So many words have been written about the herbicide Glyphosate (commonly known as Round-up), it seems almost pointless adding any more. But anyway…
Last week the European Commission postponed a decision on whether to renew a licence for the herbicide. They will have to decide by December or face legal action from its maker the US chemical company Monsanto. Monsanto are currently waiting for approval for a merger/take-over from the German chemical/drugs behemoth Bayer. The European Parliament voted (the vote was not binding – just like the UK Referendum vote) to call for the Commission to phase out the use of Glyphosate-based herbicides within 5 years, and an immediate ban on all domestic and urban uses. But when it came to totting up each Member State’s vote, there was a small majority of EU countries (including the UK) who voted in favour of renewal. This majority was not sufficient for the decision to be confirmed though, hence the further delay. France, Italy and Austria have been leading the calls for a ban. Germany is now apparently lobbying for a 3 year extension.
What’s all the fuss about? A couple of years ago the World Health Organisation cancer expert group the IARC concluded that glyphosate was “probably carcinogenic”. This means that the evidence is currently not strong enough to conclude that it is definitely cancer-causing, but there are serious grounds for concern. Monsanto, which markets Round-up, but far more importantly has a near monopoly on GM-crops: specifically crops which are resistant to glyphosate, has been orchestrating a campaign to undermine both the IARC and its findings. Light is now being shed on this campaign in the US courts, where lawyers for farmers who claim long-term glyphosate use has given them cancer (specifically non-Hodgkin’s Lymphoma) are suing Monsanto. The more one reads of what Monsanto has been up to, the more parallels appear with the Tobacco Industry tactics in the 60s and 70s.
In the UK the most vociferous campaigners trying to persuade everyone that glyphosate is perfectly safe, are those arable farmers who have adopted a no-till or minimum tillage approach to growing cereal crops. No-till means that there is no cultivation before or after a crop is harvested. The seeds are sown directly into the soil, but in order to prevent the crop from being swamped by weeds, herbicide such as glyphosate is applied. After the crop has matured, a further application of glyphosate is applied to desiccate the crop (and for other reasons – see more here), so it is easier to harvest. This saves money and energy drying what are often rather wet crops in our climate.
One of the main “weeds” that the no-tillers have to contend with is Black-grass Alopecurus myosuroides. This was not even a common arable weed before the second world war, and only became problematical in the 1970s after a switch away from mixed farming, spring crops and fallow periods, towards a winter-crop monoculture approach to food production. The ban on stubble-burning in the mid-80s further exacerbated the problem. Farmers operating no-till (apart from those few organic no-tillers) now depend on glyphosate amongst a mix of herbicides to keep Black-grass levels under control. So far, Black-grass has not evolved resistance to glyphosate; however, given how much of it is used, it can only be a matter of time before this happens.
The no-till farmers claim that their practices are much more environmentally friendly than conventional arable farming, making all sorts of claims about soil health, carbon storage (for climate change mitigation) and wildlife benefits. I have searched for quite a long time for any real scientific evidence that no-till leads to long-term increases in soil carbon that could make a significant difference to the UK carbon store, but found nothing. What I have found is evidence that the no-till claims are unfounded. This paper in Nature Climate Change for example:
which suggests that there are good reasons for adopting no-till under some circumstances, but that claims for a role in climate mitigation (ie reducing greenhouse gas emissions) are “widely overstated.”
One of the big problems for no-till as a solution to climate change is this. As crop material that has been left after harvest decomposes, it releases Nitrous Oxide. This is a far more potent greenhouse gas than Carbon Dioxide. So any benefits from no-till are likely to be wiped out by the N20 released.
Equally, there is no evidence (that I could find) that no-till is better for wildlife of arable farmland than conventional agriculture. This may not be particularly surprising, given that the farmland is given repeated doses of glyphosate, which kills all wild plants, on which insects, and the birds that eat them, depend. Anecdotal evidence from no-till farmers themselves suggests that ground-nesting birds such as skylarks benefit from the lack of disturbance from cultivation, but this needs backing up with proper studies.
