Green manure

Smallaxe

LawnSite Fanatic
This is a strategy used by farmers too bring up the "tilth" and "humus" in the useless dirt of central Wisconsin...
The idea was to grow a cover crop and plow it under to put some body into the blowsand or red clay, near the rootzone...

Why, Is This A Failed Strategy according to the "No-Till" faithful???

What is missing???
 

RoTOrganics

LawnSite Member
Location
Sherman, TX
Oxygen destroys humus. Plowing reveals the root zone and gets oxygen that much deeper into the soil, thus destroying any possible accumulated humus. Humus grows best in an anaerobic environment, usually deep in the muck under water or really deep in an undisturbed root zone.

A superior way to build tilth and humus from a no till perspective is to be studious with cover crops and winter grains. A good bed of rye can get roots 6 feet deep in one winter - scalping that grass when it is overgrown and letting the roots decompose in place will build a superior environment for humus.

That's why I don't use any green manures, at least. It is better to just cut the plants down and leave them in place as a mulch instead of tilling them in.
 

phasthound

LawnSite Fanatic
Location
Mt. Laurel, NJ
Oxygen destroys humus. Plowing reveals the root zone and gets oxygen that much deeper into the soil, thus destroying any possible accumulated humus. Humus grows best in an anaerobic environment, usually deep in the muck under water or really deep in an undisturbed root zone.
i know little about ag & no-till, but I use a different definition for humus.
http://en.wikipedia.org/wiki/Humus
 

RoTOrganics

LawnSite Member
Location
Sherman, TX
i know little about ag & no-till, but I use a different definition for humus.
http://en.wikipedia.org/wiki/Humus
Thanks for the definition of humus - I think we're talking about the same stuff. I'm not saying that somehow the organic matter is going to disappear when oxygenated, but the kinds of humus and therefore the chemicals that are usable to the plant fundamentally change.

http://www.nofa.org/tnf/humus.php

"Higher percentages of humus are found in soils formed anaerobically because conditions are more favorable for humus accumulation and less favorable for its destruction. "

Humus refers to many things, and I'm sure this is one reason why people in some groups will disagree about what builds humus.

also...

"Unfortunately, conditions for the development of humus in sand are not always ideal. In tropical environments, for example, where moisture and temperature are optimum for populations of decomposition bacteria, organic matter is quickly assimilated back into the biomass. Coupled with the abundance of oxygen in a porous sand, it is difficult if not impossible for humus to accumulate...

The accumulation of humus is naturally easier in clay soil than in sand because the environmental conditions for decay bacteria are often not as ideal. Moisture levels in clay soils often reach the saturation point leaving little room for oxygen needed by aerobic life. "

This highlights that oxygen does play a role in the stability of humus over long periods of time. The wiki link that defines humus does indicate that 'humus' usually refers to stable material that cannot be reincorporated into the soil biomass.

At the end of the day, you are better off with not tilling the crop in - the nutritional benefits all remain, and you promote the less aerobic conditions that allow more humus to stabilize.
 
OP
S

Smallaxe

LawnSite Fanatic
Oxygen destroys humus. Plowing reveals the root zone and gets oxygen that much deeper into the soil, thus destroying any possible accumulated humus. Humus grows best in an anaerobic environment, usually deep in the muck under water or really deep in an undisturbed root zone.

A superior way to build tilth and humus from a no till perspective is to be studious with cover crops and winter grains. A good bed of rye can get roots 6 feet deep in one winter - scalping that grass when it is overgrown and letting the roots decompose in place will build a superior environment for humus.

That's why I don't use any green manures, at least. It is better to just cut the plants down and leave them in place as a mulch instead of tilling them in.
I had purposely put 'humus' and 'tilth' in quotes becuz those are the commonly used terms by the old farmers who were turning red sands and clays into brown, even black loams... I believe the idea of 'tilth' is similar to 'soil structure', in the common vernacular of the region; while 'humus' was simply OM at various stages of plant decomp in the soil, that gave it the rich earthy smell and feel...
Obviously we wouldn't want our rootzones in an anaerobic environment just to produce a more stable humus...
http://www.essortment.com/oxygenate-aerate-plant-roots-41913.html

Now for the botanical life of plants and the best case scenario that we can provide for the "Rootzone"...

What type/texture is your soil? Have you watched the development on your soil structure in the no-till fields vs nearby similar fields that are continued under cultivation?
 
OP
S

Smallaxe

LawnSite Fanatic
...
http://www.nofa.org/tnf/humus.php

"... At the end of the day, you are better off with not tilling the crop in - the nutritional benefits all remain, and you promote the less aerobic conditions that allow more humus to stabilize.
Is nofa stating that anaerobic rootzone are better, therefore no-till is better? What is the meaning of what they are saying here?
 

dKoester

LawnSite Gold Member
Location
Chesapeake VA
This is a strategy used by farmers too bring up the "tilth" and "humus" in the useless dirt of central Wisconsin...
The idea was to grow a cover crop and plow it under to put some body into the blowsand or red clay, near the rootzone...

