Allelopathy.

[doorknob]

Another interesting read on the topic by Dr.Cook. Cook is a respected professor around these parts of the world. I thought some here may find some interest in the replicated trials using chaff and also his closing bit "A parallel from medicine".

Article in Plant Health International.

 

[Northdowns Martin]

Thank you for sharing that paper an interesting read.

 

[Robigus]

Very interesting.

 

[martian]

Next question: what do we do about this...soak the ground in fungicide? Presumably effect is noticeable in any plant susceptible to Pythium species, who they? And also presumably, as you proceed into a no-till regime, your soils get a better balance of bacteria/fungi etc, as this infection must contribute to the yield depression in the early years of no-till adoption

 

[shakerator]

Next question: what do we do about this...soak the ground in fungicide? Presumably effect is noticeable in any plant susceptible to Pythium species, who they? And also presumably, as you proceed into a no-till regime, your soils get a better balance of bacteria/fungi etc, as this infection must contribute to the yield depression in the early years of no-till adoption

Good article.

Phosphite is designed for this very purpose.... (Pythium pathogens, not a phophATE root boost as advertised in the trade!)

No second wheats?

I have certainly seen healthy wheat volunteers emerge from chopped straw!

Is stripper heading more 'natural' than chopped straw

 

[Simon C]

Allelopathic Effects of Wheat Residues on Crops

This is the title of a chapter in “Allelopathy in Agroecosystems” by Kohli, Singh and Batish. Apparently there are at least five phytotoxins produced by the bacteria and fungi which specialize in breaking down high carbon material like wheat straw. These chemicals are highly toxic to many plants, effecting germination and growth rate; we sort of know about this because it is what happens when straw is hairpined into the slot with the seed. Various trials have been done growing cotton, rice, soyabeans and wheat itself in the presence of decaying wheat straw, and they were all effected to some degree. One trial growing wheat as a forage crop produced twice as much bulk where there was no residue compared to where there was.

I have seen this in my own crops without realizing what the problem was. When I was min-tilling, mixing chopped straw in the top two or three inches, second wheats and rape often seemed to struggle and the general consensus was that there was competition for nitrogen. Where the combine double overlapped the straw on the headlands, the wheat would be completely dead. This is what got me into direct drilling in the first place, I thought that keeping the residue on the surface would delay the utilization of nitrogen by the soil biology and therefore give the crops a head start. Second wheats were a bit better, but rape would still not grow with any vigour, no matter how much nitrogen I put on in the Autumn.

I remember talking to Jeff Claydon when he was first developing his drill and of course he was full of how good his rape and especially his second wheats were. His second wheats were yielding the same as the firsts, with no take all and vigorous autumn growth. He said it was because of the front tine, and likened it to plants growing in a flower pot of loose compost. I think this is rubbish, apart from the release of nutrients from the cultivated strip, he was getting a big benefit from the clearance of chopped straw from the seed band by the front tine. If he put some decent row cleaners on instead of the front tine, the crops would be just as good.

This got me thinking about Carlos Crovetto in Chile. Where he has too much residue for his crop to cope with, he rakes it into windrows the width of his sprayer apart. He is happy to sacrifice 10% of the field if it means growing a decent crop on the rest. Twelve months later, he spreads the whole lot back out across the field, not sure how though. I had a look through his book, “No Tillage”, and there it is, page 164 to
170, all about allelopathic effects of residues on crops, he had all this worked out 10 or 15 years ago.


He says that the problem usually coincides with first Autumn rains and does not happen below 5 degrees C or above 18 C, residue above 3tonnes/ha will start to have an effect. Also Spring crops are safe because the chemicals are deactivated over winter. There is a graph on page 167 to show that the effect gets worse for four weeks after the onset of rain and then declines to nothing at eight weeks.


All my best cover crops have been grown in long cut or stripped stubble and I have never grown a decent one when drilling into chopped straw with the Sim-tec, so this allelopathy idea is starting to make sense to me. Also, I have mentioned before that the better the over winter cover, the worse the Spring crop does. I now think that this is partly because the toxin producing bacteria can’t get at the standing stripped straw until the Spring when it is pressed down with the drill and rolls, thus effecting the new emerging seedlings.


