| Clue | Source | Date |
|---|---|---|
| Cultivation of blue soil (6) | Puzzler Cryptic | 01 Jun 2025 |
| Change of blue soil | ||
| Soil, make dirty (OF BLUE anagram) (6) | ||
| Defile | The Guardian Speedy | 27 Dec 2020 |
| Sully | Wall Street Journal | 27 Aug 2020 |
| Soil | LA Times Daily | 31 May 2020 |
| Soil | The Washington Post | 31 May 2020 |
| Muddy | Newsday | 09 Mar 2019 |
| Make dirty | LA Times Daily | 21 Jan 2018 |
| Make dirty | The Washington Post | 21 Jan 2018 |
| Make dirty | ||
| Pollute | The Telegraph Quick | 11 Feb 2017 |
| Pollute | New York Times | 03 Nov 2015 |
| Pollute | ||
| Pollute | ||
| Pollute | ||
| Pollute | ||
| Soil | ||
| Sully | ||
| Soil | ||
| Make dirty | ||
| Pollute | ||
| Sully | ||
| Cast aspersions on. | ||
| Sully. |