Below is one piece concerning soil building.

Here is a link that might be useful: topsoil

Joel Salatin, a Virginia farmer and writer, talks about building soil in one of his books (can't remember which one). He raises cattle on a managed rotation like I have described (like, not exactly like). He followed his cattle through the pastures with chickens for a long time and then added rabbits. Chickens will return to the roost every day but rabbits won't. He put the rabbits into large cages and pulled the cages over the fields. Rabbits will dig out if there is no bottom to the cage. But rather than putting a wire bottom on the cages, he opted to lay the wire onto the surface of the soil and drag the bottomless cages over the wire. After doing that for 5 years, he found that the rabbits could dig out again. He checked to see why the wire was not keeping the bunnies in and found that the wire was 5 inches underground. He says he builds soil at a rate of 1 inch per year.

I'm just telling you what I read.

But was he feeding the rabbits, or not? If he was giving them feed from elsewhere in addition to what they are grazing from the land, then it's partially just a wealth-transfer. Most "soil-building" that people talk about is a wealth-transfer: harvesting from some less intensively used place to some smaller very intensively-cultivated place (like a garden or organic farm field).

Peter, I think you are talking about top-soil accretion on arable fields with low or no inputs? Say the input just matches more-or-less the bio-mass that is harvested. There should be some soil-buildup taking place, but it's likely very slow. Consider that they say that forested land averages one inch per century, and a forest has much more biotic activity than an arable field - it can utilize a larger percentage of the energy from the sun.

Consider that they say that forested land averages one inch per century,

pnbrown, I was under the impression that it was 800 years or so for an inch of topsoil....whatever.

I would imagine we can't talk about it without knowing the climate, type of underlying soil, etc. Regardless, natural soil-building is infinitely slower than in a typical intensive garden, which is really just shuffling diffuse fertility from large areas to concentrated form in a small area.

Here is a pretty good discussion:

http://grunwald.ifas.ufl.edu/Nat_resources/soil_forming_factors/formation.htm

It has been awhile since I read his books but as I recall the rabbits were put on the field specifically to eat grass left over by the cattle just days earlier. For rabbits he was going to feed, they were in cages in building where chickens came and went freely.

Very interesting discussion. It's been a lot of years since I studied soil science back east. My experience farming and landscaping has proven to me that frequent additions of organic material on or into soils do grow soils rather quickly, if ephemerally. Soils under natural conditions are balances of soil formation and destruction. Soils themselves are very thin veneers of living communities. Every time we or Nature disturbs these veneers, top soil is "lost".

The idea that soils continue to grow is irrational. Otherwise in some areas there would be thousands of feet of topsoil.

The only situation that accounts for deep soils is best approximated by loess, deposits of dustcarried down wind from arid lands and glacial outwash plains.

I guess I never really thought of that, Marshall. That organic matter can't persist for very long does seem to borne out by the facts. Shows how entrenched my anthro-centric thinking is. Just because soil is "growing" in our gardens, we imagine it must be everywhere, all the time.

In the case of a forest, that "veneer" is anywhere from ten to a hundred feet or more thick, when you think about it, because it includes all the bio-mass. So what explains the extraordinary natural differences in fertility in soils once cleared? Untold centuries of bio-mass transfer? Through wind-blown dust, and mostly through organic material washing down through water-sheds? But if organic matter doesn't persist and accumulate over millenia, what explains the incredible fertility of the mid-western plains, for example, or similar places? Supposedly Kansas was at the bottom of a shallow sea for eons, and that rich soil is the end result of all those years of aquatic life and dust blown onto the sea. Is the fertility entirely the result of the texture and mineral make-up, rather than trapped organics?

Inert mineral material, inorganic or organic, has little "fertility". Soils are alive and when we establish cropping on these soils, we begin a mining operation. There is more biomass within the soils of many regions than in overstory of plants. As this biomass decays, nutrients are released.

If we are wise stewards, we take up the role of replacing some of the lost nutrients and reintroduce carbon and manage the biomass of unharvested plant materials. Biological activities at and below the soil surface process organic materials and, to a limited extent, work on the mineral fraction in the top and subsoils.

There are large areas of the Great Plains that are glacial outwash and aeolian in origin. The depths of soils in the tall prairie regions are as much a creation of deeply rooted prairie plants where a high percentage of plant biomass was in the root zone. Forests have a majority of plant biomass above the surface.

