Calcium

An essential major plant nutrient, which is represented by the chemical symbol Ca. It typically forms the third highest percentage of any plant nutrient (excluding carbon, hydrogen and oxygen) within a turfgrass leaf, with a typical dry matter mid-range concentration being around 1%.

There is usually an adequate amount of calcium within most soils, although very acidic soils make calcium relatively unavailable to a plant. Calcium is a major constituent of cell walls, in particular the middle lamella, and is involved with regulation of solute concentration in cells (osmoregulation), cell division, root hair extension and seed germination. It can be thought of as the physical skeleton of plant structure.

Fertilisers which include superphosphate as a component part will rarely need additional supplementary calcium applied because of the relatively high amounts of calcium within the chemical make-up of superphosphates.

Calcium deficiency can appear as necrosis of the ends or tips of leaves and roots (tip ‘die-back’), with chlorosis of the leaves (first appearing on younger leaves), stunted growth and a shortened brownish root system. High amounts of calcium within a soil can also reduce the availability of magnesium to a plant leading to a deficiency of that nutrient within a plant. Deficiency will initially appear in young leaves as a dark red colour to leaf margins.

Calcium is often considered a mineral nutrient which should be applied to sand profile pitches due to potential leaching and limited cation exchange capacity within such rootzones. However, even though sand is often considered inert it may actually contain a considerable quantity of nutrients. For example, Baker has reported results from a 1987 study of the nutrient content of sands used in turfculture in the UK which gave a range of values for calcium as from 23.2–100+ mg per litre, stating that of these sands 100% satisfied published requirements for plant growth. (Source: Baker, S.W. (1990) ‘Sands for Sports Turf Construction and Maintenance’, STRI, p.19)