Justus von Liebig (1803-1873) is generally credited with being the “Father of the Fertilizer Industry.” Although other scientists contributed discoveries of equal importance, von Liebig built on their work and formulated “The Mineral Theory” which states:

“The crops on a field diminish or increase in exact proportion to the diminution or increase of the mineral substance conveyed to it in manure.” (Manure in this sense is anything applied to the soil to serve as plant nutrient.)

Liebig stressed the value of mineral elements derived from the soil in plant nutrition and the necessity of replacing them to maintain soil fertility. He recognized the value of nitrogen, but believed that plants could get the element from the air. He envisioned a fertilizer industry with nutrients such as phosphate, lime, magnesia and potash prepared in chemical factories. He recommended treatment of bones with sulfuric acid to render the phosphate more readily available.

Liebig also propounded the “Law of the Minimum,” which states that if one of the nutritive elements is deficient or lacking, plant growth will be poor even when all other elements are abundant. If the deficient element is supplied, growth will be increased up to the point where the supply of that element is no longer the limiting factor. Increasing the supply beyond this point is not helpful, as some other element would then be in minimum supply and becomes the limiting factor.

A concept of the “law of the minimum” is still being used in nutrient management and crop production today. It has been modified as additional elements have proved to be essential in plant nutrition and has been extended to include other factors such as moisture, temperature, insect control, weed control, light, plant population and genetic capacities of plant varieties. In fact, modern advances of agriculture have consisted mainly of identifying successive limiting factors and correcting them. Thus, attainment of optimum yields involves a complex mix of nutrients in combination with other inputs.