So now my plan is to give up planting anything into chopped straw. Early drilled cover crops, second wheat or barley (or rape if you must) will go into stripped or long cut stubble, the covers will then be mulched down before winter, mixing greenery and straw, with a flail mower or, dare I say, Sheep!! Winter beans will be OK into chopped straw because there should be at least 8 weeks between harvest and drilling.

 

[Goldilocks]

Allelopathic Effects of Wheat Residues on Crops

This is the title of a chapter in “Allelopathy in Agroecosystems” by Kohli, Singh and Batish. Apparently there are at least five phytotoxins produced by the bacteria and fungi which specialize in breaking down high carbon material like wheat straw. These chemicals are highly toxic to many plants, effecting germination and growth rate; we sort of know about this because it is what happens when straw is hairpined into the slot with the seed. Various trials have been done growing cotton, rice, soyabeans and wheat itself in the presence of decaying wheat straw, and they were all effected to some degree. One trial growing wheat as a forage crop produced twice as much bulk where there was no residue compared to where there was.

I have seen this in my own crops without realizing what the problem was. When I was min-tilling, mixing chopped straw in the top two or three inches, second wheats and rape often seemed to struggle and the general consensus was that there was competition for nitrogen. Where the combine double overlapped the straw on the headlands, the wheat would be completely dead. This is what got me into direct drilling in the first place, I thought that keeping the residue on the surface would delay the utilization of nitrogen by the soil biology and therefore give the crops a head start. Second wheats were a bit better, but rape would still not grow with any vigour, no matter how much nitrogen I put on in the Autumn.

I remember talking to Jeff Claydon when he was first developing his drill and of course he was full of how good his rape and especially his second wheats were. His second wheats were yielding the same as the firsts, with no take all and vigorous autumn growth. He said it was because of the front tine, and likened it to plants growing in a flower pot of loose compost. I think this is rubbish, apart from the release of nutrients from the cultivated strip, he was getting a big benefit from the clearance of chopped straw from the seed band by the front tine. If he put some decent row cleaners on instead of the front tine, the crops would be just as good.

This got me thinking about Carlos Crovetto in Chile. Where he has too much residue for his crop to cope with, he rakes it into windrows the width of his sprayer apart. He is happy to sacrifice 10% of the field if it means growing a decent crop on the rest. Twelve months later, he spreads the whole lot back out across the field, not sure how though. I had a look through his book, “No Tillage”, and there it is, page 164 to
170, all about allelopathic effects of residues on crops, he had all this worked out 10 or 15 years ago.


He says that the problem usually coincides with first Autumn rains and does not happen below 5 degrees C or above 18 C, residue above 3tonnes/ha will start to have an effect. Also Spring crops are safe because the chemicals are deactivated over winter. There is a graph on page 167 to show that the effect gets worse for four weeks after the onset of rain and then declines to nothing at eight weeks.


All my best cover crops have been grown in long cut or stripped stubble and I have never grown a decent one when drilling into chopped straw with the Sim-tec, so this allelopathy idea is starting to make sense to me. Also, I have mentioned before that the better the over winter cover, the worse the Spring crop does. I now think that this is partly because the toxin producing bacteria can’t get at the standing stripped straw until the Spring when it is pressed down with the drill and rolls, thus effecting the new emerging seedlings.


So now my plan is to give up planting anything into chopped straw. Early drilled cover crops, second wheat or barley (or rape if you must) will go into stripped or long cut stubble, the covers will then be mulched down before winter, mixing greenery and straw, with a flail mower or, dare I say, Sheep!! Winter beans will be OK into chopped straw because there should be at least 8 weeks between harvest and drilling.

Simon,Good to meet you at Plumpton. Very interesting post and topic.As with most problems that arise in crop production I find that sensible sustainable rotations are usually the answer. With our OSR: Wheat; Spring Beans; Wheat ; Winter barley rotation the only place where there is potentially a problem is with the winter barley after chopped wheat straw. In practice with drilling reasonably early with robust seedrates and seedbed DAP or MAP alleopathic effects are rarely a problem.

