Gardeners like to compete with each other over who has the worst soil. You wouldn't think we'd be proud of this, but what can I say, we're a strange bunch. One will argue for his hard clay, baked in the sun, another for her sand, without a trace of organic matter. I've got my own candidate for the worst soil ever - the stuff in the beds around my house.
Oh, texturally, it is among the best I've got - sandy loam, warms up nicely, isn't too wet like much of the rest of my soil. It had some nice enough foundation plantings, and I mostly ignored it for the first few years I was here. But a couple of years ago, I decided that I wanted to make use of this growing space, and then I discovered that my soil, was, well...dead.
By dead, I mean there wasn't a living thing in it. Not a beetle or a spider, and especially not an earthworm. It was weird. I knew that some previous owners of our house were umm... shiny green lawn people, and I don't know if that has something to do with it, but this stuff was "Its dead, Jim" dead.
So we embarked on a campaign of soil improvement. Any kind of soil improvement has two parts. First, there's getting your soil up to speed. In some cases, this might not be much - maybe some ashes from your stove or a little lime to even out some acidity, or maybe a little rock powder for trace minerals, or a light dressing of the rabbit poop your rabbits make sure you get anyway. If your soil is basically in good shape - you've had a soil test and you know that it is high in organic matter and sufficient in macro and micronutrients.
But what if it isn't? What if you've got dead soil, like mine, or rock hard clay, or soil (also like mine) that has been leached of nutrients? Again, there are two projects here - the first is the short term building of soil so that you can get to gardening. The second is the long term maintenence of soil health, and the addition of more organic matter, so that eventually, your soil can hold enough organic matter to save the world - or at least sequester a bit of carbon. Plus, things will grow better. Win-win.
My favorite way to build soil on something that is completely unworkable is the lasagna method, which is pretty much sheet mulching (covering the soil with newspaper or cardboard, then laying on as much organic material as you've got, with some dirt or compost on it. This makes raised beds, which is good if what you have is either wet or rock hard, or if you are, say putting your dirt on gravel or something toxic. It might be tough in a dry, hot climate though - raised beds dry out and warm up in the spring earlier, and keeping them wet might be tough. In that case, you might consider digging into the ground, creating sunken beds with the same mixture. We use leaves, grass clippings and farm bedding as the main ingredients in our lasagna beds, with a layer of find compost on top if I'm starting seeds in it.
If you need to amend soil, you'll have the choice of synthetic or natural soil amendments. Generally speaking, you'll want the natural ones. I'm not a complete organic purist - I think there are times when artificial fertilizer use is justified. But there's a price to be paid for its use, and care is needed - otherwise you can end up contaminating your water supply, wasting your money and depleting your soil overall. I don't generally use synthetic fertilizers, and if I were to use them, I'd use them only on untilled soil with plenty of organic matter added, in small and precise quantities. Most of the value of artificial fertilizers is presently lost into waterways and various other sites of contamination.
You can buy an organic fertilizer mix, or you can make your own. I generally use a mix of alfalfa meal, rock phosphate, and wood ashes, along with greensand and kelp, as well as occasionally special additions to deal with soil types or plant special needs. But I don't know about you, but I can't mine rock phosphate from my property, nor do I produce enough alfalfa to fertilize my garden. So this is not a long-term sustainable project. I use these amendments sparingly, where they are needed to bring soils up to basic fertility.
Then, we try to keep the fertility there. That means cover cropping a portion of our garden every year, integrating dynamic accumulator plants into our plantings (these are plants that bring up nutrients from the subsoil), undercropping with nitrogen fixers (these plants fix nitrogen from the air), mulching (we try to grow as much of our own mulch as possible in place - another good use for undercropping - a nice planting of buckwheat under tomatoes, or white clover under garlic can provide a living mulch and then the next planting cycle's mulching materials), and the heavy application of organic material - that is, compost and composted animal manures.
