HUME, VA © 2008 Harvey Ussery www.themodernhomestead.us. Our best soil-care strategy is the imitation of natural soil communities, which negatively means avoiding the destructive practices of industrial agriculture-monoculture, use of synthetic chemicals, and excessive tillage-and positively means increasing soil life diversity and population densities, feeding the soil from natural (and more home-grown) sources, and protecting soil structure.

In this article we will focus on specific practices to achieve these goals

Most soil-care strategies cluster around two key concepts: increasing organic matter and mineral availability, and finding alternatives to the disruption of tillage.

Increasing Organic Matter and Minerals

It has been said that organic matter in the soil consists of "the living, the recently dead, and the very dead." The "living" portion consists of all the diverse forms of living organisms that make up the soil food web, but also plant roots themselves. It is a good thing to have lots of plant roots in our garden beds, because the most intense biological activity in the soil is found in the rhizosphere-the area in and immediately surrounding plant roots-largely because of important symbiotic relations between plant roots and soil organisms. "Recently dead" (or "active") components include recently deceased soil organisms of all types, green plant material such as crop residues, and fresh manures. They decompose readily and make nutrients available quickly. The "very dead" portion is humus, the final residue of organic matter breakdown that is so important for soil structure, water retention, disease suppression, and nutrient-exchange pathways. All three forms of organic matter should be present in soil in goodly amounts, at all times, in order to cater to the specific "tastes" of the different classes of soil food web organisms, enlist their services in breaking down organic material into forms usable by plants, and improve soil structure. Our sources of organic matter should be as diverse as possible.

Manures of all domestic livestock-your own or a neighbor's-can be valuable additions to soil. Their nutrients are readily available to soil organisms and plants. The easy-to-decompose organic matter in manures makes a greater contribution to soil aggregation by soil organisms than composts, which have already largely decomposed. The manures of ruminants contain more fibre, which breaks down more slowly and is thus available as a food source for longer periods, and makes a greater eventual contribution to soil humus.

Manure application must be done with care. To guard against contamination by possible pathogens in manure (far less likely in manures from homesteads and small farms than those from high-confinement livestock operations), it is best to allow a three-month interval between application and harvest of root crops or leafy crops like lettuce and spinach. (Tall crops like corn and trellised tomatoes should have no contamination problem.) Because nutrients from manures are so readily available in a big surge, they are more subject to leaching from the soil, where they are needed, into groundwater and streams, where they most definitely are not needed. If manures are overused, especially as the sole source of nitrogen, they tend to over-accumulate certain nutrients, especially phosphorus. Perhaps it is best to restrict fresh manures to heavy feeding, fast growing crops like corn, and process additional manure by composting.

When thinking of manures, it is worth thinking a bit about our own. Flushing "humanure" away (ultimately) to the sea is highly problematic for water systems, and represents a net loss of potential fertility from agricultural soils. On the other hand, no manure requires more cautious management for safety than humanure. I recommend Joe Jenkins' The Humanure Handbook, the "bible" on this subject. Don't be hesitant about experimenting: A small proof-of-concept humanure composting operation consisting of two 5-gallon buckets and a compost bin can be very low-profile indeed. If you are nervous about using humanure compost on food crops (Jenkins has used his right in the vegetable garden for more than 15 years with no ill effects), you can use it to feed trees, shrubs, and "fertility patches" (more of which below).

Composting

Composting is the great recycler of almost any organic "waste." It reduces the bulk of organic materials, stabilizes their more volatile and soluble nutrients, and speeds up the formation of soil humus. A properly made compost heap is assembled by layering more readily decomposable materials (wet, green, fresh, high-nitrogen) such as manures, crop residues, kitchen wastes, weeds, and other fresh green plant materials such as pasture cuttings-with less decomposable materials (drier, coarser, denser, more high-carbon) such as autumn leaves, straw, and residues of harvesting such as corncobs. The carbon to nitrogen (C:N) ratio is important-say an average of about 30 parts carbon to one of nitrogen-for efficient decompositon by the microbes that feed on the composting materials and break them down into simpler, more stable compounds. Heat is generated by the process. A temperature of 110 to 130 degrees F is probably optimal for the thermophilic (heat-loving) microbes driving the decomposition, but such temperatures help kill weed seeds and disease organisms.

