As used in this chapter, unless the context otherwise requires:
1. “Book”, “list”, “record”, or “schedule” kept by a county auditor, assessor, treasurer, recorder, sheriff, or other county officer means the county system as defined in section 445.1.
2. “Commissioner” means the county weed commissioner or the commissioner’s deputy within each county.
3. “Department” means the department of agriculture and land stewardship.