Making & Using CompostUnit 1.7 | Part 1 – 299
Lecture 1: Making & Using Compost
Lecture 1: Making & Using Compost
Pre-Assessment Questions
- What is compost?
- What are some examples of composting systems and how do they differ?
- Why is aerobic high-temperature composting favored for agricultural /horticultural
purposes?
A. Compost and Types of Composting Defined
- Composting defined
a) Composting is a biological, chemical, and physical, highly aerobic process that
transforms large, bulky, coarse materials (mostly plants and animal manures) to a
homogenous, stable end product that is: uniform, brown/black in color, crumbly in
texture (slightly greasy), sweet smelling, and particulate. Finished compost is a source of
nutrients for plant growth and a feedstock for soil organisms.
b) The process is biological as it is achieved by organisms. The actual decomposition is
chemical via acids and enzymes. The physical aspect involves macroorganisms (mostly
arthropods) and their chewing, shredding, and mixing actions. See Supplement 1,
Making Quality Compost at a Garden Scale.
c) Compost can be used in two ways: As a soil builder/conditioner that improves the
physical properties of a soil (especially structure and bulk density), and as a fertilizer,
with both immediate and long-term effects
- Examples of composting systems
a) Indore windrow method: The classic high-temperature aerobic composting method
featuring animal manures and green waste, popularized by Sir Albert Howard. Growers
and commercial producers use this method and its variations (e.g., the Luebke method)
b) UC Rapid Composting: Features frequent turning of the pile (daily or every other day) to
rapidly produce compost (see Resources)
c) The UCSC Farm & Garden method: A variation of the Indore method; hand-built scale,
high-heat aerobic piles for garden use
d) Sheet composting: Spreading and burying organic material (leaves, greens, etc.) over
a garden bed or landscape, then digging it in to decompose. Additional nitrogen is
sometimes applied.
e) Vermicomposting: Also known as worm composting, vermicomposting systems rely
on earthworms (often “red wigglers”, Eisenia fetida) to digest and decompose organic
material, resulting in nutrient-rich “castings” used as a fertilizer and soil conditioner
f) In-vessel composting: Features a closed system such as a building or large metal
containers in which temperature and airflow can be controlled. Often used to compost
municipal wastes.
B. Benefits of Aerobic Hot Composting
- Advantages of aerobic hot composting process
a) Stabilizes volatile nitrogen. Composted organic matter contains nitrogen in a more
stable form (nitrate) that is more usable by plants.
b) Kills most pathogens, e.g., E. coli and Salmonella, and weed seeds (if piles are above
131 ̊F for 15 days)
c) Introduces a wider population of microbes than found in the raw ingredients
d) Reduces volume of wastes (by approximately 50%)