The average soils in our region test moderately-to strongly acid; are low in nitrogen, phosphorus, calcium, and magnesium; quite adequate in potassium; and have 3-4 percent organic matter. Mr. Organic's soil test showed an organic matter content of 15 to 20 percent with more than adequate nitrogen and a pH of 7.2. However there was virtually no phosphorus, calcium or magnesium and four times the amount of potassium that any farm agent would ever recommend. On the bottom of the test, always written in red ink, underlined, with three exclamation points, "No more wood ashes for five years!!!" Because so many people in the Maritime northwest heat with firewood, the soil tester had mistakenly assumed that the soil became alkaline and developed such a potassium imbalance from heavy applications of wood ashes.
This puzzled gardener couldn't grasp two things about his soil test report. One, he did not use wood ashes and had no wood stove and two, although he had been "building up his soil for six or seven years," the garden did not grow as well as he had imagined it would. Perhaps you see why this questioner was always a man. Mr. Organic owned a pickup and loved to haul organic matter and to make and spread compost. His soil was full of worms and had a remarkably high humus level but still did not grow great crops.
It was actually worse than he understood. Plants uptake as much potassium as there is available in the soil, and concentrate that potassium in their top growth. So when vegetation is hauled in and composted or when animal manure is imported, large quantities of potassium come along with them. As will be explained shortly, vegetation from forested regions like western Oregon is even more potassium-rich and contains less of other vital nutrients than vegetation from other areas. By covering his soil several inches thick with manure and compost every year he had totally saturated the earth with potassium. Its cation exchange capacity or in non-technical language, the soil's ability to hold other nutrients had been overwhelmed with potassium and all phosphorus, calcium, magnesium, and other nutrients had largely been washed away by rain. It was even worse than that! The nutritional quality of the vegetables grown on that superhumusy soil was very, very low and would have been far higher had he used tiny amounts of compost and, horror of all horrors, chemical fertilizer.
Climate and the Nutritional Quality of Food
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.
