Plant Nutrient Dryland Prairie Soil Humid Forest Soil
nitrogen high low
phosphorus high low
potassium high moderately high
calcium very high low
pH neutral acid
Dryland soils contain far higher levels of all minerals than leached
soils. But Albrecht speculated that the key difference between these
soils is the _ratio _of calcium to potassium. In dryland soils there
is much more calcium in the soil than there is potassium while in
wetter soils there is as much or more potassium than calcium. To
test his theory he grew some soybeans in pots. One pot had soil with
a high amount of calcium relative to the amount of potassium,
imitating dryland prairie soil. The other pot had just as much
calcium but had more potassium, giving it a ratio similar to a high
quality farm soil in the eastern United States. Both soils grew
good-looking samples of soybean plants, but when they were analyzed
for nutritional content they proved to be quite different.
Soil Yield Calories Protein Calcium Phosphorus Potassium
Humid 17.8 gm High 13% 0.27% 0.14% 2.15%
Dryland 14.7 gm Medium 17% 0.74% 0.25% 1.01%
The potassium-fortified soil gave a 25 percent higher bulk yield but
the soybeans contained 25 percent less protein. The consumer of
those plants would have to burn off approximately 30 percent more
carbohydrates to obtain the same amount of vital amino acids
essential to all bodily functions. Wet-soil plants also contain only
one-third as much calcium, an essential nutrient, whose lack over
several generations causes gradual reduction of skeletal size and
dental deterioration. They also contain only half as much
phosphorus, another essential nutrient. Their oversupply of
potassium is not needed; humans eating balanced diets usually
excrete large quantities of unnecessary potassium in their urine.
Albrecht then analyzed dozens of samples of vegetation that came
from both dryland soils and humid soils and noticed differences in
them similar to the soybeans grown under controlled conditions. The
next chart, showing the average composition of plant vegetation from
the two different regions, is taken directly from Albrecht's
research. The figures are averages of large numbers of plant
samples, including many different food crops from each climate.