Will's Interesting Links Page

[dontknowanything]

I think there is also an interesting question which concerns the distribution of soil organic matter in the soil profile. It seems fairly clear cut that ploughing gives great SOM concentrations at depth where as no-till has much higher SOM concentrations in the top 5 cms. No-till plus a cover crop can give higher water infiltration rates (read this in the last day or so) than ploughed ground.

I think it is possible thogh to have higher infiltration rates than ploughing and still have higher water content in the top few cms (where a newly sown seed might lie). Need to think about this.

In a soil with fine particles, such as your clay, you're going to get the most drainage from macropores, worm holes etc. Cultivation is going to reduce/eliminate these, so it would make sense that NT/CC will give better drainage.

 

[Simon C]

I think in this debate about SOM you are all forgetting about the effect of applied nitrogen, whether it be from fertiliser or manure. It will burn up organic matter just as much as tillage. So Organic farmers are able claim they are preserving the soil in the same way that us no-tillers do. No-tilled legumes would therefore be the best way to actually build SOM. I believe Gabe Brown claims not to need any fertiliser anymore, which would explain how he has been able improve his soils so dramatically

 

[dontknowanything]

I think in this debate about SOM you are all forgetting about the effect of applied nitrogen, whether it be from fertiliser or manure. It will burn up organic matter just as much as tillage. So Organic farmers are able claim they are preserving the soil in the same way that us no-tillers do. No-tilled legumes would therefore be the best way to actually build SOM. I believe Gabe Brown claims not to need any fertiliser anymore, which would explain how he has been able improve his soils so dramatically

Steve Townsend will tell you that you need to apply N to residues in order to convert them into SOM. Do you have research that says otherwise?

Just about to publish blog about Gabe Brown

 

[Feldspar]

Steve Townsend will tell you that you need to apply N to residues in order to convert them into SOM. Do you have research that says otherwise?

Just about to publish blog about Gabe Brown

http://onlinelibrary.wiley.com/doi/10.1111/j.1469-185X.1988.tb00725.x/abstract

ETA: Actually that's about the breakdown of organic residue rather than SOM so not totally relevant.

 

[dontknowanything]

http://onlinelibrary.wiley.com/doi/10.1111/j.1469-185X.1988.tb00725.x/abstract

Actually that's about the breakdown of organic residue rather than SOM.

Great, thanks. Always like to be able to contradict him

 

[Feldspar]

Great, thanks. Always like to be able to contradict him

See my edit above. Interesting though that it looks like adding N has no effect on residue breakdown (so says a lot of studies rather than just one or two). Backs up @warksfarmer 's piece he quoted the other day.

 

[Simon C]

Steve Townsend will tell you that you need to apply N to residues in order to convert them into SOM. Do you have research that says otherwise?

Just about to publish blog about Gabe Brown

There is plenty of evidence to show that N is highly destructive, but I'm not looking for it at this time of night.

If high carbon residue is mixed into the soil, the bugs will help themselves to any available nitrogen before your plants can get hold of it, thus the recommendation for more applied N. If the residue is a left on the surface where there is no N, only free living nitrogen fixing bacteria will be able to live and the soil N will be left for your plants.

 

[dontknowanything]

ETA: Actually that's about the breakdown of organic residue rather than SOM so not totally relevant.

"The addition of N seems to increase the formation of water-soluble, brown, recalcitrant compounds, but to decrease the amount of humus formed."

same net effect as destroying SOM?

 

[dontknowanything]

There is plenty of evidence to show that N is highly destructive, but I'm not looking for it at this time of night.

If high carbon residue is mixed into the soil, the bugs will help themselves to any available nitrogen before your plants can get hold of it, thus the recommendation for more applied N. If the residue is a left on the surface where there is no N, only free living nitrogen fixing bacteria will be able to live and the soil N will be left for your plants.

That's not what Mr Townsend says - I had this specific discussion with him less than 24 hours ago, sitting on a straw bale at Menoken!

 

[Feldspar]

"The addition of N seems to increase the formation of water-soluble, brown, recalcitrant compounds, but to decrease the amount of humus formed."

same net effect as destroying SOM?

Not sure - I need to read the full paper.