And this is really my concern about the ubiquitous use of glyphosate. Yes, it’s possible that it is a carcinogen, and given that it and its main breakdown product AMPA are now pretty much in everything and everyone, then some people are getting cancer as a result. But then cancer is a very common set of diseases, caused by a whole range of things that we do as humans. From an environmental perspective though, glyphosate use is having a series of interlocking impacts. If wild plants are constantly being prevented from becoming established, or surviving in farmed landscapes, this not only has an ongoing impact on their own chances of survival, but also on all the wildlife that depends on them. Our countryside, and indeed large parts of the countryside in Europe, is being systematically cleared of wildlife. Last week’s report that insect populations across a series of nature reserves in Germany had declined by 75% in 25 years is not unrelated. Farmers on social media were writing “but glyphosate’s not an insecticide, so it can’t be affecting insects”.
If wild plants are removed, insects have nothing to eat, nowhere to hide and nowhere to lay their eggs.
Another lesser known impact of glyphosate is on microbial communities. Glyphosate and its main breakdown product AMPA are amino acids but glyphosate also acts as a selective antibiotic. Certain bacteria are able to digest and benefit from glyphosate in soils but also in animal guts, while some evidence indicates that glyphosate may help drive antibiotic resistance. Microbiologists are also concerned that glyphosate may be affecting the balance between relatively harmless gut bacteria and their more pathogenic cousins, such as Clostridium difficile. Given how ubiquitous glyphosate now is, this is perhaps the single biggest issue for glyphosate on human health, but is widely ignored. We also know almost nothing about its impact on soil microbial and fungal communities – the assumption is that there is no impact.
And this brings me to the Precautionary Principle. This principle is woven into the legal fabric of the European Union, and we may well lose it as a result of Brexit. Apply the precautionary principle to glyphosate and, on the balance of current evidence, its use would be severely restricted, while far more research would need to be instigated. However, if we leave the EU and the EU does phase out glyphosate, we will be left with little choice but to follow their lead. Because otherwise the UK food exports to the EU would be banned. This is what is particularly exercising Monsanto (whose lobbying tactics in the EU have led to them being banned from the European Parliament estate) but also countries that have wholesale adopted GM farming, which is totally dependent on glyphosate.
Former Brexit minister Oliver Letwin believes that we should adopt the Precautionary Principle into UK law, but then ignore it for glyphosate. This opinion piece (we are blessed to have a weekly thought from Letwin) is from our local rag the Dorset Echo.
If you believe some of the claims from the farming community, the UK food supply chain sky will fall in, if glyphosate is banned. I’d just point to one previous example – paraquat. Paraquat was widely used in UK agriculture until it was banned (by the EU) in 2007, despite a vociferous campaign by the UK agrochemical industry – Sweden banned it in 1983 because its toxicity was already well established. Did the sky fall in? no. Scandalously, Paraquat is still manufactured in England, for export to countries where it is not yet banned.
There are certainly strong claims to retain glyphosate for specific applications – such as killing Japanese knotweed, where it threatens buildings or infrastructure. Scare stories like this one, where the rail infrastructure of the UK will be threatened by a glyphosate ban, do nothing to help those who argue sensibly for continued, careful use in specific circumstances.
The saga of glyphosate is also emblematic of a wider debate, which we will need to have sooner or later. Farmers are forced to farm in unsustainable ways, because consumers refuse to pay the real price of food; and the big retailers take far too big a chunk of that price for their shareholders (which may include some us if our pension schemes invest in them.)
How to untangle this particular gordian knot? At least some people are thinking about it – and this new commission on the future of food and farming is welcome.
I’ve encountered a related Glyphosate problem on the Isle of Wight. A few years ago the council created a public-private partnership contract with a consortium to manage the highways network. It’s called Island Roads. The new contractors have adopted Glyphosate as the means of ‘dealing with the weeds’ that ‘infest’ the island’s urban dry stone walls. They have a fleet of quad bikes and ride around four of five times a year, spraying off the species-rich wild flower communities. Having killed off mature, perrenial plant communities, soil washes out of the cracks, de-stabelising the walls, and, with a huge burried seed bank, annual ‘weeds’ take the place of the slow-growing perrenials, and now we have a perpetual anual ‘weed problem’, which is great news for the spraying gangs and weed killer manufacturers.
These same stone walls are a haven for slow worms (abundant througout), common lizards (not so abundant) and wall lizards (very abundant on the south coast). Over the last few years I’ve found several moribund wall lizards and, within a day or two, have noticed the ‘weeds’ wilting where I found them. Island Roads spray into September, when inch-long juvenile lizards are all over these walls. The juveniles tend to freeze (the adults rush off into crevices), and so the juvs get sprayed with Glyphosate. The adults get a dose when they re-emerge once the quad has passed.
