What is the value of calcium?

K. K. Gedroiz, scientists with the Forestry Institute in Leningrad stated in 1931 in the Soil Science Journal “After the practically complete replacement from the soil of all exchangeable calcium, the plants required for their development the introduction into the soil of calcium fertilization, without which they would not grow at all.” The need for calcium in agriculture has been scientifically proven and soils are known to contain large amounts of calcium, however most of it is not soluble in the soil solution and is not readily available.

EcoGEM Rice Terrace pic

Rice terrace in China

Calcium is an abundant mineral in the earth’s crust and is widely distributed in all living organisms. As a cation it plays a unique role in soil and is important to plant growth. Calcium has three functions in the soil that are critical to soil health and crop productivity.

Structure: Soil structure is the spatial arrangement or aggregation of soil particles forming pore space. Aggregation mainly depends on the soil composition and texture, but is also influenced by factors such as biological activity, climate, and chemical processes.

In soil, the calcium (Ca2+ cation) ion flocculates clay and organic matter particles, which improves soil structure and porosity. Good soil porosity insures adequate aeration which also provides good infiltration and drainage and promotes better root growth.

Flocculation is caused by cations in the soil solution. Calcium and magnesium (in calcareous soils) or iron and aluminum (in acid soils) flocculate soil particles into the formation of stable soil aggregates. In contrast, the monovalent cation sodium disperses these aggregates.

Biology: Soil biological activity is critical to soil health and soil productivity and benefits from calcium. The biology of the soil is aerobic by nature and responds very favorably to the porosity of the soil complex, which is provided by the flocculation of the exchange complex by the calcium cation. Also, soil biology requires calcium in soil to supply the functions.

Also, biological decomposition or organic matter creates cementing agents that enhances soil aggregation. In the formation of aggregates, biological agents are involved, as plants (roots), animals (earthworms, arthropods, etc.), microorganisms (bacteria and, especially, fungi) are important.

Nutrient: All agricultural plants require calcium for growth and is it a major secondary nutrient along with magnesium and sulfur. Research has shown that animals consuming plants with calcium deficiencies will encounter growth problems that result in production losses. Calcium is also an important nutrient for soil organisms.

How are the calcium levels in your soils? Have you noticed any calcium deficiencies in your plants or crops? And how about the health of your soil, maybe it is showing calcium deficiency signs?