Every time we take something off of the soil, we are removing nutrients from our soil, and depleting, to some degree, the organic material available to them. High levels of organic material are essential for soil life and health - so faced with dead soil, the first thing I did was put my turkey poults in a chicken tractor on top of the border for a few days. The easiest way to move the poop to the garden beds is sometimes to move the poop makers there . Now since this was raw manure, I made sure there was plenty of bedding, and I wasn't planting food plants there right away. Had I needed to use it immediately, I would have switched to already composted manure, and gotten out the wheelbarrow.
Next, I planted the foundation plantings to annual alfalfa, since it was already summer, and warm. Different cover crops are specific to different seasons - they are spring, summer or fall sown. You sow the fall crops to overwinter - to hold soil in place, and add organic material. Winter rye, hairy vetch, fava beans (in some climates) are all common winter sown cover crops. Spring sown crops are generally cut down in summer, and either stay in place all season (things like red clover), providing multiple doses of fertility and green material, or they are cut down (oats, say) to provide organic material for the fall garden. Summer crops (buckwheat, annual alfalfa) can go in after the peas or the early lettuce, and grow fast and fill the space until fall. For a site you don't plan to get to for a year or two, perennial crops can do a lot to regenerate soil.
Cover cropping is very place specific - the best crops are specific to your climate, seasons and locality, so talk to your cooperative extension. They are a powerful tool for building fertility, adding organic matter and improving soil, and one that is worth getting to know.
My goal in the long term is for these beds to provide a warm, dry, moderately fertile site for mediterranean herbs and a few flowering perennials. That is, I wasn't trying to produce fertility for growing heavy feeders, like greens or corn. So after the alfalfa, I added some greensand and kelp, a light layer of compost, and planted into the mulch I'd already established. In went lavender, oregano, several marjorams and thymes, a rosemary that probably didn't survive the winter this year, and some plants that like or tolerate similar conditions of slightly dry soil, lots of sun and only moderate fertility - catmint, echinops and malva. And they've thrived.
Many perennial plants make wonderful fertility enhancers to annual gardens - whether perennial nitrogen fixing shrubs, whose leaf litter and root nodes enhance the trees and perennial plantings around them, comfrey and stinging nettle which can be cut for mulch or compost, small trees integrated into garden sites to provide leaf mulch, or perennial living mulches. This is one of those things that has potentially enormous long term yields, and has really only begun to be explored in a deep way.
The best soils for sequestering organic matter will be those that are in perennial plantings, that have constant inputs of organic matter - these include forests that are enriched yearly by leaf drops, permanent pastures which are manured by grazing animals (It has been calculated that Joel Salatin's grazed pastures sequester as much carbon as a similarly sized forest after decades of grazing), and perennial gardens that are carefully managed to provide their own needs.
I maintain fertility in the perennial planting I established in these beds by the occasional dumping of animal bedding on the ground, permanent mulch, wood ashes from our stove, and a strewing of kelp. I've also grown an annual crop of chamomile, a good dynamic accumulator, and left everything but the flowerheads in place. I give the whole thing an occasional boost of nitrogen by dumping dilute urine over it - urine is safe unless you have tularemia (in which case you have worse problems than not being able to fertilize with your pee) and diluted 1-7 (1-10 if you don't drink enough), it provides a real boost to plants. To be paranoid stop doing so 10 days before harvest.
More demanding annual feeders get composted chicken or goat manure, plant compost, weed and manure teas. Other plants might also get living mulches, and I rotate plants as wisely and carefully as I can, following the heavy feeders with nitrogen fixers or light feeders undersown with nitrogen fixing cover crops. My whole garden gets rotating quantities of worm casting to supplement the soil and improve its texture.
Meanwhile, in maintaining, we try to put back what we take off. Crop residues are left in place, either chopped down and incorporated into the permanent mulch or they are burned in our woodstove (for heavy, dense stalks) and returned as ash. Some of the nitrogen is returned in the form of urine. We mulch as much as possible with our own mulches - grass clippings, leaves and plants grown for compost or as mulch plants. We try not to steal too much from any one other place - but we gratefuly take things people discard, like leaves from yards when we venture into suburbia, or horse manure from our horse-keeping neighbors.
