Acres USA - Soil Science and Nutrient Dense Foods

Acres USA led me down the path of understanding the multi-causal decline in the nutrient levels of foods people consume over the past several decades, perhaps centuries.  With the post WWII focus on the big three soil nutrients, NPK, other soil nutrients were neglected, which is one of the primary causes in food nutrient level declines.  To think that something as complex as soil could be reduced to three elements is understandable as people generally try to simplify complex things.  Oft times, the simplification falls outside of reality to the point where serious problems arise as the result of too much simplification.

Acres USA's go to source for identifying the problem of declining soil fertility leading to declining nutrient density is William Albrecht, a soil scientist at the University of Missouri.  Being the book nerd that I am, I have on my shelves the entire Albrecht collection of books.  Albrecht took the novel approach of using a two stage controlled study protocol.  When assessing the impact of fertilizers on forage and feed crops, he not only measured the impact of the forage and feed crops themselves, but also also through animal feeding trials.  He consistently found that animals that were fed feeds from well-mineralized soils performed better, were healthier, and were more satiated.

There are a myriad of studies which show the decline in food nutrient levels over the course of the 20th century.  Protein levels and mineral levels have with relative consistency, declined across a broad range of plant food and carbohydrate levels have increased.  Obesity and diabetes anyone?  Scientific American has identified several studies and summarized these studies in sort of a mini meta-study.  One of my favorite examples in field corn, the type of corn from which corn meal is made.  Back in the early 1900's, field corn had an average protein level of 12-13%.  Today's field corn has an average protein content of 8-9%.  Among other factors, lower soil sulfur levels drives decreased protein content.  Since farmers get paid for the corn by the bushel, lower protein levels were of no real consequence to them, unless they were feeding their animals the corn that they grew.

Separately, Washington State University has published several peer reviewed articles on the nutrient content of organic vs. conventionally raised produce.  One article outlined the benefits of organic farming methods, particularly as it relates to nutrient density and lower levels of pesticide and herbicide residues.  This is not surprising since by default, organic fertilizers contain broad arrays of nutrients, unlike conventional NPK focused fertilizers.

Many of the more sophisticated conventional soil scientists recognize the importance of many micronutrients.  The note that Liebig's law of the minimum dictate that the soil nutrient that is in the least supply relative to need becomes a limiting factor in production.  For example, if phosphorous (P) is the lowest nutrient from a relative need, production will be limited by the availability of it.  See the diagram below.  Among the things that Albrecht brought to the table that furthered the discussion was ratios of nutrients.  For example, too much calcium or magnesium can cause a potassium deficiency as they prevent plants from absorbing adequate potassium.  So in addition to the law of the minimum, there are optimal nutrient ratios.  When mineralization levels are optimum and ratios are optimum, food nutrient density also becomes optimum.

Being able to manage and control soil nutrient levels and ratios has been one of my primary motivating forces in order to provide my family with the best food possible.  Since food is foundational to good health, ultimately, the idea of providing excellent food and the resulting healthy outcomes is rooted in soil science.