Not a Nitrogen fixer but a rapidly growing annual crop that will not only lift nitrogen from the soil but will also scavenge for phosphate which is also taken up and released for any subsequent crop on incorporation. Buckwheat produces a large amount of biomass and although it’s large leaves give generally good weed suppression, some of the ground hugging weeds may survive under the canopy.

With a high seeding rate a relatively expensive seed, Buckwheat has a limited appeal for green manure use and tends to be used more in the UK for game cover. The ideal sowing time is April or May when there is no risk of frost.

Suggested sowing rate 70 kilos/hectare (30 kilos per acre)

An annual clover, grown to produce a rapid boost in soil fertility. It is especially useful for short breaks in intensive horticulture. Like most clovers, Late March – Early May or Mid – Late August are the best times to sow for a successful establishment.

Suggested sowing rate 15 kilos/ha (6 kilos/acre)

Although not a legume, because it grows in colder temperatures than most crops, Forage Rye is the ideal crop for holding Nitrogen and reducing leaching over the winter period. It is normally sown on its own or in combination with Vetches to give an excellent winter hardy cover. Because of its cold tolerance, it can be sown later than any other green manure crop, being sown in September or even October. It establishes quickly and gives excellent weed control. Because of the high sowing rate, Rye tends to be one of the more expensive of the cover crops although the later sowing time means that it has the distinct advantage that there is less of a rush to get it in after the previous crop than the majority of other cover crops.

Suggested sowing rate 180 kilos per hectare (75 kilos per acre)
Organic seed is sometimes available

One of the most rapidly growing grasses, Italian Ryegrass can be sown as a pure stand or with Red Clover or Vetches. It will go over 1 or 2 winters and has a certain amount of frost tolerance although topping prior to the winter is always an advantage. It will produce large amounts of green material but needs topping regularly during the growing season to prevent it going stemmy and producing seed heads. Italian Ryegrass can be sown from Late March to Late April or August to Late September.

Suggested sowing rate 35 kilos/hectare (14 kilos/acre)
Organic seed is normally available

UK livestock farmer are now showing interest in Lucerne, it has the potential to provide yields of 10-15 tonnes of dry matter per hectare. Lucerne is highly digestible, with high protein, rich in trace minerals and is an excellent source of fibre. With the added advantage being a legume, it will fix nitrogen too.

Typical silage analysis

• ME 9.7-11.1MJ/KG/DM
• Crude Protein 16-24 %
• D-value 70D
• PH 4-4.6

These nutritional values will save on farm imported proteins.

It is typically grown as a stand-alone crop, and usually grow for silage, but it can be grazed. With good management practices it will persist for 5-6 years. Modern varieties have been selected for their suitability for the northern European climate and are therefore suitable for the UK. Lucerne will leave considerable residual nitrogen allowing following crops to thrive. Lucerne suits most soil types however, it prefers soils that are well drained, a pH between 6.2 and 8.5 (ideally pH7), and where perennial weeds are not an issue.

Lucerne can be grown successfully with grass as a mixture. During drought periods as we have experienced of late in the UK and due to Lucerne’s drought tolerance, dry matter yields from grass and Lucerne mixtures have been several times higher than grass alone.

To get the best returns from Lucerne:

• Select a variety that is suitable for the UK
• Time between cuts a minimum of 5 weeks
• Optimal cutting height of 7cm
• Cut when at the flower buds
• Allow to flower once a year to allow nutrients to be stored in the tap root giving winter hardiness and early spring growth.

Sowing Date: From April through the spring. Summer sowing in August and early September will result in heavier crops the following spring.

Sowing Rate: Sowing rate of 8 kilos per acre as a straight stand, or as a mixture 50% Lucerne and 50% Grass up to 70% Lucerne and 30% Grass.

Mustard is one of the cheapest cover crops and grows rapidly lifting nitrogen from the soil and holding it until ploughed in. Because of its quick growth it is an excellent weed suppressant. Mustard can be sown any time after late March and will flower after around 6 weeks so is a very short term cover crop. Mustard doesn’t require topping during its growth stage but it is best to top it before incorporating.

Suggested sowing rate 20 kilos/hectare (8 kilos/acre)
Organic seed is normally available