Compost Teas
Compost tea is an extract prepared from compost that is cold-brewed using water. This picture is of one of the 1000 litre brewing tanks at Laverstoke Park.
Compost tea contains nutrients and micro-organisms of benefit to soil and plants. This means the soluble portion of the nutrients found in compost, along with active micro-organisms, can be applied directly to soil or plants as a liquid feed.
How to Make Good Tea
There is no great secret - compost tea is made from compost and water. However, the critical steps are; ingredients, aeration and monitoring. Compost tea can be made in any quantity depending on the volumes required. A typical brew takes 24 hrs and should be used as soon as it is ready.
Ingredients
You must use good quality compost which itself contains a good range of ACTIVE micro-organisms, especially bacteria and fungi. Other ingredients can be added to the brew to adjust the proportion of bacteria to fungi in order to match the requirements of the intended crop. For example, adding molasses or seaweed extract can boost the bacteria or fungal numbers respectively, and adding humic acids can further help select beneficial fungi. Whilst there are many alternative ingredients, in general there is little need for 'exotic' additives.
Aeration
The majority of plant-beneficial micro-organisms require oxygen and lots of it. The best way to make sure a brew gently gets the necessary oxygen is to provide a constant curtain of fine air bubbles, this has the added bonus that it can be used to keep the mixture constantly stirred. This picture shows the bubbles produced inside one of our brewers.
The other key thing about aeration is that while it enables beneficial micro-organisms to thrive, it creates an environment in which facultatively anaerobic pathogens, such as E.coli, are driven to undetectable levels (Note: properly prepared compost should not contain detectable pathogens). Moreover, thriving beneficial micro-organisms would rapidly outcompete the pathogens in a properly maintained aerated tea.
Monitoring
To make sure the tea is just right takes a little care and attention to detail; for example making sure the water isn't too cold and isn't freshly drawn from a chlorinated mains supply. Cleanliness and good handling hygiene are important at all stages. The tea needs to be looked at by using a microscope; to tell if the micro-organisms are there and if they're the right ones, and once made, the tea needs to be used straight away.
What it does
Simply put, compost tea acts as a plant feed and probiotic. Applied to soil it as a drench where plants need an additional boost of soluble nutrients, or applied as a spray it provides a foliar feed. Perhaps more importantly though, the micro-organisms present in the tea help develop a protective barrier around roots and improve the life in the soil in general. On leaves, the beneficial micro-organisms colonise plant surfaces and prevent disease-causing organisms from gaining a foothold and causing infection. As with compost applications to soil the improvement in soil-life from compost tea aids nutrient cycling to the plants, improves water-holding capacity and improves root penetration.
It is an extract prepared from compost that is cold-brewed using water. This picture is of one of the 1000 litre brewing tanks at Laverstoke Park.
Compost tea contains nutrients and micro-organisms of benefit to soil and plants. This means the soluble portion of the nutrients found in compost, along with active micro-organisms, can be applied directly to soil or plants as a liquid feed.