mechanical weed control (harrowing machine).
  • Using a sowing machine with broadcasting coulters will give better spreading of the plants. This will give weeds less of a chance.


Inoculating with Rhizobia
With the aid of the Rhizobium bacteria in the root nodules, the lucerne plant will fix nitrogen from the air.  Therefore, additional nitrogen fertilization is usually not necessary. However, Rhizobia are not freely  available in all soils, so it may be necessary to add inoculants during sowing. Even better, use coated seeds  with a Rhizobia inoculant. Barenbrug has developed a special Yellow Jacket seed treatment to ensure good  establishment and nitrogen fixation during growth (for more information, see page 5). The use of inoculated  seeds is generally recommended.

 

Mixing lucerne with grasses
It is possible to mix lucerne with grasses but only a few grass species are recommended for this purpose. Prior to sowing, the two species can be mixed and drilled at the same time. The best combinations of grass with lucerne are given in the table.

 

 

Mixing Partners Seed rate (kg/ha)
  Lucerne Grass
Lucerne - Cocksfoot 10 - 15 8 - 10
Lucerne - Bromus 15 - 20 25 - 30
Lucerne - Bromus 15 - 20 15 - 20
Lucerne - Tall fescue 10 - 15 10 - 12

 

2. Fertilization

Lucerne is a perennial crop with high demands in terms of soil fertility. Soil analyses will be essential to  determine the soil fertility and to set up a fertilizer plan. The main recommendations for fertilizing lucerne  are given in the table below.

 

Lime (CaCO3) Apply lime for minimum pH of 5.5 on sandy soils and 6.0 on clay soils.
Nitrogen No N fertilizer required, under good soil conditions the Rhizobia will supply N.
* 25 kg N/ha at sowing will improve establishment.
Phosphorus Depending on yield level when soil P is sufficient:
* 80 - 110 kg P2O5/ha on sandy and river clay soils.
* 50 - 80 kg P2O5/ha on sea clay and sea sandy soils.
Potassium Depending on yield level when soil K is sufficient:
* 180 - 220 kg K2O/ha on sandy soil.
* 150 - 190 kg K2O/ha on clay soil.
Magnesium 50 kg MgO/ha only on sandy soil.

 

3. Control of weeds and pests

 

Weeds
Weeds are easy to control mechanically. For this purpose, a harrowing/weeding machine can be used once  the lucerne is well-established. If you decide to control weeds mechanically, an additional 5 kg of seeds per  hectare at sowing time will be necessary to compensate for damaged plants.

 

Remarks:

  • Weeds growing above the lucerne can be controlled by mowing (topping). Mow as soon as possible, but mow the weeds only.
  • Don’t cut lucerne too short. This will give faster regrowth of the lucerne and better competition for the weeds.
  • Avoid damage from traffic. Lucerne is susceptible to this. Use low pressure tires.

 

Chemical weed control
Due to differences in legislation and registration of chemicals between countries, we recommend that you  contact your local distributor or advisory service about this issue.


Diseases and pests
Lucerne can be susceptible to diseases and pests. The species will remain healthy for a long period and  control is seldom necessary. The following problems might occur and can be controlled as follows:

 

Sitona weevil
  • This insect eats the margins of the leaves.
  • Can be controlled with Parathion* as soon as damage is visible.
  • Apply Parathion during dry and sunny weather.
        If necessary repeat the application.
Bacterial wilt
  • The top of the stems will wilt and the leaves will become yellow.
  • Can be avoided by:
  • Use of a more extended crop rotation.
  • Choice of variety (US varieties are resistant, but they carry the disease with them onto the farm!).
Verticillium wilt
  • Symptoms begin as temporary wilting of upper leaves on warm days.
  • Use an extended crop rotation. Choose Verticillium resistant varieties (Derby, Artemis, Sanditi, Alpha).
Anthracnose
  • Starts with lesions on the stem, after which upper part of stem dies off.
  • Occurs under high temperatures in old lucerne fields.
  • Use resistant varieties.
Nematodes
  • Infected plants have swollen nodules and turn yellow/brown.
  • Don’t cut under wet conditions.
  • Use clean seeds.
  • Use high nematode resistant varieties (see variety descriptions).

