Which statement about gypsum is correct when soil management?

Which statement about gypsum is correct when soil management?

• A. Gypsum can improve soil structure and supply calcium without raising soil pH.
• B. Gypsum raises pH more than lime.
• C. Gypsum lowers calcium levels.
• D. Gypsum directly increases microbial diversity without affecting structure.

Answer: (D)

Gypsum works by supplying calcium (and sulfate) and helping exchangeable calcium replace sodium on soil clays. That calcium helps separate clay particles, which flocculates the soil and improves structure and water infiltration. Importantly, this happens without a significant change in soil pH, because gypsum does not add carbonate or otherwise alkalinize the soil—unlike lime, which raises pH.

The idea that gypsum directly increases microbial diversity without affecting soil structure isn’t supported, because gypsum’s primary and direct action is on soil structure and calcium supply. Microbial diversity can change indirectly as conditions improve, but gypsum doesn’t directly boost diversity.

Similarly, gypsum does not raise pH more than lime, and it does not lower calcium levels; it adds calcium. So the best, most accurate statement is that gypsum can improve soil structure and supply calcium without raising soil pH.