Question for David Hardy from Jordan:
David, just want to verify by soil calcium calculation to get pounds per acre calcium:
If CEC is 5.9 and %Ca is 50%, then calcium in pounds per acre is: 5.9 x 0.50 x 400 = 1,180.
This should be correct?
I have adjusted my gypsum recommendations to reflect soil calcium, logistics and expense of gypsum, and data that demonstrates that rates lower than what we call a 1x rate often perform as well as the 1x rate (although not all the time but much of it.) The relationship of soil calcium and peanut yield for Virginia market types is variable compared with a more consistent response of runner market types.
Regardless of soil calcium level, we recommend gypsum on all acres of Virginia market types. It’s just a matter of whether we use 1/2x, 3/4x, or 1x with a reasonable level of risk management. Just want to make sure my calculation is correct to accompany the recommendation. In the above case, the farmer can, in many fields, apply gypsum at 0.5x (based on product and rate listed in Table 3-10 in 2026 Peanut Information) and get the same response as the 1x rate. One caveat is the uniformity of the application. If 0.5x is not uniform, the grower could increase the rate toward the 1x rate until adequate uniformity is achieved.
Details on the ranges are in Peanut Notes No. 2 2026.
David Hardy:
David,
In Table 1.4.
CEC X %CA X 356.4 = Ca in lb. acre
https://www.ncagr.gov/orange-book-soil-fertility/
David
David H. Hardy, Ph.D., CCA
Director
Agronomic Division
NC Dept. of Agriculture & Consumer Services
4300 Reedy Creek Rd.
Raleigh NC, 27607
Desk- 919-664-1601
Cell – 919-610-5922