Warmth usually speeds decomposition. Also burying what you want decomposed will expose it to more bacteria and insect activity which will also speed it along.
You could say that, if you consider eating dead animals to be speeding up decomposition.
No, it slows it down.
lava
light will produces heat which will speed up the rate of decomposition.
No. It is neither a bacteria nor a fungi.
Exposing it to heat and UV light.
For example, by increasing the temperature, by grinding the material, treating with chemicals.
how might a modern farming speeding up the decomposition of matter in soil affect the nitrogen cycle
Sugar will speed up the decomposition process because sugar does not melt, it will decompose. Decomposing sugar produces oxygen and water that certain bacteria and microbes love and then they are attracted to the area causing more decomposition in that area.
Temperature and moisture.
Several things will speed up the decomposition of hydrogen peroxide. You may be thinking of the enzyme peroxidase.
Moisture and warm temperature speed decomposition. This is a form of abiotic decomposition as it employs a chemical or physical process without the involvement of micro-organisms.