Is mechanical destruction a viable alternative to glyphosate? -A farmer Q+A

A group of farmers came together in 2017 to investigate alternatives to ploughing or glyphosate for terminating cover crops. To do this they tested a range of techniques including rolling, crimping and flailing. We caught up with field lab participant David White to ask him about the farmer-led research and the lessons he had learnt from it.

David White and group of farmers meeting    David White (far right) discusses the field lab with a group of researchers and farmers.

Can you explain the research and what you tested on your farm?

One of the reasons this field lab was set up was to see whether we could destroy cover crops effectively without using glyphosate. We had three seed mixtures of different varieties that we thought were particularly susceptible to mulch control or more frost susceptible. In the past I have observed that Phacelia and spring beans are easily controlled by frost. On my farm we tried flailing, crimping and rolling.

What results did you see?

The rolling and crimping were frost dependent and that took place rolling on around 25 November -and the crimping happened a week later. In this part of the world we don’t reliably get frosty winters, so you need to get out and do the crimping, or whatever treatment you are doing, early in the morning when you get a frost. All the methods were relatively effective. I don’t think the crimping was any more effective than the rolling and as most farmers already have a set of rollers on the farm, that makes it more practical and rolling is quite a good technique.

In my trials there was one row that was double crimped and double rolled and the cover crops there died quicker. So double is more effective but actually in the long term the single operation did catch up, so the methods were still effective. If you want to kill it quickly, though, then you want to do it twice. The whole process also depends on the soil condition, and it’s most effective if it’s frozen – you want the crop to be crispy. With flailing, what I observed was that it was good for the destruction of the crops initially, but those plants started shooting up from the base again. The plant was cut off, but we hadn’t crushed the plant enough at ground level to properly kill it.

And can you see mechanical weeding as a viable alternative to glyphosate?

While we had picked cover crops specifically that could be killed by mechanical means and that was successful, glyphosate was still needed as there was still some black grass and brome grass so that’s another element we need to look at. Whilst we can see that these methods can work, I couldn’t commercially farm like that without a glyphosate tidy up. However, it does mean we can manage with a single spray and perhaps with a lower dose of active ingredient to farm commercially with using the roller or crimper to destroy the cover crops, so we are reducing our spraying rates. Perhaps we need further adapted machinery to tackle all of it and still farm commercially.

What was your experience of being part of a field lab?

The field lab was very enjoyable. The great thing about this trial was that the people involved were from different parts of the country, so we got to travel to see different farms and see different crops and machines. It’s a great way to learn and make new like-minded acquaintances. It’s good to build up a network of farmers all doing trials all on our own farms and you can say to each other “I’m free Wednesday morning if anyone fancies a farm walk” and then you get that farmer knowledge exchange. It’s good to see other farmers coming out and looking at what I’m doing and perhaps learning from it.

Where will you be taking the trial next year?

There’s no reason why this January, if we get a decent frost, I shouldn’t adopt the rolling method as it was practical and then I can have a reduced spray rate. Whilst I didn’t do it this year there’s no reason I can’t going forward. But it very much depends on getting that first frost. It needs to be -3 or -4 degrees centigrade when you’re out there doing the treatment, because above that critical temperature the mud starts to thaw and it’s more difficult. I’d say that frost is more critical than the variety of cover crop that we grow as it makes the plant almost crispy, which makes it easier to destroy. But there are definitely some plants that are better suited. In Europe it would be easier as they have more reliable frosts. I wouldn’t do the flailing again as it is quite time and labour intensive. Having said that there are some advantages to mushing up the vegetation in this way because it makes more available to your worms and soil life, so that’s a plus. But it was more labour intensive, and the plants bounced back.

Have you got any comments on the need for farmer led research?

Farmer-led research like this gets the conversation going – in farming there are so many questions nobody has an answer to. I’ve been involved in trial plots before and the thing with farming is that it can be very difficult to generalise from farm to farm, so you need to replicate it to cater for different situations. In our more level field we would see a certain standard, but just one small change in altitude or organic matter in the soil can have quite a big effect on results. We all do our own experiments, but what farmers really need is organisations like Innovative Farmers to put a little bit of the science behind it and help us get some meaningful results. Then it’s not only me believing my personal feelings on what works, there’s science to back it up and that’s brilliant.

Get involved in your own farmer-led research

To keep informed of how this field lab and others are progressing sign up and become a member of the Innovative Farmers network. Got your own idea for a field lab? Then contact the team to find out how to get involved.


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