Making the most of Calcium (Ca) as a soil plant nutrient.

Making the most of Calcium (Ca) as a soil plant nutrient.


Calcium is a secondary nutrient and is taken up by the plant as Ca2? it is the fifth most abundant element in the Earth’s crust and is a vital nutrient for optimal plant and animal growth. In spite of this, it is often overlooked and undervalued by both agriculturalist and farmers alike. A number of health and growth problems, such as blossom-end rot, in intensive crop production can be attributed to Ca-deficiency.


Functions of Ca

  • Necessary for cell wall development and strength.
  • Hot dry weather is not beneficial for Ca-absorption.
  • Low levels of Ca in the leaf make the plant susceptible to foliar damage from heat stress.
  • Ca is important for the active transport of K for the regulation of stomatal openings.
  • Low Ca-levels in leaf means poor control of the stomata even with high K levels.
  • Low soil levels of Ca will lose yield and quality, their production costs will increase, and profitability will decrease.
  • Soil-Ca improves soil structure and porosity, improves air and moisture movement, enhance soil biology and promotes root growth within the soil.
  • Not only does Ca strengthen plants’ cell walls and bind cells together, it is important for cell division and elongation.
  • Plants also need Ca to assist with their uptake and translocation of other important nutrients, and
  • Ca helps plants to release stress and increase their tolerance to pests and diseases.
  • Finally, Ca helps increase the shelf-life of fresh produce.


Increasing Soil-Ca levels

There are four common sources of Ca that can be used to be applied to soil to improve soil pH and Ca-levels

  • Lime - calcitic and dolomitic
  • Hydrated lime
  • Gypsum
  • Ca-Salts e.g., Calcium Nitrate and Calcium Chloride


While lime is good for reducing soil acidity, supplementary soluble Ca is often required to meet the immediate crop and soil Ca requirements that is largely immediately insoluble. Gypsum is good for treating sodic soils and sub-soil acidity. It is more soluble than lime, but it is still relatively insoluble. Should a soil or crop require immediate Ca-availability, it may be best to apply the necessary quantities as a soluble Ca source.


The Table below illustrates the solubility of different lime and calcium sources

Consult with a trusted Kynoch Agriculturalist expert before deciding on which Ca salt is needed. This is because the nitrates and chlorides in these Ca salts may actually be undesirable and detrimental to either the soil or crop quality if not applied appropriately.

Source:

Reference: Fertilizer Handbook, 2007. FSSA; Bornman, JJ

Compiled by:

Hugh Smith, 0824411312

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