While the BioWicked beds are designed to be very low maintenance they do require some regular chores to keep them flourishing at their best. Incorrect maintenance, especially in hot dry conditions, can lead to the top of the beds crusting from dissolved salts. This is the same reaction as seen in inland Australia where a combination of a high water table due to tree removal plus no mulch layer has led to salinisation of vast tracts of previously arable land.
NOTE: The following is the BASIC maintenance required to keep your BioWicked garden bed healthy. Other tasks such as collecting seeds and replanting harvested areas and maintaining long-term fertility will be covered in more depth in the upcoming e-book on the BioWicked system.
Irrigation: The BioWicked beds are designed to be watered from both above and below. This is different from conventional wicking beds, which should not be watered from above as it can wash organic matter into the lower anaerobic zone. To water fully you place a hose down the inlet and slowly run water into the bed until it begins to come out the drain. As the drain is set about 15cm (6″) above the ground this saturates the lower 15cm of soil. THEN saturate from above until water begins to come out the drain a second time. This ensures the soil moisture in the top 2/3 is at ‘field capacity’, which is the most water that free draining soil can hold. In the dry tropics, which have a huge amount of evapotranspiration, the beds need a good soaking from above and below about once a week. An easy way to tell if it needs watering is to look down the inlet to see if there is water visible, and also see if you can easily push your finger into the soil.
The beds should also be thoroughly flushed at least once a year to stop the build up of salts. This may happen naturally if there is sufficient rainfall during the wet season. If not wait until the bed has been thoroughly soaked by a decent rain storm then slowly flood the top of the bed. Keep adding water from above until it soaks down through the soil and flows out the drain, and let it flow for at least 15 minutes. I often set up a banana circle at the drain exit of a number of connected beds so this flushing water is utilised.
Mulch: The mulch is designed to work in a similar way and provide similar environmental functions as the mulch on the floor of a rainforest. It needs to be saturated fully at least once a week, similar to a tropical downpour. Any organic matter can be used but as with all mulch a good nitrogen:carbon balance is necessary so the decomposing mulch doesn’t pull nitrogen from the soil. If material that is high in carbon is used the nitrogen can be supplied using dried blood and bone. The main points are to maintain a thick layer at all times and to encourage it to decompose and break down so as to feed the top soil and plant’s shallow feeder roots. In a tropical rainforest up to 3/4 of the nutrients are locked up in the decomposing mulch layer, unlike cool temperate areas where the majority of the plant nutrients are in the soil.
NEVER leave the soil uncovered and re-mulch on a regular basis as direct sunshine , especially in desert and dry topical areas, will kill the beneficial organisms in the topsoil and the feeder roots of some plants. A lack of a thick mulch layer will also lead to salting of the beds as salts will build up in the lower layer and be brought to the surface. As the water evaporates it leaves salts behind. This is avoided by always having a THICK mulch layer, and by periodic flushing. The mulch can be quite deep as long as it isn’t against the stems of the plants.
Fertilisation: Basically any organic inputs and techniques can be used in conjunction with the BioWicked beds. Chemical fertilisers, herbicides, and pesticides MUST BE AVOIDED as they will kill both the beneficial soil bacteria and mycorrhiza that help the bed to function. Diluted bokashi fermented food waste is ideal but any balanced organic fertilisers are fine to use. If installing a large community garden I will add a stand-alone large wicking worm farm to convert a mix of green waste, locally available animal manures, and food waste into soil and biofertiliser through the use of worms, bacteria send mycorrhiza (see photo). On a home level if using food waste my preferred method is to ferment the food waste with bokashi in sealed 5 or 10 litre containers for at least a month. I then put it into an in-built worm farm where the worms turn the fermented food waste into vermicompost to top up the bed and the liquid, which is bokashi fermented worm exudate, leaches into the beds’s plumbing system. I generally add either a permanent in-built timber worm farm or use a 10-litre plastic bucket with holes as a move able in-bed worm farm.
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