Since water and oxygen are essential to the microbes, the pile should be moistened as it is assembled, but should not be sopping wet, which would decrease availability of oxygen and encourage growth of pathogenic organisms. The pile must be large enough to retain much of the heat of decompositon, but not so large that oxygen cannot penetrate to the center. Aeration is encouraged by mixing in the coarser elements throughout, ensuring plenty of air spaces. After the heat peaks, the heap should be turned-with the outer layers going to the inside and vice versa-to incorporate more oxygen and generate a new heating cycle. A third turning is sometimes necessary to complete the process.

Composting is at least as much art as science. More than anything I know, it is something to "learn by doing."

Composts are great for improving soil quality and water retention, disease suppression, and humus content (though less decomposed materials such as manures and green plants give a more immediate "flush" of nutrients when applied directly). However, they are quite labor-intensive. The older I get, the more interested I am in an easier alternative. Fortunately, there are three.

In classic composting, we layer the more high-nitrogen, easily decomposed elements with the high-carbon, difficult to break down materials. Suppose instead we keep these two types of compost materials separate, and simply apply them in two layers directly to the garden bed. This is the concept of "layer composting" or "sheet mulching"-it has even been called "lasagna gardening." The more moist, volatile, high-nitrogen materials go down first, in direct contact with the soil and the microbial populations ready to feed on them, while the drier, coarser, high-carbon elements are used as a cover to keep the first layer from drying out or losing its more volatile elements to the atmosphere.

An effective-and fun-alternative to labor-intensive classic composting is vermicomposting, using earthworms to convert nutrient-dense materials such as manures, food wastes, green crop residues, etc. into forms usable by plants. You can buy manufactured worm bins in which the worms grow and convert what you feed them, or you can easily make your own. You can also buy composting earthworms. Note that the species used is usually Eisenia foetida or related species-"red wrigglers" or "manure worms" (the sort you will find in a pile of aging manure, which indeed you could use to "seed" a population in your bin), rather than species that burrow deep into soil like "night crawlers." I started out with a 3x4 ft worm bin, then last year converted the center of my greenhouse to a 4x40 ft series of bins, 16 inches deep. My worms process horse manure by the pick-up load from a neighbor who breeds and boards horses, and the earthworm castings are a major part of our fertility program. Not only do castings help feed plant roots, they carry a huge load of beneficial microbes that boost the soil organism community.

Another fun alternative to composting is chicken power. I use electric net fencing to manage my chickens, rotating them from place to place on pasture. When needed, however, I "park" them on one of my garden spaces, onto which I have simply dumped whatever organic materials I would once have used to assemble compost heaps. The chickens happily do what they love best-scratch ceaselessly through that material looking for interesting things to eat, in the process shredding it and incorporating it into the top couple inches of soil, the zone of most intense biological activity. Their droppings, scratched in as well, give a big boost to the soil microbes.

Fertility patches

It may be necessary initially to add slow-release sources of minerals such as rock powders to correct mineral deficiencies. In the long run, however, we can supply needed minerals with less reliance on purchased inputs. The organic materials we add to our soil bring with them, in addition to nitrogen to feed growing crops and carbon to boost humus, most of the minerals healthy crops need. In addition, however, planting "fertility patches" allows us to grow a lot of our own mineral supplementation. Certain plants can function as "dynamic accumulators." That is, their roots grow down into the deep subsoil, "mining" it of mineral reserves made available out of the parent rock itself, and making them available to more shallow-rooted crops. The roots of comfrey, for instance, can grow eight to ten feet into the subsoil. Stinging nettle may have a bad reputation among gardeners who have felt its sting, but it is an extremely useful dynamic accumulator. Both nettle and comfrey, in addition to high mineral content, are high in protein (nitrogen), and can be used to "fire" a compost heap or for mulches. (More on mulches below.) And both will benefit from massive infusions of organic fertility, in any form you can throw at them, even raw poultry manure.

