Composting is the process of converting organic waste into a valuable soil amendment called compost. Compost enriches soil, helps retain moisture, and promotes healthy plant growth. Not all composts are created equal, however. There are several different types of compost, each with their unique properties and uses.
Compost Types
There are four main categories of compost:
- Garden compost – Made from yard and kitchen waste. The most versatile and commonly used type of compost.
- Manure compost – Made from animal manures like cow, horse, chicken, etc. High in nutrients but needs proper composting.
- Green manure compost – Made by growing nitrogen-fixing cover crops and then incorporating the plant material into the soil. Adds nutrients and organic matter.
- Vermicompost – Compost made with the help of worms. An excellent, nutrient-dense form of compost.
Within these broader categories, there are more specific types of compost. The major factors that distinguish compost varieties are:
- Starting materials used – This affects nutrient levels and properties.
- Composting method – Affects speed of decomposition and finished compost quality.
- Intended uses – Each compost has attributes that make it better for certain uses.
Now let’s explore the different compost categories and types in greater detail:
Garden Compost
Garden compost, also called backyard or homemade compost, is the most common and versatile type of compost. It’s made by combining yard waste like leaves and grass clippings with kitchen scraps and allowing the materials to break down over time.
Benefits of Garden Compost:
- Made from readily available materials
- Inexpensive and easy to produce at home
- Contains a blend of organic matter, nutrients, and beneficial microorganisms
- Improves soil structure, fertility, and moisture retention
There are several different types of garden compost:
Hot Compost
Hot compost is made by closely monitoring temperatures, moisture, aeration, and materials to achieve very high temperatures and rapid decomposition. Producing quality hot compost requires more effort but can decompose waste in as little as 4-6 weeks. Hot composting methods include:
- Turned piles – Materials are layered then turned or mixed frequently to distribute heat, moisture, and oxygen.
- Aerated static piles – Piles have layers of bulking material like wood chips to let air flow through.
- Enclosed bins – Bins like rotating drums or multi-chamber bins are designed to mix and aerate as they tumble or are turned.
Cold Compost
Cold composting involves simply piling organic materials and letting them break down gradually over several months to a year or longer. Cold composting requires less labor but yields compost more slowly. Methods include:
- Compost piles – Piles can be contained in bins or left open. Turning or mixing speeds decomposition but isn’t required.
- Sheet composting – Materials are spread directly onto the soil surface to decay in place.
- Trench/pit composting – Waste is buried trenches or pits, then dug up once composted.
Vermicompost
Vermicompost uses worms to digest organic wastes. Materials like food scraps are fed to species like red wigglers which create castings full of nutrients and beneficial microbes. This is one of the richest types of compost.
Seaweed Compost
Seaweed collected from beaches makes an excellent additive to compost piles. It adds micronutrients that are beneficial for plants and helps compost retain moisture.
Coffee Grounds Compost
Used coffee grounds can be added to compost in moderate amounts to add nitrogen, acids, and organic matter. Too many can make the compost too acidic so they should be mixed thoroughly with other materials.
Compost Tea
Compost tea is made by steeping mature compost in water. The resulting liquid contains concentrated nutrients and beneficial organisms from the compost. It can be sprayed directly onto plants or soil as a fertilizer.
Manure Compost
Manure compost is made by composting animal manures. Herbivore manures like cow, horse, sheep, goat, rabbit, and chicken manures are typically used. Composting manures kills pathogens, reduces odors, and converts the nutrients into plant-available forms.
Benefits of Manure Compost:
- Excellent source of plant nutrients including nitrogen, phosphorus, and potassium
- Contains beneficial microorganisms
- Improves soil texture and water retention
- May be sold commercially in bags or in bulk
Some types of manure compost include:
Cow Manure Compost
Composted cow manure has moderate nutrient levels. It may come from dairy farms, feedlots, or other cattle operations. Cow manure compost is widely available.
Horse Manure Compost
Horse manure has a high carbon to nitrogen ratio, so it often needs supplementation with nitrogen sources. Ends up with abundant organic matter. Best aged at least 6 months.
Sheep & Goat Manure Compost
Sheep and goat manures have lower carbon to nitrogen ratios than many manures so they compost quickly. The finished compost contains higher levels of nitrogen.
Chicken Manure Compost
Chicken manure is very high in nitrogen and composts rapidly. Finished chicken manure compost is a concentrated, nutrient-rich product but can burn plants if overapplied.
Guinea Pig, Rabbit & Rodent Manure Compost
Pig, rabbit, and rodent manures have similar properties as chicken manure, though maybe slightly lower in nutrients. Their manure composts also make valuable fertilizers.
Green Manure Compost
Green manures are cover crops grown to enrich the soil. Common green manure crops include legumes like clovers, vetch, peas, beans, and alfalfa. Grasses like rye, wheat, oats, and buckwheat can also be used.
