William Albrecht, arguably the father of the science of soil fertility, was a professor at the University of Missouri. During his working life he, and his students, performed painstaking experiments to find out just what constituted a fertile soil in terms of balanced mineral and organic matter content to grow healthy plants which, in turn, provided nutritious food for stock and people. He was a prolific communicator, publishing many scientific papers and also expressing the science in layman's language in articles for farming and health magazines. He was also a constant critic of the stupidity of the N-P-K system pedalled by the fertiliser companies, the land-grant universities and the US government and for good reason; his predictions are now painfully true for all to see around the world.
We aren't going to go into great detail here with an interpretation and justification of Albrecht's work, we shall just present some basic findings relevant to an on-farm fertility programme. We're going to use a soil laboratory test result sheet that uses his methods to explain the principles of the mineral analysis, click on this soil test link to open it up. If you're interested in a more in-depth study of Albrecht's work then we suggest you start by reading Eco-Farm and if you want to go into more detail after that, follow up with The Albrecht Papers.
The idea behind fertility management is to create a balanced system that contains the right nutrients in the correct proportions to support healthy plant and animal life. The nutrients are held on the soil colloid, a sort of gel-like state of matter that is a mixtue of clay and humus (the organic matter). The amount of nutrients that can be adsorbed by the colloid is governed by the Total Exchange Capacity (TEC) of the soil. We can conveniently divide the nutrients up into the major and minor elements — this is a very simple approach based entirely on the quantities required by a balanced soil, it has nothing whatever to do with their relative importance in a physiological sense.
The major elements comprise calcium, magnesium, potassium, sodium and hydrogen. The first four are all alkaline in solution, hydrogen creates acidity. Together they should ideally occupy roughly 99% of the available space on the soil colloid, their relative proportions govern the final soil pH and are shown on the accompanying pie chart.
The minor nutrients occupy the remaining space on the soil colloid and also exist in solution in the soil water. Many of them have an importance for plant growth and health that apparently far outweighs their miniscule presence in the earth. They often function as catalysts for biochemical reactions or processes; a catalyst acts to help a chemical reaction to proceed and then gets liberated on completion so it's available for use again. Laboratory investigations are also still finding out more and more about other trace elements that aren't shown on the pie chart below.
As you can see, the minor elements are all present at the parts per million (ppm) level.
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