Of course, wall lizards were (presumably) introduced. But the common lizards and slow worms are natives. The wall lizard population has declined rapidly around Ventnor in the last few years. I’m quite sure that slow worms and common lizards are also being hit.
Island Roads claim that Glyphosate is completely safe……..
thanks Steve. PAN UK might well be interested in this story. Have you been in touch with them?
Many thanks for this post – and Steve’s pertinent observation.
My own experience, similar to Steve’s, that dramatic effects of Glyphosate on soil mobility occurred when used (as recommended) around young tree saplings in a plantation. I planted the saplings and applied the Roundup … the desiccation and break up of soil so dramatic I use a photo for presentations; illustrating soil microbiology issues – usually opposite a picture of a gently pulled young barley plant, no-till, germinated during a drought, with accumulated humus & water hanging thickly around every root, like Rasta’s Dreadlocks.
Returning to an agriculture with no externalized costs, that depends largely on the sun and rain with few other inputs, higher profits for farmers and certainly no grants or subsidies, should be the goal post EU.
But disentangling the ‘Gordian Knot’ of modern farming practices is like the wider economic mess; we have made little progress with the vaunted ‘Re-balancing’ that we were told was necessary after the last crash.
Good summary piece,and worth doing.
I’m a little surprised that carbon in soil improvements aren’t tangible,one of the big assumed advantages to no or min-til agriculture.Nitrous Oxidisation not surprising but a lot of root material locked underground should be a big gain as should lack of disturbance of a lot of life through not ploughing in particular.Any surface protection by material living or in decay is good for soil below,as per forest leaf litter.Worms in particular appear to be more numerous whereas cultivation can severely affect them and they process massive amounts of soil.
On most of our land we have to plough every 2/3yrs and are always interested on how mowed surface material,clover,chicory,etc reacts/incorporates when ploughed/power harrowed at varying soil depths.I don’t see much research going on to clarify this.Org.Matter(OM) levels so far appear to be stable/rising but a long term project.
My perception is that most arable farmers readily see the gain in quicker turnarounds between crops but are pleasantly surprised but how much better their soils are too.Often because previously they had v.low OM,meaning clods=slugs+poor seed contact,poor drainage,etc.Cover crops are being used as well and are inevitably breaking up soil pans and leading to nice pics on twitter when they flower! Gabe Brown in USA seems to one of the more thoughtful proponents while quietly acknowledging Glysophate as part of his plan.
Some some more writing on AMPA might be timely(wikipedia entry notably wooly).
What about the argument that no- or low-till protects soil and improves soil structure? Ignoring C sequestration, this seems important in terms of future-proofing agriculture
If no-till or low-till are dependent on glyphosate to operate, then it’s not clear to me how this is a long term solution.
To walk in a field just sprayed is indeed to walk amongst the dead. The sadness and loss of life is profoundly saddening. What good are crops thus produced? What vitality exists to nourish you? Regrettably few actual produce food of any real nutritional value. Any doubt? Take a Brix meter to the supermarket and find out. Look at the nations health for the result of chemical farming.
Glysophate is a detail. The whole paradigm and practice of food production has to change.
1.Glyphosate came off patent years ago. There are many companies now making products containing glyphosate, not just Monsanto
2. The IARC classification is “probably carcinogenic” other products in this category include coffee, sitting in front of a log fire, working a night shift, and working in a hair dressers. Just for a little context. Also, there currently appears that one of the lead scientists working on glyphosate classification actually withheld test results which gave a negative carcinogenic response. I’d treat the IARC classifications with caution unless you fully understand them.
3. No-till. Here in the UK, GM crops are illegal. We can’t grow them. Therefore Glyphosate is applied to the CROPPED AREA BEFORE the crop is sown to kill any weeds. The crop can then be sown into a clean seedbed. Often I’ve found, especially with legumes, I then don’t have to apply anymore herbicides to that crop whilst it is growing, whereas in my plough based system I do have to.