Animal manures have a very powerful role in gardening - in a perfect world, we'd compost all human manures until they were thoroughly pathogen free, and restore the soil with what we take off. But whether this is safe is debatable, and anyone who shares food will not want to risk a lawsuit. So composted animals manures are a powerful tool for maintaining fertility - one of the reasons that polycultures of animals and plants are generally more effective than either alone. We use composted human manures only on decorative and tree plantings.
Two particular ways of maintaining fertility deserve mention here - fungal soil support, by mycorrhizae (tiny fungus that colonize the soil) and biochar. Mycorrhizae have a symbiotic relationship with the roots of many plants, and can enhance the ability to plants to uptake nutrients and deal with water stress among other things. Many soils are fungi deficient, and an application of mycorrhizae can improve your plants ability to absorb the nutrients in your soil.
Biochar/Terra Preta is a fascinating subject - and one still uncertain. Terra Preta involves adding plant based charcoal (ie, not the briquets at the grocery store) to your soil. What this does is still a matter of speculation - it isn't clear, for example, whether the charcoal itself or the organic processes it enables are actually what creates the rich soil involved. Nor is it clear that all soils respond equally well to terra preta inputs - for example a study found that boreal forest soils did not seem to respond to biochar applications. That said, however, there have been some fascinating results - biochar supplemented soils seem to stimulate nitrogen fixing in legumes, for example, and while charcoal supplemented soils enable plants to take up more minerals, the soils deplete more slowly. This is a project still in the exploration stages, but one that home gardeners and small farmers can contribute to with experimentation.
We're not a closed circle by any means - we still take advantage, as long as they are available and we can afford them, of valuable amendments. But the idea is to lose as little as possible, while getting the best possible balance between improved soil, the health of the world, and a system in which you need to bring in a little less from offsite each year. This, it seems, is an entirely achievable goal.
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mycorrhizae are over-rated. It's a feel-good product that seldom delivers. The current research indicate that different species of fungi affect various plant species differently. The ones that boost your rosemary might impede your basil, for example.
RE: using urine -- 3 of the 4 of us are on bp meds and 1 on diabetic meds. If I can talk them into saving urine (fat chance), is it safe to use the medicated ones?
have you considered the possibility of lead in the soil around your house, a relic of lead paint possibly? lead is known to inhibit microbial activity, as are other heavy metals.
agree with commenter #1 regarding mycorrhizal fungi, for different reasons. inoculating rarely seems to successfully introduce new species, better to encourage the ones already present than try to introduce ones that may be poorly suited to the soil and location.
#1: I realize that when you say "mycorrhizae are over-rated" you mean that commercial mycorrhizal inoculants are over-rated for boosting garden productivity, but as written your statement sounds silly since without symbiotic mycorrhizal fungi there'd be no terrestrial plant communities as we know them on Earth. Many plants have specific mycorrhizal symbionts but there are also plenty of generalists. If a person is interested in trying fungal inoculants it would be worth while to research which species are appropriate for a given crop.
#2: Medicated urine should be composted first. Microbial activity should degrade most medications & their metabolites. Only "clean" urine should be applied to garden soil directly.
There is usually charcoal in my wood ashes. In the past I have sieved out the charcoal (thru hardware cloth) for returning to the fire but rarely do so anymore. Hence, some is ending up in the soil. This is a good thing in terms of carbon sequestration, I guess, but a bad thing in that I have to cut & burn more wood when some of it is "wasted" as the result of incomplete combustion.
Adding wood ashes to high pH Western soils is a mixed blessing. Nutrients are added but high pH problems are exacerbated. (In the East wood ash amendment is an unmitigated good.) With high pH nutrient cations become ionically bonded to negatively charged clay minerals and are thus rendered unavailable for plant uptake. Soils may be quite high in iron, zinc or magnesium, for instance, but little good it does if these elements are unavailable to plants. Gypsum (CaSO4-2(H2O)) may be added to the soil to lower pH, improve texture & mitigate sodic conditions. Gypsum exchanges S for Na, binding sodium & allowing S to react with water to form sulfuric acid which lowers pH. Unfortunately, it may take a LOT of gypsum (2 - 10 tons per acre) to be effective. Another recourse is to add chelated micronutrients but this is more expensive. EDDHA is a more effective (and more expensive) chelating agent than EDTA.
