Composting
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Compost is probably the single most helpful thing you can add to your soil. It's not just for staunch organic
and natural gardeners, either. Whether you're green to the core, or use synthetic chemicals liberally in the
garden, compost has multiple benefits for your garden.
Soil texture: Compost (or more broadly, organic matter in general) is widely recommended as a fix for both
clay and sandy soils. Composted organic matter is superior to other forms because it's already been broken
down to a great degree, so it won't draw nitrogen from the soil. (Decomposition of carbon-based material
usually requires nitrogen.) It's also biologically active, teeming with billions of beneficial microbes.
The organic particles in compost, plus the slime secreted by the microbes in it, work to bind tiny clay particles
into larger crumbs. This allows more pore space for water and air to penetrate. In sandy soils, the compost
particles help to retain moisture and nutrients that quickly drain through sand.
Fertility: The nutrients in compost vary greatly, depending on what kinds of materials were used to make it,
but it generally contains some of each of the three major nutrients plus an assortment of minor ones.
Beneficial microbes: One of the most overlooked benefits of compost is that it infuses soil with fresh
colonies of beneficial bacteria and fungi and provides food for their continuing growth. These tiny
decomposers work to break down organic matter and release the nutrients contained in it so plants can take
them up through their roots. They also make inorganic minerals more usable by binding them to organic
molecules (a process called chelation.)
Even if you use a readily available synthetic fertilizer, microbes help. Microbes slowly releasing natural
sources of nutrients can help to even out the peaks and valleys between applications of fertilizer. Also, since
most garden synthetics don't contain micronutrients, plants rely on natural sources for them.
Finally, having healthy populations of beneficial microbes in the soil means less food and space for harmful
ones. The good guys crowd out the bad.
and natural gardeners, either. Whether you're green to the core, or use synthetic chemicals liberally in the
garden, compost has multiple benefits for your garden.
Soil texture: Compost (or more broadly, organic matter in general) is widely recommended as a fix for both
clay and sandy soils. Composted organic matter is superior to other forms because it's already been broken
down to a great degree, so it won't draw nitrogen from the soil. (Decomposition of carbon-based material
usually requires nitrogen.) It's also biologically active, teeming with billions of beneficial microbes.
The organic particles in compost, plus the slime secreted by the microbes in it, work to bind tiny clay particles
into larger crumbs. This allows more pore space for water and air to penetrate. In sandy soils, the compost
particles help to retain moisture and nutrients that quickly drain through sand.
Fertility: The nutrients in compost vary greatly, depending on what kinds of materials were used to make it,
but it generally contains some of each of the three major nutrients plus an assortment of minor ones.
Beneficial microbes: One of the most overlooked benefits of compost is that it infuses soil with fresh
colonies of beneficial bacteria and fungi and provides food for their continuing growth. These tiny
decomposers work to break down organic matter and release the nutrients contained in it so plants can take
them up through their roots. They also make inorganic minerals more usable by binding them to organic
molecules (a process called chelation.)
Even if you use a readily available synthetic fertilizer, microbes help. Microbes slowly releasing natural
sources of nutrients can help to even out the peaks and valleys between applications of fertilizer. Also, since
most garden synthetics don't contain micronutrients, plants rely on natural sources for them.
Finally, having healthy populations of beneficial microbes in the soil means less food and space for harmful
ones. The good guys crowd out the bad.
Compost can be purchased already made, and will work just fine. If you have a little space near the garden
and access to compostable materials, though, you may want to make your own. Contrary to many people's
misunderstandings, a properly constructed and maintained compost pile is not a health hazard, doesn't
produce offensive odors, and does not attract rats and vermin. It's a great way to usefully recycle yard and
kitchen waste.
The ideal size for a compost pile is about a 3' to 4' cube. If it's much larger, air won't reach the middle of the
pile. If it's smaller, it won't retain heat and the compost won't reach the temperature needed for best
decomposition, or to destroy weed seeds. While it's possible to make compost in an open pile, for several
reasons it's often better to contain it in a bin. A variety of compost bins and containers are available in
stores, from very simple to elaborate tumbling cylinders that turn the compost with a simple crank of a
handle. These will work to make compost, some more effectively than others, but it's also possible to make a
perfectly functional compost bin yourself, often for a lot less money.
