Keyline Plow

[dominiquer60]

Geoff,

“First – since soil microbial activity seems to be pretty important, do we know which groups or species predominate in “healthy” soils w/ good tilth? And, if so, how easy would it be to do an estimate of soil microbe presence or populations – instead of having an N P K soil test (probably better in conjunction with NPK)? Kind of like thinking of your soil like your compost pile – is it active? why or why not? what needs to change? ….”

The Nordells have used various soil labs in the continuous fine tuning of their market garden. I don’t have the issue on hand at the moment, but one of their SFJ articles compared 4 soil labs. One of them was Woods End Lab in ME. From what I recall they test soils for microbial health/activity by taking a fresh sample and measuring how much CO2 the microbes create from respiration in the course of a week. The more CO2 the higher the microbe activity and in theory the healthier the soil. Here is ATTRA’s list of alternative soil labs and the Woods End link.

http://attra.ncat.org/attra-pub/soil-lab.html
http://www.woodsend.org/

Erika

[Stable-Man]

@near horse 15140 wrote:

Again, lots of food for thought here so I’ll try and add something. First – since soil microbial activity seems to be pretty important, do we know which groups or species predominate in “healthy” soils w/ good tilth? And, if so, how easy would it be to do an estimate of soil microbe presence or populations – instead of having an N P K soil test (probably better in conjunction with NPK)? Kind of like thinking of your soil like your compost pile – is it active? why or why not? what needs to change? ….

This kind of speaks to the dilemma of farming and harvesting in general. These actions aren’t natural. For example, the nutrients in a hayfield or a tree would never leave the site en masse as when we harvest those materials and it is also highly unlikely that fields would naturally be plowed and turned over in such short order (like a few days when we plow). So, what to do? We can try, as Carl says, to mimic natural processes as best we can and I think some of the forestry practices discussed on this site are great examples. But it us truly THE challenge before us to .

In “The Plowman’s Folly” (mentioned here at DAP by others), the effect of inverting the topsoil with a moldboard plow is unnatural, even if it doesn’t bring up subsoil. Instead, they encourage using a disc plow or now, a chisel plow. But they require increased HP in their use. The same can be said of the “No-till” drilling systems being pushed out here in the west. I think the engineering has come from the top down – in other words, “here’s this problem with moldboard plowing AND we have a 350 HP tractor at our disposal, so what can we do?” WE need to think, as Carl mentioned he does, “here’s this problem and I have draft animal power at my disposal, what can I do?”

I have to add that “if that’s the case, why are they trying to keep all that nature off of them in their A/C cab with digital surround-sound stereo and plush bucket seats, riding 8 feet off the ground at 8 mph?”:(

I guess my point in this is we are changing an ecosystem by doing what we do. We are continually resetting “natural succession” to a stage more desirable for our needs. For example, the 60 yr old forest plantation Carl mentions wouldn’t become a pasture or cropland on its own. It would likely become a climax woodland of whatever species fit in that area. But that’s not what he needs it to be and that’s fine and I’m sure he recognizes this.

Unfortunately, as bad a rap as moldboard plowing gets, it’s still something I really enjoy doing with my team. Perhaps I can keep it to skimplowing in green manure crops or something?:o

Can’t two horses disc plow? I don’t really know, but just from looking at pictures 2 seems like enough. Carl mentioned leaving the tree roots and stumps. The decay and roots near the surface probably keep compaction to a minimum. Looser soil could mean using regular equipment instead of heavy, expensive no till drills. Plowing, however, breaks the soil and makes it easier to compact. I think it’s likely we can create the forest/root system conditions by mulching crops and growing new crops in the mulch, and over time the soil becomes less compact and the organic matter extends deeper into the soil, and you don’t need 300hp to do it.

There aren’t many modern ag implements for the draft animal, but apparently one can hook up the cover crop roller to a team, and crop rollers have existed since the early 1900s.

So my point is it may take longer but crop/grass roots are probably all the keyline tillage that is necessary. These tractors that weigh I don’t even know how much are probably significant contributors. Since they weigh more than almost anything that would naturally tread on the soil, you need to take unnatural steps to fix problems to which they contribute.

