Teaching Organic Farming and Gardening

Soil Biology and Ecology

Unit 2.3 | 31

Demonstration 3: Assessing Earthworm

Populations as Indicators of Soil Quality

for the instructor

Overview

This demonstration introduces

students to techniques for assessing

earthworm populations as indicators

of soil quality.

You have a choice of two methods

for this demonstration. The shovel-

count method will be more tedious

for the students because they

will have to sort through the soil

and remove all earthworms. The

vermifuge method may take a little

more effort at first to gather the

materials needed, but it will make

the students’ work easier.

MateriaLs

SHOvEl-COUNT METHOD

•        Shovels

•        Earthworm  Data    Sheets  (appendix   5)      

•        Pencils

vERMIFUGE METHOD

•        Sample rings*

•        Clippers

•        Watering   can 

•        Scoop  

•        Stirring   rod

•        Fresh  water

•        Jars

•        Earthworm  Data    Sheets  (appendix5)

•        Pencils

•        Ground yellow  mustard seed    (available  in  bulk    from        

health  food    stores  or  from    herb    companies)**

*Sample rings   define  the sample  area    and prevent vermi-

fuge from escaping sample area. A simple design is to cut

the top 8–12    inches  from    a   5-gallon    drum    and weld    on  a   

piece of metal pipe that overhangs each side by 6 inches

to  use as  a   handle. The ring    is  pressed into    the soil    to  2–3 

inches depth, and vermifuge is added within the sample

ring.   Sample  rings   can also    be  fashioned   from    sheet   metal,  

housing duct pipes, or large clean paint cans with the bot-

tom cut off.

**60    ml  (volume)    or  32  grams   of  yellow  mustard powder  

to  4.5 liters  of  tap water   =   13  ml/1    liter   or  7g/liter.   

4.5 liters of vermifuge is the amount required per sample

area in this demonstration.

Instructor’s Demonstration 3 Outline