Still, it's just astounding how those soils will raise a crop of wheat year after year even without fertilizer. I know a guy out there who did it his whole life - to cheap to buy fertilizer or cides - and still pulled in 40-60 bushels every year on the same ground. Made more money in the long run than those who fertilized and made 80-bushel wheat (I bet he's come out of retirement now with wheat at $10 a bushel). That's an incredible amount of fertility to be residual from prairie-land root-mass, isn't it? That tired old wheat-land is still a lot more fertile than any ground I've ever used. It seems to me that the difference must be geological.

I've been doing, for ten years now, I believe very much what you describe as a "wise steward" with a plot of ground. Just rainfall, replacing some if not all and more lost nutrients, the biomass of unharvested plants (easily 95% of what grows there) is left on the ground. I get exceedingly little return for the labor. Vanishingly little. Nobody would keep on other than a scientist or a nut, so I must be the latter since I'm not the former. I'm lucky to get three times return on my seed-potatoes. Corn is always a failure. Squash is usually a failure. Carrots are ratty. Beets do ok, greens do well if they are weed-like - mustards, or actual weeds. Parsnips (quite close to their weedy origin)are my premiere crop. Walking onions do fine.

My conclusion is, after ten years, that if one doesn't do what gardeners normally do, ie, irrigate and fertilize regularly, then the most weed-like of the cultivated plants will do the best. Hardly a surprising finding that those crops closest to uncultivated origin would do best in a little-cultivated setting. What I'm curious about is what the difference would be in this experiment in simplicity if it were conducted in soils with higher base fertility.

Pat, let's admit it, you are a lousy gardener. ;-)

What you are describing is soil mining and like mineral mining, some "geology" will yield more ore longer. Bigger equipment and higher technology will expand production and extract more at scales of economy hand digging alone couldn't approach. Loessial soils (chernozems) represent the imported fertility of distant topsoils eroded by sustained winds and deposited as silts downwind.

Benign neglect is not a substitute for good horticulture in most soils. If a patch of ground can grow good weeds, it can be make to grow good crops.

My current acre was a gravel parking lot with two buildings, diesel tank, and a paved road through the middle. In late 1970s the buildings and gravel and roadway were removed in part. In 1990 weeds struggled to reach knee heights and coverage was sparse. I knew I was going to have to move the farming operation into this section by 1996 so began to rehabilitate the ground by first putting in rainbird irrigation system and adding a layer of compost and a thin veneer of organic mulch. The soil tested Well, damn little of the crop/cover was successful but some of the weeds managed to penetrate the compacted ground. So we came back and "ripped" to 12 inches both ways (couldn't get deeper) and tried again. We went through several cycles of grow out and mowing, allowing the material to break down on the surface.

By 1996 we could see lots of improvements in soil productivity; however, in the stand of heirloom wheat we were growing, the effects of road base and compaction show up as if I had cut half the height away. That effect lasted until 2002.

In the end we went to a system of permanent raised beds to compensate for the compacted subsoil, giving us now an effective soil depth ranging from 12 to 30 inches.

What you are describing in your garden could be closer to Ruth Stout's method of sheet composting or Fukuoka's natural farming system, both of which are sustainable with limited effort if not high productivity. OTOH you perhaps have a naturally poor soil or one so played out or one contaminated by some past activity that you can't grow even crops requiring low nutrients.

Have you had soil chemical tests done? Which are your most vigorous weeds? Have you been practicing rotation of family of crops? Are you plagued with cutworms and excessive herbivores among the creepy crawlies. I get way way to many symphylids, rootknot nematodes, and fleabeetle larvae in season. Wish we had sufficient cold to lower the pest pressure.

Probably I am lousy. Certainly somewhat lax, interspersed with bouts of hard gardening labor. Also I have more of a curiosity to see how nature works than necessarily in conventional maximum production.

Wow, a parking lot. That's a tough assignment. Raised beds certainly cure all sorts of problems. Typically a "raised bed" represents a huge input, do you agree?

No soil tests have I done. Most vigorous weeds besides grasses - probably thistle, queen anne's lace, winter-cress, dock and some others I don't know by name. I generally attempt some leguminious cover crop every summer. These get browsed pretty hard by deer, but that helps to keep them off of other crops. I let the successful plants self-seed - the parsnip and mustards, and I suspect that the amaranth that I introduced last fall will naturalize quite well. These are effectively the cover crops, as they grow abundantly and I pull them and sheet-compost them where they are in the way.