(This next but applies to all systems, no just no till) Glyphosate IS NOT then applied to dessicate the crop for drying. Sometimes, granted, yes. But this isn’t not the norm. It doesn’t “dry” the crop – it’s only speeds senescence when used. It’s quite useful in Scotland where harvest is late, and often stems are still green going into September. Glyphosate could assist the harvesting of the crop up there, and enable it to be gathered before more unsettled weather arrives. The grain still has to be dried, unless the sun shines! Equally, occasionally a crop may have lots of weeds present near to harvest, and glyphosate could be used to kill these to stop those weed seeds going into the clean grain sample. Milling wheat requires high quality wheat. Wet harvests can ruin the quality. Sometimes milling wheat growers will use glyphosate to speed up harvest to ensure the grain quality is high. NOTE. – it is the exception, not the norm for glyphosate to be used Pre harvest for cereal crops.
4. Blackgrass. we have some blackgrass. We also have 6 year rotations including 2 spring crops, and always have done. Its wrong to say it’s from monocropping or short rotations.
5. Studies into notill proving no benefit to wildlife. Studies are great. They are conducted in labs. You need to set foot on a farm. We do some no till and some conventional. It’s blatantly obvious just by looking at species mix and amounts of wildlife which is better.
6. Nitrous Oxide. This doesn’t get magically locked into the ground. Whether you no till or not, it gets released at some point.
7. Wild plants are not removed by glyphosate. We use it on cropped areas of fields. Every field, must, by law, have a minimum cross compliance strip which cannot be sprayed. Here, and in the ditches and hedgerows, and on the countless environmental features farmers put in, you will find many wild plants. Again, get on a farm.
“Wild plants are not removed by glyphosate “. Of course they are, or glyphosate would not work. Just because you perceive wild plants growing in arable as having no value doesn’t mean that they are not wild plants. Don’t forget, or maybe you don’t know, but some of the rarest plants in the UK are arable plants.
anyone interested in rare arable plants can buy this excellent book, which er I co-wrote.
1) Glyphosate is now off patent. Monsanto are only one of many manufacturers of glyphosate.
2) The reasons behind member states voting against reauthorisation are political, not scientific – take Germany for example: Merkel is trying to form a coalition with the Green Party, so science is ignored in favour of populist decision making. Countries with stable political situations like the U.K. voted to reauthorise.
3) ECHA, the European chemicals agency, an independent body, do not classify glyphosate as a carcinogen. This is a panel of many scientists who looked at HUNDREDS of studies. It’s safe. They recommended full reauthorisation. Look at their report. Read it. It debunks the IARC conclusion which is widely accepted as being an anomaly flawed due to biased actions by a certain Mr Portier.
4) Notill. Where do I start. This is a world wide practice by some of the most conservation minded farmers, me included. These farmers actually use less pesticides as a result. They also use glyphosate just like a conventional farmer – killing weeds before planting when necessary. Occasionally but not often crops are desiccated with glyphosate before harvest, but this is not common practice as you infer. In the absence of grass weeds many no till Farmers use crimpers, rolls or even sheep to destroy broadleafed vegetation. We’re talking about a system that not only sustains, it regenerates I.e. soils improve. Get on a farm and see for yourself rather than cherry picking and misinterpreting isolated studies that agree with your theory that a chemical invented by Monsanto must be bad.
5) blackgrass, yes it’s an issue caused by over reliance on tight rotations and chemical control. But, we know this now, how do we move ahead? By using wider rotations, spring cropping, and taking out flushes of blackgrass pre drilling. Blackgrass thrives on cultivation: the more you cultivate, the more seeds grow. So notill systems can reduce populations of blackgrass
Notill is also a system that utilises cover crops, which harvest sunlight, promoting carbon sequestering, increasing earthworms, balancing predator prey relationships, improving water infiltration. You pick a report that says Notill does not work because farmers have to cultivate? Bizarre. I suggest visiting a no till farm. Today, I’ve seen flocks of starlings on every field, Sky larks, fieldfares and lapwings, all enjoying the habitat. There are many worm middens too. The field drains run clear, showing topsoil is not lost. I could go on.
6) Residues left by crop debris are food for the soil. Worms suck dead plant matter into their burrows. Fungi work on the surface. Bacteria do their bit too. All part of a natural ecosystem the same as a forest floor. The fact that I use glyphosate to control weeds and yet these fungal and bacterial populations are thriving shows how non toxic glyphosate is the soil. Studies that show otherwise use overdosed levels of glyphosate and obselete formulations that aren’t available now.