 

[Simon C]

Simon,Good to meet you at Plumpton. Very interesting post and topic.As with most problems that arise in crop production I find that sensible sustainable rotations are usually the answer. With our OSR: Wheat; Spring Beans; Wheat ; Winter barley rotation the only place where there is potentially a problem is with the winter barley after chopped wheat straw. In practice with drilling reasonably early with robust seedrates and seedbed DAP or MAP alleopathic effects are rarely a problem.

I think it has a lot to do with how much rain you get after drilling as well. If the straw stays dry, then there will be little activity by the fungi/bacteria, that was the case this year for rape and is why there are so many good crops around now.

Also soil type has an influence. The toxins will wash through a light soil easier, being dispersed through a higher volume of soil, whereas it takes a lot more water to wet up a heavy soil, so the toxins are concentrated in the top layer where the seeds are trying to grow.

 

[Andy Howard]

Allelopathic Effects of Wheat Residues on Crops

This is the title of a chapter in “Allelopathy in Agroecosystems” by Kohli, Singh and Batish. Apparently there are at least five phytotoxins produced by the bacteria and fungi which specialize in breaking down high carbon material like wheat straw. These chemicals are highly toxic to many plants, effecting germination and growth rate; we sort of know about this because it is what happens when straw is hairpined into the slot with the seed. Various trials have been done growing cotton, rice, soyabeans and wheat itself in the presence of decaying wheat straw, and they were all effected to some degree. One trial growing wheat as a forage crop produced twice as much bulk where there was no residue compared to where there was.

I have seen this in my own crops without realizing what the problem was. When I was min-tilling, mixing chopped straw in the top two or three inches, second wheats and rape often seemed to struggle and the general consensus was that there was competition for nitrogen. Where the combine double overlapped the straw on the headlands, the wheat would be completely dead. This is what got me into direct drilling in the first place, I thought that keeping the residue on the surface would delay the utilization of nitrogen by the soil biology and therefore give the crops a head start. Second wheats were a bit better, but rape would still not grow with any vigour, no matter how much nitrogen I put on in the Autumn.

I remember talking to Jeff Claydon when he was first developing his drill and of course he was full of how good his rape and especially his second wheats were. His second wheats were yielding the same as the firsts, with no take all and vigorous autumn growth. He said it was because of the front tine, and likened it to plants growing in a flower pot of loose compost. I think this is rubbish, apart from the release of nutrients from the cultivated strip, he was getting a big benefit from the clearance of chopped straw from the seed band by the front tine. If he put some decent row cleaners on instead of the front tine, the crops would be just as good.

This got me thinking about Carlos Crovetto in Chile. Where he has too much residue for his crop to cope with, he rakes it into windrows the width of his sprayer apart. He is happy to sacrifice 10% of the field if it means growing a decent crop on the rest. Twelve months later, he spreads the whole lot back out across the field, not sure how though. I had a look through his book, “No Tillage”, and there it is, page 164 to
170, all about allelopathic effects of residues on crops, he had all this worked out 10 or 15 years ago.


He says that the problem usually coincides with first Autumn rains and does not happen below 5 degrees C or above 18 C, residue above 3tonnes/ha will start to have an effect. Also Spring crops are safe because the chemicals are deactivated over winter. There is a graph on page 167 to show that the effect gets worse for four weeks after the onset of rain and then declines to nothing at eight weeks.


All my best cover crops have been grown in long cut or stripped stubble and I have never grown a decent one when drilling into chopped straw with the Sim-tec, so this allelopathy idea is starting to make sense to me. Also, I have mentioned before that the better the over winter cover, the worse the Spring crop does. I now think that this is partly because the toxin producing bacteria can’t get at the standing stripped straw until the Spring when it is pressed down with the drill and rolls, thus effecting the new emerging seedlings.


So now my plan is to give up planting anything into chopped straw. Early drilled cover crops, second wheat or barley (or rape if you must) will go into stripped or long cut stubble, the covers will then be mulched down before winter, mixing greenery and straw, with a flail mower or, dare I say, Sheep!! Winter beans will be OK into chopped straw because there should be at least 8 weeks between harvest and drilling.

All makes sense. I have found crops are a lot better drilled into long stubble. How are you going to plant into long stubble. Won't the simtech struggle in autumn?
Thinking of our wheat after oats. It emerged fine, then rained and went backwards (no where near as bad with starter) and now has picked up. I was thinking a nitrogen problem.
Another interesting thing is this year my standing stubble is rotting very well standing up. More than I have seen before.

