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3.3.1.1 The Benefits of Composting: Safely Utilizing Organic Materials
Composting employs microorganisms naturally present in OM to decompose and
mineralize organic materials. Finished compost is recognized as a soil conditioner
that provides an organic nutrient source for soil microbial populations that assist
with plant productivity (Brinton et al. 2012). Compost is comprised of decomposed
material containing primary, secondary, and micro nutrients (Egrinya et al. 2008).
Proper composting techniques are dependent upon many factors, including OM
substrate, substrate carbon to nitrogen ratios, oxygen and moisture levels, surface
area of the OM, and the form and duration of compost processing (UMass Amherst
2018). Shredding OM substrates increases the available surface area for improved
microbial decomposition.
Microorganisms are naturally present in all life; the human body, for example, is
abundant with living bacteria. Diverse soil microbiology facilitates plant nutrient
uptake and associated plant growth parameters (Molina-Romero et al. 2017). Plant
matter and human and animal excrement is also naturally rich with microorganisms.
The compost process mimics most natural ecosystems and requires greater carbonbased materials to lesser nitrogen-based materials for proper microbial decomposition rates (an approximate 30:1 carbon-nitrogen ratio). Examples of common
carbon-based materials include dried leaves, shredded paper and newspaper, paper
towels, and agricultural organic waste materials such as sugarcane bagasse. More
common nitrogen-based materials include “fresh” green grass, animal and human
excrement, and most fresh plant detritus, including food waste.
The more prevalent forms of compost processing include thermophilic/“hot”/
aerobic composting, anaerobic (without oxygen) composting, enclosed aerated systems (which often encompasses ventilation and/or forced aeration systems), and
vermicomposting (the employment of worms, primarily red wigglers “Eisenia fetida” as the primary OM decomposers). Simplified compost processes with minimal
mechanization that may be more suitable for non-industrialized countries include
smaller-scale boxed compost systems and/or “covered” systems that encase
nitrogen- based organic materials with a locally available shredded carbon source.
Thermophilic (“heat loving”) bacteria proliferate in properly established and
maintained compost systems. Effective aerobic composting produces high temperature pathogen and weed seed killing heat created by organic exudates and action
from the rapid microbial decomposition of OM. The finished compost product is a
stable, humus-like material that can be safely handled, stockpiled, and utilized.
Conversely, simply applying organic materials to a soil, such as animal manures,
will not ameliorate potential pathogen loads or mitigate weed seed transference. To
be noted, although the finished compost product typically contains a multitude of
nutrients, it is not considered a fertilizer as the exact nutrient proportions cannot be
consistently determined.
Composting can be accomplished in small- or large-scale systems; however a
minimum of a cubic yard of initial organic substrate material is recommended for
thermophilic processing. Larger on-farm composting or compost facilities, found in
E. F. Creegan and R. Flynn
3.3.1.1 The Benefits of Composting: Safely Utilizing Organic Materials
Composting employs microorganisms naturally present in OM to decompose and
mineralize organic materials. Finished compost is recognized as a soil conditioner
that provides an organic nutrient source for soil microbial populations that assist
with plant productivity (Brinton et al. 2012). Compost is comprised of decomposed
material containing primary, secondary, and micro nutrients (Egrinya et al. 2008).
Proper composting techniques are dependent upon many factors, including OM
substrate, substrate carbon to nitrogen ratios, oxygen and moisture levels, surface
area of the OM, and the form and duration of compost processing (UMass Amherst
2018). Shredding OM substrates increases the available surface area for improved
microbial decomposition.
Microorganisms are naturally present in all life; the human body, for example, is
abundant with living bacteria. Diverse soil microbiology facilitates plant nutrient
uptake and associated plant growth parameters (Molina-Romero et al. 2017). Plant
matter and human and animal excrement is also naturally rich with microorganisms.
The compost process mimics most natural ecosystems and requires greater carbonbased materials to lesser nitrogen-based materials for proper microbial decomposition rates (an approximate 30:1 carbon-nitrogen ratio). Examples of common
carbon-based materials include dried leaves, shredded paper and newspaper, paper
towels, and agricultural organic waste materials such as sugarcane bagasse. More
common nitrogen-based materials include “fresh” green grass, animal and human
excrement, and most fresh plant detritus, including food waste.
The more prevalent forms of compost processing include thermophilic/“hot”/
aerobic composting, anaerobic (without oxygen) composting, enclosed aerated systems (which often encompasses ventilation and/or forced aeration systems), and
vermicomposting (the employment of worms, primarily red wigglers “Eisenia fetida” as the primary OM decomposers). Simplified compost processes with minimal
mechanization that may be more suitable for non-industrialized countries include
smaller-scale boxed compost systems and/or “covered” systems that encase
nitrogen- based organic materials with a locally available shredded carbon source.
Thermophilic (“heat loving”) bacteria proliferate in properly established and
maintained compost systems. Effective aerobic composting produces high temperature pathogen and weed seed killing heat created by organic exudates and action
from the rapid microbial decomposition of OM. The finished compost product is a
stable, humus-like material that can be safely handled, stockpiled, and utilized.
Conversely, simply applying organic materials to a soil, such as animal manures,
will not ameliorate potential pathogen loads or mitigate weed seed transference. To
be noted, although the finished compost product typically contains a multitude of
nutrients, it is not considered a fertilizer as the exact nutrient proportions cannot be
consistently determined.
Composting can be accomplished in small- or large-scale systems; however a
minimum of a cubic yard of initial organic substrate material is recommended for
thermophilic processing. Larger on-farm composting or compost facilities, found in
E. F. Creegan and R. Flynn