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WEATHER, PEANUTS AND CALCIUM

By: John Doyle Atkins, Santa Rosa County Ag Agent

Calcium is needed for high quality peanuts and that makes calcium management one of the more critical aspects of peanut production. Soil moisture plays a critical role in absorption of calcium.  Failure to supply adequate soluble calcium in the pegging zone during pegging and pod fill results in “pops,” poor pod fill, low seed germination and higher incidence of aflatoxin.

Calcium taken up by the roots is transported upward through the plant by the “xylem,” but little if any is transported downward through the “phloem.” Once the peanut begins to peg, and since calcium is transported upward through the xylem and not carried downward by the phloem, the downward developing fruit must absorb its needed calcium directly from the soil-water solution around it.

This is also one reason why it is so critical to maintain soil moisture during the pod-fill period 60 to 90 days after planting. Here in Santa Rosa County, for the most part, our acreage is not irrigated, so we cast up a prayer when moisture is needed. There must be enough water in the soil for the calcium to go into solution and move into the developing pod. Calcium deficiencies have been observed when a water soluble form of calcium was applied under extremely dry conditions. However, it has also been shown that application of gypsum to the pegging zone improved calcium uptake by the pod in dry years and caused a significant increased in yield and grade.

                                                                                      Peanut Pegs and Developing Fruit

Calcium is “passively” absorbed by the developing peanut fruit. In other words, the amount absorbed depends on the concentration of water soluble calcium in the soil solution and the amount of water absorbed by the plant. Very little calcium is absorbed by the peanut foliage and essentially none is translocated from the foliage to other parts of the plant, including the developing fruit.

For the most part the period for timely application to the pegging zone of a water soluble calcium source such as gypsum has passed. The application of a foliar calcium source would be a waste of time and money. The peanut plant just does not work that way.

Permanent link to this article: http://santarosa.ifas.ufl.edu/blog/2012/07/18/weather-peanuts-and-calcium/