 

[Simon C]

All makes sense. I have found crops are a lot better drilled into long stubble. How are you going to plant into long stubble. Won't the simtech struggle in autumn?
Thinking of our wheat after oats. It emerged fine, then rained and went backwards (no where near as bad with starter) and now has picked up. I was thinking a nitrogen problem.
Another interesting thing is this year my standing stubble is rotting very well standing up. More than I have seen before.

Andy, I also have two disc drills.

I suppose all this rain is helping with straw breakdown this year. Every year is different, we never will have all the answers to all the problems

 

[Jim Bullock]

Over here in the "Wet West" we are baling more straw than we used to simply because we are suffering from a number of the problems mentioned thus far in the thread.. But as we are now about 50% winter wheat with most of our break crops spring sown (at present) we are going to try and make up for the loss of OM in the exported straw with cover crops, FYM and compost.. After 17 years of direct-drilling I have as yet to find any drill or system that can deal with a wet mat of chopped straw..

 

[Simon C]

Over here in the "Wet West" we are baling more straw than we used to simply because we are suffering from a number of the problems mentioned thus far in the thread.. But as we are now about 50% winter wheat with most of our break crops spring sown (at present) we are going to try and make up for the loss of OM in the exported straw with cover crops, FYM and compost.. After 17 years of direct-drilling I have as yet to find any drill or system that can deal with a wet mat of chopped straw..

Better to bale the straw and grow a decent cover crop than leave the straw and grow a rubbish cover, I would have thought. However a mixture of both, as with stripping and disc drilling, would provide the soil biology with the perfect Carbon to Nitrogen ratio.

It is the ease with which the Sim-tec drills into chopped straw that has lead me into these problems, I think.

 

[willy]

I have a twin rotor combine and mentioned to massey it would be good to have the option to put 1 rotor through the chopper and row the other row up. At least this way if you have a massive straw crop you can effectively bale half the straw and leave the other half for mulch.

What do you reckon?

 

[SorenIlsoe]

Over here in the "Wet West" we are baling more straw than we used to simply because we are suffering from a number of the problems mentioned thus far in the thread.. But as we are now about 50% winter wheat with most of our break crops spring sown (at present) we are going to try and make up for the loss of OM in the exported straw with cover crops, FYM and compost.. After 17 years of direct-drilling I have as yet to find any drill or system that can deal with a wet mat of chopped straw..

Hello Jim
I do not agree! Baling does after my opinion not work very well with DD (and certainly not with Conservation Agriculture) because you get a lot of random traffic in the field by the baling process and then the loading job with heavy loads out of the fields often with poor high pressure tires on the trailer. And in a wet harvest it has to be turned one or several times to get dry after rain. I just don't understand how you can say that with your heavy soil, because what heavy clay soils mostly need is SOC! Under 2% carbon in the 25cm topsoil it begins to make yield drops and problems......
Here we can just pick the phone a sell the straw for 26,8€/t from the field without doing ANY work yourself - just down in your pocket! But it is more worth in the soil unless you have cattles on the farm and recircles it back to the soil in that way. Here it is used for heating and nutrients is just lost (30 kg N/ha+p+k+??). Selling straw is loosing carbon every year and your soil starts to loose structure. And the argument about compensation with cover crops does not work if you sell all the straw and has perhaps only 20% spring crops - cover crops on 20% of the area can not compensate for removing straw on 100% of the area.
And if the straw is choppped - it is still allowed to grow cover crops and expand SOC levels and soil structure at the same time.
Buy a smaller and lighter combine and a stripper header - get 50% more capacity, lower grain moisture and the same harvest capacity as a big combine - that must be the way ahead as I see it.
I just has a problem, because I have 50% ownership of a combine together with a plowing partner - and he doesn't need a stripper header !!! Discussions ahead......