Some cutworm problems when I grow bulb-onions. The worst herbivore is CPB, which has been a big problem but was less bad last year. Too cold for nemotodes here, fleabeetles are sometimes a problem. I suppose the simple fact is that I don't introduce enough fertilizer for heavy-producing crops like potatoes and squash. The lack of irrigation is not so much laziness on my part as the fact that it's a remote site with no water, on land that I don't own.

Your situation sound tough too. You should be able to grow crops in Mass. on rainfall alone unless your soil is very coarse-textured. You haven't mentioned exposure, competing tree and shrub covers, and drainage.

Raised beds are an investment in time and money but are worth the effort in long run. The best raised bed system I ever constructed was done for a grower of rarer cut flowers on poor red clay. We dug to 3-4 feet by 4 feet wide and long along the contour. From various sources we brought in lots of tall weeds and grasses and straw and began to backfill, laying first about 2 feet of coarse organic material down, then a foot of soil, another foot of organic material followed by soil and repeated up to about 2 feet above grade. We watered as we went. Then we waited and watered and waited, adding more organic matter and soil to keep the height up a foot or more. We waited 8 weeks before transplanting the rare flowering plants into the beds, by this time given redwood sides and structure to keep birds and deer out.

Well, the grower made back in profit what it cost him within two months of harvesting. The beds were still producing well two years later without additional inputs.

My point is that initial effort can make a big difference. Instead of leaving the organic matter just on the surface, try incorporating the stuff by mixing it a bit with the upper soil.

marshallz10, it would have been interesting to see what your acre would be like today if you had fed a herd of 150 organic goats on it for a few days back in the 90s.

dchall, we did run a small herd over about 5 acres for a couple of months of late winter for a friend. A hundred and fifty goats on an acre sounds noisy. :) They'd have eaten everything to the ground and pounded the soil surface to dust.

What benefits, other than manure and weed control, are you suggesting?

It's sandy soil, prone to drying out pretty badly in summer, so without the irrigation crops that need to fruit up at that time will yield poorly in a dry summer. Which more summers tha n not seem to be now. Yes, I should do more incorporating, but it's generally a struggle just to keep up with the weeding there. I do some deeply-dug beds at home, where it's worth the effort, but am loathe to invest much on land I don't own. This spring though I do plan to dig deeper than normal trenches for the potatoes and line them with seaweed that's been composting. I'm hoping that'll get me up to five-fold return!

New to the thread here, but a couple of observations and thoughts.

This idea of intensively pasturing livestock on a moveable, fenced, small acreage is nothing new; it was all the rage in Africa back in the late 70's, I used to do 50 odd head of sheep this way on my fish ponds, following strict instructions from folks who knew more about it than I did. The issue came up that sheep and fish pond dikes didn't coincide all that well, what with sharp hooves on muddy near vertical slopes. But I got the idea.

It seems that every 10 years or so, there is some guru that shows up and promotes this all over again, siting the wildebeest herds of the Serengeti, the buffalo herds of the North American Great Plains, stomping and pooping and mixing and all kinds of bugs coming along for the ride, their way around the ecosystem.

My take? If you run cattle, you probably want to create the best ecosystem for them as your situation / finances / climate and what not allows. There are all kinds of different soils all over the world, and this technique might work for some of them, but certainly not for all. High rainfall and slope will get you bare rock in about a year, I saw that in Costa Rica, Huge stomp full of noxious, exotic weeds? Visit the Navajo Reservation. Some places it works? Sure, my neighbors do it all the time, but they have completely changed the natural ecosystem from arid, highland pinion/juniper forest into heavily irrigated pasture. So they move their cattle from pasture to pasture, and feed them hay during the winter, that pasture then turns into the best hay meadow next year, and it rotates around.

Pat, if you have acid sands, you ought to try to both lime and grow a grass/grain-rich cover crop. Chop and scratch in before frost, prep and plant in the spring. You will get a lot more benefit out of a densely rooted grass than a weakly rooted forb or even deeply rooting half-clovers. Annual ryegrass might be good, ranging up to 2-3 feet and roots to similar or deeper depths. Assuming, of course that your sandy topsoil doesn't overly a hardpan.

Yes, acid sand is an accurate description, I think. If there is a hardpan I havn't yet found any indication of it, and I often pick down to 10-12inches or so. I limed in the beginning, 9 or 10 years ago, probably time to do it again - though I use wood-ash from time to time. I've been working on grains from the get-go. I did rye for a while but then got turned of by the allelopathic affect. I have wheat and barley self-seeding in parts, but they have quite a hard time competing with better-adapted grasses. Areas where I've raised the fertility considerably with compost favors the grain much more, not surprisingly. Areas with some slope and little fertility don't seem to want to grow anything but grass; I try to keep those heavily covered with cardboard, etc, to cut down the grass population.

