Blogpost: Preparing the ground for #OurField: Cover crops and how to terminate them

As you all know, #OurField is all about grains, or “cereals” - which along with legumes, are one of the two main types of commercial grain crops. “Cereal” is the word used for any grass cultivated for the edible components of its grain - like rye and wheat for example!

The question on many of your minds is likely to be around what comes first: planting the seeds! Traditionally, cereal crops are planted in the autumn. However, since we are kicking off #OurFieldWeston mid-winter, this means our farmer John will be planting a ‘spring crop’ - which is usually sown around March-April time. A no-till farmer like John will drill two weeks later than a conventional farmer, meaning that most likely the #OurFieldWeston seeds will be sown towards the end of April.

One factor to consider is that this is weather dependent and a warm spring could mean an earlier start for John. The collective’s first decision will be around what crop John will sow in #OurFieldWeston: an exciting decision which will set the scene for the rest of the growing season. This will happen around the end of February so John has enough time to procure the seed in time for planting.


In the meantime, John has been moving forward on decision-making around a crop that comes before even planting our chosen cash-crop. This is called the cover crop. Read on to find out what a cover crop is, and the sorts of decisions John is making around how to “terminate” this crop to make way for our grain!


What is no-till farming?

No-tillage farming is a farming practice where the soil is minimally disturbed from planting to harvest. During the planting process, holes are drilled into the soil where the seed will be planted and then covered up. This method leaves ground surface in tact, along with the residues from the previous crop.


No-till is a conservation agriculture system growing in popularity across the UK. It means no ploughing, no disturbing the soil and its natural structure in order to plant the seed. As the land is not ploughed, residue ((a fancy word for “plant leftovers”)) from previous crops is left on the surface of the ground preventing moisture from evaporating and reducing water run-off. By not disturbing the soil and leaving previous crop residue on the ground the soil ecology gets healthier creating the conditions for beneficial insects and soil microbes to thrive. The increase in soil health and water infiltration can boost cash crop yields.

John’s farm has been no-till for 5 years. He held a conference called Groundswell at Weston Park Farm in 2016 to bring no-till farmers together to learn about this practice. Read more about the pros and cons of no-till farming here.


 John, pictured left, on his farm in Hertfordshire

John, pictured left, on his farm in Hertfordshire

“No-till at it’s simplest is a form of establishing a crop with the minimal disturbance of the soil.”

John Cherry, Groundswell Agriculture

Why do we need a cover crop?

The no-till farming movement goes hand in hand with planting ‘cover’ crops as part of a crop rotation in a field, before planting the cash crop. What is a ‘cover’ crop, I hear you ask?

“A cover crop is a plant that is used primarily to slow erosion, improve soil health, enhance water availability, smother weeds, help control pests and diseases, increase biodiversity and bring a host of other benefits to your farm.”

Research shows that cover crops can increase the yield of the cash crop grown on the field after them. They stabilise the soil structure, making the soil resilient to wind or water erosion, a weather predicament usually out of a farmer’s control. In the case of no-till farming, cover crops which break down to a residue on the surface of the ground retain moisture, preventing it from evaporating and helping it to infiltrate into the soil.

Some cover crops take longer to break down than others, bringing about different benefits. Non-legume cover crops (e.g. grasses)) are high in carbon and low in nitrogen, taking longer for soil microbes to break down. This makes nutrients in the residue less available to the next crop (( called ‘nitrogen scavenging’)) and increases organic matter in the soil. However, legumes, low in carbon and high in nitrogen, break down faster making nutrients readily available for the next crop (( called ‘nitrogen fixing’)) but not adding as much organic matter. Using the right cover crop can be a great alternative to using  various inputs to the soil used in conventional farming, such as nitrogen-based fertiliser, pesticides, fungicides and weedkillers, while providing similar benefits. Cover crops can reduce the necessity of these inputs in conventional and no-till farming systems.

 Worm hunting on #OurFieldWeston!

Worm hunting on #OurFieldWeston!

Often a ‘cocktail’ of different cover crops are planted to get all of these  benefits. In the case of #OurFieldWeston, a winter ‘herbal ley’ cover crop of legumes, brassicas and linseed has been planted. This is a yummy combination of key plays providing nitrogen scavenging and fixing while keeping weed and soil erosion under control. Pioneering farmer Newman Turner, a great advocate of herbal leys, described them as his “fertiliser merchant, food manufacturer and vet all in one”. You can read more about herbal leys and Newman Turner here - we’re a big fan of him and his motto of ‘health from the soil up!’.