In addition to their role in bringing mineral content up from the depths, fertility-patch plants can be used to correct mineral imbalances. For instance, if overuse of manures has led to excessive levels of soil phosphorus, alfalfa-which benefits from high levels of phosphorus-can be grown as a "sponge" to take up excess phosphorus in the soil. When cut and used in composts or mulches, it makes the phosphorus available elsewhere on the homestead where it is needed.

If you have some pasture, think of it as well as fertility patch par excellence: Especially when growth is fast and lush in the spring, you should be able to take one or two cuttings, perhaps even more, for use in composting or as mulches. If you do not have any pasture, consider using parts of your lawn instead, perhaps those less visible if you are nervous about a neighborhood outcry. I have begun overseeding my lawns each fall with the same sort of grass/clover mix I use on the pasture. In the spring, I allow some areas to grow about eight or ten inches before cutting with the scythe for fertility applications elsewhere.

Cover Crops

Often a distinction is made between "cover crops," planted to protect the soil, and "green manures," planted for incorporation into the soil in order to feed soil life and the following crop. For simplicity, I will refer to crops intended for both uses as cover crops.

Growing cover crops is perhaps the most valuable strategy we can adopt to feed our soil, build up its fertility, and improve its structure with each passing season. Freshly-killed covers provide readily-available nutrients for our microbe friends and hence for food crop plants; and the decaying roots of cover crops open up channels into the soil which permit penetration by oxygen and water, and ultimately add to the store of humus in the soil. Legumes (clovers, alfalfa, beans and peas) are especially valuable as cover crops, since they fix nitrogen from the atmosphere into forms readily available to subsequent crop plants. (Plants cannot use atmospheric nitrogen directly.)

Mixes of different cover crops are often beneficial. For example, in mixes of grasses and clovers, the grasses add a large amount of biomass and improve soil structure because of the size and complexity of their root systems, and the legumes add nitrogen to help break down the relatively carbon-rich grass roots quickly.

Cover crops should be an essential part of our crop rotations-we should work them into our cropping plans with the same deliberation that we bring to our food crops. An easy way to do so is to maintain two separate garden spaces, plant one to food crops and one to cover crops, then alternate the two types of crop in the following year. Since most gardeners cannot devote that much space to such a strategy, effective cover cropping must be fitted into a unified garden plan, a concept that in practice gets fiendishly complex. Gardeners who like jigsaw puzzles will love the challenges.

Fortunately, there are cover crops for each of the four seasons, and for almost any cropping strategy. Fast-growing grain grasses (rye, oats, wheat, barley) might be appropriate in early spring in those beds not planted to the early harvest crops. A cold hardy legume like peas can be started in late winter and allowed to grow two months or longer to precede a warm-weather, heavy-feeding crop like winter squash. A warm-weather legume like soybeans or cowpeas can fertilize beds that will be planted to fall crops that like plenty of fertility, such as broccoli or fall-planted garlic and shallots. For a quick-growing "filler" between spring and fall crops, nothing beats buckwheat, the "instant cover crop" (thirty days from seed to flower), for suppressing weed growth, and shading the soil and thus protecting soil life and retaining moisture. Don't forget winter-an opportunity not to be missed for adding organic matter to the soil in the form of cover crops, which also protect soil life from winter's assault. Grain grasses again are an excellent choice. A mix of hairy vetch and rye (cereal rye, the sort of rye used to make bread, not perennial rye or annual grass rye) will start later in the cold season than any other choice.

