Secondary nutrients calcium

The secondary nutrients, Calcium (Ca), Magnesium (Mg), and Sulfur (S), should be supplied in the hydroponic ingredients in the proper percentages required by plants. Always be attentive to the use of each different formula as the nutrients are mixed... 

Macro Nutrients - the secondary nutrients calcium, magnesium, and sulfur... 

Nine plant nutrients are required in relatively large amounts and are referred to as major elements or macronutrients. Of these, carbon, hydrogen, and oxygen are obtained from the carbon dioxide in the atmosphere and water and therefore are not dealt with as nutrients by the fertilizer industry. These three plant nutrients make tqa 90%-95% of the dry matter of all plants. The other major elements are subdivided into primary nutrients (nitrogen, phosphorus, and potassium) and secondary nutrients (calcium, magneaum, and sulfur). The remaining seven plant nutriente are required in much smaller amounts and are known as micronutrients or minor elements. 

This calcium sulfate can be removed by filtration, but generally it is left in the slurry where it may be considered as a diluent that supplies two secondary nutrients-, calcium and sulfur. 

Plants need other nutrients as well-such as the secondary nutrients (calcium, magnesium, and sulfur) and the micronutrients (boron, chlorine, copper, iron, manganese, molybdenum, sodium, vanadium, and zinc)-but these are needed in smaller quantities and rarely need replenishment in soils. 

Secondary nutrients Elements required by plants in moderate amounts (calcium, magnesium, sulfur)... 

Secondary nutrients and micronutrients usually are expressed on an elemental basis althou calcium and magnesium sometimes are ejq ressed in the oxide form. However, several countries express all plant nutrients on an elemental basis. Plante actually use neither tile pure element nor the pure oxide form, so the difference is largely academic. Conveireion factors for those plant nutrients that may be expressed in the elemental or oxide form, depending on the country, are shown in Table 1.2. 

Calcium, Mg, and S are. called the secondary nutrients of the macronutrients because they are not as widd deficient as N, P, and K. They may also have been considered secondary in that they are often contained in materials that are applied to supply another nutrient or need. For instance, Ca and Mg are supplied in large amounts in dolomitic limestones that are applied to raise the pH of acidic soils. Similarly, S fertilizers are not usu-ally applied simply as S sources but are secondary to another nutrient, e.g., in P fertilizers such as single superphosphate, or in the N fertilizer ammonium sulfate. One should not be misled by the term secondary -deficiencies of Ca, Mg, or other nutrients can be as serious as more common deficiencies of N, P, K, or S. They can also very severely limit plant growth. 

Calcium, magnesium, and sulfur are designafi as secondary nutrients. Plants require these nutrients in fairiy... 

The International Fertilizer Development Center conducts an annual survey of NPK granulation plants in the United States. By 1995 the number of operating plants decreased to only 25, from about 200 in 1965. No estimate has been made of the number of NPK granulation plants worldwide, but aImost-all-of-these-plants,-pIus-all nitrophosphate plants, incorporate secondary nutrients, primarily calcium and/or sulfur, in their products as the preferred, least expensive raw materials. Magnesium is different and is usually incorporated as a special additive. 

In Table 11.1, the elements calcium, magnesium, and sulfur are shown under their usual designation as secondary nutrients. These elements are required by plants in moderate amounts, but in most agricultural situations are not found to be deficient in the soil. There are exceptions, however. Areas of sulfur deficiency are well recognized in Australia, some U.S. locations, and elsewhere. Correction usually is made by application of fertilizers that are naturally high in sulfur content, such as normal superphosphate and ammonium sulfate, or by special application of gypsum or elemental sulfur. A very considerable amount of sulfur enters many soils dissolved in rainwater. The origin of this sulfur... 

Different works show that the nutritional status of certain nutrients, such as boron (B), calcium (Ca), nitrogen (N), phosphorus (P) and iron (Fe) can trigger changes in phenolic metabolism. Of these nutrients, B is attributed with a clear and significant effect on the metabolism of these secondary compounds. As we shall discuss below, the relationship between B metabolism and phenolics is complex and depends largely on the sensitivity of the plant to B deficiency or toxicity. 

Lime deficiency is characteristic of most sphagnum and woody peats. As already stated, the pH of these peats commonly lies between 3.0 and 5.0, which is in a region too low for the growth of all but the most acid-tolerant plants. Cultivated crops prefer a pH between 5.0 and 7.0. There is some uncertainty as to whether a very low acidity inhibits directly, or whether poor growth results primarily from lack of the proper nutrients, especially calcium (lime). Undoubtedly, both pH and nutrient deficiencies are important, but pH as such seems to play a secondary role. More important is likely to be lack of... 

There are thirteen mineral nutrients that plants obtain from the soil, and these are divided into the categories of macronutrients and micronutrients. The primary macronutrients include nitrogen, phosphorus, and potassium. Plants require these primary macronutrients in relatively large quantities and deplete them from the soil more rapidly than others. The secondary macronutrients include calcium, magnesium, and sulfur. Micronutrients are required in smaller quantities than the macronutrients, and these include boron, copper, iron, chloride, molybdenum, manganese, and zinc. 

Dicalcium phosphate (anhydrous or sometimes as the dihydrate) has many uses. These include glass manufacture, plastics stabilisation, fertilisers and animal feeds. In addition, it is used as a dough additive, a nutrient and a dietary supplement. In pharmacy, it is used as a tablet diluent and dispersant calcium phosphates have other medical applications [32]. Other uses include paint and pigments and in toothpaste as a secondary abrasive. 

---