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Timing, species and methods: Considerations if you're destroying your cover crop

Valley-Views

We don't doubt that almost every farmer in the UK is now thinking about and incorporating different strategies to improve and maintain soil health. 

Farming is changing (something our colleagues touched on recently in a previous blog) and we've now officially started the transition towards 2024's Environmental Land Management (ELM) scheme. Of course, as we embarked upon that journey, we simultaneously departed from the European Union, the focus on our industry's ambition to become carbon neutral increased, and any requirements for Ecological Focus Areas (EFAs) ended.

A sea change in land management

Yearly we tend to see a gradual change in legislation and a reduction of man-made inputs across the available pesticide lists and, unsurprisingly, this creates additional management challenges for strategic crop production systems. At the same time, unprecedented weather events continue to cause difficulties. We're seeing warmer and wetter conditions; with the latter often coinciding with key periods in the agricultural calendar such as harvest and spring crop establishment.

If we bring all of the above parameters together, coupled with the need to look at and embrace new technologies and solutions, it is clear that trials work and scientific study are increasingly important to the development of sustainable agricultural practices. Our ability to test and observe new crop production strategies is vital for us to make the correct decisions going forward, ensuring our soil systems are robust and reliable for the future.

The benefits seen with cover crops

Approaches to cover cropping and soil health developed quite substantially last year and, whilst the EFA options and greening rules are no longer in place, many farmers who were in these schemes experienced measurable benefits and consider cover crops a significant part of their rotations. The value of soil nutrients that would have been lost from places traditionally left as bare winter stubbles is becoming increasingly apparent.

How we design and manage profitable, efficient crop rotations can be influenced by the use and management of available cover crop positions within them. When incorporated well, they can lead to the introduction of wider sustainable crop establishment systems, having the potential to gradually reduce some crop inputs and the overall cost of crop establishment.

The integrated use of more summer-sown, short term cover crops and a better understanding and management of overwinter cover crops has allowed these regenerative farming and establishment systems to perform well. Some farmers are benefitting from additional crop establishment windows and, at a time where weather and planting conditions can be increasingly varied, this is certainly welcomed.

Your cover crop management strategy

If you have a good cover crop that has been successfully absorbing available nutrients, improving soil structure and supporting soil biota, you may be wondering what to do.

First and foremost, careful thought and consideration is required when planning your next move.

1.  Was the cover crop planted as part of an agri-environment or EFA option?

The last of the outgoing EFA cover crop options ended on 15th January which was the minimum date they needed to be retained until. While some of you may have already begun the process of removal, others who have seen – or are still seeing – tangible benefits may feel unsure.

Some of our most common advice to farmers is: don't rush to make a decision just because you can. You've had a really effective soil management system on farm for some time now and if it's still working for you, you might decide to leave it for a while.

2.  Identify the species in your cover crop and think about the management required

Species such as buckwheat, phacelia and mustard are frost-sensitive so, if the weather is on side for long enough, you may find that it does a good enough job of destroying the crops for you.

On the other hand, species such as radish, vetch and cereals are more robust; their ability to remain hardy through harsh winter conditions often means they will need greater attention when it comes to removal. Start to plan well ahead of establishing your next crop; time spent speaking to your agronomist about the most suitable options and approximate dates is always time well spent!

3.  Consider your options for destruction – which best suits your circumstances?

Mechanical

The mechanical destruction of cover crops can take the form of full inversion (ploughing), flailing and crimping/rolling.

Full inversion may be the preference for some growers but others would argue it goes against the very principle of minimising soil disturbance to encourage soil fauna, while also helping to control black-grass populations and seed germination.

If you are part way into this journey and full inversion is your chosen method then the need to spray off the crop is not necessary. Rather, a chop, disc or flail is the most suitable option.

Flailing will reduce the bulk of your crop, whereas crimping/rolling can work well in conjunction with prolonged, hard frosts of -4⁰C and below. Flattened crops with broken stems are far more susceptible to the elements so, if conditions are favourable, frost can make quick work of them. Importantly though, remember that crimping/rolling alone will not deal with full crop or weed destruction.

Another important consideration is the direction of crimping or rolling, especially if your next intention is to direct drill the following crop. The drill should always be travelling in the same direction as the rolling or crimping process (across the rolling or crimping works well too). Taking the opposite direction of travel can create major blocking or hairpinning problems. 

Taking time to experiment with rollers or crimping tools on a frost is well worth the effort and can be very effective. 

Animal

With grazing you can convert green cover biomass into fat lambs and more readily available nutrients. Before opting for this though, think about your soil types and overall ground conditions. If you have light to medium soils then you should be able to carry stock well but you need to think about timings rather than leaving them on the crops for a prolonged period.

Remember: if you do opt to graze, you must prepare your Livestock Manure Nitrogen Farm Limit. Help on how to do this is available here.

For many of our growers who opt to graze their cover crops, they see it as a cost effective solution that holds wider benefits for the farm's bottom line. Often, the returns gleaned can go towards covering seed and establishment costs. 

Chemical

The use of chemistry to destroy a cover crop can have a 'two for one' element. For example, a herbicide will efficiently remove both sown crops and weed species but it's also a good way of simultaneously managing grassweeds.

If the chemical means of destruction is your method choice, you'll certainly need to consider point 4.

4.  When is best to spray?

In order to make the most informed decision around this, speak to your agronomist for expert guidance. You are not just considering the cover crop – you need to think about following crop requirements, ongoing management and whether or not weeds are a problem.

You also need to think about when to sow your spring crop. Working back from your target drilling date by a minimum of six weeks is usually enough time to ensure that any actives used in destruction have had time to break down the cover crop and any accompanying weeds. However, cover crops with large canopies or very dense biomass will likely need more attention. These crops can be much harder to kill in just the first pass of herbicide application so you may need to make time for a second.

It's also wise to be mindful of potential cover crop re-growth in crops such as peas, beans and sugar beet. Consider the possible effects of residual herbicides when choosing products within the combined cover and conventional crop rotation. 

Last, but by no means least...

For those of you who intend to direct drill your following crop – particularly if you're not doing it for a few months yet – it may be sensible to leave your cover crop in the ground for longer so it can benefit from the extra daylight hours in January and February. This extra time will further increase crop biomass and rooting activity, giving you just a little bit more soil cover should you need it.

If, however, you are opting for more conventional methods of crop establishment – particularly if you have heavy soils – you may find it more preferable to drill as soon as conditions allow. If this is the case, removing your cover crop at the earliest opportunity will allow time for the biomass to break down and it will also give you a longer window to ensure good seedbed preparation ready for the following crop

Get in touch for more guidance

With the recent changes to farm policy, the successful integration of cover crops and the benefits they provide is garnering more attention than ever. It's important to reiterate the multiple advantages; both environmentally and economically. Timing is everything of course, but with a well advised and well planned approach, the positive impacts that cover crops can have on soil health, soil structure, nutrient availability and overall farm profitability are significant.

For some this journey is one of development but for others, it may be altogether new. As the face of farming changes, our team of advisors are here to help you navigate the options available and ensure you get the best results for your farm.

To speak to a member of the Kings team about anything covered above, please email or call 0800 587 9797. Alternatively, please speak to your Frontier agronomist for guidance or get in touch. 



Clive Wood, Kings Business Development Manager & Technical Advisor
 
Robert Nightingale, Frontier Break Crop Production and Sustainability Specialist

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