I'm probably exaggerating the paucity of the return on this project. Given the small amount of labor and inputs, and lack of irrigation, it's not so bad. It also serves as a valuable little reservoir of seed and live plants - can't have too much of that, not to mention what I've learned about the most promising strategies for any kind of emergency self-reliance situation, or shall we say reduced-import situation.

pnbrown: your entry of Jan. 19 greatly interests me. But I can't get the page to appear. Would you check the address please and, if possible, provide a direct link. Regards, Peter B.

A hundred and fifty goats on an acre sounds noisy. :) They'd have eaten everything to the ground and pounded the soil surface to dust.
What benefits, other than manure and weed control, are you suggesting?

Can you get them galloping around, too? Manure is part of it. Hopefully you could have derived some benefit from dung beetles. Animal hooves create seed-to-soil contact, helping dormant seeds to germinate and establish. The hooves break soil crusts that keep seeds from germinating. Animals trample standing vegetation into an organic mat that protects the soil and keeps it moist. By pruning stale growth, livestock keep forage plants at peak production. And finally pruning a plant's top causes its roots to self-prune. These dead roots become organic material already buried in the soil.

This picture shows the result of a real life experiment in restoring fertility to a piece of desert. The soil is a huge pile of sterile strip mine tailings that has sat barren in the Arizona desert near Globe and Miami for 60 years. Even weeds don't grow on it. The right hand side of the image shows what the pile has always looked like. Notice the erosion. The left side shows the pile where cattle have been grazing. They started with electric fencing and bales of hay tossed into the dust. The only seed was what came in the hay. No fertilizer was used. The only water used was to water the animals, not the grass. If sterilized and pulverized soil, on a steep slope, in the middle of the desert, can sprout like a tall grass prairie, then I think there is some merit to the idea.
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Interesting. Are you saying the prairie assemblage of plants came in to replace the initial cultivar/weedy hay seed that germinated first? Is that the mine tailings in the background? Looks like a pile of brown coal.

I have an acquaintance that has been clearing off chaparral (ranging up to 15 feet) using a flock of Nubian goats. They fence an area of about a half acre to keep the animals in and the coyotes and bears out. Takes about 3 months to take this woody browse down to stumps. Unfortunately heavy rains will wash away the equally disturbed soil.

Peter, google "sabine grunwald" and you'll find her page at UFL. Seems to be a major soil scientist.

Sorry I wasn't clear on that. I am so familiar with the site that I forgot to clarify. The giant terraced pile in the background is the mine tailings. I believe the terracing is used to prevent washouts (as illustrated in the picture) from washing into the adjacent town of Miami. I used to drive past that pile when I was a kid. It was an old and abandoned pile by the late 1950s. The tailings are the consistency of talcum powder and sterilized by an acid wash to remove the metallic minerals. Whatever is growing there (on the left side) started with whatever was in the original hay. With 60 or more years of accumulated seeds blowing in, I would be surprised if many of those plants had not germinated. I have some personal pictures of the area, but they were taken in late January, and the forage was dormant. I need to go by in the spring when the grass is green. For anyone reading who wants to take a drive, the pile is on the north side of US 70 just outside Miami, AZ on the way to Globe.

Regarding goats: I found an historical record of agriculture in Texas. When the Spanish arrived they brought goats to clear the land. After a year of goat herding, they brought in cattle on a 1:1 basis with the goats. The cattle and goats were grazed together. Where are you in California with chaparral and bears? I'd be interested in more info on the clearing operation. And I would be surprised if the rain washes away the soil. Saving the soil is what this is all about. In fact in the mine tailings situation, the local community hired a company to hydroseed one part of the tailings to stop the pile's erosion. When the local monsoon came in the next season, the hydroseeded area eroded away but the cattle grazed area did not.

Hydroseeding needs initial gentle irrigation to germinate the imbedded seed if expected rainfall is scattered and/or heavy. Hydroseeding works if the underlying soil is decent and already prepared some for optimal growth of germinating seed. Done a lot of acres of hydroseeding in my time (or at least contracted for the coverage.)

