Windrow Systems

Windrow systems are a traditional, low technology method for large-scale vermiculture activities. They consist of long beds placed directly on the ground with compostable organic material being applied to the surface and sometimes covered to reduce the incidence of pests.

Windrow systems are relatively inefficient as nutrients are lost through volatilisation and leaching and they require large areas of land. These systems also process organic materials relatively slowly taking between 6 and 18 months to complete processing (Edwards, 1995).

Windrow systems are most suitable to agricultural enterprises where large areas of land are available.

Materials that can be processed

A range of compostable organic materials can be processed in vermiculture units, however some form of pre-processing may be required. Pre-processing usually involves:

�� size reduction – to increase the

surface area for microorganisms

to attack;

Plate 2. Commercially available continuous flow vermiculture units.

Vermi-Converter 2000 – Vital Earth Company Worm Wigwam – EPM Inc. Eliminator 1200 – Pad Engineering

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�� mixing – to achieve a suitable structure, moisture content and nutrient balance; and

�� addition of a bulking agent – to improve structure, increase surface area and to absorb excess moisture.

Earthworms more readily process a mixture of compostable organic materials rather than monostreams of specific waste types, for example, just bakery waste (Recycled Organics Unit, 2000).

Common compostable organic materials produced by the C&I sector that are readily processed by vermiculture units include:

�� mixed fruit;

�� mixed vegetables; �� mixed food organics (mixed fruit

and vegetables, breads, meat/

poultry); and

�� mixed garden organics (lawn clippings, non-woody plant materials such as stems, leaves and twigs of various plant species).

The addition of a bulking agent, such as paper or cardboard, is very important when preparing compostable organic materials for processing in a vermiculture unit. Cardboard or paper are carbonaceous materials that absorb excess moisture, increase the porosity and structure of the material and increase the carbon to nitrogen (C:N) ratio.

The C:N ratio is the ratio of the weight of organic carbon to total nitrogen within the material. Some organic materials, such as meat and poultry, are rich in nitrogen. If these nitrogen-rich organic materials are processed in a vermiculture unit, carbon needs to be added to achieve a C:N ratio of 20 to 25 parts carbon to every one part nitrogen (C:N ratio of 20-25:1).

Carbon can be added to a

Plate 3. Shredded cardboard is a common source of bulking agent produced by the C&I sector.

vermiculture unit as shredded paper or cardboard. These high carbon materials are called bulking agents and are common packaging wastes in the C&I sector.

The addition of a bulking agent, such as paper or cardboard (Plate 3), not only increases the C:N ratio but improves the structure and porosity of the material. A bulking agent will also absorb excess moisture and result in a less dense material. All these factors produce a material that is more readily processed by the worm population.

The amendment of compostable organic materials with a bulking agent to increase the C:N ratio may result in the material becoming too dry. Worms need a moist environment, as previously discussed, and so the material that they consume needs to be moist but not too wet.

The final mixture of organic material amended with a bulking agent and water (if necessary) is called feedstock. Feedstock is the result of blending the different components to produce a suitable source of food for the worm population.

These factors are important for acceptance of the feedstock by the worm population. A number of feedstock recipes and the process of mixing a suitable feedstock will be covered in Information Sheet No. 4.

Materials that cannot be processed

Some compostable organic materials cannot be processed in a vermiculture unit.

Materials that are very high in nutrients, such as seafood and dairy products, are not recommended for vermiculture processing in any significant proportion. These materials can cause problems such as anaerobic (low oxygen) conditions that result in worm death.

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Microorganisms break down these Management of Overview of best practice

high nutrient materials very quickly vermiculture units guidelines for on-site resulting in rapid oxygen consumption. This can lead to health ^{Vermiculture units can be used to vermiculture technology} and safety issues such as odour ^{process a limited range of The Best Practice Guideline to} production and the attraction of pests ^{compostable organic materials into a Managing On-Site Vermiculture}

_{and vermin.} useful end product called vermicast. Technology series of information sheets provides an excellent

More information on materials that ^{However, effective vermiculture} introduction to the science of can and cannot be processed in ^{processing requires significant} vermiculture and the best practice vermiculture units can be found in ^{management of the unit to ensure} procedures for establishing and

_{Information Sheet No. 3.} reliable performance and to prevent _maintaining

a successful health and environmental issues from _{vermiculture unit.}

developing.

The process of achieving a successful Effective best practice management _{vermiculture organics management}

^{of vermiculture units requires a} system based on these best practice

^{dedicated approach to feedstock} guidelines is illustrated in Figure 4. preparation, monitoring regimes and site hygiene.

Figure 4. Overview of the Best Practice Guideline to Managing On-Site Vermiculture Technology Information Sheets.

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Information Sheet No. 2 How much compostable material is produced?

Simplified waste audit

Quantifying the compostable material in

health and safety risks for staff (Plate 1).

This Information Sheet provides simplified methods that are more effective for quantifying the amount of organic material produced by your organisation.

Rather than conducting an unpleasant and unsafe “waste audit”, simply collect compostable organic materials (eg. food) separately in dedicated bins. The quantity of this compostable material can then be determined. The challenge is to keep general waste out of the “organics only” collection bins (and vice versa), but this is simpler than sorting through mixed garbage.

Unnecessary risks are identified and removed, allowing for simpler and more accurate estimations than typical waste auditing practices.

Implementation

When implementing a source separated collection system, the needs of operations staff must be

Plate 1. Conducting a waste audit of non-source separated waste material. Even if safety clothing is used, this may still involve unnecessary risks if sharps and/or other contaminants are present.

The ROU is the NSW centre for organic resource management, information, research & development, demonstration and training

addressed. If a new operational system is designed without adequate consultation, opportunities to create simpler and more efficient systems may be lost, contributing to problems that prejudice staff against the system.

Staff support is mandatory to maximise the diversion of organics from the