Zeolite - A volcanic ash clay mineral, mined in rock form in the U.S.A. When groun and aplied to fields in a form similar to lime, it is claimed to have very strong ammonium ion holding powers which reduce the leaching of nitrates.

Zero Grazing - A grazing system in which grass (or other fodder) is cut daily and then taken to cattle kept in a yard or in a small exercise paddock near the buildings. The system obviates problems of poaching (particularly on heavy land), fouling, overeating and wastage due to selective grazing. More grass can be provided from a given area by the system then by grazing. Also called mechanical grazing or soilage.

Zinc - Plant food element which is absorbed as zinc (Zn²⁺) ion. It is considered essential in enzyme systems necessary for important reactions in the plant metabolism: of life activity of plants. Zinc helps in the formation of some growth hormones, considered helpful in the reproduction of certain plants.

Zinc Arsenate - Zn (AsO₂)₂' a compound used as a component of some insecticidal sprays.

Zinc Chloride - ZnCI2. A compound used as fungicide and wood preservative.

Zoonoses - A group of infectious disease transmissible from animals to man. The commonest include salmonellosis, leptospirosis, campylobacter infection and Q-fever.