Chaparral on steep slopes creates fairly hydrophobic topsoils so that once the cover and roots have been mostly removed, the heavy ororgraphically enhance rains we get in the winter wreck havoc on slopes. The last two main storms thru here left 10-12 and 5-7 inches over 24-36 hours on the upper slopes of the Santa Ynez range where the goat are being raised.

The people in question are clearing so as to expand their llama herd and to feed the goats. The chaparral is not killed, only reduced to the lignotubers and burly crown. Regrowth starts as soon as the goats come off,

I guess a pro should have known that hydroseeding sterile talc would be a problem in an area with very unreliable rain but still subject to annual monsoons.

So if I'm driving NW on 154, the goats on my left. Are they on the coastal side of the hill or the 154 side? And if they are on the coastal side, are they above the normal early morning cloud tops? Being in the chaparral I'm guessing they are above the clouds or on the back side. One of the things the goats should do is allow the rain to penetrate rather than rolling off. What did your friends see happening to the area where the goats were after the recent rains? And do they see grasses coming in or is it still the chaparral brush?

I wonder if their llamas like to eat the coast live oak leaves. We have a Texas live oak that the llamas and camels eat like it was candy.

The goats are off W. Camino Cielo up near the crest line among all those sandstone outcrops. Lots of impervious stone and sharp runoff. During recent rains the nearby San Marcos Pass recorded maybe 12 inches of rain for December in 3 storms and has more than that since then. Looking at perhaps at 40-inch season.

The Chaparral passes right over the frontal ridges, but north-facing slopes and canyons carry vegetative covers more typical of 400 miles north: Cal. laurel, manzanita, bigleaf maple, etc.

I just learned that animal control busted her for having too many roosters (near 100). Animal control called me to ask that I "rescue" them from the rescuer but no more than 50 in fenced chicken runs and no eating them. No what good is a rooster that one hasn't raised as a pet?

Those crestline roads are always fun to drive. Did your friends get a good price on some land with a view of the islands? If your friends are at the ridge and above the daily morning clouds, they pretty much have the worst of all worlds. They have maximum cold, minimum precip, and all the wind. Oh, and as you said, bears...probably puma, too. We used to visit the hippies on Paradise road where it crosses the Santa Ynez River. I think there is some sort of permanent settlement out there now.

No what good is a rooster that one hasn't raised as a pet?

On a cattle ranch devoid of dung beetles, roosters will dig through the cow patties looking for parasites. When they find them they eat them, but in doing so they scatter the manure around about a 3 square foot area from the 1 square foot area it previously occupied. So the roosters spread manure and clean up parasites. You don't get any eggs, but how much would you pay to have your manure piles spread out and parasites eliminated? One rancher says the coyotes can have all the chickens and he'll continue to restock them simply because they are cheaper than alternatives.

David, did these western dung beetles evolve with buffalo? Obviously there have only been beef cattle around for a short time in the time-scale of dung beetle evolution. Or did they get imported with the cattle?

The community of homes in the Los Padres National Park is being phased out as the leases run out. There are a couple of private pieces not on lease. The youth authority has a camp out there that likely will remain.

Cougars are common to the area but not as destructive as bears. There are several large groups of wild turkeys that seem not to be controlled much by big cats.

We don't run much cattle anymore in the county and then mostly north of the Santa Ynez coastal range. Some botique ranching is done on the old coastal ranges but many are slated for development or conversion to public park or some combination of the two.

Yeah, what about dung beetles?

Dr Patricia Richardson is the best expert I know of on dung beetles. Her research says that there are specific species of dung eating creatures that evolved for each species of creature. Her research now is working on discovering the specific dung processors for dogs and cats.

Since we are cut off from the other continents, the American mammals must have had their own species of dung creatures. When European, African, and Asian cattle were brought in, they had to have their dung beetles brought in, too. I'm not sure if anyone did that on purpose or not. Or it could be the bison dung beetles worked for imported cattle??? The Australians apparently discovered this to be a problem as recently as the 1980s. Apparently they had a very serious problem with fertility because the proper cattle dung beetles were not in place. Once they got them, everything has turned back around for the better.

If you Google Dick and Pat Richardson, you will fine them at a University of Texas website and can get more information.

Thanks. I'd forgotten about the Richardsons. I ran across their work during correspondence with an Australian cattleman. The article linked below comes from my files.

