Calcium for crop quality
It has long been understood that many physiological disorders are associated with poor calcium. Apples can suffer from bitter pit and internal brownspot. Cabbages get internal tipburn. Carrots get cavity spot. Celery has blackheart. Potatoes get hollowheart and poor skin. Peppers and tomatoes fall victim to blossom-end rot. All these crops store poorly when calcium is deficient.
When it comes to crop diseases, many organisms that infect plants do so by penetrating the cell tissue with enzymes known as pectinase, which dissolve pectins. The higher the calcium content in plants, the higher the concentration of pectins holding cells together and the greater the ability to withstand these enzymes. Therefore the crop becomes more resistant to diseases.
The dreadful consequences of calcium deficiency make it all the more important that its widely understand how plants get their calcium and what from.
The difference available calcium in soil makes
Calcium is as important to the soil beneath plants as it is to growth above it. In soil, calcium helps maintain chemical balance, reduces soil salinity, decreases soil crusting and improves water penetration.
Farmers often apply calcium-containing soil amendments, such as lime or gypsum, to their land. However, we should not confuse the benefits of such soil amendments containing calcium, with the need for available calcium for plant uptake. Many believe incorrectly that application of mineral amendments to soils will do two jobs in one: enhance the soil and sufficiently supply the calcium requirement of crops. That is not the case.
The truth is that calcium-containing soil amendments and calcium fertilizers have different roles. They can complement each other but cannot do each other’s work.
Polysulphate: the perfect calcium source
Yes, Polysulphate perfectly provides available calcium to crops. Here’s just a little biochemistry to explain what makes it so perfect.
Plants take up Ca as the Ca
2+ cation. In Polysulphate, calcium is present as calcium sulphate (CaSO
4), which dissolves in the soil solution as SO
42- anion and Ca
2+ cation, just as plants like it from the tropics to the temperate regions and everywhere in between.
Polysulphate is a great calcium source for tropical, acidic soils where Ca deficiency is often found. In addition, Ca supply through Polysulphate can alleviate aluminum and manganese toxicity symptoms which are common in those regions.
In sandy soils where calcium can be easily leached by rain or irrigation water, there can be a Ca shortage which Polysulphate can easily correct.
Because, as explained above, calcium does not relocate in the plant, it is very important that it is available throughout the growing season. Our
solubility laboratory experiments show that Polysulphate releases calcium steadily, thus providing prolonged calcium availability through the crop cycle: perfect.
Of course, in Polysulphate calcium sits as one of four powerful and key nutrients (Ca, K, Mg and S). Perhaps we should turn the spotlight on one of the others in a future edition of the Missive?