For the past 16 years I have added large amounts of organic material to my garden beds, and the people who previously lived where I do did the same. Hence, my garden soil is a far cry from native soil on the rest of the property. The garden soil pH averages 7.8, which is a bit high but outside the garden can be as high as 9.4 & averages 8.2. (Remember that the pH scale is logarithmic.) My garden soil pH would probably be nearly neutral if I never added wood ashes. The garden soil is high in organic matter while surrounding soils are virtually devoid of organics (less than 1%). Garden P averaged 43.75 ppm while samples from outside the garden went as low as .84 ppm & were typically in the vicinity of 2 - 4 ppm. Likewise, mean garden K was 324.5 ppm & most samples outside were less than 100 ppm & none exceeded 200 ppm. Mean garden NO3-N was twice that of any sample outside the garden.
I was wondering about the practicality of gardening on some property I have in northeastern Pennsylvania. The soil presumably isn't very good - as far as I know it was never cultivated, but maintained as sheep pasture a few generations ago. (Now it's forest, mostly, though the beavers have a veritable clear-cut going on.) On the other hand it sits on a freshwater lake with a near infinite supply of muck. How does lake muck compare to other strategies (e.g. manure) as far as building decent soil? It's not something I'm going to do this season, but I'm just looking ahead . . . .
The Chinese used to maintain an extensive canal system for irrigating rice and providing transportation of foodstuffs from the farms to the cities and manure from the cities back to the farms. The canals would silt in so an ongoing task was dredging the canals & composting the muck as a soil amendment. Your lake muck should be excellent unless the lake is polluted. Be aware that getting it out of the lake & onto your soil requires a huge effort without power equipment.
Biochar sounds "too good to be true". For one thing, charcoal is a very valuable archaeological find because it really sticks around (and can be dated). So even if it is useful as a soil amendment it would not be something to add every year, ad infinitum. Also, I haven't read any convincing explanation of its benefits, just speculation that it might provide an environment for microscopic organisms to occupy.
The biggest risk with urine is probably synthetic birth control hormones. Some of them can be quite resistant to degradation.
How about growing worms on the crop residue and then feeding them to your chickens? Earthworms are (effectively) cold blooded ruminants. They should have a very high efficiency of converting cellulose to animal biomass.
I think terra preta is under rated and composting is over rated. All the nutrients in biomass are completely available after partial charring (except for some nitrogen which might be lost). Composting doesn't have any advantage that I can see. You want your soil to be light and aerated, charcoal does that quite well. The reason you want the soil to be aerated is so that roots can get O2 and derive growth energy aerobically not anaerobically. Charcoal leaves the soil aerated, organic matter puts a demand for O2 and nitrogen to support the bacteria that are decomposing it.
Terra preta was made by native Americans in the Amazon and in some places it is still meters thick and highly fertile even with very high leaching. There is a pretty good wikipedia discussion of it.
Plants don't need âorganic matterâ. All that plants need are trace minerals, NPK and water. That is why hydroponics works, plants can synthesize all the organic compounds they need from CO2. Plants release organic acids into the soil to dissolve minerals and liberate them so they can be absorbed.
An advantage of charcoal is that it has ion exchange sites that can adsorb anions. Silicates in soil have lots of sites that can adsorb cations, but none that can exchange anions. The most important anion is probably nitrate, which leaches very rapidly. Ammonium is a cation and leaches very slowly because of the cation exchange sites in soil.
Charcoal also adsorbs toxic organic compounds and provides surface that bacteria can grow on. I don't think there is a limit on how much charcoal can be used. Most of the minerals in soil are inert anyway. Inert silicates or inert charcoal, what is the differentce? Charcoal adsorbs organics and provides surface for bacteria and is porous so it can hold air and water.
