BIOTECHNOLOGY - V. H. Herasymenko - 2006

Part II. Applied Biotechnologies

Chapter 23. BIOTECHNOLOGY FOR ORGANIC WASTE DISPOSAL VIA VERMICULTURE

23.6. ASSESSMENT OF THE EARTHWORM POPULATION STATUS

The status of the earthworm population is assessed by GROWTH AND DEVELOPMENT indicators through monthly counts of their numbers and determination of age Structure. This is carried out as follows. Substrate samples containing earthworms, measuring 10x10 cm, are taken from the full depth across various locations of the bed (in a checkerboard pattern or diagonally). All earthworms are collected from these samples, counted, and their biomass is determined (i.e., weighed). The resulting average values are then multiplied by 100 to determine the average population density and biomass of earthworms per 1 m².

However, an increase in earthworm biomass is not a definitive indicator on its own. When feeding nutritious feed, one may achieve significant weight gain in the earthworms, yet they may fail to produce cocoons.

Earthworm reproduction is significantly influenced by population density. As density increases, earthworm excitability rises, and overcrowding stress negatively impacts reproduction. Therefore, when cultivating vermiculture, it is essential to determine the optimal population density, which in turn will heavily depend on the ultimate objective—obtaining vermicompost or earthworm biomass.

Reproductive intensity is also heavily influenced by the feed itself: its availability, quality, caloric value, palatability, and diversity.

Therefore, when conducting quantitative assessments of earthworm numbers, the age STRUCTURE OF THE population is also determined by separately counting cocoons, juveniles, and adult earthworms, while the average number of embryos per cocoon is also recorded. The ratio of different age groups provides insight not only into the General condition of the population but also into its future outlook. For instance, if adult earthworms and cocoons outnumber juvenile forms, this indicates that the vermicompost conditions are hindering embryonic development and The Emergence of young worms. A proper analysis will enable adjustments to the housing conditions and the optimization of the vermiculture process parameters.

For sampling convenience, it is practical to use a 4-tine blunt pitchfork with a 10 cm working width.