Gypsum and K Peanut Notes No. 96 2019
Native levels of calcium in soil are often not adequate to supply the calcium needs of developing kernels and pods for Virginia market types and jumbo runners. Variation in response to gypsum is certainly common but in general yields are greater and in most cases market grades (sound mature kernels and extra large kernel fractions) increase following application of gypsum. A portion of the response comes from overcoming K and Mg that are in the pegging zone but even in absence of these elements, calcium needs to move into developing pegs in soil water. A higher concentration of calcium in soil helps with this process, especially in dry weather. Several weeks ago most of the state was very dry but now we have adequate soil moisture in many areas, and this will help move calcium into the pegging zone. Excessive rain can leach calcium below the pegging zone and a concern in some years is whether or not there is enough calcium late in the season. For more information of peanut response to gypsum and sources of gypsum that are available, see pages 27-29 in 2019 Peanut Information.