To make green manure compost:
- The cover crop is grown and allowed to mature until it fills out the area.
- Once mature, the green manure is cut down and incorporated into the soil. It can be mixed right in or allowed to wilt for a few days first.
- The green manure breaks down in place and releases nutrients.
Benefits of Green Manure Compost:
- Source of organic matter to improve soil
- Nitrogen-fixing types like clover add nitrogen
- Can suppress weeds and reduce erosion
- Controls are in place over what goes into it
Green manure compost retains more nutrients than typical plant residue since decomposition happens right on site. It sustains soil fertility for multiple growing seasons.
Vermicompost
Vermicompost, also called worm compost, uses worms to digest organic wastes. Materials like food scraps, shredded paper, livestock manures, and crop residues are fed to species like red wigglers, white worms, and earthworms. As the worms feed, they produce castings full of plant-available nutrients, beneficial microbes, and soil-enhancing humus.
Benefits of Vermicompost:
- Contains concentrated nutrients and beneficial organisms
- Excellent for boosting plant growth and vigor
- Improves soil porosity and water retention
- Helps suppress plant diseases
Vermicomposting systems can be created at home or on a commercial scale. Here are some common vermicomposting methods:
Worm Bins
Worm bins are containers like wooden boxes that house worms and composting material. Food scraps and bedding are added to the top and worms migrate upwards leaving finished castings below.
Windrows
Windrows are long outdoor piles or beds of organic matter and worms. The worms work through the windrow as it’s gradually moved down the length.
Worm Bags
Simple worm bags made from burlap or mesh are buried in soil or suspended. Worms process wastes added into the bags then migrate out into the surrounding soil when finished.
Large-Scale Vermicomposting
Large vermicomposting operations may use cement tanks, automated feeding, mechanized harvesting, climate control, and more for high yields. These systems allow collection of huge volumes of high-quality worm compost.
How to Choose the Right Compost
Now that you know the major types of compost available, how do you pick the best one for your specific needs? Here are some tips:
- Match the compost with your soil type and nutrients required. For example, nitrogen-rich manure compost for depleted soils. Or acidic, ericaceous compost for rhododendrons.
- Consider compost maturity. Very fresh, unfinished compost can damage plants. Only use mature, stabilized compost.
- Choose coarse compost for aeration or fine grades for seed starting. Particle size affects uses.
- Select bulk/bagged based on project scale. Bulk compost may be more economical for large areas. Bagged makes sense for small beds.
- Buy from reputable sellers. Ask for compost analyses and production process details to ensure quality.
- Try different composts and take notes. See what works best for your conditions over time.
Compost for Specific Uses
Here are some examples of choosing the right compost varieties for particular gardening and landscaping uses:
Vegetable Garden Compost
For vegetable gardens, use:
- All-purpose garden compost to enrich soil overall
- Extra nitrogen from manure composts or green manures
- Vermicompost to boost plant growth
- Compost tea to provide soluble nutrients
The mix of nutrients from these compost sources will help grow healthy, high-yielding edible plants.
Potting Mix Compost
Good composts for container and seed starting mixes include:
- Coarse-textured garden compost for drainage
- Worm castings or vermicompost for nutrients
- Composted chicken manure for an extra nutrient boost
- Seaweed compost to help retain moisture
Blend composts to create a fertile, well-structured potting medium.
Landscaping Beds & Tree Compost
For landscaping projects, use:
- Garden compost, green manures, or aged manure compost to improve soil
- Finer composts to topdress lawns
- Coarser compost as mulch around trees and shrubs
- Compost tea drenches on plant roots
Improving soil and plant health supports better growth and survival rates in new plantings.
Acid-Loving Plants Compost
For azaleas, blueberries, rhododendrons and other acid-lovers, choose:
- Sphagnum peat or pine bark based composts
- Aged pine needle or oak leaf composts
- Coffee grounds added to compost piles
- Finished compost tested to confirm acidic pH
Acidic composts help these plants thrive. Too much alkaline compost can damage them.
Key Takeaways on Compost Varieties
With so many types of compost available, it pays to understand the key differences and applications. To recap:
- There are four main categories: garden, manure, green manure, and vermicompost.
- Factors like starting materials, methods used, and intended purposes affect compost characteristics and quality.
- Match compost variety and properties to your specific soil, plant, and project needs for best results.
- Try different compost products and blends over time to see what works best for your conditions.
- Buy from reputable compost producers and check compost maturity, appearance, smell, etc. to ensure it’s finished properly.
Compost is a valuable soil amendment with many benefits. With so many options to choose from, you can tailor compost to provide ideal nutrition and growing conditions for your individual gardening and landscaping goals. Know your choices and make compost work for you!