Calcium in crops: application under extreme conditions

The role of calcium

Why is calcium such an important and indispensable element? Calcium plays a major role as a building block for cell walls and membranes, thereby contributing to crop firmness. In addition, it is an essential element for cell division and the growth of young tissues, while also promoting the quality development of storage organs such as fruits and tubers.

Calcium deficiencies in crops

The nutrient calcium is known for its immobile nature, meaning it cannot easily be redistributed within the plant once it has been fixed. Calcium absorbed by the roots is transported through the active sap flow to all other parts of the crop. Young root tips are best able to absorb calcium because their cell membranes are still highly permeable. In older, more corky roots, the cell membranes become far less permeable, making calcium uptake significantly less effective.

When the sap flow is disrupted, poor calcium distribution within the crop quickly becomes an issue. The greatest risks arise during hot and dry weather, when the plant maximizes transpiration to cool itself. Calcium deficiencies are therefore first noticed in the poorly transpiring extremities of crops, such as leaf tips and edges, flowers, as well as fruits and tubers.

When sap flow is impaired, calcium concentrations in these tissues decrease, causing cell walls and membranes to weaken, cell fluids to leak, and tissues to eventually die off (necrosis — yellow/brown discoloration). Well-known physiological disorders resulting from this are often referred to as tip burn, internal rust spot, cork spot, and blossom-end rot.

Optimal calcium fertilization

Calcium uptake during the season mainly depends on the calcium reserves in the soil, soil pH, root condition, and climatic factors. Soil analyses show that plant-available calcium levels in the Netherlands are structurally declining. Particularly in arable farming, open-field vegetables, and fruit cultivation, this can lead to quality damage in harvested products.

To further stimulate calcium uptake early in the season, it is important to start with a strong foundation. When necessary, liming can be carried out to improve soil pH and structure. Good calcium availability helps prevent soil crusting and compaction. In soils with a relatively high pH, calcium (Ca²⁺) is generally more available and experiences less competition from the cations potassium (K⁺) and magnesium (Mg²⁺).

It is also important during the establishment phase of the crop to focus on keeping young roots active, as these root tips are highly effective at absorbing calcium. Root is a special combination of nutrients, various biostimulants, and other components designed to stimulate root growth.

Under unfavorable growing conditions, such as drought and heat, or when plant or soil analyses indicate deficiencies, it is essential to take timely and targeted action. Due to the immobility of calcium, the fertilizer should preferably be applied directly where the deficiency occurs. Foliar fertilization with Optima Leaf-Ca and/or Optima Vigor+ can therefore be applied to above-ground plant parts. The best timing is during leaf development and/or during the setting of flowers, fruits, bulbs, and cabbages. These rapidly growing and poorly transpiring tissues are especially susceptible to calcium deficiencies.

Recommendations

Optima Leaf-Ca provides organically complexed calcium combined with a balanced amount of supporting nutrition to improve calcium uptake. Apply at least 2 × 1.5 L/ha of Optima Leaf-Ca at intervals of 7–14 days. For a single corrective application, 3.0 L/ha may also be used.

More information? Click here: Optima Leaf-Ca

Optima Vigor+ contains a high concentration of calcium combined with manganese and organically complexed trace elements. Virtually all crops — and sugar beet in particular — benefit from additional calcium during the growth phase. Apply 3 × 5 L/ha at intervals of 7–14 days.

More information? Click here: Optima Vigor+