Things to consider:

Aim of the cover crop - nutrient capture, compaction relief, increasing organic matter.
Duration of the crop - is it a summer catch crop, or an over winter option?
Options such as Phacelia or Mustard may have problems later on in the season with the bulk produced, and trying to get the following crop in.

Phacelia

leaching prevention

increased soil organic matter
soil structure
weed control.
attracts bees.
suitable with OSR in the rotation

Vetch

N fixation
organic matter
soil structure
some weed control.

Ideal before OSR

Mustard

Leaching prevention
Builds organic matter.
Improved soil structure

Weed control.

Radish

Leaching prevention
Builds organic matter.
Improved soil structure – tillage radish is great for compacted soils.

Weed control.
Some nematode control depending on type.

Berseem Clover

N fixation
Some weed control.

Easy to incorporate.

Crimson Clover

N fixation
Rapid spring growth
Will grow on poor sites.

Buckwheat

build organic matter.
some weed control.
Easy to establish.
Encourages bees and wildlife.

Phosphorus scavenger

Westerwolds

N lifter
Large root mass
Provides a bulky hay or silage crop – ready to cut after 12 weeks.

Suggested mixes:

Grabber – 80% Rye, 20% Vetch

Autumn DM - 80% Rye, 15% Vetch, 5% Phacelia

EcoCover - 80% Rye, 20% White Mustard

Sprinter – 80% Black Oats, 30% Vetch

N Fixer – 80% Red Vetch, 20% Berseem Clover

Green Reward – Rye, Oats, Radish, Mustard, Vetch & Phacelia

Soil Improver – Oats, Mustard, Radish & Phacelia

Commando – Oil Radish, Carbon, Mustard

Red Reviver – IRG & Crimson Clover

Soil Conditioner – Rye, Buckwheat, Linseed, Oil Radish, Mustard & Phacelia  

Most mixes can be sown between August and September to create an over winter cover.

Following on from the cover crop trial we ran over the winter of 2020, we have introduced some of our own new mixes which incorporates some of the species trialled.

The mixes have been designed to create useful options which will benefit both the soil and the surrounding environment. These mixes are not exhaustive and can be amended or bespoke mixes can be created.

Why use a mix?

Mixes are a great way to maximise the individual benefits of the species. Using species with different rooting depths and growth habits offers the most advantages, improving the soil for future uses.

Choosing a mix or even an individual species should be decided by what you want to achieve - for example, relieving compaction or reducing nutrient run off. Other crops in the rotation should also be considered, as volunteers or species in the same family could cause problems.

New Bartholomews Mixes

Soil Erosion Mix

50% Black Oats

3% Phacelia

10% Buckwheat

25% Oil Radish

12% Crimson Clover

Brassica Free Mix

15% Vetch

5% Crimson Clover

80% Rye

Brassica Free Mix 2

3% Phacelia

25% Buckwheat

25% Berseem Clover

47% Vetch

Beneficial Insect Mix

15% White Mustard

50% Rye

5% Crimson Clover

5% Berseem Clover

25% Buckwheat

Other Key Benefits

Reduced leaching and run off - environmental impacts/ protecting our countryside good farming practice.

One of the greatest pollutants from agriculture is diffuse source pollution, which can arise from both nitrate leaching and soil run-off which deposits phosphates into surface waters in the UK. Both nitrates and phosphates in surface waters cause detrimental effects to local water sources, such as eutrophication which causes excessive algal blooms that reduce oxygen levels in the water and therefore reduces biodiversity in surface waters. Nitrates leach over winter when winter rainfall washes out nitrogen in bare soils not covered by a crop, whereas phosphates, which are bound to soil particles are deposited into surface waters by soil erosion. This is most prevalent in soils which have poor soil structure. Over 55% of river water bodies and 73% of lake water assessed for P in England failed the revised phosphates standards for good ecological status according to a survey carried out by the Environment Agency  in 2019. These statistics highlight the problems caused by agriculture to our local environment, but you can help reduce these pollutants on your farm by planting a cover crop such as our Grabber mix or our Soil Improver which will scavenge for leachable nitrates and help bind the soil thereby preventing further phosphate deposition in your local water.

Organic matter/ climate change and carbon sequestration

Asides from preventing soil erosion and phosphate enrichment of local surface waters, the beneficial effects of cover crops on your soil structure includes the building up of soil organic matter. Soil organic matter is the organic fraction of the soil, formed from decaying organic material such as vegetation and animal deposition. The carbon from the decayed vegetation is stored as complex carbon chains which forms organic matter. These carbon chains are often depleted by heavy tillage systems in arable farming and consequently the average arable farmer in the UK may only be achieving 1-2 % organic matter. By growing cover crops and incorporating into your soil, you are helping to reduce your farms carbon footprint as you are capturing the carbon otherwise released to the atmosphere into the soil. As well as reducing the amount of carbon in the atmosphere, soil carbon sequestration can also improve soil health and its ability to retain warmth, moisture, and fertility; all of which are conducive to crop growth. A study by Defra found that, where soils were as low as 1% organic matter, cereal yields could be as much as 5% lower than soils containing 4% organic matter; implying that the building of soil organic matter is linked to yield.

Better soil structure

Cover crops which have vigorous rooting such as black oats and forage rye help form good aggregates within the soil, opening pores for free movement of air and water which is good for crop growth. Other species, such as tillage radishes have extremely strong tap roots which can break up compaction in soils thereby reducing the need for expensive machinery passes to break up the compaction.

Weed control

As outcompeting weeds is a well-known cultural control of weeds, growing a cover crop can form an integral part of an Integrated Weed Management programme. Certain species, such as White Mustard, Forage Rye and Berseem Clover are very vigorous at growing and therefore outcompete and suppress weeds. This natural suppression in weeds can lead to reduced herbicide use which is better financially and environmentally to the farmer. Other species, such as Black Oats may have some allelopathy effect on weed growth. Allelopathy is the secretion of natural chemicals by one plant to inhibit the growth of another.

Speak to our cover crop team today by calling 01243 755788, or email seed@bartholomews.co.uk

Choosing summer cover crops