By Clint Thompson
A potential gypsum shortage this year could impact the peanut farmer’s ability to apply calcium to their crop. University of Georgia Cooperative Extension soils and hydrology specialist Glen Harris encourages producers to sample their soil after the peanut plant emerges. This is done to see if the peanuts need gypsum at all.
“We have a test where they can sample the top three inches of soil after the peanuts come up to tell where they need it or not. If you can’t get a lot of gypsum, lets put it in fields that we know really need it,” Harris said. “Problem is this year there might not be enough to go around to everybody. That makes you think that if we have a tight supply, lets put it where we need it.”
Lack of calcium in the pegging zone to be absorbed through the hull can result in “pops” or no kernels which reduces yield. Calcium deficiency on peanut can also lead to pod rot. Calcium is critical to germination for peanuts saved for seed the following year.
Why the Shortage?
Harris said the shortage stems from the fact that a lot of the coal burning powerplants that produce a lot of the “smokestack” gypsum that is used on peanuts shut down production of gypsum. There are multiple theories as to why they shut down.
“Almost last minute to when we really needed the gypsum this year, some of those plants shut down the production of gypsum. Depending on who you talk to, it was either due to something with the coronavirus or natural gas prices were cheaper than coal,” Harris said. “At one point, everybody thought we weren’t going to get any gypsum at all. That didn’t turn out to be true. We think it’s just going to be a tight supply.”
When Should Gypsum Be Applied?
There is a fairly narrow window as to when gypsum should be applied. Gypsum applications should be made at “early bloom” or approximately 30 to 45 days after planting. However, “peak pod fill” is around 60 to 90 days after planting. Producers can still see benefit from gypsum applications made any time before 60 days after planting.
Harris said there are some alternatives to gypsum that can be used but are not as good a gypsum, specifically calcium chloride through the pivot or with lime. But lime needs to be applied before planting since the calcium in lime is not as soluble as the calcium in gypsum. Also, if you deep turn, you need to deep turn before applying lime, so you do not bury it. So, placement is important as well.