 

[Feldspar]

Not all trials show increased, or any, carbon sequestration through no no-till. I keep on referring to this, but FAR results from NZ show no difference in SOM levels between no-till and ploughing over 13 years. The same trial does show yield advantage to no-till however.

My point is, only taking the results from trials you agree with, and pretending the others don't exist, is not a sensible way to make decisions on how to run your business.

More reading for you. Not too long. NB this 2007 so things may have progressed since then.

ETA: I'm going to try and get a full version of this too:

http://www.sciencedirect.com/science/article/pii/S0167880911004361

 

[Feldspar]

I think in this debate about SOM you are all forgetting about the effect of applied nitrogen, whether it be from fertiliser or manure. It will burn up organic matter just as much as tillage. So Organic farmers are able claim they are preserving the soil in the same way that us no-tillers do. No-tilled legumes would therefore be the best way to actually build SOM. I believe Gabe Brown claims not to need any fertiliser anymore, which would explain how he has been able improve his soils so dramatically

Just to fulfill the role of the contrarian (nice and recent and specific to northern Europe):

http://www.tandfonline.com/doi/abs/10.1080/09064702.2013.779316#.U6YE3pRdVH4

Quote: "Indeed, our results suggest that C stocks can increase with 1–2 kg C for each kg of mineral N fertilizer applied."

I think another thing that people miss is that if you adopt no-till and your yields drop (for the same N say) then you are reducing your C inputs back into the soil.

 

[Feldspar]

I've just found a gem which is hot off the press:

http://www.sciencedirect.com/science/article/pii/S0167880914000942

I really like this one because they sample to a decent depth (60cms rather than 30cms); they investigate proper no-till (rather than reduced tillage which can still be fairly aggressive); they look at cover crops and rotation too (a common complaint about no-till studies); they account for bulk density changes in different tillage regimes; and it's over a long time.

Note especially the comment about the correlation between SOC changes and water balance. I.e. in a UK climate you are going to see much lower gains (or even losses) than in much drier climates.

OK, so as another paper pointed out, there are other arguments for no-till and against ploughing. But on the specific point of C sequestration, I don't see the EU getting excited about paying no-till farmers for this service anytime soon, especially with this sort of stuff appearing.

 

[dontknowanything]

I've just found a gem which is hot off the press:

http://www.sciencedirect.com/science/article/pii/S0167880914000942

I really like this one because they sample to a decent depth (60cms rather than 30cms); they investigate proper no-till (rather than reduced tillage which can still be fairly aggressive); they look at cover crops and rotation too (a common complaint about no-till studies); they account for bulk density changes in different tillage regimes; and it's over a long time.

Note especially the comment about the correlation between SOC changes and water balance. I.e. in a UK climate you are going to see much lower gains (or even losses) than in much drier climates.

So basically different tillage regimes have little effect on SOC?

 

[Feldspar]

So basically different tillage regimes have little effect on SOC?

I've got no access to full papers atm, but I really want to read this one. From what I have read recently there is certainly no clear message that no-till does add to total SOC stocks. If anything, as with this paper, there's more stuff coming out which shows little or no difference. I have certainly had to revise my opinion on this quite a bit recently. However, as the conclusion of that full file I attached a few posts ago says, there are other arguments for no-till.

 

[Feldspar]

So basically different tillage regimes have little effect on SOC?

And to explain why, I think this may be the reason why in the UK we may struggle:

https://dl.sciencesocieties.org/publications/sssaj/abstracts/48/6/SS0480061267

Particularly if you take N20 into account which is a much more potent GHG.

 

[Clive]

No till makes sense in arid climates, that is almost undeniable.

However, we do not live in an arid climate. Moisture is the limiting factor on our farm, as it is on @Clive 's. But we are very spoilt in a global context, and when we get yield reductions from lack of water then we are probably looking at 15-20% in a very dry year, and maybe 15-20% higher yields in a good year. Compare this to drier (and equally important, hotter) parts of the US, where they will lose 50-100% of their yield in what they consider to be a drought. I suspect the same is true in southern Spain.

Therefore moisture conservation techniques, such as no-till, make a proportionately smaller difference in the UK than they do in other places. Using data from southern Spain, USA or Australia to justify no-till in the UK is not a terribly clever thing to do in my opinion; it is a form of cherry picking to suit an agenda.

