Termination timing

Most of no-till studies that have been conducted thus far have been concerned with moisture conservation in regions where evapotranspiration more freqently exceeds precipitation than in the UK. In the UK, however, we need to be concerned not so much with moisture conservation but rather moisture reduction at planting.

With this in mind if we are drillling into a cover crop we want it to be removing moisture as best it can so the soil surface is not overly wet and sticky. The choice of when to terminate a cover crop has a bearing on this requirement. This study

http://www.jswconline.org/content/44/1/57.short

concludes that drilling into a live cover crop would better achieve this aim than a termination with glyphosate a few weeks prior to drilling. A further benefit of this method would be that the cover crop has a further 2 weeks of growth which will increase biomass and possibly fixed N.

So my quesiton is whether cover crop users have noticed differences in soil moisture as a result of cover crop termination timings? Also, to anyone that heard Frederic Thomas speak, what were his reasons for drilling into live cover?
 

Clive

Staff Member
Arable Farmer
Location
Lichfield
We drilled into live cover this year (not drilled cover crops but 1ft tall volunteer OSR stands) the advantages seem wide spread, the extra growth of the cover so ultimately more OM etc returned to the soil, the drying effect of the cover using the moisture and also the "drilling on the green" effect Fredric talked about where the cover crop help carry the machinery on a mattress that protect the soil beneath, this year that was a BIG help and the reason we managed to get as much drilled as we did. Where we destroyed cover early soils were sticky and we couldn't get on, they are still undrilled to this day

Another advantage seems to be the slug issue - they were keen to keep eating the cover rather than seek out our wheat seed, even after emergence they seemed to prefer the cover to the wheat, they only started to graze wheat once the cover was all but gone by which point the wheat was big enough to start to look out for itself

in conclusion I won't be in any hurry to terminate a cover again !
 

Richard III

Member
Arable Farmer
Location
CW5 Cheshire
I tried three different cover crop destruction timings last spring, December, February and day before drilling. In last years dry spring there seemed little difference between soil moisture contents of different timings. The main difference was the soil was 2 deg colder under the live cover, but because the weather turned so cold after drilling there was little difference in crop growth between destruction timings. I will try again this spring!

As Clive found, drilling into rape volunteers worked so well here last autumn that in future I am prepared to slug pellet after rape harvest to make sure I get a good volunteer take.
 

martian

DD Moderator
BASE UK Member
Location
N Herts
I'm under pressure to spray covers off now as last year we had a similar programme to Richard above, ie some sprayed off at Christmas, some Feb and some the day before drilling. In the dry spell we had last spring the last ones were slowest to get away, drilled into the green (basically a thick stand of winter oats). None of the spring barley yielded particularly well last year, whereas most people round here growing barley found it the crop of the year. We are only two years in to the no-till regime on most of the land and I'm expecting the soil to get more friendly to deal with as we go on. I'm inclined to leave termination as long as possible, but have cold feet after last spring...
 
Location
Cambridge
Feldspar said:
Most of no-till studies that have been conducted thus far have been concerned with moisture conservation in regions where evapotranspiration more freqently exceeds precipitation than in the UK. In the UK, however, we need to be concerned not so much with moisture conservation but rather moisture reduction at planting.

Speak for yourself! We are more worried about moisture conservation - and this is one of the worries I have with cover cropping.
 

martian

DD Moderator
BASE UK Member
Location
N Herts
Feldspar said:
Martian, do you think termination timings should depend on the crop being drilled. For example, might spring beans be more tolerant of late termination than a spring cereal crop?
I think you are right. One of our best ever spring bean crops was cut into a stand of oats (many years ago) on Steve T's advice iirr, why we never tried it again I can't now think...barley is famously a bit pathetic at getting going. I also wonder whether the roundup wasn't having a negative effect and possibly a bit of alleopathic oat inhibition too. And, as Richard observed, the soil will warm slower under cover.
 

martian

DD Moderator
BASE UK Member
Location
N Herts
dontknowanything said:
Feldspar said:
Most of no-till studies that have been conducted thus far have been concerned with moisture conservation in regions where evapotranspiration more freqently exceeds precipitation than in the UK. In the UK, however, we need to be concerned not so much with moisture conservation but rather moisture reduction at planting.

Speak for yourself! We are more worried about moisture conservation - and this is one of the worries I have with cover cropping.
The American experience is that cover-crops conserve as much moisture as they transpire, bizarrely. In extreme drought they fail anyway, which is why in parts of Australia no-tillers seem to have given up on them. But in the UK that shouldn't happen..
 

