There are three main elements necessary for plant life: Phosphorus, Nitrogen and Potassium. However, these are not the only useful nutrients found in the garden soil. There are a host of others elements, necessary to a lesser extent but still important for crops. Among these there are sulfur, calcium and magnesium which are considered macroelements, due to their fundamental presence, and other no less important microelements, such as iron, zinc and manganese which are considered microelements.
Each microelement has its own role in the many processes that occur during the vital activity of plants, a deficiency or excess of one of these substances can create imbalances that manifest themselves with physiopathies.
The deficiencies of elements in the soil are not always due to their actual absence: often the cause lies in the excesses of other antagonistic microelements that hinder their absorption. The pH of the soil also plays an important role in facilitating or not the absorption of nutrients by the plant.
The role of fertilizers therefore does not end in the restoration of the famous macroelements: it is important to provide the soil and therefore the root system of the plant with a great wealth of substances to feed on. For simplicity, in this article we list all the useful elements among the microelements with the exception of the N P K triad, namely nitrogen, phosphorus and potassium, and we report the main elements of interest for the farmer.
Recognize the shortcomings and excesses
A first symptom that often occurs in case of imbalance in the presence of a microelement is the anomalous coloring of the leaves of the plant. Yellowing not due to dryness or redness of the leaves can be a sign of a deficient microelement. Even the drop of leaves and flowers or the arrest in growth may be due to a soil lacking some important substance.
Keep the soil of the garden rich
If you want to avoid running into problems due to the lack of a microelement, remember to keep the soil nourished with periodic organic fertilizations. Another fundamental agricultural practice that avoids excessive exploitation of soil resources is crop rotation, which, accompanied by appropriate associations, greatly helps the plant to always have all the resources it needs available. Since different plants consume different substances it is very important to cultivate our garden by doing the rotation of the types of vegetables, this allows you to make the most of the contribution that each family of plants can provide to the soil and triggers synergies instead of competitions.
Main microelements in the soil
Calcium (Ca). Many elements are important for the garden, the main one being the football (Ca), essential for the growth of horticultural plants. The amount of calcium available is correlated to the pH value of the soil, which can be measured with a litmus paper that detects the pH of the soil. Where the pH is particularly acidic, calcium can bind with phosphorus and become difficult to assimilate. Lack of calcium is manifested by yellowing of leaves, general weakness in the plant tissues and poor root development. The excess of calcium, on the other hand, occurs mainly with calcareous soil, therefore always related to the pH, and causes a lower availability of other microelements, which cause problems for the plant. In particular, acidophilic plants, such as berries, do not tolerate soils that are too rich in calcium.
Iron (Fe). Iron is important for plants, although the soil usually contains enough iron. The garden plants with the greatest need for iron are salads, peppers and tomatoes. The microelement is deficient when excesses of some other elements inhibit its availability, an effect that also occurs in soils with a high pH. Iron deficiency or ferric chlorosis is seen in a yellowing that starts from the leaf veins.
Magnesium (Mg). Magnesium deficiency in a soil is very rare and this element is found in practically all fertilizers. Therefore, although it is very important for plant life, the horticulturist usually has little concern for verifying any shortage of magnesium.
Sulfur (S). If there is a lack of sulfur, the plant slows down its growth, the young leaves remain small and turn yellow, even an excess of sulfur can be problematic because it causes difficulties in the absorption of other microelements. The need for sulfur is high especially for the cultivation of cabbages and brassicaceous plants in general. The characteristic smell given off by cooking cabbage is due precisely to the presence of sulfur in the vegetable.
Zinc (Zn). Zinc is rarely lacking, the deficiencies are rather due to absorption difficulties, which can be caused by basic soils or excesses of phosphorus.
Manganese (Mn). This element is better absorbed when the soil pH is low, which is why acid soils can cause excesses of manganese that are harmful to plants.
Copper (Cu). Another microelement almost always present, so copper deficiencies are rare. However, be careful that an excess can cause iron chlorosis, limiting the absorption of iron by the plant.
Chlorine (Cl) and Boron (B). Elements of which the soils are quite rich, the boron requirement of the plant is very low. For this reason, shortages almost never occur. The excesses are harmful, in particular you have to pay attention to chlorine if you irrigate frequently with tap water or if you cultivate a soil rich in salts.
Silicon (Si). Silicon is important for plants because it helps cells to be more resistant and less susceptible to pathogens. It is certainly not a rare microelement and generally occurs naturally in the soil, but it may be useful to provide a higher dose to prevent any cryptogams diseases. Horsetail decoction and fern macerate are herbal preparations useful for providing plants with silicon.
In addition to these elements there are the fundamental carbon (C), oxygen (O) and hydrogen (H) which, however, we can not consider due to the fact that they are practically always available in nature.