Agriculture was until recently considered an archaic branch, and therefore some people believe there is nothing complicated in this occupation. In fact, without the necessary body of knowledge it is hard to succeed. Of course, the first and main thing is understanding what the soil or the plant itself needs, and only then choosing the necessary fertilizers. Given the wide variety of fertilizers on the market, this is quite a difficult task.

The aim of this article is to explain in accessible form the basics of correct use of the range of substances used in mineral nutrition and present on the Ukrainian market.

Macroelements are chemical elements that the plant takes up from various sources to build yield mass on an area of 1 ha (10,000 m2) in amounts measured in tens and hundreds of kilograms. They include: carbon, hydrogen, oxygen (our influence on their supply in field conditions is very slight). Nitrogen, phosphorus, potassium are first-order macroelements, with which comfortable nutrition conditions can be provided through a fertilization system. Calcium, magnesium, sulfur are second-order macroelements, whose supply can also be regulated by fertilization.

Microelements are chemical elements whose uptake by a crop ranges from a few kilograms to a few tens of grams. They include: boron, iron, manganese, copper, molybdenum, zinc. This group also includes silicon, cobalt and selenium. The effectiveness of these compounds as nutrients and as a means of obtaining food and animal feed that are «healthy» in chemical composition may show in districts where their content in soils is insufficient. For example, a few decades ago, thanks to a state programme, Finland got rid of the spread of a severe disease that developed in people in areas where selenium was deficient. As crop production intensifies with rising yield levels, plant need for them grows. Sources of input into the soil are: organic fertilizers, low-concentration potassium fertilizers as admixtures in other fertilizers, mainly phosphorus ones, and special fertilizers. Recently the problem of supplying plants with the necessary microelements has been successfully solved with foliar feeding using special fertilizers. The market has a large number of such fertilizers from domestic and foreign manufacturers. This variety makes choosing quite problematic without detailed familiarization, even for professionals.

Let us try to build certain evaluation parameters that can guide the choice:

  • By physical state, fertilizers can be liquids, powders, granules and also microgranules for application at sowing or planting. More important is knowing in the form of which compounds the nutrients are present.
  • If they are salts dissolved in water, the uptake of such compounds is low, and interaction is possible even with the water poured into the sprayer, not to mention other components such as fungicides or insecticides. Possible negative consequences are reduced effectiveness of accompanying substances in the sprayer tank mix and even plant burns.
  • Organo-mineral compounds have a higher availability, but the disadvantages are the same as for the previous group.
  • Chelates, unlike salt solutions and organo-mineral compounds, have the highest indicators of stability and nutrient uptake. For this class of compounds it is important to understand the degree (completeness) of chelation or the presence of other classes of compounds. Their effectiveness in use depends on exactly this.

  • An important quality indicator is the content of nutrients calculated in g/l.

    In addition, it is important to know in the form of which compound phosphorus is present in the fertilizer. The speed and amount of uptake, and hence the effect, depend on this. Phosphorus in the form of phosphate is «slow» in uptake. Phosphorus in the form of phosphite is «fast» in uptake with a number of advantages: it can be taken up at 5–6 degrees of warmth, which removes signs of phosphorus shortage, activates root system growth, shows fungicidal properties against a wide spectrum of plant disease agents and is tolerant to other tank mix components.

    A separate group is compositions containing biologically active substances of various nature.

    Compositions containing amino acids.

    It is scientifically proven that amino acids, like solutions containing nutrients, can penetrate through leaves and be absorbed. Amino acids are derivatives of carboxylic acids in whose hydrocarbon radical one or several hydrogen atoms are replaced by an amino group.

Depending on the nature of the hydrocarbon radical, aliphatic and aromatic amino acids are distinguished. The aliphatic series amino acids that are part of proteins are the most important. The role of amino acids in plant feeding is many-sided. In particular, their use lets plants overcome stress quickly and promotes better flowering and pollination. Amino acids show the phenomenon of optical isomerism. Whether it is an L or D isomer determines whether plants can absorb them. L isomers are absorbed easily and quickly and thus show an anti-stress action. To absorb D isomers plants must spend extra energy.

Polysaccharides are a source of quickly available energy and a component for the synthesis of other compounds.

Phytohormones are chemical substances produced in plants that regulate their growth and development. They form mainly in actively growing tissues at root and stem tips. Agronomically important groups of phytohormones include auxins, gibberellins and cytokinins, ethylene and abscisic acid. The first three groups are currently widely used in compositions for treating seed before sowing, roots before planting, and feeding growing plants.

Products with phytohormones from the Gros line show extremely high effectiveness: GROS Rootgrowth for pre-sowing seed treatment and foliar feeding in the early growth and development stages, GROS Health for foliar feeding to strengthen growth energy, and GROS Quicelium for foliar feeding in the budding to start of flowering period to form more fruit set and grains per ear or pod and improve the quality indicators of the harvest.

In our opinion, using the criteria named above will be useful for consumers when choosing special fertilizers.