Now, how many people have I upset?

I guess in the uk it depends upon the severity of your soils ability to drought, you say moisture limits you but having seen your soils trust me when I says it's much less of a limit for you than me on red sands over gravel. Last year dry June /July cost me over 1t/ac I reckon.

Ability of zero-till to retain a bit more moisture is always going to be more relevant for those in more arid climates but that doesn't mean it also can't help a light land uk farm in a dry year.

Where I have "soil armour" now I have moisture today when as fields without are desperately dry and will need rain this week to maintain the potential they have, I reckon I might have bought an extra week of drought tolerance via zero-till in my best case scenarios this year and that could be very significant some years as once a plant is dead it's dead !

 

[SilliamWhale]

My main reason is nothing to with carbon but its about reducing soil erosion, reducing establishment fixed costs and about developing a more resilient and flexible cropping system. ie you can go out in an afternoon and establish 40 acres of crops if the weather suits and you can grow a range of crops seeding from August to May throughout the year (rape, wheat, barley, grass, beans, swedes, linseed)

I think the hand wringing about needing data and research for this and that isn't as relevant if you decide that your going to start no tilling and stop ploughing for your crops over the longer term. That's the system you choose and that's how you make it work for you. Its obvious to me that I don't get such bad erosion, I don't have to spend so much on diesel and steel and that I'm perfectly capable of getting 4t/acre of Wheat, 1.75t/acre rape and 3.5t winter barley with no till crops.

Will I always make the most money each year? Probably no, not every year. Will I have a chance of getting some excellent crops for lower environemental and economic input? Yes.

 

[martian]

I don't suppose many farmers are that bothered by carbon sequestration, but policy makers may well be, which is why I mentioned it. Areas of Andalucia have the same annual rainfall that we do here, but just it all tends to all come in the Spring. Ploughed ground suffers terrible erosion (which was hardly mentioned in the ECAF video) and leads to fast run-off and flooding etc so I am thrilled to bits that the Government there is promoting no-till as it will make a huge difference to Spain. It feels a bit like Spain here today, siesta beckons...

 

[dontknowanything]

I guess in the uk it depends upon the severity of your soils ability to drought, you say moisture limits you but having seen your soils trust me when I says it's much less of a limit for you than me on red sands over gravel. Last year dry June /July cost me over 1t/ac I reckon.

Ability of zero-till to retain a bit more moisture is always going to be more relevant for those in more arid climates but that doesn't mean it also can't help a light land uk farm in a dry year.

Where I have "soil armour" now I have moisture today when as fields without are desperately dry and will need rain this week to maintain the potential they have, I reckon I might have bought an extra week of drought tolerance via zero-till in my best case scenarios this year and that could be very significant some years as once a plant is dead it's dead !

My main reason is nothing to with carbon but its about reducing soil erosion, reducing establishment fixed costs and about developing a more resilient and flexible cropping system. ie you can go out in an afternoon and establish 40 acres of crops if the weather suits and you can grow a range of crops seeding from August to May throughout the year (rape, wheat, barley, grass, beans, swedes, linseed)

I think the hand wringing about needing data and research for this and that isn't as relevant if you decide that your going to start no tilling and stop ploughing for your crops over the longer term. That's the system you choose and that's how you make it work for you. Its obvious to me that I don't get such bad erosion, I don't have to spend so much on diesel and steel and that I'm perfectly capable of getting 4t/acre of Wheat, 1.75t/acre rape and 3.5t winter barley with no till crops.

Will I always make the most money each year? Probably no, not every year. Will I have a chance of getting some excellent crops for lower environemental and economic input? Yes.

I don't suppose many farmers are that bothered by carbon sequestration, but policy makers may well be, which is why I mentioned it. Areas of Andalucia have the same annual rainfall that we do here, but just it all tends to all come in the Spring. Ploughed ground suffers terrible erosion (which was hardly mentioned in the ECAF video) and leads to fast run-off and flooding etc so I am thrilled to bits that the Government there is promoting no-till as it will make a huge difference to Spain. It feels a bit like Spain here today, siesta beckons...