Calcium Needs of Peanuts
Peanuts do require good nutrition to obtain high yields and quality. However, fertilization needs of peanuts are less than many crops that are commonly grown in Florida. Rotating peanuts with cotton or corn often leaves enough residual phosphorous (P)and potassium (K) in the soil for a peanut crop. Calcium (Ca) needs are especially high for peanuts and the fruit develops from nutrients absorbed directly from the soil rather than from nutrients transported from roots to shoots and back to the fruit which is the case for most crops.
Calcium deficiency results in high incidences of pod rot and unfilled pods called “pops”. This results in low yields, low grades, and poor germination. Relatively high concentrations of Ca are needed in soil solution, and critical Ca absorption period begins about 20 days after the entrance of the peg into the soil and for 6-8 weeks thereafter.
Since peanuts are often grown on sandy soils, which are drought prone, there is a limited ability of these soils to replenish soil solution Ca. Heavier soils and irrigated soils are better able to supply the needed Ca for proper uptake. The Ca needs are primarily for pod and seed development and not for growing a healthy plant. Test soils and apply the needed amounts of Ca for good yields and quality. Calcium is much more important for non-irrigated peanuts than for irrigated peanuts. 2013 was a perfect year for peanut production since a high amount of rainfall occurred in both July and August, resulting in Ca moving to the pods of peanuts with some of the highest non-irrigated grades ever.
Calcium is routinely applied as gypsum at pegging on sandy soils for rapid replenishment of soil solution Ca. Test the top three inches , or the “pegging zone” of the soil, and apply needed amounts of Ca for good yields and quality. Soil test levels of about 450 lb/A of Ca result in maximum yields of runner type peanuts, while levels almost double this are necessary for maximum yield of Virginia type peanuts. Gypsum is often applied to peanuts at pegging time so that peanuts will have an adequate Ca supply. Rates of 250 lb/A of dry gypsum in a band, and up to to 1000 lb/A of wet gypsum are often applied to peanuts, when soil tests have indicated a deficiency, or on peanuts that are to be saved for seed.
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