Over geologic time spans, water passing through soil leaches or
removes plant nutrients. In climates where there is barely enough
rain to grow cereal crops, soils retain their minerals and the food
produced there tends to be highly nutritious. In verdant, rainy
climates the soil is leached of plant nutrients and the food grown
there is much less nutritious. That's why the great healthy herds of
animals were found on scrubby, semi-arid grasslands like the
American prairies; in comparison, lush forests carry far lower
quantities of animal biomass.
Some plant nutrients are much more easily leached out than others.
The first valuable mineral to go is calcium. Semi-arid soils usually
still retain large quantities of calcium. The nutrient most
resistant to leaching is potassium. Leached out forest soils usually
still retain relatively large amounts of potassium. William Albrecht
observed this data and connected with it a number of fairly obvious
and vital changes in plant nutritional qualities that are caused by
these differences in soil fertility. However obvious they may be,
Albrecht's work was not considered politically correct by his peers
or the interest groups that supported agricultural research during
the mid-twentieth century and his contributions have been largely
ignored. Worse, his ideas did not quite fit with the ideological
preconceptions of J.l. Rodale, so organic gardeners and farmers are
also ignorant of Albrecht's wisdom.
Albrecht would probably have approved of the following chart that
expresses the essential qualities of dryland and humid soils.