One of my favorite winter covers is a mix of oats and "field pea" or "winter pea" (pisum arvense, a close relative of pisum sativum, the common garden pea): Both plants are cold-hardy enough to sail through the early frosts, attaining lush knee-high growth, but then reliably winter-kill when the ground freezes-and lie down into the most beautiful mulch-in-place you can imagine, ready for spring transplants right through the mulch, and with the fertility "bonus" from the nitrogen-fixing peas. (I say "reliably" with reference to my own conditions-I grow in Zone 6b-you Florida and California homesteaders are on your own on this one!

Since most garden beds are given over to food crops most of the growing season, how do we find opportunities to "shoe-horn" in the cover crops? Fortunately, we can utilize undersown cover crops to grow soil-building covers together with harvest crops. For example, we can sow Dutch white clover in a bed we are planting to tall crops with a small "footprint" such as trellised tomatoes or pole beans. Dutch white comes up fast and establishes a tight cover which suppresses weeds, retains soil moisture, increases bioactivity in the topsoil (remember that the zone of greatest activity is in the rhizosphere), and adds biomass and nitrogen to the soil for future crops. Since it is low-growing, it does not interfere with managing or harvesting the taller crops above it. What more could you ask of one plant?

Another strategy comes to mind for establishing an overwinter cover. A crop like broccoli is quite cold-hardy, so-by the time its harvest is complete-we have lost the opportunity to start an overwinter cover in its place. Rye and vetch, on the other hand, are great winter covers, but rather slow to get started. It's a marriage made in heaven: When transplanting, we undersow the broccoli with the rye and vetch. They take some time to establish, so do not overwhelm or shade out the broccoli. By the time we harvest the last of the broccoli, however, the rye/vetch cover is coming on strong-for protection of the ground over the winter, and a big boost to fertility in the coming spring.

A final thought about cover crops: Perhaps many homesteaders are a bit too paranoid about "weeds." Some weeds are deep rooted, and can be used like comfrey as dynamic accumulators to bring minerals up from the deep subsoil. An example is yellow dock (Rumex crispus), against which gardeners usually feel compelled to make war. Why not allow some yellow dock to grow here and there, in edges and corners where it is not in the way? When the plants start to make seed heads, cut them off just above the crown, to prevent huge numbers of seeds loose in the garden, and use them in mulches or composts. The deep, persistent roots will quickly replace the lost growth. You could say that we are using the dock as a "pump" to bring up additional minerals from the deep subsoil for use near the surface.

According to Stuart R. Ellins, Professor Emeritus of Psychology at California State University and author of Living with Coyotes, there is a way to work with a system of nature to condition wild animals in their food choices, helping them remain wild and free among us to choose natural foods in their area such as the rodents we want them to eliminate, while keeping us and them safe from becoming lazy and dependent on our more docile and often trapped farm animals and pets. The system is called 'food aversion conditioning,'

Protecting Soil Structure with Alternatives to Tillage

In an article on my webstie (see below) considered ways in which excessive tillage is seriously detrimental to soil life and a contributor to greenhouse gases. Proper soil care reduces the need for tillage. Nurture of soil life by constant introduction of organic matter helps to open and loosen soil structure. That improved structure can be protected by practices designed to do one thing: keep the soil covered at all times. Repeat after me: "Bare soil is anathema! "

Mulches

An obvious way to keep the soil covered is the extensive use of organic mulches. It is often said that high-carbon materials such as straw or leaves are not good additions to soil, since soil microbes "rob" available nitrogen from the soil in order to break down the excess amounts of carbon. This is true, however, only if we incorporate these high-carbon sources into the soil. I once tilled in some coarse compost containing large amounts of oak leaves not yet fully decomposed, and found that crops grew quite poorly there the entire season. However, if high-carbon materials are laid down on top of soil as mulches, there is no problem. The mulch benefits soil life by retaining soil moisture and protecting against temperature extremes (freezing chill in winter, blazing heat in summer); and microbes, earthworms, etc. can "nibble" at the mulch in the contact zone between soil and mulch, a layer of intense biological activity, and slowly incorporate their residues into the topsoil. Actually, high-carbon mulches are preferable to materials that decompose readily, since they persist longer before being incorporated into the soil food web. (Every gardener who has used mulches knows the story: You put down a nice thick layer early in the season, then suddenly one day notice-The garden ate my mulch! ) Even so, it is usually necessary to renew mulches that are in place for the entire growing season.

