An interlude seems to be indicated if we are to register all the points so subtly unveiled by William A. Albrecht. Students of Albrecht found, soon enough, that excessive calcium will cause magnesium, phosphate and minor element deficiency. This assuredly means vegetables without digestive calcium. In general, it means plants with imbalanced hormone and enzyme systems; ergo poor health, the magnet for bacterial, fungal and insect attack.
High magnesium and low calcium permit organic residue to decay into alcohol, a sterilant to bacteria. It may also prevent normal dry down and nutritional ripening of any growing crop. It may cement clay soil tightly together; thereby creating a crust that can easily exclude oxygen and water retention and proper insoak and capillary return during dry spells. It is no accident that such soils produce abundant weed crops. Lessons even Albrecht learned standing on the shoulders of giants have become current coin in the literature of eco-agriculture. Albrecht’s student papers figure, of course. So does a swayback shelf of books published since his death.
Because the folklore of “lime and lime some more” hangs on even in academic circles, Albrecht felt compelled to issue a clear and succinct explanation whenever he spoke and often as a constituent part of his papers.
If basic soil meant little or nothing, the principles of base exchange and cation exchange capacity meant everything, not only for calcium—the general subject of this volume—but also for magnesium, sodium, potassium, etc. The key word is milliequivalent, generally written as meq. It represents the amount of colloidal energy needed to absorb and make secure to the soil’s colloidal mass calculated amounts of positively charged cations or base metal elemental nutrients. Each of these nutrients has its own atomic weight. The old handbook Albrecht used for his post-professional correspondence course compared the different values of nutrient elements to the differences encountered in weighing out grain—corn, wheat, soybeans, alfalfa seed all having different weights per bushel, give or take from the average.
As the saying has it, comparing a bushel of shelled corn at 55 pounds compares to a bushel of barley at 48 pounds the way an apple compares to an orange.
One meq of base exchange capacity was Albrecht’s practical unit representing the colloidal energy needed to adsorb—note the spelling of the word—and hold 400 pounds of calcium to the top seven inches of an acre of soil.
Obviously, the base exchange capacity of soils varies. Pure sand has no meq reading. As clay, organic matter and a humus fraction settle in the sand, substructure picks up exchange capacity. That is why a sandy soil will exhibit only, say, an exchange capacity in the five or six range. A soil enriched with organic matter and talcum-fine clay can easily run up a 40 meq number. Assuming the absurdity that a soil exchange capacity be entirely satisfied with calcium, then a six meq soil would adsorb, hold and exchange 400 x 6, or 2,400 pounds of calcium. A soil with a 30 meq reading could adsorb, hold and exchange 400 x 30, or 12,000 pounds of calcium.
These different capacity levels pour ridicule on many liming recommendations. Using pH to compute liming applications with no reference to the base exchange expressed as milliequivalents for a four or five meq soil has been compared by Brookside Laboratories to using a five horsepower motor to run a sewing machine. This is the mandate for a soil audit, a computation of existing calcium in the soil, and an equally astute calculation of room for more, taking the necessity for other nutrients into consideration.
All of Albrecht’s papers must be read with this equation in mind.
–Charles Walters, Editor