Topsoil takes a very long time to recreate, (25mm of topsoil can take up to one thousand years). Topsoil can also be lost in a matter of seasons through soil erosion. Care must be taken so that soils are not left bare. This can be done by ensuring pastures and crops are established before seasonal droughts followed by torrential wet weather scour the top soil.
Avoid over stocking pastures. Over stocking may increase the availability of organic matter to the soil surface but increase soil compaction therefore reducing plant root depth. Over stocking also runs the risk of potentially damaging the soil surface severely by pugging when saturated.
Adding organic matter to soil (such as hay, chicken manure, silage or growing shelterbelt trees) will give soil organic matter. Specialised enzymes then break the materials down, which worm castings mix with other minerals, which have been brought up by the deep burrowing worm species. The castings have great water retention abilities as well as a natural soil conditioner.
Worm tunnels are strengthened by the mucus from the worm’s skin. Once the mucus dries on the walls of the tunnels it acts as a soil binder (aggregates) these strengthen the soil structure against erosion, allowing air and water to penetrate into the soil structure.
Once a healthy earthworm population is established (over eight million per hectare, or 32 earthworms per 200mm cubic dimensions) there may be noticeably less difficulties with facial eczema spores. This is due to the earthworms ability to consume organic debris from the soil surface reducing the occurrence of facial eczema spores.
Earthworms prefer pH levels of 6.5 to 7.5. Dolomite lime is a calcium magnesium additive to help maintain the pH balance. Soil tests are an option to detect specific mineral deficiencies and imbalances. Organic rock phosphate, seaweed and fish extract organic fertilisers give good results, but more importantly is the continual use of organic matter such as chicken manure or compost.
Using deep rooting pasture plants such as red clover, chicory, docks or cocks foot help retain moisture during dry spells, yet encouraging the earthworms to remain active.
Earthworms will migrate if there is a lack of organic matter present, so apply compost, blood and bone plus other ingredients like untreated wood ash and lime to ensure the worms willingness to continue making improvements to the soil structure.
To aim for a balance of trace elements within home made compost, use a nitrogen/carbon ratio of around 1:30 and use natural additives such as comfrey, borage, nettle and seaweed which will help achieve the right balance of nutrients in the garden soil, therefore producing healthy flowers and vegetables.
Moisture levels are retained when vermicast and compost are applied. Using mulch on the surface acts as a weed suppressor.
Use garden forks opposed to spades.
The growing of Pasture Worms can be a trial and error procedure. Earthworms for breeding can be brought from specialist earthworm farmer or collected from certain locations. Such locations may be oxidation ponds, cow shed races, cow shed sump pits, septic tank outlets and swamps.
When collecting Earthworms caution is needed not to collect the Tiger Worm variety as these worms will over populate the worm beds forcing the Earthworm species to migrate. The Earthworms can be placed into worm bins at least 200 worms per metre, covered with carpet or underlay.
A bed suitable for breeding pasture worms is a raised bed, walls up to 50cm high, 1m wide and up to 2m in length, using untreated timber. Line the inside of the bin with weed matting, then 50mm of free draining solid or fine pumice.
Locate the ongoing supply of well-rotted silage and semi fresh cow manure to mix with water to apply to the worm bed. This prepared food mixed with soil will help when relocating your worms stocks. After one week, fork the material. Remember that moisture needs to be monitored to ensure the bedding temperature does not exceed 28o C.
Watch out for Flat Worms which is a predator of the Earthworm and Compost Worm. It is recognised by a distinctive hammer head and flat long body.
After approximately 12 months there should be enough Earthworms to introduce into the garden or pasture. Autumn is the ideal season as this allows the worms to adjust to the new environment before the onset of summer.
Pasture Site Preparation for the Introduction of Earthworms
Choose a site that is low lying or near trees eg hedges, shelter belts or under deciduous trees where the leaves provide extra organic matter for the Earthworms to thrive and multiply. For the preparation of the soil, dig a 30cm hole, apply a spade full of food mix and up turn the grass sod. Leave for one week, then introduce approximately 10 worms per up turned soil sod.
Come spring, there should be a visible healthy green patch as the Earthworms multiply and eventually populate the pasture. An application of lime every 3-4 years will help boost the Earthworm population.
Earthworm Population Calculation
An estimated Earthworm calculation can be done by digging a 20cm x 20cm x 20cm hole thereby retrieving both worms and soil. Count the worms from this sample then multiply this number by 25, then multiply that total by 10,000, this will give an approximate number of worms per hectare. Optimum numbers are 10,000,000 earthworms per hectare, which is 40 earthworms per 20cm x 20cm x 20cm.
Earth worms in New ZealandEric Wilson
Earth worms unlimitedWorm farm Managemen