Farm Carbon Cutting Toolkit


27.6.14 Managing green manures

What is a green manure?

A green manure is a crop growth to improve the soil and benefit the subsequent crop.  Once the green manure crop is grown, it is usually incorporated into the soil shortly before sowing the next crop.  This return to the soil will increase the amount of organic matter in the soil as well as improving soil fertility.  

There are numerous benefits that come from growing green manures in crop rotations.  However how green manures perform and whether they are successful or not depends on how they are managed and what the ultlimate goal is of growing them.

The information in this blog comes from a great publication from Cotswold Grass Seeds entitled Sort out your Soil, A practical guide to Green manures.  It contains specific information on different species of green manures including details on growing them as well as some of the considerations that are needed from incorporating green manures into your cropping plans.

So where do you start?  Below are some practical points to consider in managing green manures on-farm.


Spring or autumn are the best times to sow.  This ensures that there is sufficient moisture for germination and that the soil temperature is warm enough.  If you do need to plant after September, the best option to use is grazing rye as it will establish rapidly and is good at preventing nitrogen leaching losses over the winter.  Green manures can be broadcast or drilled, but ensure that they are sown at the correct depth.


Undersowing is an efficient way of ensuring that a green manure will establish quickly after harvesting.  Cereal crops can act as a "nurse crop" protecting a green manure crop in its early stages.


Mowing is an essential part of growing most green manures, especially when the crop is young.  Early mowing will make a difference between a well established green manure and one with a high weed burden.

Most species can tolerate being topped close to the ground, but care must be taken with some species, especially fenugreek and vetch.  It is best to remove cuttings as this encourages Nitrogen fixation in legumes.  If cuttings are left, the rotting material will release N which suppresses the N fixation capacity of the plant.


Green manures can be incorporated ready for the following cash crop by rotavating or ploughing.  It is easier to incorporate if the crop has been cut with a flail mower first.

For more information on the benefits a green manure can bring to your soil and information on the different plants available, click here to access the Green Manures booklet.

One of the FCCT case studies Iain Tollhurst, uses green manures in his rotations to great effect, not just on soil structure and building fertility but also in the emissions from his farm.  Read more here.

18.06.14 The use of cover crops in controlling crop pests

With increasing legislation in terms of chemicals permitted to control soilborne pests, any cultural options that can help improve yields and reduce pest and disease levels ins always advantageous. Over the last 18 months research has been going on into the use of cover crops and their biofumigation properties to control nematodes and pathogens found in soil.

How does it work?

The most commonly used biofumigants are members of the Brassica family, and in particular mustard species. These species contain glucosinalates (the compound which also makes mustard hot) that can be deadly to weeds, soilborne pathogens and nematodes.

When these species are cultivated and broken down, plant cells are broken and the glucosinalates are released. This release (combined with another enzyme) releases various other substances one of which is termed ITC's (isothiocynates). These ITC's then produce a fumigant which is similar to metam sodium.

As well as these beneficial biofumigant characteristics, the process of macerating the plants and incorporating them into the soil leads to increased soil organic matter levels and healthier, more productive soil.

Research projects

One area which is the subject of research at the moment is the use of cover crops (and biofumigation) for the control of potato cyst nematode (a highly damaging parasite of potatoes). This project which is being run by SRUC and Baworth Agriculture and funded by the Potato Council is looking at how best to incorporated these biofumigant plants into current rotations and how to grow them in the field conditions. This will allow them to develop sustainable guidance for potato growing on how to optimise their use.

The project look at the factors which may influence the efficacy of biofumigation including soil moisture / irrigation inputs and equipment used to macerate the foliage.

Farmer experience

The project is still underway but FCCT will keep you up to date on the results. In the mean time, Farmers Weekly have highlighted one farmer’s experiences of using cover cropping to help control PCN in his potato crop. The farmer is using a mix of caliente mustard and fodder radish which is broadcast in July after winter barley and rolled. Read more of this case study here.

13.06.14 Cover cropping and blackgrass research

Cereals has been on this week, and as such the spotlight is shining on new Research and Development projects that are running (as well as lots of shiny new kit to look at!). One area within cereal production that is being targeted in terms of research is the grass weed blackgrass.

Blackgrass can seriously reduce crop yields through competition for nutrients especially nitrogen. The tillering capacity and the competitiveness ability of blackgrass depends greatly on the vigour of the crop. Recent research from Rothamsted has advocated that very high levels of control are needed with fields to prevent black grass populations increasing. In winter wheat grown in a non inversion tillage system, control levels of 97% are needed, to prevent blackgrass population increases.

Within conventional farming systems, herbicides are considered the primary method of control, however even in these systems where chemicals are the main control strategy for controlling blackgrass there is a growing incidence of herbicide resistant blackgrass.

Herbicide resistant blackgrass is very widespread in the UK and has been confirmed on over 2,000 farms in 31 counties of England. Grass weed control is critically dependent on only 4 herbicide classes within conventional arable systems. With little prospect of new herbicides in the near future, non chemical control measures are increasingly important in combatting resistance, by reducing the reliance on post emergence herbicides.

HGCA - research into herbicide resistant blackgrass and cultural methods of control

HGCA have been showcasing some of their research proposals at Cereals. One of their projects (which also helpfully fits into our theme this month here at FCCT), is the use of cover crops to help with blackgrass control.