* Can only be applied if this chemical is registered in your country.

 

4. Harvesting and yield

Harvesting
Although lucerne can be grazed, the use of the crop as silage creates the initial interest. Lucerne is very  well-suited to zero-grazing systems (fresh feeding) and for making silage. The regrowth of lucerne is very  strong depending on the availability of food reserves stored in the roots. Just at the beginning of flowering,  sufficient food reserves are present for good regrowth of the crop.

 

Recommendations:

  • The best time to cut Lucerne is when 5 - 10 % of the plants are flowering.
  • Lucerne is susceptible to damage from traffic, so don’t cut it under wet conditions.
  • Stubble length:

         - 5 cm before flowering or when the first flowers are not fully out.
         - 7 - 10 cm at 5 - 10 % flowering. Lower cutting heights will kill the new sprouts.

  • If Flemish types (winter dormant types) are used, make sure the plants are able to recover following the cut before they go dormant in the autumn. It will also be possible to mow late in the autumn and let the lucerne go dormant with bare stubble instead of having new sprouts.
  • Frequent cutting at a very young stage will exhaust the crop too much. It will persist only for about two years. It is better to cut at least twice a year at the beginning of flowering (5 - 10 % flowering). If the crop is too weak it will be better to let the crop flower fully before cutting. This will ensure the lucerne persists for 4 - 5 years. There will be no risk of losing feed value because the digestibility and palatability of lucerne are less likely to fall in comparison with grasses.

 

Silaging
Spreading the lucerne after mowing will increase leaf loss. It is therefore better to cut the Lucerne with a  mower + conditioner. After this the crop can be turned carefully. After one day of dry weather the product is  usually ready for silaging. Using a chopper tends to give the best results. The use of a reliable silage additive  is strongly recommended. Compressing and closing the clamp as soon as possible will ensure a good fermentation process.


Dry matter yield
The number of cuts in the sowing year (spring sowing) will be limited to two to three cuts. The dry matter  yield in the first year will about 6 - 9 tonnes. In the second year the total dry matter yield can vary between 12 - 17 tonnes depending on the dormancy class of the variety. Varieties with a high DC will give more cuts  per year resulting in a higher dry matter yield per ha.

 

 
5. Nutritional aspects

Well silaged lucerne is very palatable to cattle and provides excellent rumen stimulation. The stems stimulate  the rumen, improving digestion. The saliva produced by animals during rumination results in  stabilisation of the rumen pH. The main advantage of lucerne is the fast digestion of the crop. The rumen   remains full of feed without the risk of congestion. As a result, lucerne offers a lot of effective fibre in  combination with high dry matter intake.


Lucerne is also a highly nutritious forage for dairy cattle. It combines good digestibility with high protein. For dairy cattle, lucerne silage is the most suitable forage type, whereas lucerne hay will be more suitable for  feeding young stock or horses. Lucerne provides excellent milk yield despite the fact that lucerne silage has  lower energy per kg dry matter compared with grass silage.


However, farmers can enhance the feeding qualities of lucerne by cutting it earlier, just before flowering.  This results in more energy (ME/MJ Nel/VEM) and protein per kg dry matter (see table). Earlier cutting is only  possible if selected varieties are used, such as Sanditi and Artemis. For all other varieties, it is recommended that you cut when the plants show 5 - 10 % flowering. The table below gives an example of the differences in forage qualities which can result from early cutting compared to normal cutting of lucerne silage.

 

Lucerne silage Early cut Normal cut
Crude protein (g/kg dm) 210 172
Crude fibre (g/kg dm) 228 303
Crude ash (g/kg dm) 139 119
Digestibility organic matter (%) 70.5 64.5
VEM/Mj Nel/ ME 797/5.8/9.4 719/5.2/8.5
Dry matter intake (kg) 14.2 13.3