7) The breakdown product of glyphosate (its broken down by microbes in the soil) is AMPA. Sounds dangerous. Its not. It’s an amino acid, a building block of life.
8) Wild plants don’t exist in any farming system, whether it’s organic, conventional or Notill. If they did they would be weeds – things to be pulled, sprayed or hoed depending on your system. They do, however, live in field margins and managed habitat. In all systems.
9) And finally, I will re iterate the point that glyphosate is one of the safest herbicides in the world. We’ve used it in the U.K. for 40 years, with not one health issue related to its use. It’s the most studied chemical product in the world, and the overwhelming weight of evidence points to its safety. See ECHA above.
Glad some conventional arable producers are catching up on proper rotations,some way to go perhaps.Anybody previously doing conventional arable will see improvement with less tillage,particularly with cover crops(well done for catching on to those too,eventually). It was so bad before improvement isn’t so surprising.
Achieving less tillage,more Org.Matter,etc,etc at the cost of using a magic bullet is the nub of the issue.The more vigorously we are told the Glyphosate bullet(and several earlier herbicides)degrades harmlessly into the soil the less convincing it becomes,particularly when the record of the manufacturers are scrutinised.Things that sound too good to be true usually are.
Min-til is pursuing the age old dream of maximising production from finite land,while sober farmers always realise the limitations of how much output we can genuinely sustain. Tackling the UK’s awful access to land might go some way to changing who decides on the production systems.Innovation is not being driven by the power or influence of the CLA or NFU.
Most innovative thing in arable production appears to System Chameleon but I think still only 1 in the UK……more precision, less spraying might be a habit to go for.Decent research done by non-compromised academics always useful too.
Guy Watson wrote a piece on Glyphosate use a while ago relevant here;
“No wild plants exist in any farming system”, err well yes they do, I could list about 200. And yes they are what a farmer would call a weed but they are still wild plants, just inconvenient ones (from a farmers perspective).
There are “known knowns, known unknowns, and unknown unknowns” …
The ‘science’ referred to from ECHA is fairly clear and in no way states that Glyphosate is “safe” (1).
ECHA thus, “glyphosate as a substance causing serious eye damage and being toxic to aquatic life with long-lasting effects”. Hard to conceive that anyone would allow such a substance at any dilution near either our food or watercourses …
And in terms of the carcinogenic enquiry …”that the available scientific evidence did not meet the criteria in the CLP Regulation to classify glyphosate for specific target organ toxicity, or as a carcinogen, as a mutagen or for reproductive toxicity.” In other words they do not have the data – this does not mean the data does not exist, or has even been looked for. These are otherwise wholly unsafe assumptions.
A huge percentage of UK population apparently discharge glyphosate residues in their urine (70% in one small sample study, 2). We have absolutely no idea of the consequences of this.
There’s a whole bunch of issues to think about regarding the reliance of farming on glyphosate. A big one is scant in field research as evidenced by Miles’ challenge in finding peer reviewed studies. If we are to use novel artificial substances across entire landscapes then we really do need to understand their impact at different scales on the environment and on human health. What we have now, started post WW2, is the biggest chemistry experiment ever for which we still don’t understand the full implications for nature, planet & people.
This is a useful debate but I am getting mixed messages about dessication which seems a non vital use if what farmers deem a ‘vital’ chemical. I have looked but could only find levels for OSR which was in 86% of farmers used it. If less for cereals can I see the data? Is it collated independently?
technically it’s not used as desiccant Vicki – that was my reading, but this briefing suggests pre-harvest use for a variety of reasons – notwithstanding that this is from the glyphosate industry, so obviously needs to be read with that in mind.
if you look at the farming forums it’s for drying but ease of harvest machine use. Clearly a link to uniformity demanded by end user too. And varies depending on how wet it is.
A few thoughts on wildlife under Conservation Agriculture – i.e. no till plus covered soil plus diverse rotation (definition: http://www.fao.org/ag/ca/) – based on my farm, prompted by your blog.
We’ve been doing this for c5 years, using glyphosate once a year to prepare seedbed (but not pre harvest). [I know the name Conservation Agriculture annoys some people because we do still use a range of pesticides. I use the name because it encompasses what we do; not because I think we are necessarily beacons of conservation good practice.]