 Herbal ley cover crops on #OurFieldWeston

Herbal ley cover crops on #OurFieldWeston

The legumes will add nitrogen to the soil improving conditions for strong growth of the cash crop which is planted afterwards. The brassicas and linseed reduce the amount of weeds which grow as soil microbes take longer to break them down due to their high carbon content. This means they take longer to release nutrients which give life to the weeds, and they keep the ground covered preventing them from springing up. All cover crop species in the cocktail will prevent soil erosion by stabilising the soil with deep root systems and add critical organic matter to the soil. They also provide the right habitat for advantageous insects ((disadvantageous insects can cause havoc!)) and pollinators like bees by providing them with a food source of pollen and nectar.

The cover crop is not harvested like a cash crop. When the cover crop has done its job the farmer will ‘terminate’ the cover crop ((more on terminating cover crops in just a second)) leaving the residue on the ground before or just after the cash crop is planted. It has to die in order to break down, and allow for the cash crop to gain all the benefits from the cover crop residue.

Read about cover crops in more detail here.


How do we  terminate cover crops?

The cover crop on #OurFieldWeston will need to be terminated in January leaving a residue on the ground which the cash crop will be planted through in the Spring. A lot of the cover crop has already been killed by heavy frosts in the first months of winter ((how handy!)) and there are various ways to terminate the rest. So what are they?


Crimp it!

A cold spell in January could bring another crippling frost, a delight for a farmer ready to terminate their cover crop. The frost will destroy some of the cover crop and make the rest vulnerable, so the farmer can jump on a tractor and terminate the cover crop by ‘crimping it’. This means rolling the field with a ‘crimper roller’ which has blunt blades or knives arranged on a cylinder to flatten or crush the stems of a cover crop so that it stops growing and dies. The residue left from the cover crop prevents weeds from growing, protects the soil from erosion and conserves soil moisture before planting the cash crop in April.


Round it up?

Conventional farmers can terminate cover crops by spraying them with Monsanto-produced herbicide Glyphosate, - a.k.a. the infamous Roundup! . Cover crops can be sprayed before or after planting the cash crop. John has previously tried this with oats planted straight into a cover crop and then sprayed with Roundup to kill the cover crop. This worked well as oats are a very hardy plant and grew well despite being sprayed with the herbicide. The cover crop died and the residue remained on the ground, providing organic matter and preventing weeds from springing up.

However, wheat and barley planted into a cover crop and then sprayed tend to struggle because the cover crop residue rots on the ground and kills the vulnerable seedlings. Roundup doesn’t work so well in lower temperatures so it is recommended to do this when the weather warms up to over 10 degrees in the Spring. Roundup is used a lot in conventional farming, but not everyone is a fan, read more here.


 #OurFieldWeston cover crops close up

#OurFieldWeston cover crops close up


Get your sheep involved

Some farmers use animals to graze off cover crops, and the herbal ley cover crop on #OurField is a particularly good choice for grazing livestock on. Herbal leys are often planted with livestock in mind - as they can be an excellent source of a healthy, wholesome and mineral-rich natural feed, and make up part of a holistic farming system! Excitingly, John has already been approached by a farmer who would like to graze his sheep on #OurFieldWeston.

The livestock graze off the crop, leaving stems and roots to rot and form residue on the ground, creating organic matter along with livestock manure, an added bonus! Unfortunately livestock grazing does not kill black grass, one of the toughest and most pesky weeds to plague our farmers. If you mention this weed to my father, a 2nd generation farmer, he will chew your ear off about all the things he has tried to exterminate it! Black grass competes with cash crops reducing their quality and yield. So if we could come up with an innovative way to remove it from #OurField while maintaining a healthy ecosystem, many farmers would be eternally grateful! Shall we take on the challenge?

 Black grass at Weston farm

Black grass at Weston farm


What next?

As with much of farming, the weather guides the practice. There are some years when there is no frost to kill cover crops naturally so spraying them off with roundup would be the preferred option for conventional/ no-till farmers. As the cover crop on #OurFieldWeston needs to be terminated in January, this will not be a decision made by the collective. John will make the decision depending on the weather conditions at the time. He will keep an eye on the temperature in January, and if frost appears he will jump on the tractor and roll the cover crop that day to terminate it. This is a way of life for conventional farmers guided by the hand that our natural world deals them.

 John and Aspen examining #OurFieldWeston

John and Aspen examining #OurFieldWeston

Annie Landless