The most basic design is a simple box made of wire mesh with fence posts at the corners. This keeps the
pile contained and allows air to circulate. When turning the pile or taking out finished compost, simply detach
the wire from one side of the box. A bin made of stacked cinder blocks, turned sideways so that the
openings allow air to reach the pile, is a similar but more durable design. If you have space, a system with
two bins side by side, one containing the current compost pile and one empty, can make things easier when
turning the pile (see below.)
and access to compostable materials, though, you may want to make your own. Contrary to many people's
misunderstandings, a properly constructed and maintained compost pile is not a health hazard, doesn't
produce offensive odors, and does not attract rats and vermin. It's a great way to usefully recycle yard and
kitchen waste.
The ideal size for a compost pile is about a 3' to 4' cube. If it's much larger, air won't reach the middle of the
pile. If it's smaller, it won't retain heat and the compost won't reach the temperature needed for best
decomposition, or to destroy weed seeds. While it's possible to make compost in an open pile, for several
reasons it's often better to contain it in a bin. A variety of compost bins and containers are available in
stores, from very simple to elaborate tumbling cylinders that turn the compost with a simple crank of a
handle. These will work to make compost, some more effectively than others, but it's also possible to make a
perfectly functional compost bin yourself, often for a lot less money.
The most basic design is a simple box made of wire mesh with fence posts at the corners. This keeps the
pile contained and allows air to circulate. When turning the pile or taking out finished compost, simply detach
the wire from one side of the box. A bin made of stacked cinder blocks, turned sideways so that the
openings allow air to reach the pile, is a similar but more durable design. If you have space, a system with
two bins side by side, one containing the current compost pile and one empty, can make things easier when
turning the pile (see below.)
A compost pile needs both carbon and nitrogen. Carbon materials are usually tough, fibrous substances
such as straw, dry leaves, wood chips or shavings, and shredded newspaper (don't use color or glossy
paper.) Materials that contain nitrogen include manure, blood meal, cottonseed meal, fresh grass clippings,
and kitchen waste. Some composters refer to these materials as "brown" (carbon) and "green" (nitrogen.)
Build the compost pile in layers, alternating carbon and nitrogen materials. As a rule of thumb, a mix of one
part green to four parts brown is a good balance. Some "brown" materials may need to be chopped or
shredded if they're very large chunks (tree limbs) or prone to matting (leaves.) Don't shred too finely. You
want them small enough to break down easily, but coarse enough to resist compacting and provide lots of air
space inside the pile.
Other ingredients can be added for extra nutrients (bonemeal, wood ash, rock phosphate, greensand, lime)
or to stimulate microbial activity in the pile (garden soil or finished compost) or both (kelp meal.)
such as straw, dry leaves, wood chips or shavings, and shredded newspaper (don't use color or glossy
paper.) Materials that contain nitrogen include manure, blood meal, cottonseed meal, fresh grass clippings,
and kitchen waste. Some composters refer to these materials as "brown" (carbon) and "green" (nitrogen.)
Build the compost pile in layers, alternating carbon and nitrogen materials. As a rule of thumb, a mix of one
part green to four parts brown is a good balance. Some "brown" materials may need to be chopped or
shredded if they're very large chunks (tree limbs) or prone to matting (leaves.) Don't shred too finely. You
want them small enough to break down easily, but coarse enough to resist compacting and provide lots of air
space inside the pile.
Other ingredients can be added for extra nutrients (bonemeal, wood ash, rock phosphate, greensand, lime)
or to stimulate microbial activity in the pile (garden soil or finished compost) or both (kelp meal.)
Straw
Leaves (dry)
Fir needles (dry)
Wood shavings
Newspaper (shredded)
Yard and garden waste*
Bark dust or mulch
Leaves (dry)
Fir needles (dry)
Wood shavings
Newspaper (shredded)
Yard and garden waste*
Bark dust or mulch
Kelp meal
Bone meal
Wood ash
Rock phosphate
Greensand
Lime
Garden soil
Finished compost
Bone meal
Wood ash
Rock phosphate
Greensand
Lime
Garden soil
Finished compost
Meat scraps
Bones
Oily or greasy food scraps
Dog or cat droppings
Diseased plant material
Bones
Oily or greasy food scraps
Dog or cat droppings
Diseased plant material
*Includes prunings, non-diseased plant material, branches run through a chipper-shredder, etc.
**Includes fruit and vegetable material, egg shells, coffee grounds, bread scraps, etc.
**Includes fruit and vegetable material, egg shells, coffee grounds, bread scraps, etc.
Carbon (Brown)
Supplements
Materials to Avoid
Breaking It Down
Making Compost
What Goes in the Pile?
In order for decomposition to take place, the pile needs both air and water.
There are two main types of decomposition, aerobic (requiring oxygen) and anaerobic (without oxygen.)