HGCA are investigating whether cover crops could provide growers with a useful cultural control option for blackgrass. The adoption of this approach will need a better understanding of the agronomy and associated economic and environmental benefits of using cover crops. This research will hopefully provide answers to this and see what the effect is in terms of weed control.

Read more about the project here.

Project Lamport

Agrovista and Bayer Crop Science are also joining forces on a new initiative entitled Project Lamport which aims to look at different developmental approaches to help in the constant battle to control blackgrass. This project is looking at seven different rotational systems, incorporating spring and winter cropping as well as the use of autumn cover crops. The project will consider the nutritional and soil conditioning benefits that come with the inclusion of cover crops in the rotation.

Read more about Project Lamport here.

FCCT will keep you up to date on the results of these two studies as they are released.

12.06.14 Cover cropping and Controlled Traffic Farming

Below is a link to an interesting video that pinged into the FCCT inbox this week from Controlled Traffic Farming Europe about the use of cover crops in controlled traffic farming systems.

The video features a farmer from Bedfordshire who manages his soil and cropping using a controlled traffic farming system as well as direct drilling and using cover crops. The farmer in question was able to direct sow a cover crop of spring oats immediately after wheat harvest, and then again direct sow linseed intonthe sprayed off oats in the spring.

What strikes me when watching this video, is the growth of the linseed, even under what seems to be a dense mat of oat crop residue. Surely if these crops can grow away and produce a good yield, while at the same time, getting all the benefits of keeping the soil anchored in the field, and minimising nutrient losses, its an interesting prospect?

Watch the video here and let us know what you think. Are you growing cover crops on your farm and willing to share your experiences with other farmers? Get in touch here.

05.06.14 - Cover cropping R and D - filling in the knowledge gaps

So following on with this month’s theme of cover cropping, I have come across an EU funded project that is tasked with looking at how cover crops fit into rotations and their subsequent management. One of the barriers that seems to be there at the moment in terms of using cover crops in the field is a lack of clear information about management, advantages, disadvantages and cost.

The OSCAR (Optimising Subsidiary Crop Application in rotations) project is aiming to look at all of these issues. It is an EU funded project that aims to extend the existing knowledge available on these subsidiary crops and to disseminate this information to growers and producers. The project includes 20 partner organisations from 9 European countries plus Morocco and Brazil. The project is collaboration between scientific researchers, agronomists and small businesses experienced in technological innovation for the production of farm machinery.

The project is looking specifically at the use of cover crops and living mulches. As discussed in an earlier blog, cover crops are primarily grown to provide cover, and are normally incorporated into the soil or killed off with herbicides. Living mulches grow for a long time with the main crop and are intended to serve the function of a mulch (such as weed suppression, and regulation of soil temperature). It is aiming to develop new cropping systems based around the use of cover crops and living mulches and will optimise these systems for use in low tillage agriculture.

The project started in April 2012 and is due to run until March 2016. It has varies work packages attached to it which are designed to look at different aspects of cover crop growth and management. Some of the particularly interesting bits are below. If you want to explore the project site in more detail click here.

Field trials

The overall aim of the field trial sites is to improve the understanding and use of cover crops under a broad range of environmental conditions and interactions with management techniques and farm technology.

Different cover cropping and mulch systems will be compared in the context of a series of co-ordinated field trials in different European and Mediterranean environments and on-going long term experiments. A two year sequence of wheat and a spring crop (maize, potatoes or veg) is the common experimental base on which to compare the different cover crops.

Identification of potential new genotypes and species

To maximise the economic and environmental benefits, investigation is needed into potential new genotypes and species to improve the balance between main crops and subsidiary crops, fill niches in crop rotations and improve soil conditions.

The main characteristics of a cover crop species should be that its fast growing and highly productive and fit in with the off season between the main crops. In contrast a living mulch should not be competitive and should complement the main crop.

Both types of crop should contribute to soil fertility and soil health as much as possible and potentially generate additional income from the farming system.

Farm technology and machinery (the kit stuff)

This part of the project will assess the current state of technology in use for min till systems that are based on cover crops and living mulches. It will also assess the requirements in terms of appropriate machinery design for sowing mixed stands, direct drilling and planting into cover crops, for complete or partial cover crop suppression, and for weed management.

Weed control

Improved understanding of how cover crops, main crops and weed plants compete with each other in cover cropping systems is essential in terms of making the cropping systems profitable. Knowledge will be used to develop new cultivating methods and to inform development of appropriate machinery for weed control. Competition depends on numerous factors – the most important ones are the plant density, spatial distribution pattern, acquired competitive advantages, competing ability of involved genotype and environmental factors such as day length, temperature, rainfall and nutrient availability.

Current project resources

As well as the research described above, the project is also providing helpful advice and info on species, management, growers experiences, and benefits, of different cover crops and living mulches. The “Cover Crop and Living Mulch wiki page” is an interactive knowledge source of relevant information on leguminous and non leguminous cover crop and living mulch species, machinery and farm case studies. Access it here.

When this project starts to produce some results from its field experiments we will highlight it on the FCCT website so keep an eye out. Also if you are inspired to delve slightly deeper into the world of cover cropping and fancy giving it a go on your farm, let us know and we would love to hear from you. Contact us here

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