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Agrochemistry

Antoine Lavoisier's contribution to the development of modern agrochemical science

For students

4 min read

AGROCHEMISTRY A

From precise scales to the language of mineral nutrition

Every agronomist has to calculate dosage for fertilizer application, evaluate soil acidity and the balance of nutrients. The foundation of this work lies in the laws of precise chemistry, which began to take shape in the second half of the 18th century. The transition from alchemical theories to quantitative analysis made it possible to understand exactly how plants absorb nutrients from the environment.

The basis of this new approach was the use of precise weighing in the study of chemical transformations. Guided by the law of conservation of mass, scientists refuted the erroneous hypothesis of phlogiston — the "principle of inflammability" that was supposedly released during combustion. Experiments proved the complex composition of air and defined combustion as the process of substances combining with oxygen. Investigations also showed that water is a compound of hydrogen and oxygen, rather than a simple indivisible element.

For practical work, a new unified chemical nomenclature was required. Scientists replaced old classification principles dating back to the times of alchemy with a rational system. It was based on the rule that the names of complex bodies should be derived from the names of simple elements.

Old name Modern name Justification for renaming
Vital air Oxygen (oxygene) When burning in it, most substances turn into acids
Lime Oxides Compounds of metals with oxygen
Inflammable air Hydrogen (hydrogene) Forms water when reacting with oxygen
Suffocating air Nitrogen Does not support life, harms it
Vitriolic acid Sulfuric acid Obtained from sulfur
Phosphoric acid Phosphoric acid Obtained from phosphorus
Aerial acid Carbonic acid Obtained from coal (carbon)

Based on the concept of oxygen as a chemical element, scientists identified three classes of compounds: acids (compounds of oxygen with non-metals), bases (compounds of oxygen with metals), and salts (compounds of acids with bases). This system lies at the core of modern soil composition analysis.

Nutrient cycling and the aerial nutrition of plants

In 1789, the "Elementary Treatise on Chemistry" was published, where this discipline was defined as the science of the composition of substances and their analysis. Simple substances were defined as those that at that time could not be decomposed into simpler components. These included all metals, non-metals, as well as earths, radicals, and hypothetical weightless fluids — light and caloric — known at the end of the 18th century.

These works were of decisive importance for unraveling the essence of crop nutrition. In an unfinished manuscript, published only in 1860, the cycle of elements in nature was described in detail. It was discovered that plants draw the materials necessary for their life functions from the air, water, and the mineral kingdom of the soil. Livestock animals receive these elements through plant-based feed, while the processes of fermentation, decay, and combustion return them back to the soil and atmosphere.

  • Life period of the author of the new chemical system — 1743–1794.
  • Publication of the first textbook on the analysis of simple substances — 1789.
  • Publication of the work on plant mineral nutrition — 1860.
  • Assessment of the significance of the new chemical theory in literature — 1885.

Before these discoveries, researchers of gases could not correctly interpret their results, remaining adherents of the phlogiston theory. In fact, new data stood the entire chemical science on its feet, which previously had been standing on its head. Agronomists received scientific proof of the existence of aerial and mineral nutrition of plants. Understanding the cycle of organic and mineral substances allowed for the subsequent development of principles for rational fertilizer application.

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