I have been experimenting with compost teas and other natural liquid fertilisers over the years but, until now, have not found an easy way to delivery the nutrient easily to large areas.
Liquids are heavy, foul smelling (often) and must be will contained for transportation to their delivery zone. Using full buckets and watering cans is slow and heavy work and the liquids are best diluted before application so siphoning directly from a drum is not so practical.
Introducing the venturi mixer! This is a simple fitting that can be inserted into a pipe that uses the energy of passing water to drag in and mix a small flow from a side inlet.
This is fantastic because it solves the problem of diluting the compost tea on application and can also be used, in reverse, to fill the drum with oxygenated water for improved microbe growth.
First off I had to change my technique of just chucking biodegradable materials into a drum as this made a thick soup which easily clogs the lines. I created a large 'tea bag' about the size of a pillow case using wind netting sewn together with fishing line. Into this I put my nutrient dense materials such as seaweed, pig manure, rotten plums, chopped herbs including comfrey, yarrow etc. The bag goes into the drum which is then filled with water passing through the venturi mixer. The inlet for the mixer is open to the air so oxygen is combined with the flow of water. We do this so that the bugs living in the liquid have a nice rich environment to live and reproduce. The frothy bubbles are a good sign.
After letting it brew for a few days and periodically dunking the bag up and down to excite things it's time to pump this goodness out onto the crops.
Water now passes out of the pump / tap, through the venturi mixer and on to the destination. As it passes the suction input of venturi (which is submerged into the drum of liquid) it draws in some of the liquid mixing and diluting it with the water and applying it to the crops. Perfect. The adjustable dial on the input line allows for a level of control over the concentration of the mix.
Once the drum is empty, refill with oxygenated water, let it steep and then go again.