"Peanut Response to Interactions of Soil pH and Gypsum"

Soil pH and supplemental calcium applied as gypsum can affect peanut yield. The interaction of soil pH and gypsum applied at flowering is not clearly defined in the peer-reviewed literature. Research was conducted in North Carolina in the USA to determine peanut yield when grown in soil with pH values of 4.5, 5.2, 5.6, and 6.0 when no gypsum or gypsum at 340 and 680 kg/ha was applied at the flowering stage of peanut. Peanut yield increased as soil pH increased in absence of gypsum. Applying gypsum at both rates increased peanut yield when soil pH was 4.5 or 6.0 compared with the no-gypsum control. However, at a soil pH of 5.2 gypsum did not increase yield. At a soil pH of 5.6 gypsum did not affect yield when applied at 340 kg/ha; gypsum at 680 kg/ha decreased yield. Results from these experiments demonstrate that peanut response to gypsum can be dependent on soil pH and that soil pH should be considered when deciding when to apply gypsum to supplement native calcium in soil.