Non-Aerated Compost tea being made in two ols Bokashi bins.
Gutter down-pipe with pop-sock used to filter the tea.
NCT is made by simply soaking sweet-smelling mature aerobic compost in water. Soaking and stirring removes microbes as well as soluble nutrients from the compost
so that the finished tea will contain the range of enzymes, hormones, microbes, nutrients and plant growth compounds found in the original mature compost. The tea will reach low oxygen levels or be anaerobic is minimal if mature compost is
used. The full food web may be present if oxygen levels do not drop below the levels required for aerobic respiration.
On the allotment or in the garden the procedure is convenient requiring little time
and effort as the compost is just soaked and stirred periodically.
NCT may contain non-beneficial anaerobes because the air surface of the container cannot provide enough oxygen for microbes in the lower
portions of the container to respire aerobically. The likelihood of anaerobic conditions occurring increases if the compost used is immature. One of the reasons that non-aerated compost teas do not normally have additional food sources added to the brew
as this will also increase the likelihood of anaerobic conditions. Tea in which anaerobic conditions have been allowed to develop will be less effective as a foliar feed.
Simple Compost tea in water was
traditionally made by suspending a sack, cheesecloth bag, a pillow case or an old pair of tights, containing compost in a barrel or bucket of water for 7 to 14 days. The bag should be suspended by string from a rod across
the top of the bucket but completely submerged in the water (a stone can be added to the bag as a weight) The microbes will be filtered through the material to give a liquid feed that could be applied with a watering can or a sprayer. Some methods
suggest putting holding the “sack” on the bottom of the bucket using a stone. If this technique is used when making any teas or feeds it is best to tie it with string which reaches outside of the container to make it easier to
The technique has been modified slightly over the years using different water containers e.g. buckets or water butts and filtering the liquid after the tea has been made rather than soaking it in a sack. Under this
“free compost” variation, which makes easier to aerate the mix and mechanically remove organisms by stirring, the compost is left loose in the water and filtered at the end of the process. The tea needs to be filtered through muslin or an
old pair of tights to avoid it blocking the watering can rose when being applied to the plants or soil. I use a short length of plastic drain pipe with the leg of a pair of tights over one end as a reusable filter.
Every composter seems to have their own variation on the basic to suit their site and the materials available.
Basic Non-aerated Compost Tea Recipe: 3-4-day brew
Using a spade add freshly harvested, mature compost to third fill a bucket and then add water almost to the top of the bucket (unchlorinated rain water if available). If using chlorinated tap water, it is best to fill the bucket the night before
use or degas the chlorine from fresh tap water by stirring vigorously for 10 to 20 minutes before adding the compost.
Soak: Different sources recommend different soaking (brew) times
from 3-4 days to several weeks. The longer period and regular stirring enable more organisms to be extracted from the compost. Stirring also adds some oxygen to the solution. If the mixture is
left unstirred for a long
period, the it is more likely that the resultant feed will contain a high proportion of anaerobes.
Strain: It is necessary to filter the liquid to avoid it blocking the rose of the watering can, or spray,
be using to apply it. After the 3-4 days strain the liquid through an old pair of tights, cheesecloth or other porous fabric (burlap) , into a second bucket. I find that a three-foot length of downpipe with one end covered by a “pop-sock”
works as a reusable filter. If washed out between sessions the pop-sock will last several months. The sludge that remains in the bucket, after filtering, should be added to the compost bin. Alternatively, the compost can be contained in a pair
of tights, burlap sack etc. before being added to the water. While this avoids the need to filter the finished liquid it does mean that the compost will not be as effectively washed when stirred.
The filtered liquid is diluted with rainwater until it is the colour of weak tea, or 10 :1 ratio of water : tea, and used immediately.
Non-aerated Compost tea: 10-day brew
Mix: Three quarters fill a 5-gallon bucket with non-chlorinated water.(If chlorinated must be used treat it as described above) and add about 2lbs of mature finished compost and stir well.
The brew is stored in a warm but shady part of the garden for 10 days where it is stirred frequently. The tea can be used immediately or stored for up to 6 months, If the tea is stored it should be checked to ensure that it smells healthy. If it
has an unpleasant odour it has turned anaerobic.
Strain: Strain through cheesecloth or tights as above.
Dilute: Dilute 1:5- 1:60 with fresh
rain water or unchlorinated water before applying to plants, lawn, and soil.
Non-Aerated Worm Compost Tea
Finished worm compost is an excellent
compost for use when making compost tea. It can be used on its own or 50:50 with conventional compost ideally prepared in a hot composting system from predominately green waste compost. I spade full of is put into a pair of old tights, cheesecloth or
pillow case into 5-gallon bucket of rainwater of one, r two days or even just over night. Alternatively, the compost can be added directly to the water and be filtered after soaking. I prefer this method as it allows the compost to be stirred or
aerated more effectively than if it is contained in tights
Dilute until it is light brown in colour, not unlike weak tea, and use immediately before the beneficial microbes in the start to die.
The sludge left in the bucket can be used on the garden or be added to the compost bin as a way of supplying moisture and activator to the bin.