I don’t have detailed numbers or trends but hopefully my experience is still informative. I also don’t present a comprehensive list of all farm wildlife – much as I’d like to create one. Time and expertise are both factors against me.
Small mammals such as hares, mice/voles/shrews, moles seem to find it beneficial. Burrows/forms are undisturbed year to year. Plus leaving stubbles intact provides good cover to avoid predators. See e.g. link below for discussion of increasing rodent populations under no-till: https://www.aphis.usda.gov/wildlife_damage/nwrc/publications/07pubs/witmer075.pdf
Higher populations of these mammals must be reasonably good news for their predators. We have several kestrels, buzzards, barn/tawny/little/occasional short eared owls, occasional red kite on farm.
Earthworms: some fields you now cannot put a foot down without touching a midden. Lots to learn but worms seem to love Conservation Ag.
Insect wise, this year I’ve been looking out for butterflies as something easy to ID. List on farm for 2017: Cabbage White; Tortoiseshell; Painted lady ; Skipper; Gatekeeper ; Meadow brown; Comma; Peacock; Ringlet; Red Admiral. Each of those seen multiple times. Plus a blue & a yellow one I couldn’t ID. I don’t know if that list is good or poor & I didn’t keep a log of frequency. I’m also not saying these are present because of Conservation Ag. But they are present.
I’m horrified by German study showing 75% declines. And keen to find practical solutions to a problem we mustn’t ignore or deny.
Walking across an 8ha field yesterday I saw 15 skylarks in the air. I don’t know what range they cover. I expect to see skylarks in every field I enter. Again the cover and camouflage potential offered by our practices seem beneficial. Flock of c60 starlings on same farm walk – they seem to feed in the chaff and straw left on surface. Also see yellowhammers every time I walk the farm. (I’d really like to be more comprehensive on bird life but don’t have ID skills yet, so focused on obvious red list species I can identify)
There are lots of reasons why (*if* those are positive indicators) this farm might be doing well. Historically diverse rotation even before our adoption of Conservation Ag, smaller fields, many hedges, several small unfarmed areas. But for mice / moles / hares / larks / carabid beetles among others I’m optimistic that Conservation Ag plays a key role.
Cover crops/companion crops/more diverse rotations -ie core Conservation Ag tenets- should all be wildlife wins. And if farmers can improve soil health via Conservation Ag (as the study in your blog post states we should be able to) we’ll be in a stronger position to act yet more responsibly; healthy soil should require fewer inputs & therefore give us a surer financial footing from which to act.
I do think there’s further to go in terms of considering impacts on wildlife of agronomic decisions. Point re glyph depriving (at least temporarily) creatures of food source seems a good challenge. Mitigations might include having a wide enough rotation that nearby fields can provide a replacement food source – I have no idea if that’s feasible for individual species.
My position on glyphosate – as discussed with you on Twitter – is it’s the best available tool to enable a system which can be both financially and (I hope) environmentally sound while building soil health.
While organic farming arguably does some or all of that too, if all UK arable farmers switch to organic, I don’t see how any/majority of them could remain financially viable in face of massive increase in supply of organic food & therefore reduction in price? Perhaps that’s my misconception. I agree with your wider point about the food system & real price of food.
I also agree that we do need more understanding of (i) impact of glyph on above and below ground life (ii) alternatives to glyph – but rushing to ban a tool without a clear alternative is likely to be counter productive.
Thanks very much Francis – this is a really valuable insight into your experiences. As you say, it’s difficult to know whether these things have happened as a result of your adoption of conservation agriculture; and if so, which elements of it are most important – and this is why the research needs to be done. I’d be interested to know what plants you use to create your cover; and what happens to the cover then you apply glyphosate to prepare the seedbed. Do you kill the cover and then re-seed with new cover at the same time as sowing the crop? I’m interested in the details – you might have spotted I am making some visits to no-till practitioners in light of the blog and comments received.
Thanks for publishing Miles.
“Cover” comes in two forms (apologies if I’m stating the obvious or seem pedantic):
1) The stubble & volunteers from the preceding cash crop
2) Cover crops planted soon/immediately after harvest
Those stubble “covers” falling into category 1) will vary depending whether you cut them low or high or use a “stripper header”, which leaves the entire stalk intact. Different crops have different amounts and qualities of this stubble “cover” (think of e.g. ryegrass vs peas). They will also have “volunteers” which grow after harvest if you let them – e.g. OSR and barley fields will be covered in green a few weeks after harvest due to the seeds lost from the harvested crop. All our autumn-sown crops will have this “cover” alongside the growing plants themselves – we apply glyphosate to ensure the volunteers (and any weeds) don’t outcompete the new crop.