Simon C

Member
Arable Farmer
Location
Essex Coast
martian said:
I'm under pressure to spray covers off now as last year we had a similar programme to Richard above, ie some sprayed off at Christmas, some Feb and some the day before drilling. In the dry spell we had last spring the last ones were slowest to get away, drilled into the green (basically a thick stand of winter oats). None of the spring barley yielded particularly well last year, whereas most people round here growing barley found it the crop of the year. We are only two years in to the no-till regime on most of the land and I'm expecting the soil to get more friendly to deal with as we go on. I'm inclined to leave termination as long as possible, but have cold feet after last spring...

It could be that the oats had taken up every last bit of nitrogen and left nothing for the barley to get started on. The sooner the cover is terminated, the sooner it will start recycling and provide nutrients for the following crop.
 

Simon C

Member
Arable Farmer
Location
Essex Coast
The advantage of legumes in the cover is that they are highly dependent on mycorrhizae and other fungi, and so while they are growing, they will be changing the soil biological profile to being more fungal. This will be a huge help to any following crop that is mycorrhizae dependent, ie. cereals.

I have also heard that if beans in a cover are burnt off early, they go black and therefore absorb the sunlight and help the soil warm up much quicker.

Actually, I think it is all about soil type when considering termination timing. All the photos of Frederic Thomas drilling into green covers are on light land, even sand, where any drill will work in the presence of reasonable amounts of moisture. The cover takes water out and by capillary action the whole soil profile has the same moisture content.

On heavy clay land you don't get capillary action, it can be dry on top and wet below, of wet and sticky on the top and dry below. So the only way to get the surface of heavy land dry enough to drill into is by the action of the sun and wind, which is prevented by a green cover on top.

Because of this I often curse having these covers when drilling in the Spring, the soil stays so wet underneath them, but I do believe they are essential if we are going to make any progress in building back organic matter. So my conclusion is that it is best to finish them off at some point in the winter, then the nutrients can start recycling and the soil can become exposed to dry out. The only down side is that it is not adhering to the doctrine of having something growing in the soil all year round, but I do wonder if that really matters when it is too cold for anything to be growing anyway. Plants aren't feeding the soil biology when they're not growing.

That's the theory, in practice it's been too wet to run the sprayer round here for three months, so what little covers I did get established are still there, but pretty small and thin, so probably won't be too much of a nuisance anyway.
 

shakerator

Member
BASE UK Member
Location
LINCS
a very good post simon.

jill clappertons video on soil temp variations in winter is worth a watch!

i queried dwayne beck on this

he was of the impression drilling into a livng root system is best.

i am less nervous driling a legume into green. esp beans strong seed, less chance of glyph toxicity/ n lockup etc.
although last year beans were drilled into dying resdue, dessicated brown prob safer in spring.

in 3 or 4 years hopefully wheat into green in late october....
 

martian

DD Moderator
BASE UK Member
Location
N Herts
Thanks Simon, wise words indeed!
One of our early sprayed off fields last year had died off so much that there was barely any mulch cover come drilling. It wasn't a huge problem as we didn't have much rain in early 2012, but I'd be nervous in a year like this that the surface would get battered down by rain. So I guess mid-Feb would be about right to terminate in front of barley, still be some residue to take the weather. We are clayey here, but not as stiff as yours!
 

Fran Loake

Member
BASE UK Member
Location
North Bucks
Simon Cowell said:
The advantage of legumes in the cover is that they are highly dependent on mycorrhizae and other fungi, and so while they are growing, they will be changing the soil biological profile to being more fungal. This will be a huge help to any following crop that is mycorrhizae dependent, ie. cereals.

I have also heard that if beans in a cover are burnt off early, they go black and therefore absorb the sunlight and help the soil warm up much quicker.

Actually, I think it is all about soil type when considering termination timing. All the photos of Frederic Thomas drilling into green covers are on light land, even sand, where any drill will work in the presence of reasonable amounts of moisture. The cover takes water out and by capillary action the whole soil profile has the same moisture content.

On heavy clay land you don't get capillary action, it can be dry on top and wet below, of wet and sticky on the top and dry below. So the only way to get the surface of heavy land dry enough to drill into is by the action of the sun and wind, which is prevented by a green cover on top.