Yes, the microscopic pits & lacunae become colonized by N-cycling & other beneficial bacteria. Charcoal also improves soil texture, aerates soil & holds water, as daedalus2u states. Because charcoal is so refractile, it's primary benefit probably is that it keeps carbon out of the C cycle over the meso- timescale.
This said, I think that daedalus2u over-states the benefits of charcoal as a soil amendment. This is especially true if one heats & cooks with wood. The caloric value of charcoal as a fuel outweighs its benefit as a soil amendment. The reason that biomass needs to be composted before being added to the soil is so that the uptake of N to support the synthesis of microbial enzymes takes place in the compost heap rather than in the soil, where such uptake would deprive plants of available N. In the long run, net N increases with biomass amendment, composted first or not, but this is of no avail if N is temporarily unavailable to plants during the growing season. Charring biomass virtually eliminates N via pyrodenitrification.
darwinsdog, when you compost organic matter, the carbon goes up as CO2. If you converted that carbon into charcoal and added it to your soil your soil (and the planet) would be better off.
I agree that there is N loss during pyrolysis. High nitrogen wastes are (I think) better used to feed worms (and the worms used to feed chickens) rather than being composted.
I think it is much better to convert excess biomass into charcoal and incorporate it into soil, rather than compost it into CO2 and put it in the atmosphere. There are no good ways to do this yet, but I think there is a great unrecognized need to do so.
Most of it does indeed, as does all of it when it's burnt completely. Many organic compounds, however, are quite resistant to enzymatic degradation by microbes, or their immediate hydrolysates, oxidation products or metabolites are. These compounds partially degrade to the weak humic & fluvic acids you mention, that buffer pH, contribute to the slow weathering of soil parent material & improve tilth or soil texture. Many of these compounds have half-lives of centuries. To my mind, amending soils with the organic products of composted biomass is preferable to doing so with inert charcoal. Compost also contains some nitrogen, as you point out. Allowing earthworms to consume biomass & in turn be eaten by pooping chickens is a form of composting. Verts & macroinverts do the heavy lifting for the microbiotia & the whole process gets sped up. Your point about sequestering C in soil as inert charcoal is well taken. It does no harm, probably provides some benefits to the soil, & beats turning it loose into the atmosphere where it contributes to climate change. In the overall economy of the household, though, one has to figure what's the most efficient use of one's resources. I contend that the charcoal is more valuable as a fuel than it is as a soil amendment.
Hi Sharon! In my experience, raised beds don't dry out so much if they're kept deep-mulched year-round, Ruth Stout/Emelia Hazelip style. You might still have to add water in exceptional dries, but nowhere near so much as in bare-soil husbandry.
I used to be a Ruth Stout/mulching devotee for all the obvious reasons: less weeding, less watering, an easy way of adding fertility. However, over time a colony of voles moved in and cleaned out all my root crops and destroyed many other plants, again and again. Now I have learned to appreciate the virtues of clean/bare soil cultivation and the voles have moved on. I still mulch a bed or two for short periods of time, but never the whole garden again.
I find this to be pretty amusing, because it does show the degree to which, well, gardening is various. I love mulch, but I know plenty of real dryland gardeners that find it ineffective - see Steve Solomon for that. I have cats to eat the voles, too ;-). I am ambivalent about terra preta - I simply haven't seen enough good evidence for it, and it seems pretty clear it is more effective in some kinds of soils than others.
I should say, I wasn't clear about what I meant by applying mycorrhizae - I would suggest people culture them out of their own compost piles.
YMMV is the watchword of agriculture ;-).
Sharon
I don't doubt that the cats would occasionally take a vole, but at what cost? Voles are active at night and cats that run free day and night are going to kill a wide variety of wildlife. If you love bluebirds in your garden, you won't have cats.
