Agriculture Reference
In-Depth Information
INTRODUCTION
The importance of biological processes in the management and recycling of organic wastes has
been widely recognized; this chapter deals with vermicomposting, which is one of the most efficient
methods for converting solid organic materials into environmentally friendly, useful, and valuable
products for crop production. Vermicomposting is an accelerated process of biooxidation and
stabilization of organic wastes that involves interactions between earthworms and microorganisms.
Although Darwin (1881) already drew attention to the great importance of earthworms in the
breakdown of organic matter from dead plants and the release of nutrients from them, it was
necessary to wait almost 100 years until this concept was taken seriously as a technology or even
a field of scientific knowledge. After 2 decades of research and technical development on vermi-
composting, it is still necessary to depend on a series of fundamental aspects to understand how
the process works.
Certain species of earthworms, the main actors in the vermicomposting process, are described
briefly in terms of biology and ecology, showing how these animals can be important organic waste
decomposers to produce useful materials. The different earthworm species suitable for vermicom-
posting organic wastes have quite different requirements for optimal development, growth, and
productivity. In this chapter, the life cycles of these species and the general requirements of ideal
vermicomposting species of earthworms are first reviewed.
Vermicomposting is a complex biological and ecological process; to illustrate some of the
important physical, chemical, and biological actions and transformations occurring during it, a case
study is presented. Although earthworms are critical in the process of vermicomposting, complex
interactions among the organic matter, microorganisms, earthworms, and other soil invertebrates
result in the fragmentation, biooxidation, and stabilization of the organic matter. As an example,
some of the interactions between earthworms and nematodes are presented. Finally, some comments
are made on the applications of vermicomposting to plant growth, and some new perspectives on
vermicomposting research are discussed.
WHAT IS VERMICOMPOSTING?
The disposal of organic wastes from domestic, agricultural, and industrial sources into landfills and
other outlets has caused increasing environmental and economic problems, and many different
technologies to address this problem have been developed and tested. The growth of earthworms
in organic wastes has been termed
vermiculture
, and the managed processing of organic wastes by
. Vermicomposting, which involves the
breakdown of organic wastes through earthworm activity, has been successful in processing sewage
sludge and solids from wastewater (Neuhauser et al. 1988; Domnguez et al. 2000); materials from
breweries (Butt 1993); paper wastes (Butt 1993; Elvira et al. 1995, 1997); urban residues, food
wastes, and animal wastes (Allevi et al. 1987; Edwards 1988; Elvira et al. 1996a, 1997; Domnguez
and Edwards 1997; Atiyeh et al. 2000a); as well as horticultural residues from processed potatoes,
dead plants, and the mushroom industry (Edwards 1988).
Vermicomposting is a decomposition process involving interactions between earthworms and
microorganisms. Although the microorganisms are responsible for the biochemical degradation of
the organic matter, earthworms are the crucial drivers of the process by fragmenting and condi-
tioning the substrate, increasing surface area for microbiological activity, and altering its biological
earthworms to produce casts is termed
vermicomposting
