What Is High-Temperature Composting? A Full Breakdown of the Key Technical Points

Compost is a kind of organic fertilizer with relatively rich nutrients and a long-lasting, stable fertilizing effect, and it can also increase the soil's ability to retain water, hold heat, allow air through, and retain fertilizer. Ordinary compost is made by decomposing under anaerobic conditions, and the compost temperature does not exceed 50°C. The decomposition time is relatively long, about 3-5 months. The piling method varies with the season and other conditions, and there are three types: flat-ground type, half-pit type, and underground type. So what is high-temperature composting? What are the key technical points?

I. What is high-temperature composting?

High-temperature composting is an organic fertilizer. After straw, manure, and urine are treated at high temperature, harmful substances such as pathogens, insect eggs, and weed seeds can be eliminated. High-temperature composting must be inoculated with high-temperature cellulose-decomposing bacteria and set up with a ventilation device; in cold regions, cold-protection measures should also be taken.

There are two ways to pile high-temperature compost: the flat-ground type and the half-pit type. The piling method is the same as for ordinary compost, but thermophilic high-temperature cellulose-decomposing bacteria must be added to promote the decomposition of the straw.

High-temperature composting generally goes through several stages: heating, high temperature, cooling, and decomposition. The high-temperature stage can kill insects and sterilize.

II. What are the key technical points of high-temperature composting?

1. Choose a site. Choose a place relatively close to a water source and convenient for transport; the size depends on the site and the amount of material. Build a 30 cm high earth ridge around the site to prevent water loss.

2. Material ratio. For every 1 tonne of straw, mix 1 kg of straw decomposing agent and 5 kg of urea (or 200-300 kg of decomposed human manure and urine or sludge) to meet the nitrogen needed for microbial fermentation. If conditions permit, adding 2-5% calcium magnesium phosphate fertilizer or 2 kg of lime gives better results.

3. Piling method. Generally pile in 3 layers, each about 30-50 cm thick, and evenly sprinkle straw decomposing agent and urea between the layers. If there is no straw decomposing agent, human manure and urine or sludge can be poured between the layers. To ensure ventilation inside the pile, before piling insert wooden sticks vertically at set intervals so that the bottom contacts the ground; after piling, pull out the wooden sticks, and the remaining holes serve as ventilation holes. The pile width is generally required to be 1.6-2 m, the pile height 1.0-1.6 m, and the length depends on the amount of material and the size of the site.

4. Straw treatment. Before piling, soak the straw thoroughly with water. The ratio of dry straw to water is generally 1:1.8, so that the moisture content of the straw reaches 60%-70%. Generally, it is appropriate when a liquid drop can be squeezed out by hand when holding the material; this is the key to the success or failure of composting.

5. Seal the pile well. After piling, seal it tightly with plastic film (or mud). When the pile gradually sinks and the temperature inside the pile slowly drops, turn the pile, mix the poorly decomposed material at the edges evenly with the material inside, and pile it up again. If white mycelium is found on the material, add an appropriate amount of water and reseal the pile.

6. Judge the degree of decomposition. When fully decomposed, the pile shrinks by 1/3-1/2, the straw turns blackish brown to dark brown, is soft and easily broken, the leachate color is blackish brown to light yellow, and there is an ammonia odor.