It is often recommended to turn manures and composts into the soil, but if we wish to reduce tillage and attendant soil life disruption, it is possible to apply the manure or compost on the soil surface, and keep it from drying out (hence degrading) with a thick high-carbon mulch (along the lines of "sheet mulching," described above).

Grass clippings should not be lost as a resource-certainly, shipping them off to the landfill is a crime against sustainability. Unfortunately, grass clippings from a power mower are difficult to use efficiently for either composts or mulches: They mat down and become putrid (rot) in a slimy layer which inhibits transfer of oxygen into a compost heap or into the soil. A grass-clippings mulch can be hazardously slippery underfoot, and most unpleasant to work on. I much prefer to let lawn or pasture grasses grow to eight to twelve inches, then cut with a scythe, rake after a couple of days drying out a bit, and apply where needed. The scythe may be the homesteader's best friend.

An undervalued potential source of organic matter is the huge volume of wood fiber the typical family "exports" in the form of newspapers and cardboard. I never send these into the waste stream anymore, but use all that come my way for mulching. All the reading I've done on the subject convinces me that modern newsprint in this country, and cardboard produced in the United States and Europe, do not pose environmental hazards. When establishing "kill mulches" (mulches over a living grass sod intended to kill it in preparation for planting trees and shrubs), I lay down a thick layer of newspaper/cardboard, then cover with leaves, grass cuttings, etc.
Wood chips make good mulch for some situations-e.g., pathways, kill mulches where trees will be planted, etc.-and are often free for the dumping from tree-trimming services. Inoculating chips with spawn of wood-loving mushroom spieces speeds decomposition and offers the bonus of edible mushrooms.

Wide beds

A key strategy for protecting soil structure is to grow in wide beds and restrict foot traffic to the pathways-thus avoiding compaction in the growing areas-and to plant as closely as possible in the beds. Close planting boosts bio-activity in the soil, since as noted earlier, the zone of greatest activity is the rhizosphere in and immediately surrounding plant roots. It also shades the soil surface, benefiting both soil life and plants by conserving soil moisture and moderating temperature extremes.

Interplanting slower-growing with faster-growing crops can help keep the bed constantly covered. For example, rows of carrots in the bed can be interplanted with radishes and/or beets, both of which mature earlier than the carrots. As we harvest the radishes and beets, the carrot tops meet and interlace, closely shading the bed. Similarly, brassicas such as cabbages and broccoli can be interplanted with faster-growing lettuces. The strategy of undersowing cover crops, noted above, also helps keep the bed covered when planted to an appropriate food crop. Such strategies also reduce weed pressure, further obviating the need to till the soil.

Paths between beds

Don't forget soil-care opportunities offered by paths between beds. Mulching the paths also protects garden soil from drying and from temperature extremes. In addition, foot traffic helps shred or grind mulch materials such as straw or leaves. From time to time, this finely-shredded material can be transferred to the beds, where it will break down much more readily than in its coarser forms.

Another possibility is to allow somewhat wider pathways, plant them to cover crops that can take a fair amount of foot traffic (rye, Dutch white clover), then cut the path covers from time to time with a sickle and use them for mulches in the beds.

When tillage is necessary

Consider well before assuming that tillage, especially power tillage, is "necessary." Almost invariably, alternatives exist. Power tillers are stressful to use-loud, stinky, and jarring-and worse, invert and mix the different layers in the soil profile, disrupting the soil food web and breaking down the "crumb" structure we and our friends in the soil have worked so hard to achieve. Even garden-size tillers tend to form "plow pans"-compression zones formed by "spanking" of the soil by the rotating tines-which resist penetration by water, earthworms, and plant roots. Even in the case of cover crops which must give way to the planting of a harvest crop, it is not necessary to turn them into the soil, as usually recommended.