Because of this I often curse having these covers when drilling in the Spring, the soil stays so wet underneath them, but I do believe they are essential if we are going to make any progress in building back organic matter. So my conclusion is that it is best to finish them off at some point in the winter, then the nutrients can start recycling and the soil can become exposed to dry out. The only down side is that it is not adhering to the doctrine of having something growing in the soil all year round, but I do wonder if that really matters when it is too cold for anything to be growing anyway. Plants aren't feeding the soil biology when they're not growing.

That's the theory, in practice it's been too wet to run the sprayer round here for three months, so what little covers I did get established are still there, but pretty small and thin, so probably won't be too much of a nuisance anyway.

That's an excellent post thank you Simon, and probably saves 2 or 3 years of learning for me. I do think that a lot of the timings (especially this year) will be done when we can sensibly get on the ground - often just prior to drilling. We are grazing off our first year of cover crops at the moment so shouldn't have too much plant matter to drill through.

A question that came up at a meeting the other day was whether blackgrass will be inhibited from germinating under the cover crop until spring, and then germinate and give problems, whereas in a non cover crop situation it would have been dessicated out of the way. Any thoughts on that?
The same thing worried me at one time but I've kinda put it to the back of my head recently, what with the weather and all...
Fran
 

Simon C

Member
Arable Farmer
Location
Essex Coast
Fran loake said:
A question that came up at a meeting the other day was whether blackgrass will be inhibited from germinating under the cover crop until spring, and then germinate and give problems, whereas in a non cover crop situation it would have been dessicated out of the way. Any thoughts on that?
The same thing worried me at one time but I've kinda put it to the back of my head recently, what with the weather and all...
Fran

There is all sorts that can befall blackheads seed on the surface over winter, rotting, being eaten etc so I don't think it is a big deal. It is when seeds are buried that they becoming long term dormant and then appear when you are least expecting.
 

Simon C

Member
Arable Farmer
Location
Essex Coast
martian said:
Thanks Simon, wise words indeed!
One of our early sprayed off fields last year had died off so much that there was barely any mulch cover come drilling. It wasn't a huge problem as we didn't have much rain in early 2012, but I'd be nervous in a year like this that the surface would get battered down by rain. So I guess mid-Feb would be about right to terminate in front of barley, still be some residue to take the weather. We are clayey here, but not as stiff as yours!

Yes, I know what you mean about rain bashing down the soil surface, I have a lot like that this year where there is no cover, that's partly why I want to get some more gypsum on everywhere. I posed the question at meeting last week, why do we do everything to help break down straw with bio-mulch and encouraging worms so that half the way through winter the whole lot has gone and the soil is then exposed to the weather?
 

Yes, I know what you mean about rain bashing down the soil surface, I have a lot like that this year where there is no cover, that's partly why I want to get some more gypsum on everywhere. I posed the question at meeting last week, why do we do everything to help break down straw with bio-mulch and encouraging worms so that half the way through winter the whole lot has gone and the soil is then exposed to the weather?[/quote]

And why do you?
 

Simon C

Member
Arable Farmer
Location
Essex Coast
SilliamWhale said:

Yes, I know what you mean about rain bashing down the soil surface, I have a lot like that this year where there is no cover, that's partly why I want to get some more gypsum on everywhere. I posed the question at meeting last week, why do we do everything to help break down straw with bio-mulch and encouraging worms so that half the way through winter the whole lot has gone and the soil is then exposed to the weather?

And why do you?[/quote]

To feed the worms and recycle nutrients in the straw. This is partly how we manage not using any P, K or lime for 15 years. I suppose it is a timing thing really, maybe now I could be content to wait two years for the nutrients to become available, but more mulch means slower soil drying which is what I was talking about before with the green covers.

I think my attitude is only relevant in a heavy soil situation. If your soil can be drilled when moist, you can cope with more surface trash, Drilling here is always tricky at the best of times and often needs a harrow pass as well for slot closing, something you can't do with loads of residue about.
 

Simon C

Member
Arable Farmer
Location
Essex Coast
SilliamWhale said:
Yes but do you think by using biomulch you are speeding up a process that would happen anyway a little bit later on?

Yes, I think you are right Will, but there is a whole lot more to the latest Bio-Mulch compared to when Plumbo started making it ten years ago. It is a sort of work in progress. You now get a bucket full of soil bugs to mix with it, plus a load of other beneficial stuff. I'm not his salesman, so that's all I'm saying, but I am happy to keep using it.
 

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