Why, Is This A Failed Strategy according to the "No-Till" faithful???

What is missing???
Worms, shredders etc. A balanced ecosystem.
 

RoTOrganics

LawnSite Member
Location
Sherman, TX
I had purposely put 'humus' and 'tilth' in quotes becuz those are the commonly used terms by the old farmers who were turning red sands and clays into brown, even black loams... I believe the idea of 'tilth' is similar to 'soil structure', in the common vernacular of the region; while 'humus' was simply OM at various stages of plant decomp in the soil, that gave it the rich earthy smell and feel...
Obviously we wouldn't want our rootzones in an anaerobic environment just to produce a more stable humus...
http://www.essortment.com/oxygenate-aerate-plant-roots-41913.html

Now for the botanical life of plants and the best case scenario that we can provide for the "Rootzone"...

What type/texture is your soil? Have you watched the development on your soil structure in the no-till fields vs nearby similar fields that are continued under cultivation?
You certainly cannot grow roots in an anaerobic environment - in order to talk about this fairly, we have to not oversimplify the complex biological and chemical processes at play in soil. Most importantly, not all humus is created equal, and there are some aerobic and some anaerobic kinds.

"The term "Humus" doesn't really describe anything specific. Its like using the word "dog" to describe a German Short Haired Pointer."

My roots do not grow in anaerobic humus - and yet having anaerobic humus below my roots will do an incredible job of retaining moisture and allowing the more aerobic forms of humus above to wick it up. Tilling changes the structure and chemical composition of the humus that much deeper in the soil.

Let me also point out that when I talk about humus I am not primarily talking about organic matter - it includes many humic substances such as humates or salts of humus and fulvic acids that are the residues of the decomposition of OM. Humus is OM that has been decomposed to the point where it cannot quickly rejoin the biomass.

"During humification of organic matter, microbes dismantle most of the sugars, starches, proteins, cellulose and other carbon compounds to utilize them for their own metabolism...Some of the more easily dissolved components of the residues end up being used and re-used over and over, by many different varieties of organisms, and may never actually become humus...

Much of the nutrient and energy assimilated into the bodies of microbes is re-used by other microbes when they die. Some is mineralized back into plant food and some is changed into biologically resistant compounds that accumulate as components of humus.

...In the soil, organic matter is dissolved and absorbed by microorganisms utilizing the nutrients and energy for their own metabolism. Their activities convert most of the organically bound nutrients back into a mineral form which is usable by plants and other microbes. The undigested portion of the residues accumulate as humus. However, humus is not completely immune to decomposition. Microbes will eventually recycle all the elements in humus back to where they initially came from, even if it takes a millennium to do it."

Exposing that humus to oxygen allows it to be quickly re-assimilated by aerobic bacteria and the existing biomass, ergo destroying its existence as humus and its water holding capacities.

I think this would be easier for all of us if we had someone with a nice understanding of organic chemistry and soil biology who could clear up some of these important scientific nuances. :dizzy:

As for my soil type - I live in NE Texas and have some of the world's sorriest black clay gumbo to work with. We are in the middle of a historic drought, and yet during the winter the soil still won't drain; during the growing season it is brutally dry and our soil cracks are large enough to steal a family dog.

The difference in the no till fields that I have access to - which are admittedly limited, as my 1/2 acre garden is the only no till operation in town - is that I can put my hand down into the dirt past my fingers and then form a fist. That's what I call tilth, although perhaps I misuse the term. I also notice that I've overall decreased my watering needs by about 1/4" per row per week, which is significant considering this is during our drought.

But I'm admittedly new to no till and wasn't here trying to sell anyone on it based on my expertise - I was trying to offer some science up so that anyone who is interested can take this discussion from conjecture to something they are field testing for themselves.

If we read more science about the relationship of oxygen and humus, it would make obvious more reasons why no tillers claim to preserve humus and tilth, and also elucidate how those claims are based in science, not speculation. While lab science can't account for field trials, this is a subject where modern scientists are doing lots of field trials and basing their claims on field knowledge. :drinkup:
 

RoTOrganics

LawnSite Member
Location
Sherman, TX
If we read more science about the relationship of oxygen and humus, it would make obvious more reasons why no tillers claim to preserve humus and tilth, and also elucidate how those claims are based in science, not speculation. While lab science can't account for field trials, this is a subject where modern scientists are doing lots of field trials and basing their claims on field knowledge. :drinkup:
I don't like how this sounds and I can't edit my post - this might have sounded a little pretentious, and I was just trying to throw a toast up to science for giving us so many factors to consider in how to raise soil. :hammerhead:

With google scholar and other similar free databases, so many peer reviewed research papers and master's theses are available to folks like us at the touch of a few keys, it makes talking about these things so much more accessible. Scientific writing is definitely hard to wade through :weightlifter: but submitting our methods to examination and confirmation by our peers is necessary to move organic science into the forefront.
 

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