When working at the garden scale, alternatives include:

• Simply bury the cover crop under a sufficiently heavy mulch to kill it. (You'll be amazed at how quickly the soil life digests it.)
• If the soil is in loose, friable condition, it is easy to pull the cover plants up by the roots and lay them on the bed as mulch.
• Certain plants such as rye and vetch are difficult to kill without tillage, but cutting them immediately above the crowns after seed stalks or flowers form will kill them. Use the upper plants as a mulch to help break down the roots more rapidly.
• Chickens can be used to till in cover crops. They cause some disruption of soil life, of course, especially fungal hyphae networks and the larger animals such as arthropods, nematodes, earthworms, ground beetles, etc. However, the disruption is only in the top couple of inches of soil, does not invert layers or pulverize structure deeper down, and is likely to be quickly repaired, especially as the birds' droppings give a boost to bacteria and other soil life.

When it is necessary to loosen the soil at depth-as in a "young" garden whose soil has not yet "mellowed" sufficiently to grow good root crops-I recommend the broadfork, a hand tool that, like the scythe, makes joyful, all-round use of the body in a rhythm that becomes a garden meditation. Unlike a power tiller, the broadfork loosens the soil without inverting the natural soil layers or breaking down the "crumb" structure of the soil. (See photo of Harvey above with a broadfork.) The broadfork is much easier to use in soil that is already in fairly good condition-it is not the tool of choice for converting a tough grass sod over compacted soil to new garden ground. Does that mean that in this case we are forced to revert to power-driven steel? Not on my homestead, where once again chicken power comes to the rescue. Normally I would rotate the birds on to another plot after a week or so to prevent excessive wearing of the pasture sod, but in this case "excessive wearing" is exactly what I want. I use electronet to "park" a flock of chickens on the sod I want to convert to garden. With their constant scratching, the birds kill and till in the sod. I remove the birds, grow a mixed cover crop, and then return the chickens for another round of tilling. Now the new ground is ready to start working as garden. Be sure to note the state of the soil before you start-the changes by the end of the season will amaze you.

If you don't have chickens, a no-till way to develop new ground is to lay down a "layer compost" or "sheet mulch," discussed above, heavy enough to kill the existing sod. If you can be generous with watering through the germination phase, you can start a cover crop in the top layer of the sheet mulch, the roots of which will greatly accelerate the breakdown of the mulch. Plant a second cover in the fall. This strategy works better if you can give the area over completely to soil building for a full year. If you have to get some production out of the ground the first season, simply open up holes in the sheet mulch and plant (a strategy that works better with some crop plants than others). One way to get significant production on new ground in the first season is to use pototoes to do the heavy work for you. Simply lay your seed potatoes directly on the established sod, and cover with a thick mulch. As the sod plants die, their fresh green matter converts readily to a flush of available nutrients for the heavy-feeding pototoes, and the potato roots speed breakdown and loosening in the root zone of the sod. Renew the mulch as needed to keep the growing tubers well covered. When time to harvest, simply push the mulch aside and pick up your spuds. The new garden soil still has a long way to go, but it's well on its way.

The only time I do massive tillage in the garden is when digging root crops such as potatoes (if not mulch-planted), sweet potatoes, and burdock. With such crops, I dig deeply and thoroughly with the spading fork-a total disruption of soil structure and inversion/mixing of its natural layers. My goal, however, is to make such intensive disruptions the rare exception rather than the rule, and trust that the intact soil life communities in surrounding beds will soon help reconstitute the soil food web in the disturbed areas.

Harvey Ussery and his wife, Ellen, homestead and teach rural skills on two and a half acres. All content on the MEF site is fully copyrighted. Visit Harvey's website for more information and for permission and guidelines for further using any of his material. www.themodernhomestead.us

Teaming with Microbes:
A Gardener's Guide to the Soil Food Web