William Otieno, a farmer prepares compost manure in Kisumu. Hot composting is quite simple and requires a minimal amount of daily effort.
Getting good compost can take a long time due to regular composting method commonly known as “cold composting”. This method involves placing a variety of organic materials in a compost bin, enclosure, or even just in a large heap, and leaving it there until it breaks down several months later.
It is hands-off method which is slow and can take six to 12 months. To hasten the process, farmers would turn the material at the bottom of the heap to the top and vice versa to mix it up and get more oxygen in there, but it’s still a long wait. To hasten the process of composting, University of Berkeley California has developed a “hot composting method that maximises microbiotic activity to produce high-quality compost in only 18 days.
Hot composting is quite simple and requires a minimal amount of daily effort. Hot composting kills weed seeds and pathogens.
In contrast, cold composting does not destroy seeds, so if your cold compost has weeds, they will grow when you put the compost into the garden. Cold composting does not destroy pathogens either, so if you put diseased plants into your cold compost, the diseases may spread into the garden. The other issue with cold composting is that you end up with lots of large pieces left over in the compost when the process is completed, whereas hot compost looks like fine black humus (soil). So how is hot composting done?
Location
Locate your compost heap in an area protected from too much sun or heavy rain, to prevent the compost from drying out or becoming water-logged and slowing down the composting. The composting materials have to be a specific mix of carbon (brown) and nitrogen (green) rich materials.
The nitrogen-rich materials are where the heat comes from. The ratio of carbon to nitrogen should be around 30:1. Nitrogen-rich materials include grass clippings, dead headed flowers, clippings from green pruned trees and shrubs, weeds, fruit and vegetable scraps. Others are eggshells, fresh manure from non-meat-eating animals (goats, chickens, horses and cows). Carbon-rich materials include straw, corrugated cardboard, paper, dried corn stalks, fallen leaves, sawdust, straw and hay, wood chips, or shredded tree bark.
Pile alternating thin layers of greens and browns on top of each other until your heap is about one square metre. Wet the compost heap down very well so it is dripping water out of the bottom and is saturated. Leave it for the next four days (no turning).
Use a garden fork to turn the compost. When turning compost, move the outside of the pile to a spot next to it, and keep moving material from the outside to the new pile. When you’re done, all the material that was inside will be outside and vice versa.
Ensure that moisture stays constant. Put gloves on and squeeze a handful of the compost materials - it should only release one drop of water, or almost drips a drop. The compost heap should reach its maximum temperature on day six to eight. Stick a thermometer into the middle of the heap to confirm it’s between 50 and 65 degrees Celcius. When earthworms move into the compost, you know it is ready, cooled down and full of nutrients.
You know you are succeeding if you can feel the heat coming off of the pile, and it has a slightly pleasant ‘warm’ odour. You may also see water vapour coming off the pile when you turn it or see white fibres of mycelium developing. You’ll also notice the pile is shrinking. Hot composting may sound hard until you try it. Good luck and share your experience with us!