[near horse]

Make sure we’re talking about the same thing – discing the soil isn’t the same as plowing with a disc plow. Disc plows are basically setup like a moldboard plow minus the moldboard/shares etc. Instead they have a large concave disc (maybe 24″ diameter?) that is angled like the moldboard would be to the direction of travel – the disc(s) slice into the soil which should break up without turning over completely. It always “appeared” like it would have more draft than a moldboard – maybe I’m wrong. I’ve never really seen one in action and or even pictures of one hitched up!

It takes a frickin’ long time to build more topsoil – what’s the rule of thumb? Like 100 yrs per inch or something? Tim, help us out here. Is that assuming “natural” soil development alone or is that the best we can do?

I’m no soil scientist but the way I understand it, most of us are really talking about increasing soil tilth not just breaking up the hardpan. The additional humus in the soil affects how soil particles aggregate and, in turn, how the soil holds water. The trees we have in our area don’t seem to do much for the soil’s tilth – if they end up blowin down, it’s surprising how small the root ball is for such a large tree and the soil fractures into chunks along the root lines but those chunks are rock hard. So I guess I am agreeing that the fibrous root system(s) of grasses may be the best bet for increasing soil “health” – at least in this area.

[blue80]

http://mview.museum.vic.gov.au/paimages/mm/243/24378.htm

[Stable-Man]

Yeah, I meant to say disk harrow. Like you said near horse, soil building’s going to be slow, even with a concentrated farming effort. Part of the problem may be that we want to get things done too quickly. Of course we kind of have to because of the immense world population and we depend on soil quality for survival.

[Joshua Kingsley]

In regards to top soil building, We moved onto this farm in 2003 and started with croping in 2004. The soil was basically sand and had no body to it at all. Through intensive grazing and some cover cropping as well as heavy doses of compost there is now a layer of rich dark soil that is 4 inches deep. I think that with additional compost applications and more organic matter there can be significant chainges in soil health, tilth, and fertility.
Just some observations on one creek bottom farm. Joshua

[Tim Harrigan]

The interest in slot tillage in row crops started in the midwest probably 15 years ago. The deep slots are formed in the fall and provide planting zones the following spring. The process was promoted by a very interesting story about why yields were stagnating;restrictive soil layers, lack of soil quality insufficient microbial activity. The machinery companies tuned in to the concerns being discussed and this was their solution to improve soil quality. Oh, and it sold subsoilers.

In our on-farm work with farmers we heard many anecdotes of great yields with this system, but in several side-by-side trials we failed to detect any yield increases compared to other zone-tillage or chisel plowing planting methods. That did not seem to matter though, and slot planting took on a life of its own. The story was good. It offered a solution that was acceptable to the power needs of modern farming. Like Eric said, no one wanted be a luddite. Proof? Who needs proof?

Many meaningful and beneficial options like adding organic carbon from manure applications or cover crops are not acceptable to most crop farmers. Modern tillage equipment is designed to allow farmers to control soil temperature and moisture so entire fields are ready for planting on the same day. Manure, cover crops, those are just more operations, more management, more opportunity to lose control. Carl captured it, mostly weather watchers. Thats just the way it is when you have 8000 acres of corn and beans to run. So a good story with a simple solution looks pretty good. Their perception of soil quality problems are correct, but their range of suitable solutions are somewhat limited when they relie primarily of subsoil tillage.

Soil respiration is a measure of microbial activity but in our work we have not pursued it as the best measure of a balanced and active soil. The reason is it can be manipulated fairly easily by tillage, moisture, etc. so a measure of respiration is more like a snapshot than a reliable indicator of a longer-term stable and sustainable state. Our approach is to incorporate practical and effective management options, manure, cover crops, low-disturbance tillage of the topsoil, permanent vegetative cover with botanical diversity where practical,etc. We know these things will improve soil quality. And, our goal is not to maximize microbial communities but to produce sustainable yields of grass and pasture. So that tends to be the focus of our measurements and assessment.

A real challenge is that as we look for effective management and assess the list of practical options it is not a ‘pick one’ selection. A few years ago we did some calculations and determined that the best we could do to raise soil organic matter with no-till cropping, returning all crop residue, and applying manure would be a 1% increase in ten years. It is no surprise that our cropland soil organic matter is 2% or less and fence row OM is 10-12%. And that is measureable, not just a good story.