My observation is that cats and gardens and birds can coexist fairly well - some cats don't hunt birds at all, and ones that do are confined on our property. Close observation has been very clear to us - we have more than 30 species of songbirds nesting on our property in various places, and we've never seen any incident of bird predation (not counting when they chase the chickens, but that's a different issue ;-)). It is certainly possible we've missed a couple, but not a huge number, particularly, since our cats generally bring their prey to us. We don't do things like encourage songbirds to nest in low places right near the garden (the ground nesters generally prefer the meadows anyway), but we've had yellow warblers, Pheobes, Robins and others make nests quite low to the ground, and watched the babies fledge without any signs of predation, even in the garden. We have confined the cats during nesting periods, but it has mostly been unnecessary - even when they range, the cats that don't hunt birds, don't hunt birds.
The problem is that some domestic cats do hunt birds, and they hunt them on a large scale, wildly in excess of their needs. But it isn't as simple as "if you love bluebirds, don't have cats" - cats fill an ecological niche that is necessary in a lot of areas, in both cities and farms - they control rodent populations in ways that permit gardening and support the ecosystem - given that we've removed most of the small predators from many ecosystems, it isn't necessarily healthier to abjure cats. But it isn't something you can do without attention, either.
Sharon
Sharon - question on artificial vs natural soil amendments - I seem to recall Rodale showed that organic vs conventional fields had approximately similar nitrate runoff over the course of 10 years (If I remember right the organic performed admirably some years and was horrendously polluting (comparitively) other years) - given that most N you put into the soil ends up getting in to the plant in the form of nitrate (at least in soil based wossnames, rice prefers ammonium as is illustrated by its relative abundance of ammonium transporters) is there any actual good data out there supporting the hypothesis that artificial amendments cause less runoff for the same amount of applied nutrient? Graph from his report at end of this paper (took me forever to find that as for some reason I had confused Benbrook with Rodale... which is a rather bloody bizarre mental switcheroo by any standards)
"But it isn't as simple as "if you love bluebirds, don't have cats" Not what I said.
I said... "If you love bluebirds in your garden, you won't have cats." (My observation.)
There's something about bluebirds in a garden setting. Do you know the difference between a bluebird and a bluejay? I have yet to see a gardener, who promoted bluebirds by growing certain fruit-bearing bushes and trees and/or by erecting bluebird houses in their yard, also have free-roaming cats. Just my experience. Some additional information on this subject: http://www.sialis.org/cats.htm
I don't doubt that the cats would occasionally take a vole, but at what cost? Voles are active at night and cats that run free day and night are going to kill a wide variety of wildlife. If you love bluebirds in your garden, you won't have cats.
One thing that have I read, either in Stockman Grassfarmer, or in ACRES USA (can't remember) is that raw milk mixed with water is great for increasing the growth of plants. I don't remember the proportions, But I know diluted was fine. It probably adds to soil life in addition to minerals.
Ok, I like bluebirds *on my farm* but I'm contented to have them outside my garden. I grow fruit in a lot of places on the farm, not just in the garden, and yes, I recognize the difference between bluebirds and blue jays. I'm happy to see them by the creekside and nesting along the pasture instead. We encourage the cats to hunt ground critters in the *garden* but don't allow them hunting over the property. And the thing about being attentive to your land is that you can actually distinguish between a cat that is a major danger to birds and one that isn't, between appropriate and non-appropriate uses of predation. I can understand why one wouldn't want cats in one's garden, but I also can understand why one would.
Sharon
"We encourage the cats to hunt ground critters in the *garden* but don't allow them hunting over the property."
How do you do that? Do you inform the cats of your rules at the start of each day? Cats are natural born killers. To a cat its like "a chipmunk, a vole, a baby bird...eh, what's the difference? Game is afoot."
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I have a cat who likes to dig up my seedlings and eat the leaves from my squash and cucumber plants (she has left the tomatoes alone, surprisingly, though all of those sprouted from the worm farm, so they took less work from me to get them going). I have read that cayenne pepper sprinkled over the soil would keep cats away, but that didn't work. Any tips?