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Agrochemistry

The contribution of Lawes, Sachs, and Knop to the development of agrochemistry

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The contribution of Lawes, Sachs, and Knop to the development of agrochemistry

Modern plant nutrition schemes are based on classical field experiments of the XIX century. Research by French scientists was confirmed by the work of an English colleague (1814–1900), who founded the oldest agricultural experiment station. The data he accumulated proved that nitrogen fertilizers are highly effective, and that atmospheric nitrogen on its own cannot provide normal crop nutrition.

In parallel, the experiments proved the key importance of phosphorus for yield. The results of these long-term trials formed the basis for the industrial production of mineral fertilizers. Thanks to long-term experiments, the experiment station itself turned into a major scientific and methodological center for agrochemistry.

Period of experiment Practical research results
1836–1838 Vegetation experiments proved the important role of phosphorus in plant life
1840–1841 Field experiments confirmed the high effectiveness of phosphorus fertilizers
1842 The first superphosphate production plant was opened
1843 The world's longest-running experiment on nitrogen application rates on continuous wheat was established
1859 Cereal crops were successfully grown for the first time in an artificial environment until full seed maturation

How the water culture method helped determine fertilizer composition

After the first discoveries in the field of mineral nutrition, researchers focused on the composition of fertilizers. To understand exactly which elements and in what quantities plants need, they began growing them in artificial conditions — water and sand. Two German scientists (1832–1897 and 1817–1891) independently developed the water culture method.

The essence of the method was to grow crops in distilled water with the addition of soluble salts. This helped to precisely determine which elements from the soil and ash are vital for plants, and which they can do without. Based on these experiments, researchers identified a group of essential nutrients.

  • Potassium (K)
  • Calcium (Ca)
  • Magnesium (Mg)
  • Nitrogen (N)
  • Phosphorus (P)
  • Sulfur (S)
  • Iron (Fe) — in a very small amount

Elements like silicon, sodium, and chlorine were initially considered unnecessary, as water cultures yielded good results without them. Later, when salt purification technologies improved, scientists revised these conclusions and made significant adjustments to the list of essential nutrients.

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