Calcium Products: A healthy Life For an Old Star!

摘要

CALCIUM, THE FORGOTTEN NUTRIENT? Certainly not anymore. The market for calcium products has been tremendously increasing on a number of soils and crops and in particular on fruit and vegetables. Does one know of many places in the world where growersengaged in intensive High Tech cropping techniques can live without applying some calcium? These are the reasons why the market primarily develops in intensive and protected cropping systems through foliar spray and fertigation products whereas it started long ago as a pure field fertilizer. The fear of visual symptoms on the leaves or the fruit (although the symptoms of calcium deficiency are not always as clear as those observed for many of the other cations), and the clear evidence of a plant stresshave so to say won the battle against the soil and the roots sufferings! Still, those who would think that spraying calcium on the plant solves the whole problem, make a mistake: because of the plant's inability to move calcium in the phloem to new growth points and meristem tissues, foliar applications are for sure a valuable complement to soil supplied calcium but in order to keep roots strong, there must be available calcium in the soil solution. And this is not a given! The amount of calcium in soils varies a lot, depending on soil origin and cultural practices. At times, the amount of available calci-um in the soil solution can be very low, even if the total calcium content is very high. The reason is very simple: calcium is often found in the soil as a component of salts having very low solubility (e.g. calcium Sulphate and calcium carbonate). Thisexplains why crops may suffer from calcium deficiency even in calcareous soils.