N u t r i - Fa c t s Agronomic fact sheets on crop nutrients
Calcium
No. 5
North American Edition Table 1. Calcium uptake in the harvested portion of various crops2.
Crop Yield level Ca uptake, lb
C alcium (Ca) nutrition plays a vital role in the production of high-
quality crops. It also has an important function as a valuable
soil amendment in many situations.
Alfalfa
Bermudagrass
8 tons
8 tons
175
52
Calcium in Plants Corn 200 bu 49
Calcium is classified as a “secondary nutrient” that is needed Cotton 1,000 lb lint 14
in relatively large amounts by plants in the form of Ca2+. In Grain Sorghum 140 bu 60
some species, the requirement for Ca is greater than for the
macronutrient phosphorus (P). The critical Ca concentration in Oranges 540 cwt 80
plants varies widely, ranging from about 0.2% in grasses, 1.0 to Peanuts 4,000 lb 20
1.25% in fruit crop foliage, to 2.0% in cotton leaves1. The amount Rice 7,000 lb 20
of Ca taken up by various crops is listed in Table 1.
Soybean 60 bu 26
Calcium plays a key role in cell wall structure and membrane
integrity. In addition to plant stability, strong cell walls help Tomato 40 tons 30
prevent invasion by numerous fungi and bacteria. Calcium also Wheat 60 bu 16
promotes proper plant cell elongation, participates in enzymatic
and hormonal processes, and plays a role in the uptake processes
of other nutrients. Calcium has an important influence on soil properties, especially
as it prevents dispersion of clay. An abundant supply of Ca can
help reduce soil crusting and compaction, leading to improved
Calcium in Soils
water percolation, and reduced runoff.
The total amount of Ca in soils normally ranges from 0.7 to 1.5%
in non-calcareous, temperate soils. Highly weathered tropical soils Fertilizing with Calcium
typically have a lower Ca content, ranging from 0.1 to 0.3%, while
calcareous soils may contain as much as 25% Ca. Although there Calcium is not typically formulated into fertilizer sources
may be tens of thousands of pounds of total Ca/A in the root zone, specifically to meet plant Ca requirements, but rather as a
it is common to have less than 100 lb of Ca actually soluble at component of other materials. The most common Ca sources are
any one time. The solubility of Ca depends on several soil factors, liming materials, mainly CaCO3. Most acidic soils that have been
including: limed to the proper pH will not have Ca nutritional problems.
Calcium is often supplied as gypsum as an amendment to
• Soil pH – soils with higher pH typically contain more available
improve soil chemical or physical properties.
Ca on cation exchange sites
Clays can disperse in soils with high sodium (Na) content,
• Cation exchange capacity (CEC) – available Ca is affected by
resulting in poor soil structure and reduced water permeability.
both the soil cation exchange capacity and the Ca saturation on
Added Ca replaces the Na+ on the cation exchange sites and
the soil cation exchange sites
corrects clay dispersion problems. Calcium is a component of
• Presence of other soil cations – Ca is preferentially adsorbed several common nitrogen (N) and P fertilizer materials (Table 2).
on cation exchange sites. Its solubility and plant availability are
influenced by other cations in the soil.
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This Nutri-Fact is one of a series of fact sheets written by scientific staff of the International Plant Nutrition Institute (IPNI) that is focused on essential plant
nutrients and their use. This series is available as PDF files at www.ipni.net/nutrifacts.
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Blossom end rot in tomato and peppers can Bitter pit develops in apple Tip burn in romaine lettuce Stunted development of the
develop when inadequate calcium moves with fruit when supplied with is associated with inadequate growing point of corn is caused by
transpiration stream to the end of the fruit. inadequate calcium. calcium uptake. calcium deficiency.
Table 2. Common calcium fertilizer sources. leaves and fruit (Table 3), or as a result of improving the
physical condition of the soil (Figure 1). Local recommendations
Source Ca content, %
should be obtained before adopting techniques to boost the Ca
Calcitic limestone (CaCO3) 32 concentrations in plant leaves and fruits that may be lacking an
22 adequate supply.
Gypsum (CaSO4 · 2H2O)
Triple superphosphate (Ca(H2PO4)2 · H2O) 15 Table 3. Increase in apple fruit Ca concentration from foliar or soil
applied treatments compared with untreated control apples.3
Calcium nitrate (Ca(NO3)2) 19
Treatment Increase in fruit calcium
Calcium ammonium nitrate solution 8 concentration, ppm
Chelated calcium (various formulations) 2 to 5 8 foliar sprays (22 lb Ca/A) 45
Calcium chloride (CaCl2) 36 5 foliar sprays (12 lb Ca/A) 25
Calcium thiosulfate (CaS2O3) 6 2 foliar sprays (5 lb Ca/A) 10
Gypsum on soil (440 lb Ca/A) 12
Calcium fertilizers are most often applied directly to the soil, but All foliar sprays were made with CaCl2 diluted to 300 gal/A. Apples with
foliar applications are also common for fruits and vegetables. low Ca concentrations can be susceptible to cork spot and bitter pit,
Foliar applications are made during the growing season to resulting in nonmarketable fruit.
correct deficiencies and improve crop quality. Soluble Ca
fertilizers are sometimes applied through the irrigation system
Calcium Deficiency Symptoms
Calcium deficiencies are not common in most crops, but may occur
in acidic soils. Deficiencies occur with some horticultural crops
where Ca is not adequately supplied to developing plant cells due
to restricted uptake or movement within the plant. Calcium is not
moved from older plant tissue or redistributed, so young tissues
rely on the continual supply of Ca in the transpiration stream.
Since transpiration is low in young leaves, in fruit, and in enclosed
tissues, various Ca-related disorders can occur.
Deficiencies of Ca typically occur:
1. In young expanding leaves (such as tip burn in lettuce)
Figure 1. Calcium sulfate (gypsum) can improve soil physical
2. In enclosed tissues (such as black heart in celery) properties by enhancing water infiltration and percolation
3. In plant tissues fed primarily by phloem (such as blossom-end in some soils.4
rot in tomato, pepper, water melon; bitter pit in apples; empty
pod in peanuts)
Other symptoms associated with Ca deficiency may include:
1. Abnormal development of growing points (terminal buds) References
2. Abnormally dark green foliage 1. Plank, C.O., and D.E. Kissel. 2013. Plant Analysis Handbook for Georgia.
3. Premature shedding of blossoms and buds http://aesl.ces.uga.edu/publications/plant/default.asp. (verified Apr
2015).
4. Weakened stems
2. IPNI. 2006. Soil Fertility Manual. International Plant Nutrition Institute.
Norcross, GA.
Crop Response to Added Calcium
3. Autio, W.R., and W.J. Bramlage. 2001. Univ. Massachusetts Extension
As with all essential nutrients, when soluble Ca concentrations Factsheet F-119R.
fall below a critical level, crops are likely to respond favorably 4. Chen, L. and W.A. Dick. 2011. Ohio State Univ. Bull 945.
to fertilizer application. Calcium uptake occurs primarily at the
root tip, so conditions that damage root health will also impair Ca
uptake.Since most soils have Ca present, favorable crop responses
Further Reading
de Freitas, S.T., and E.J. Mitcham. 2012. Hortic. Rev. 40:107-146.
are generally due to enhancing the Ca supply to developing
Ref. #5 15040