Here is a link that might be useful: Dung beetles and their effects on soil

That's an interesting site, Marshall.

pnbrown: thank you for the Grunwald site. I read her article on Soil Formation. It told all about soil formation processes, which I have lots of good material on, but not about the actual rates of soil formation on arable land, which I want to understand in order to better assess the seriousness of soil erosion. So I sent her an email. She replied that she couldn't answer my question, because the rates of soil formation are so different on different sites. What I am looking for is on-the-whole-and-on-the-average data. I begin to think that noboby knows the answer, so I am forced to take their soil erosion pronouncements with a grain of salt. Regards, Peter.

Soil loss and formation cannot be averaged meaningfully. Different types of soil are naturally going to vary, and then under human management they will vary differently.

Upland soils erode, and are deposited in the lowlands or in the ocean. Soil building through addition of organic matter will vary with what plants are growing, whether the soil is the kind that can store that OM, and whether someone's harvesting the plant material. If you are harvesting, you are removing the source of soil buildup.

Talk about wealth transfer. How about alluvial soils being deposited by floods? Here in southwestern Washington State, the Chehalis River flooded in December, with Interstate 5 closed by up to 10ft of water over the road for nearly a week. Farms in the area found themselves buried under up to 2 FEET of new soil, washed down from the commercial timberland upriver of them. Amid all the death of livestock and destruction of farm buildings and machinery, I would think this would be a godsend, yet people are actually scraping off and pushing aside the new soil to clear their ground for spring planting!!! What am I missing here??

I was under the impression that alluvial deposition is a major soil building factor, although of course it is really a wealth transfer from higher elevations to lower. But I believe that the rich agricultural soils of the Midwest were largely built by wetlands, through alluvial and lacustrine deposition of sediments and decomposing plant matter. They are deep rich soils, and will be fertile for a long time, but we're not allowing them to rebuild themselves anymore than we're allowing coal and oil deposits to rebuild themselves. The water has all been diked and drained for one, and the plant matter is removed every year, as well as the soil being continually disturbed by agriculture and by urbanization.

Why do some soils produce lots of crops with little input, and others don't? it all depends on what kind of soil you have and what kind of crops you're trying to produce. Soils that support forests don't necessarily support herbaceous crops. Here in western Washington, we have very lean gravelly soils. They don't produce good crops. You can do ok for a while, but not great and not long. On the other hand, if you pick a crop that's adapted to the soil, you do great! we produce some of the most valuable timber in the world, with minimal inputs, on soils that won't produce a decent grain crop no matter what you do. Of course our climate is all wrong too for things like wheat and corn. The Indians used camas and bracken fern and tree cambium for their starch sources, and had started raising potatoes introduced by British traders before Lewis and Clark showed up. Not grains. They maintained prairies by burning, but for the camas and bracken, not for the grasses.

Midwestern prairie soils stored most of their organic matter in the soil, so there's a huge bank of nutrients and OM there. Pacific Northwest temperate rainforest soils stored most of their OM above ground, in the trees and shrubs. Remove the forest, and most all the OM goes with it. Remove the midwestern prairie, and much of the OM is still there, for a while.

Pnbrown, I suspect that your garden in Mass. suffers from the same general kind of soil and climate I have: recently glaciated, lean, coarse, well-drained soil that did not naturally support herbaceous crops but rather forest; and a cool climate unlike what tomatoes and corn are adapted to, both being from subtropical southern Mexico. I don't even try to grow either one here - waste of time and effort.

Here's a tidbit I found interesting. I read recently that African farmers are doing much better recently, than they have been, productivity and income wise. The article I read this in attributed it to - urbanization. There are less people trying to work the land now, so each farmer has more land at his disposal, and bigger cities mean a larger market to sell to. I'm hoping that less people in the countryside can translate to better stewardship, which does seem to be happening on at least a small scale according to the article. In this country we complain about urbanization gobbling up the land and ruining it! but it isn't necessarily causing the same problems in Africa, but solving problems instead.

Peter, Ms Grunwald was correct and just because she says that such "averaging" would be invalid, she can be ignored. You are right that general statements about general rate of soil development are suspect...for the reasons she cited. Maybe that is what you meant.

Most soils are in some stage of active formation and/or destruction, depending upon topographical,geological and other environmental and biological conditions. Soils are, in geologic frame, ephemeral.