 

[kiwi]

Very interesting discussion so I thought I had better sign in, after watching the new forum for some time. I don't believe the straw cover is the issue as we have burnt paddocks and see the same issues as where the straw is. I believe it has to do with the root disease mentioned above and maybe you should google trichoderma and see what comes up . I think maybe the future lies in inoculating with trichoderma strains that are beneficial to the crops we are growing. I would like to see a lot more research done on this. Here in n.z they have found that some strains of trichoderma inoculated on o.s.r have resulted yield increases of 25 percent apparently. Australian crop scientists have also done a lot of work on this as well and believe longer rotations are the answer to pythium diseases and also trichoderma inoculates.

 

[Hartwig]

He says that the problem usually coincides with first Autumn rains and does not happen below 5 degrees C or above 18 C, residue above 3tonnes/ha will start to have an effect. Also Spring crops are safe because the chemicals are deactivated over winter. There is a graph on page 167 to show that the effect gets worse for four weeks after the onset of rain and then declines to nothing at eight weeks.

Simon,
interesting what you found out from Crovetto - is that maybe the answer why at least here in my region there is a clear observation in many years that osr is growing better just seeded the other day after combining wheat versus when it is grown after barley with two proper stubble cultivations, spread slurry to break down straw, and have around 4-5 weeks time between harvest and drilling !?
That observation was in ploughing as well or even more in min-tillage.
Usually it`s always wet enough here, so Crovettos "onset of rain" has no meaning and straw yields are well above 3 tons as well.

 

[Simon C]

Welcome Kiwi, it is good to have your input from NZ

You may know that some of us use Plumbo's Bio-Mulch to help break down straw residues. He has been putting trichoderma in the mix for a few years now, as I understand, for the very reason you suggest, but it has not cured the problems we are talking about. Pythium on the roots may well be having an effect, but it is not the whole cause.

Croveto says that Corn, Lupins, rape, sunflowers and all legume residues have no allelopathic effect and he has no problem drilling into them. I think it is the specialized bacteria and fungi that can live on high carbon wheat straw that produce the phytotoxins.

The Stripper Header is brilliant, but I still have issues with losses. I really need to have a way of quantifying how much grain is left on the ground in financial terms and then set that against all the benefits ie fuel saving, time saving, drying, better and earlier cover crops etc.

Cutting the stubble high is a good compromise so that what goes through the combine and then gets chopped and spread is kept below Croveto's 3t/ha.

 

[Andy Howard]

Andy, I also have two disc drills.

I suppose all this rain is helping with straw breakdown this year. Every year is different, we never will have all the answers to all the problems

Sure, though I thought you were getting more consistent results from the simtech. Back to the straw problems. I suspect it is a bit of everything discussed here and the answer is going to be more than one thing. For me we are already cutting straw high, using starter with some N and biology but the other thing I think could help would be having an undersown crop already there. So there is more varied soil biology. The green cover will mean drilling into a narrower C:N ratio and probably more free soil N. Managing and establishing the undersown crop is the key for me at the moment .

 

[SilliamWhale]

@Simon C - with regard to cover crops in the spring and slow warm up etc. I seem to remember something about Sarah Singla talking about "black" and "white" cover crops. Black cover crops could be more bulbous brassica type species or them and some warm season annuals that would have died off in the frost/cold. And more soil exposure. I guess it depends what your following crop is.

I hope your not drawing too many conclusions on covers from last spring alone because it was particularly cold for seeding into covers. I would call that an event that may happen once in 5 years maximum rather than regularly that cold. Soil temps here were biting cold well into May, some barley plants were ankle high on May 25th here with the cold winds.

I think Crovetto managed away from windrowing in the end. I don't think its sustainable from a management point of view, its too awkward. He probably didn't get as much straw as us sometimes. Also he does have an egg farm on the place and put plenty of muck on with that! He also has the advantage of growing a tidy crop of grain maize which gives him a bit of variety and a spring cropping preponderence incl lupins, barley etc.

Personally I see no harm in baling straw now and again. Even better if you put muck/compost muck back.

p.s Crovetto is on facebook if you want to fire a question. Carlos Crovetto Lamarca.

 

[dontknowanything]

What an interesting thread. We will be drilling into grazed covers for the first time this year (last year they were ploughed after grazing). I really should have left a bit without a cover crop to see if there was a difference. I'm inspired to try cutting a bit of wheat stubble very high this year and see what difference it makes - and if the drill can deal with it.