Aerobic decomposition is more rapid, and produces a rich, crumbly, earthy-smelling compost. Anaerobic
decomposition is slower, and generates a slimy mass that smells like rotting garbage. Obviously, aerobic is
greatly preferable for the compost pile, so you'll need to make sure it is well-aerated and doesn't become
compacted. Once or twice a week, the pile should be turned. This rotates material that was on the bottom
and in the middle of the pile to the outside, and vice-versa, exposing it to fresh air. A pitchfork or spading
fork is the best tool for turning a pile. If you're using a two-bin system (see above) you can simply move the
compost from one bin to the other during each turn. Even simply stirring the pile in one bin helps speed up
decomposition and keeps the inside of it from turning anaerobic.
As you're turning the pile, you may notice that it's warm and steaming. This is normal and good - it means
that things are coming along nicely. The process of breaking down organic matter releases a lot of heat
energy, as all those decomposer microbes get down to work. The interior of the pile may become quite hot,
reaching temperatures of 120 degrees F or more. This helps to kill weed seeds and disease-causing
spores. A compost pile doesn't have to get hot to be effective - the heat is just a sign that it's composting
rapidly. If you're not in any hurry, there's no need to be too concerned over how hot your pile is.
The compost-in-progress should be moist but not soggy. Too dry, and the decomposition process will be
greatly slowed. Too wet, and it becomes waterlogged, prevents air from penetrating the pile, and becomes
anaerobic. You may want to cover your pile during rainy weather, to keep it from becoming waterlogged and
to prevent nutrients from being leached away. If the pile becomes too dry, a light sprinkling with a hose
during turning will correct it easily.
There are two main types of decomposition, aerobic (requiring oxygen) and anaerobic (without oxygen.)
Aerobic decomposition is more rapid, and produces a rich, crumbly, earthy-smelling compost. Anaerobic
decomposition is slower, and generates a slimy mass that smells like rotting garbage. Obviously, aerobic is
greatly preferable for the compost pile, so you'll need to make sure it is well-aerated and doesn't become
compacted. Once or twice a week, the pile should be turned. This rotates material that was on the bottom
and in the middle of the pile to the outside, and vice-versa, exposing it to fresh air. A pitchfork or spading
fork is the best tool for turning a pile. If you're using a two-bin system (see above) you can simply move the
compost from one bin to the other during each turn. Even simply stirring the pile in one bin helps speed up
decomposition and keeps the inside of it from turning anaerobic.
As you're turning the pile, you may notice that it's warm and steaming. This is normal and good - it means
that things are coming along nicely. The process of breaking down organic matter releases a lot of heat
energy, as all those decomposer microbes get down to work. The interior of the pile may become quite hot,
reaching temperatures of 120 degrees F or more. This helps to kill weed seeds and disease-causing
spores. A compost pile doesn't have to get hot to be effective - the heat is just a sign that it's composting
rapidly. If you're not in any hurry, there's no need to be too concerned over how hot your pile is.
The compost-in-progress should be moist but not soggy. Too dry, and the decomposition process will be
greatly slowed. Too wet, and it becomes waterlogged, prevents air from penetrating the pile, and becomes
anaerobic. You may want to cover your pile during rainy weather, to keep it from becoming waterlogged and
to prevent nutrients from being leached away. If the pile becomes too dry, a light sprinkling with a hose
during turning will correct it easily.
The Finished Product
The amount of time needed to finish a batch of compost varies, depending on the mix of ingredients, how
often it's turned, the size of the pile, and other factors. You'll know your compost is ready when the pile
starts to cool down and the compost is fairly uniform, dark, and crumbly and has an earthy smell. It may still
have some bits that haven't broken down completely; that's perfectly fine. It will continue to decompose after
you work it into the soil or use it as a mulch, releasing nutrients over time.
often it's turned, the size of the pile, and other factors. You'll know your compost is ready when the pile
starts to cool down and the compost is fairly uniform, dark, and crumbly and has an earthy smell. It may still
have some bits that haven't broken down completely; that's perfectly fine. It will continue to decompose after
you work it into the soil or use it as a mulch, releasing nutrients over time.
Having trouble with your compost pile?
Click here for our Compost Troubleshooting Guide.
Click here for our Compost Troubleshooting Guide.
Benefits of Compost
Manure
Kitchen waste**
Grass clippings
Alfalfa (hay, meal, or
pellets)
Blood meal
Cottonseed meal
Kitchen waste**
Grass clippings
Alfalfa (hay, meal, or
pellets)
Blood meal
Cottonseed meal
Nitrogen (Green)