Subsoil tillage is not even on my list of sustainable options for pasture management.

[near horse]

In our on-farm work with farmers we heard many anecdotes of great yields with this system, but in several side-by-side trials we failed to detect any yield increases compared to other zone-tillage or chisel plowing planting methods. That did not seem to matter though, and slot planting took on a life of its own. The story was good. It offered a solution that was acceptable to the power needs of modern farming. Like Eric said, no one wanted be a luddite. Proof? Who needs proof?

Hi Tim – I assume that another problem would be that each year is really one observation being that crop yields are measured annually. Weather can be so variable from one year to the next that it would require some years of data to reliably evaluate the effect. I’m not saying that there is or isn’t a benefit. Just that when I was at UI, we assisted with a grazing study over 2 grazing seasons – one had the wettest spring to date while the other year was incredibly dry. It really made the data messy and was likely not a long enough period to say anything of substance.

low-disturbance tillage of the topsoil,

What do you use for this? Isn’t chisel plowing considered low disturbance?

An interesting sidelight to the use or lack of green manure use in farming here on the palouse is that back in the 40’s or so, farmers planted sweet clover as part of their rotations and plowed it back in when the time was right. Some of the old timers talk about plants as high as the hood of their crawlers but they also complained about how difficult it was to plow under – balled up on the moldboards. Although they were gaining both OM and N from the clover BUT there was no income from those fields. Now they grow field peas or lentils instead. Some N fixation for sure but I think significantly lower OM provided.

As Tim said, modern farming systems are based on covering the most ground, as quickly as possible and making as few trips across the field as possible.

A few years ago we did some calculations and determined that the best we could do to raise soil organic matter with no-till cropping, returning all crop residue, and applying manure would be a 1% increase in ten years. It is no surprise that our cropland soil organic matter is 2% or less and fence row OM is 10-12%. And that is measureable, not just a good story.

Is a 1% increase over 10 yrs the best most of us can hope for as well?

[Marshall]

We had renters from 2003 until 2009 that had an outfit that cut the slits in the ground in the fall and never worked the field. They never cultivated, they just sprayed everthing a lot of times thru out the summer. The soil was packed and stayed wet. The weed are really taking over. Never could get a straight answer on the yields. I was not inpressed. New renters for 2010.

[Tim Harrigan]

Geoff: Yes, it is important to evaluate over a range of environments, we generally looked at 2 year increments, more would be better. It seems that potential benefits would be most likely in extreme weather years, for example very wet years if the tillage improved drainage. When it is hard to detect changes in most years it is further hard to assess the cost:benefit of these operations. Subsoil tillage is power intensive and so expensive to do or custom hire. If you only see benefits 2 years out of 10 that needs to be considered in the investment consideration. Again, I am not critical of anyone doing it if they have determined that it works for them, but I would like to see some in-field, side-by-side results to base that decision on. If one just buys the machine and goes to work they become invested in it and it becomes hard to assess objectively.

Is a 1% increase in soil OM in 10 years the best we can hope for? I am sure that is not exactly the number, but probably a good ball park number. Biological transformations in the soil are very complex and my knowledge of soil ecology is limited. Building OM is not as easy as turning under 3 tons of corn stalks to chalk up a 3 ton increase in OM. OM, nutrients and other things were extracted from the soil to create that 3 tons of corn stalks so there is a lot of cycling going on. Microbes degrade the corn stalks and contribute to building soil OM, and in doing so respire moisture, heat, carbon dioxide, ect. So there are losses. The microbes live on the decaying plant material so some of the 3 tons goes to support the microbial community. Some of the 3 tons goes to the subsequent crop. So when you account for all the losses that go into sustaining the system only a small part, if any, of that 3 tons goes into restoration.

The rate of OM formation will be influenced by soil temperature and moisture so my guess is it will be even tougher to achieve 1% in 10 years in more arid climates such at CO. Probably a little faster in GA. Probably faster if you are importing OM such as with compost. I think the bottom line is that you can lose it fast but the building process is very slow. Topsoil is built from the subsoil below. The rate of topsoil formation is slow, I have read estimates in the range of 1 inch in 250 to 500 years. It seems like a good idea to protect it.

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