Secondary Nutrients
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Calcium is an essential part of plant cell wall. It strengthens the cell wall structure, improves stomata function and protects the plant against diseases. Calcium also participates in metabolic process of many other nutrients uptake. Moderate Calcium will guarantee fruit quality and crop yield.
Calcium deficiency is usually caused due to low soil pH, high nitrogen applications, high potassium levels or low transpiration rates. Since calcium mobility in plants is limited, calcium deficiency will appear in younger leaves (die back or burns) and in fruits (blossom end rot, bitter pit).
Therefore, it is necessary to have a constant supply of calcium for continued growth.
Calcium containing fertilizers
Calcium Products % CaO Application Calcium ammonium nitrate 25.6 
Calcium Boron (CAN+B) 25.6
Calcium nitrate 23
EDTA-Ca10 10
Amino Acid Chelated Ca 12
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Magnesium is an essential plant nutrient. It participates in photosynthesis and helps in producing chlorophyll, which makes leaves appear green. It's also the specific activator of many enzymes involved in the metabolism of carbohydrates, nitrogen, protein synthesis and the synthesis of fats.
Magnesium Deficiency always occurs in low pH soils, low temperatures, dry soil conditions and high levels of competing elements, such as potassium and calcium, reduce the availability of magnesium. The calcareous soils with a calcium/magnesium ratio exceeding 6:1 are in need of applying Magnesium containing fertilizers to guarantee high qualitative-quantitative crop production.
Magnesium containing fertilizers
Magnesium Products % MgO Application Magnesium nitrate 15.3
Magnesium sulphate anhydrous 33
Magnesium sulphate monohydrate 25
Magnesium sulphate heptahydrate 27
EDTA-Mg6 6.0
Amino Acid Chelated Mg 6
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Sulfur involved in the formation of chlorophyll. Most of the sulfur in soils is in organic matter, which is not available to plant. In order to become absorbable to plant, the sulfur must be converted to the sulfate form (SO42-) through breakdown of organic matter and mineralization process.
Sulfur Deficiency is more likely in sandy soil with low organic matter. However, even in high organic matter soils, when the conversation process is not rapid enough to meet the sulfur requirement of the crop. At that time, Sulfur containing fertilizers should be applied.
Sulfur containing fertilizers
Sulfur Products % S Application Ammonium sulphate crystal 24
Potassium sulphate 18