As a rule, soils are NOT grown under agricultural regime. Most field agriculture is analogous to mining. Agriculture may change soils but these become as much cultural artifact as natural media.

marshallz: I appreciate your point but -- considering what I want to understand -- it's not relevant. Let us consider instead the totallity of all the arable soil in the US. For this entity I should like to understand the extent to which erosion is exceeding formation and, at these rates, how long our soil will remain supportive of the population. Agriculture is about 10,000 years old and, clearly, needs to be sustainable for the next 10,000 years at least -- not just the next 25. Now, if your mining analogy is correct and the mining continues the outlook is grim. Because the graphs of increasing population and the food available to feed them will cross.

dchall refers an Australin farmer who has "grown" soil substantially in just a few years. I'm familiar with the article and I also try to inrease soil organic matter every year and in every way. But surely there comes a limit where the loss of soil carbon will come to equal the inputted carbon. If not, then the process when taken to its logical conclusion is absurd because it visualises soil that is 95% organic material and 5% mineral -- the reverse of the presnt "ideal" arable ratio. If there is a limit to growing soil with inputs of organic matter then the rate of soil formation must eventually be limited to the rate of weathering of parent rock, which is very slow indeed.

Now, is this a real concern, or is my reasoning faulty? Regards, Peter.

You have to define arable soil. Arable for what purposes and what limitation. There is much acreage of open land in this country. How do you describe arability of such diverse soils and terrain and climates, and marketing/transportability of products?

The first waves of immigrants stopped, farmed/ranched, abandoned the land and moved on. Some left dust bowls and deeply eroded ground. Others exhausted the land or water supplies or faced weather-related crop failures. These are the same soils now supporting millions of acres of corn, soybeans, wheat, cotton, and other industrial crops. So why are these so productive (i.e. arable) now and earlier were unable to sustain farmers and communities?

If you can find a copy, look at a pre-WWII USDA annual yearbook entitled "Soils". This yearbook has some of the best evaluations of soil resources in different parts of the country. Most ag and soil scientists today are into micro-matters, not in the larger socio-economic aspects of soils. Ag and soils are no longer the underpinning of our culture.

For the purposes of modern industrial agriculture, dirt is required to hold up the plant while nutrients, air and water are managed in the root zone and a chemical haze and plant genetics are employed to control pests.

Most available land of the highest quality (Class I) is already under cultivation in this country or has already been lost to future cultivation through urbanization and other uses. Erosion is not as important as loss to non-agricultural uses. California is a notable example.

Elsewhere and especially in densely populated regions of the world, agriculture has long moved onto poorer soils on unfavorable terrain and under less favorable climatic conditions. Erosion may not be as much a problem in many of these regions as is soil exhaustion and fragmentation of farming units.

Let me get back to the elements of soil formation: Nature does not make arable soil. We find well watered and convenient pieces of ground and wrest crops from them in competition with other organisms. We destroy native soils and disrupt soil making processes appropriate to place and climate. We do not make soil.

In parts of Asia, 8,000 years of intense agriculture have created agrisols. Along the Amazon tributaries there are small black-carbon-rich soils left over from millenia of intense occupation and agriculture. The surrounding alluvial soils are typical for the region. The Dutch have reclaimed sea bottoms for agricultural purposes. These were not arable lands of Nature.

Arable montane xeric soils are fundamentally different from soils found in high-rainfall deep alluvial soils. Under one kind of agriculture/livestock raising, the first soil could yield for thousands of years but if you introduced intensive row cropping under irrigation you might ruin the soil through salt build up or excess erosion. Soils are cultural artifacts defined by technology and other cultural inputs.

Soil erosion can remove a 1000 year's worth of soil building in a single storm. Other soils down hill with be destroyed by inundation of debris flowing or falling from above. When a forest is blown down by a tornado, forest soils are torn up and exposed to sun, wind, and changed microbiology.

Now, I'll stop lecturing and listen some.

The link below takes you through a tour or soil over thousands of years. Read and weep.

Here is a link that might be useful: USDA oldtime

Marshallz: thank you for your insights. I am reminded of the words of a wise old biologist: "If you can't measure it you don't know what you're talking about." You see, in order to decide whether the gap between soil erosion -- using the best agricultural practices -- is indeed "the issue of the century" and therefore worth a concerted effort, we need to be able to measure it. And, thereby be able to convince others.

Some authorities think that an average "tolerance rate" for soil erosion on arable land (you may define arable) is 11t/ha. Soil loss tolerance is defined as "the maximum permissible rate of erosion at which soil fertility can be maintaine over 20-25 years" which -- in the 10,000 year context -- is utter rubbish. In that context am I right or am I wrong that the permissible rate of soil erosion is the rate at which soil if formed by weathering of parent rock since the "plants make soil" proposition ultimately has a limit? Regards, Peter.

