What’s the limiting factor?

Sometimes the “experts” get it wrong. Early in the 19th century, a school master declared a young man to be “hopelessly useless.” This pronouncement, coupled with a worrying interest in explosive fulminates, did not hint of the immense contribution he would make.

Justus von Liebig, circa 1850
from Wikipedia

Justus von Liebig (1803-1873) changed chemistry in Germany more significantly than any other chemist of his time and was responsible for the development of the teaching, research, and technology of modern chemistry. Forty-four Nobel laureates in Chemistry are scientific heirs of Liebig.

Liebig was one of the first chemists to organize a laboratory as we know it today. He improved organic and inorganic analysis of compounds. With Friedrich Wöhler, he developed a theory of radicals and made the first experimental discovery of isomerism. Liebig wrote books about agricultural and animal chemistry where there was a practical application of organic chemistry to animal and plant science.

Liebig’s Theory of Mineral Nutrients for Plants reformed agriculture during the mid 1800’s. This theory made the following major points:

• plants take minerals up through their roots from the soil
• soil is fertile only if nutrients removed by the plant are replaced
• each kind of plant species requires different nutrients
• one nutrient cannot substitute for another, which led to the “Law of the Minimum” 

The idea that plants take minerals up through their roots from the soil may not seem a great breakthrough, but we need to remember when this theory was formulated. Someday (hopefully soon!) the carbohydrate theory will be as readily accepted!

Liebig's Barrel
From here

Liebig’s “Law of the Minimum” in plant nutrition states that whichever nutrient is present in the least amount, relative to the requirement, will determine the yield of a plant. Liebeg used the image of a wooden barrel with staves of different lengths to illustrate this law. The effective volume (yield) of the barrel (crop) is determined by the shortest stave (limiting nutrient). Until that stave is increased, increasing the length of the other staves will, at best, be a poor investment. At worst, it may produce harmful effects (for example, nutrient toxicities).

Let’s apply this barrel analogy to a pasture-based livestock production system. I remember a visit to a pasture-based dairy farm in north western California. The farm’s pastures were subdivided into a number of smaller pastures, or paddocks. The farmer was concerned that the grass species he had planted were not persisting. He was renovating his pasture, by conventional tillage, on a five year rotation. “Perennial” pasture ought to last longer than five years!

As we walked across the paddocks, we saw that the grass-clover content increased from clover dominant (minimal grass) at the “head” of the paddock (where the animals are first turned in) to optimal in the middle, to grass dominant (with the grass too mature for dairy cow feed) at the far end of the paddock.

Each paddock had a single, fixed water source at the “head” of the paddock. These paddocks were managed, essentially, in a strip-grazing fashion. A portable fence would be set up ahead of the animals to give access to fresh feed. Each day the fence would be moved forward to provide a new grazing area. Each paddock would provide at least six days of grazing. Because of the fixed water supply, the animals could not be excluded from the previously grazed sections with a back fence and the animals would re-graze these sections. The grass at the head of the paddock was declining because it didn't have sufficient rest period after the initial grazing. The grass was dominant at the far end of the paddock because the cows preferred to remain closer to the water source and eat the higher quality herbage.

The majority of pasture Dry Matter (DM) yield is produced by the grass component. This farmer thought that his DM yield per acre (and therefore his milk fat production per acre) was limited either by the species (or varieties) of grasses he’d been planting, or by the fertility of soil in those pastures. He was prepared to pay a significant amount of money to address these conditions. In fact, the limiting factor was the lack of water in each grazing area. Given the costs of complete pasture renovation, the investment in improving the water supply system would produce the greatest economic return.

Now let’s apply Liebeg’s barrel analogy to human nutrition and health. The evidence indicates that the Standard American Diet (SAD) contains too much carbohydrate. Hyperinsulinemia (chronically elevated insulin) is a health problem for many. There are compelling, biologically plausible explanations for the more than 100 years of epidemiological observations strongly suggesting that highly refined carbohydrates are the most likely dietary cause of dyslipidemia, hypertension, heart disease, diabetes, obesity, cancer, Alzheimer’s disease, and other chronic diseases of civilization.

If a typical American, eating the SAD were to merely switch their meat sources to grass-finished ones, while the rest of their diet remained the same, how much health improvement could they expect? Probably not much, since the differences in meat due to feeding practices are NOT the limiting factors. These differences are real. They are quantifiable and they've been well documented. But they are not the short staves in this situation. Making an investment of money and effort here will not produce the best response.

Okay, how about if they were to switch to grass-finished meat AND only consume organic vegetables, grain products, sweeteners, and vegetable oils? Again, the evidence strongly suggests that they will NOT see the greatest “bang for their buck.” The short staves in thier diet are the grain products, sweeteners, and vegetable oils. Their elimination from the diet is more important than how they were produced. Organic "carbage" is still carbage!

It's hard to talk about this without being mis-understood. Nancy and I enjoy locally produced, grass-finished lamb (from Cattail Creek Lamb) and beef, and our pork comes from a local producer (Heritage Farms Northwest) who fatten their Red Wattle pigs on hazelnuts. Most of the vegatables we enjoy are locally produced and organic (and non-starchy!). We are making conscious decisions about supporting our local farmers. We are blessed to be able to afford to eat this way. And because we've eliminated grain products, sweetners and vegetable oils from our diet, we're more likely to realize the benefits from eating these wonderful foodstuffs. We've addressed the "short staves."