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
strategies cluster around two key concepts: increasing organic matter
and mineral availability, and finding alternatives to the disruption
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.
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.
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).
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.
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.
at least as much art as science. More than anything I know, it is
something to "learn by doing."
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.
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.
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.
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
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
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 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
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.
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.
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?
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.
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,'
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! "
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
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
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.
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
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.
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.
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.
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.
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.
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
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.
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