Wayne: thank you so much for your online library link. Super classic stuff. It reminds me that while soil mightn't be the underpinning of our civilization it is the sina qua non! Regards, Peter.

Of course it has limits. The assumption of your experts is that no measurable soil will be added through in situ conversion of substrate (e.g. regolith) to soil during a generation of agricultural use. So the depth of available soil will determine how long arability will last against soil loss under ag management.

The maximum recommended figure you mention, 11 t/ha (5 T/A), is something like 4.5 pounds per square foot, which is something like an inch or two off the top a year. This is not a sustainable rate, obviously. Back to my mining analogy.

Plants can convert subsoils to top soils but not very well under continual surface disturbance of agriculture and not at the rate of soil loss. No-till agriculture protects the upper soil much better than tillage does.

Remember my previous post where I mentioned ag land as an area of dirt capable of holding up a plant while the ag. manager applies water and nutrients and protects the plants with pesticides. In the past, plowing (and in an earlier age, burning) not only loosened the soil for planting but got rid of the trash. Now the value of previous crop is recognized as protection against excessive erosion. A byproduct of this practice is adding or perserving organic matter and incorporated nutrients to the soil. Another byproduct of no-till is that the soil increases water permeability and water hold capacity.

Wayne, thanks for the link. I hadn't read that piece since graduate school.

This discussion, while rather over my head, reminds me that permaculture is probably humanity's only long-term option. (that and a gradual and hopefully painless diminishment of the population through declining birth rate). Fields should obviously be small and intensively managed with a lot of human labor and appropriate crop rotations for some years, and then put into mixed fruit, nuts, and timber trees (as an example) for a much longer period. For many soils that as Reg points out support forest much better and more efficiently than crops this would over centuries give an enormously better return.

Permaculture is basically a subsistence model of land tenure and land use. My experiences with permaculture projects are not as great as maybe some on GardenWeb. Most projects can not generate a sustained market of their products. Most members work off-site to earn income. Many permaculture project never mature because of conflicts over finances, levels of contribution, and other divisive matters.

If every permaculture endeavor contributed a similar mix of products to sell and to sustain the projects, the market place would collapse unless there was a wider net of marketing outside the region. Before long, there would be a transportation industry and regional marketing systems run by folks not associated with the permaculture operations in the hinterlands.

Rural areas of the US with vast agricultural development are basically emptying of people; those that remain are centered on small (and often diminishing) service centers. Moving urbanites into this vast openness where basic amenities are scarce would be cruel and inhuman punishment. They are not prepared by experience nor temperament to go back to the land for their livelihood.

Well, I wasn't suggesting that permaculture is titillating, but it might be better than having half the population starve to death. And any place that finds itself with a much greater population will develop amenities pretty quickly, I suppose. No doubt you are right, though, about the much reduced variety of output. Long-distance exchange would be required, though it's hard to imagine that there would be more movement of goods than presently.

Remember that there are just barely 2 million farms in this country with perhaps fewer than 10% of those accounting for the bulk of production. So when we speak of ag transportation system, we are seeing BULK and distance to markets.

We need to localize our food systems, or what is now referred to as Relocalization, a concept advanced but the same people who brought us the international movement called Slow Food.

So you don't see permaculture fitting into "relocalization"?

I might under the right circumstances and perhaps integrated with urban farming organized into foodsheds and cooperative marketing arrangements. What most folks don't appreciate is the time and skill needed to market in consistent fashion perishable products. Converting significant acreage to permaculture distributes the resources and labor over many economic and social activities. Food production may well be a secondary interest.

Moreover, follow the Guild concept, permies are likely going to grow the same complex of crops thought appropriate to the bioregion. What will likely happen is local overproduction of tree fruit, for example, and lots of excess to be preserved or exchanged with other regions, or otherwise handled too many times over too long a time. Costs really rise.

In traditional agrarian systems, food is produced and consumed quickly and fairly close of when produced. The problem with trying to "commercialize" simple agrarian societies is the lack of infrastructure to handle, protect, ship and distribute food stuffs. Small holder permaculture resurrects subsistence farming as part of sustainability and more self-sufficiency. The practice of permaculture is more land and water management than economic productivity.

Composting & organic gardening is thousands years old. What did we do before government started Organic Standards.
I never heard of this stuff in my organic circles, maybe in
environmental circles.
wayne 5, I have not thought of the dung beetles in years.
We no longer have cows or pigs.
Thanks for the link.