Which statement about compacted-soil indicator weeds is true?

• A. Only prostrate knotweed indicates compacted soil.
• B. Geesegrass indicates compacted soil but broadleaf plantain does not.
• C. Prostrate knotweed, goosegrass, and broadleaf plantain are indicators of compacted soil.
• D. None indicate compacted soil.

Answer: (C)

Indicator weeds reveal soil conditions. When soil is compacted, pore space for air and water is reduced, roots have a harder time growing, and certain hardy weeds take advantage of the stressed environment. Prostrate knotweed, goosegrass, and broadleaf plantain are classic examples of weeds that commonly appear in compacted soils, so finding all of them together is a strong signal that the soil is compacted. This is why the statement that these three indicate compacted soil is the true one. If you see these weeds, it’s a good cue to check soil structure (e.g., via a soil probe or infiltration test) and consider remediation like aeration or amendments to improve soil conditions.