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The Albrecht Method: Just How Important Are Nutrient Ratios?

Author: Shane Bugeja, Local Extension Educator, Blue Earth and Le Sueur counties with edits and review from Natalie Hoidal & Carl Rosen

With the advent of soil and foliar testing, we can analyze dozens of specific nutrients and tailor applications of fertilizer to each field and crop. With this wealth of information, several philosophies about how best to feed the soil have emerged. These include the “sufficiency/feed the plant” and the “build and maintain” methods, where the amount of fertilizer is determined by maximum profit or lowest risk, respectively. However, one alternative approach deals with soil nutrient ratios rather than pounds per acre.

Intro to the Albrecht Method

Ratio-based fertility programs first emerged from potassium research in the 1930’s and 40’s in New Jersey. The agronomists there noticed that the highest quality alfalfa plants tended to have similar Ca/Mg/K ratios within their leaves and stem. They then extrapolated that an “ideal soil” must also have a corresponding ratio of these nutrients. Based on soil averages in New Jersey, the original ratio these researchers suggested was 13 parts calcium to 2 parts magnesium to 1 part potassium.

Later, this idea was championed by Dr. William Albrecht, an agronomy professor at the University of Missouri—hence the name “Albrecht Method.” Dr. Albrecht later connected these ideal nutrient amounts to animal and human health. He also tweaked the 13:2:1 ratio—providing narrow, “acceptable” ranges. The Albrecht Method has become popular in organic farming books and media, with certain publications and individuals citing Ca:Mg ratios as a key indicator of soil health.

However, the research from Dr. Albrecht and his colleagues lacked rigorous field experiments to back up their claims. Certain key measures of soil fertility, such as pH, were only briefly mentioned. In addition, no soils from the upper Midwest were examined by these scientists. This is important to note since the 13:2:1 ratio was largely driven by soil averages on the East Coast.

Image from “The Ideal Soil : A Handbook for the New Agriculture”
 by Micheal Astera and Agricola.

Issues with Ratio-Based Recommendations

Subsequent studies in the 1980’s by other land grant universities such as Wisconsin and Ohio State also sowed doubt about the Albrecht Method. These experiments noted that agronomic crops such as corn, soy, and alfalfa could tolerate a wide range of Ca/Mg/K ratios in the soil with no clear effects on yield.

More recently, Ohio State revisited the Albrecht Method in a multi-year study. Once again, results showed no significant yield benefits to manipulating Ca or Mg ratios. These consistent findings from multiple researchers across multiple states are a key reason why few Extension or University researchers support ratio-based nutrient recommendations.

In fact, aspects of the “ideal ratio” paper written in the 1930’s were based on even earlier papers from the 1900’s (and before). At that time in soil science, there was little known about what made nutrients available or unavailable to plants. These early agronomists emphasized total nutrient content in the soil, which we know today does not always mean high yields and fertility.

For instance, tomatoes can suffer from blossom end rot, a disorder caused by low calcium levels in the plant. However, this is frequently caused by water stress rather than any real calcium deficiency in the soil. Another example is iron chlorosis in soybean. The total amount of iron in the soil may be large, but due to chemical reactions with carbonates and salts, the iron is bound in an unavailable form.

Even if the ratio of a soil is corrected to an “ideal” level, the total amount of the nutrient is also key. Think about a sourdough bread recipe; you may have the right ratio of water, flour, and starter mixed in your bowl. But if you only make a thimble of dough after all the kneading, you would still be hungry after it is baked. This situation could also happen in a poor soil. Even after all the nutrients are balanced just right, if the total amount is too low for plants, it will still negatively affect yield.

Costs to Making a Soil Ideal

Another major drawback for “correcting” nutrient ratios is the cost to adjust a high fertility soil. Many Midwestern soils contain thousands of pounds of calcium per acre. Even slightly imperfect ratios (perhaps a 10:2:1 ratio instead of 13:2:1) could entail literally tons of additional calcium fertilizer per acre and more trips into the field to spread it.

A three-year, 11 farm Iowa State Extension study examined these added input costs in corn, soybean, and small grains. The study assumed a local source for lime and did not account for extra application costs. Even with these assumptions, the researchers found that the Albrecht Method cost an additional $9.27 per acre over a “sufficiency/feed the plant” method. Moreover, there was no statistically significant yield advantage found, despite the increased input costs demanded by the Albrecht Method.

