Final answer:
Volcanic ash fallout is a volcanic hazard that can bury crops, release toxic chemicals, and damage machinery by clogging and abrading moving parts.
Step-by-step explanation:
The type of volcanic hazard that buries crops, spreads toxic chemicals, and destroys moving parts in machinery is known as volcanic ash fallout. This fine, glassy material can be carried over long distances by the wind and can cause a range of problems when it settles on the ground. It is not only harmful to agriculture but also to human health, as inhaling ash particles can be detrimental to the respiratory system.