• Calcium (Ca)
    2040.08
    Ca
  • Ionic form
    Calcium (Ca) ionic formula image
  • Anion/Cation
    Ca2+
  • Calcium (Ca) influance image
    Fruit
  • Calcium (Ca) origin image
    Origine: Sea
  • Calcium (Ca) mobility image
    8-10mm around the root

Calcium

(Ca)

Calcium serves as an important nutrient for crops and to neutralize soil acidity. Further, it serves as a flocculating agent, which influences the stability of the soil structure. In most soils it is not a limiting nutrient, nevertheless for some crops the relocation within the plant to their generative organs is difficult.
Ca
Plant
Plant
Soil
Soil
Crops
Crops
Origin
Origin
Keys
Keys
IMPORTANCE FOR PLANT LIFE
Calcium is essential for the construction of cell walls. It contributes to good fruit conservation in particular. Supply of calcium in the soil is seldom a problem, but rather the transport and availability of calcium to the areas of the plant where it is needed.
ABSORPTION MECHANISMS
Calcium is assimilated less easily than other major elements such as nitrogen and potassium. It migrates less easily to locations with high requirements, especially in storage organs.
INTERACTIONS, SPECIFICITY
Calcium in soils plays a major role in terms of acid-base status. By properly occupying the exchange sites of the clay-humic complex, calcium is the most important element in creating a favourable environment for the biological activity of soils (cellulolytic and nitrifying bacteria) and for the maintenance of a crumby and well-aerated physical structure.
Non-calcareous soils acidify naturally, which means that regular but not excessive liming is necessary. Typical losses range between 100 and 400kg of CaO per hectare per year. Conversely, calcareous soils always contain excess calcium, which is impossible to eliminate. It is therefore necessary to guard against possible blockages, probably even in trace elements.
CYCLE DIAGRAM

1. The recycling of nutrients contained in organic matter such as livestock effluent, crop residue and other organic by-products from human activities, are an important resource for fertilization.

2. Calcium is obtained from quarries in the form of calcium carbonate (limestone rock). Crushed or pulverised, it is a basic mineral fertilizer for agriculture. The rock may also be calcined in a lime kiln to produce quicklime that is also used in agriculture.

3. Calcium evolves in the soil between fixed, adsorbed and soluble forms.

4. The leaching of soluble calcium (deep entrainment by excess soil water) must be taken into account when establishing a nutrient balance.

5. Runoff and erosion (calcium bound to solid particles) from the plot also takes place.

6. Via the roots, crops only absorb calcium as Ca2+ dissolved in the soil solution.


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INDICATOR
Soil analysis measures exchangeable calcium from similar extraction methods. The interpretation is done by evaluating the analysed calcium with respect to the cation exchange capacity (CEC) of the soil. An optimum level in ionic form should at least occupy 68% of the CEC. This optimum stock is large in relation to the crop requirements.

Sensitivity table

Sensitivity meter:
  • nutrient very sensible icon

    Very

  • nutrient very fairly icon

    Fairly

  • nutrient very moderately icon

    Moderately

CaO
Tomato
Apple
Strawberry
Pear
Sugar Beet
Sunflower
Cabbage
Lettuce
Winter Rapeseed
Carrot
Cherries
Cucumber
Grape Vine
Spring Barley
Potatoes
Fiber Flax
Grain Maize
Silage Maize
Winter Barley
Winter Wheat

Sensibility table & Symptomes

Calcium deficiency in plants is rather rare; it mainly occurs in acidic soils low in calcium. It causes chlorosis on young leaves and fruits. In apples, for example, it causes bitter pit on fruits, which are bitter corky blemishes.

Excess & Needs

An excess of Ca is rare, but it does occur in calcareous soils. The alkaline pH reduces the availability of phosphorus and some micronutrients. Calcium also forms insoluble calcium phosphate, reducing the availability of phosphorus.

Most soils rich in calcium are ancient seabeds. Calcium carbonate is either burned to make quicklime or micronised sufficiently finely (<150μm) so that the Ca2+ ions are able to diffuse and saturate the clay-humic complex. Geologically it is often associated with magnesium. Calcium, as a component of lime, acts as a soil enhancer and is also a valuable nutrient as a component of mineral fertilizers (e.g.: NAC 27 N). 
SOIL CONTENT
The calcium content of the soil (EDTA extraction) is assessed in relation to the CEC value (>60% of the complex must be occupied by Ca2+). In general, a content between 2300 and 3300ppm is satisfactory. Below 1600ppm, it is very low. Above 5000 to 8000ppm means excess of calcium where its antagonism has to be managed.

TEXTURE
In loamy soils, calcium deficiency deteriorates the soil structure as well as the soil fertility.
pH
The pH of the soil (and its possible correction) is not directly influenced by calcium, but it is the most common changeable base for maintaining good soil fertility. The neutralizing value is often calculated as "CaO equivalents" and the CaO-amounts required in order to correct the pH increase when approximating the neutral phase as well as with the size of the clay-humic complex.
CLIMATE
Under humid conditions, calcium is less present in the soil solution than in a dry situation.