Those falling into 2) are up to your creativity and wallet size. Most in this category are planted to precede a spring crop but some will be before an autumn crop. People are planting combinations which might include buckwheat, linseed, phacelia, vetch, berseem clover, rye, black oats, mustard, oil radish, sunflower, spring beans. That list only scratches the surface. On farm here, we have stuck mainly with black oats/vetch and some mustard – but there are people doing really interesting combinations & some indications that a really diverse cover crop is great news for soil biology, not to mention habitat & food for above ground life.
The question of when to terminate covers is a good one. I don’t have the “right” answer – but glyphosate might be sprayed any time between six weeks before and a number of days after. @FarmingGeorge has a recent tweet showing a barley stubble full of volunteers (i.e. category 1 above) where he sprayed 12 days after planting into it – that gets into territory where there is continuity of green plant life in the field (which has its own challenges – “green bridge” if you’re familiar with the term) but seems a promising avenue in other respects. You’ve got to be confident you’re not going to kill your cash crop before you do spray that late though.
In answer to question of seeding a cover at the same time as a cash crop, there are people trying to create continuous cover (“living mulch”) using e.g. white clover (the cover) under wheat (the cash crop). This is very rare currently, albeit another promising sounding idea. The other practice that sounds like what you are describing is companion cropping – where e.g. clover/buckwheat/vetch “companions” are planted with the cash crop e.g. OSR. I saw @OOOFarmer had some pictures of this on Twitter – and plenty of farmers are doing this.
That said, generally at the moment the sequence is cash crop/cover/cash crop one after the other – with the detail that each cash crop’s stubble, straw and chaff should be a form of semi-permanent cover (perhaps a thatched roof is a good analogy) for the ground – and that while that straw & stubble gradually gets pulled underground by worms it is then replaced by the next cash crop.
To reiterate, if any of the above is patronisingly basic that’s not my intention – thought better to be comprehensive than to assume knowledge.
Very pleased to note your upcoming visits!
not patronising at all Francis – very interesting.
The Powlson et al paper again raises the quibble over what we should understand by “sequestration”. Ordinary people probably think it is equivalent to making something temporarily unavailable ” – as in “glyphosate was synthesised in the 1950s as a sequestering agent for metal ions in water softening”. For the purposes of the CCA, it has come to mean permanent removal – so any intervention not permanently removing carbon from cyclic carbon is not regarded as able to sequester carbon. The headline conclusion from the Powlson et al paper is that no-till is not to be regarded as effective for that purpose. Fine.
But also in the paper are statements that it is entirely appropriate to consider opportunities to slow or reverse emissions through land-management practices, that (although) soil C equilibria can take a very long time to be reached, reduced tillage certainly has a role to play as one of the strategies contributing to global food security and the protection of soils, and thus to climate change adaptation through building agricultural systems that are more resilient to climate and weather variability. In regions where low/no-till has potential to deliver significant benefits for farmers and sustainability it should be promoted on these grounds. I contend that the temperate maritime climate and soil characteristics found in the UK are suitable for low/no till, both a priori and from user experience so far. It is the reliance on glyphosate that I find problematic.
However – the message from the Clean Growth Strategy is that UK agriculture is doing quite so far to maintain output while cutting GHG emissions, but that emissions from land use and agriculture need to fall further – by about a quarter from today’s levels. This could be achieved, net, by increasing woodland substantially and reducing the emissions intensity of agricultural outputs. The message from the Climate Change Committee is that the UK must “vigorously pursue” efforts “with urgency” to meet its existing carbon budgets to 2030. From these messages I infer that to maintain this direction of travel it would help not to regress to inversion tillage where it has been replaced by low/no till, and we should probably have more of it to increase soil OM, protect against soil erosion and safeguard our waters from particulate and phosphorus pollution. The “trade-off” – apparently a euphemism for acceptable perverse outcome – will be the continued loss of biodiversity as long as glyphosate (or its successors) remain an essential part of the toolkit.
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