Is There Value in Using the Albrecht Method?

As mentioned earlier, the biggest weakness of the research that supported the Albrecht Method was a lack of controlled field studies. Many of the observed benefits could possibly be explained by other processes in the soil:
  • Liming effects: if producers added calcium or magnesium in a carbonate form (i.e. lime) to achieve a “correct” ratio, soil pH will also be raised. This may explain increased yields, particularly in acid-sensitive legumes. Notably, pH was not accounted for in Dr. Albrecht’s early research.
  • Sulfur deficiency: when gypsum (CaSO4) or Epsom salts (MgSO4) are applied to adjust ratios, these minerals could add a significant amount of available sulfur, an important plant nutrient that can be limiting in sandy or low organic matter areas.
  • Removal of excess sodium: gypsum is also commonly applied to soils high in sodium, also known as sodic soils. These sodic soils tend to have very poor soil structure due to the chemical interactions between sodium and clay. Calcium in gypsum can bind with sodium and can be leached out with water, improving soil structure and drainage. Read more about sodic soils here.
  • Mg or K deficiency: some soils in Minnesota can have limiting amounts of these nutrients. Typically, these areas are in very sandy environments and/or ones with acidic soils (pH below 5.5). Thus, any addition of these nutrients could potentially help crop growth, depending on its form and amount.

A Kernel of Truth

Some of the early papers supporting the Albrecht Method worried about K inhibiting Ca and Mg plant uptake. It is true that certain nutrients can cause “antagonistic effects,” where excessive amounts of one nutrient can interfere with the uptake of others. Indeed, Minnesota potato growers must make sure K fertilizer is not applied at extreme rates to avoid Mg deficiencies. Since many potato growing regions are in sandy areas with little binding capacity for nutrients, there could be real competition between K and Mg for these sites in the soil. However, in irrigated potato, the applied water typically contains plenty of Mg to avoid this “antagonistic effect.”

Regardless, keeping a close eye on pH and making sure Mg, Ca, and K are non-limiting via soil and/or tissue testing can avoid these issues directly rather than forcing ideal ratios. If you are curious about recommended levels of nutrients, UMN Extension can assist. There is information available for both horticultural as well as agronomic growers on its website.


The “sufficiency/feed the plant” or the “build and maintain” models have many years of dedicated research behind them. Ratio-based fertilization theories like the Albrecht Method provide scant proof that they offer any economic or soil health advantage to farmers. While the best alfalfa field in 1930s New Jersey had that 13:2:1 ratio, without a better designed study, other factors could have played a more important role. Modern soil science has consistently shown over the decades that farms with various ratios of Ca/Mg/K can still produce healthy crops and soil—provided none are lacking or fertilized to excess.

Works Cited and Additional Reading

Brock, C., Jackson-Smith, D., Kumarappan, S., & Brown, C. (2019). Farmer and Practitioner Conceptions and Experiences with Soil Balancing. OSU Technical Report. Available online:

Chaganti, V. N., & Culman, S. W. (2018). Historical perspective of soil balancing theory and identifying knowledge gaps: A review. Crops & Soils, 51(1), 40-47. Available online:

Eckert, D. J. (1987). Soil test interpretations: Basic cation saturation ratios and sufficiency levels. Soil testing: Sampling, correlation, calibration, and interpretation, 21, 53-64. Available online:

Exner, R. (2007). Soil Fertility Management Strategies - Philosophies, Crop Response and Costs. Iowa State University Extension. Available online:

Gaspar, A. P., & Laboski, C. A. (2016). Base saturation: What is it? Should I be concerned? Does it affect my fertility program? In Proc. 2016 Wis. Crop Manage. Conf (Vol. 5, pp. 55-61). Available online:

Kopittke, P. M., & Menzies, N. W. (2007). A review of the use of the basic cation saturation ratio and the “ideal” soil. Soil Science Society of America Journal, 71(2), 259-265. Available online:

Schulte, E. E., & Kelling, K. A. (1985). Soil Calcium to Magnesium Ratios--should You be Concerned? (Vol. 2986). University of Wisconsin--Extension. Available online:

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