Getting your soil right part 1: Cation Exchange Capacity and base saturation

I’ve already mentioned a few times that to produce healthy fruit, vegetables, cereals, animals and ultimately humans, soil need to be “balanced”. And by “balanced” I don’t mean any esoteric term. I mean that minerals and plant nutrients need to be in the soil in certain quantity and they need to be balanced with each other.

I don’t know will you believe me, but the knowledge how to grow high quality food was known for at least 50 years. The person who is responsible for finding “the recipe” for the perfect soil is William A. Albrecht (Ph.D.). The guy was a genius. In his time he was a very respected scientist. The best “endorsement” I can give you is the fact, that Weston A. Price in his famous book “Nutrition and Physical Degeneration” dedicated a whole chapter for Albrecht’s famous speech – “Food is fabricated soil fertility”.

Unfortunately because Albrecht’s message was somehow contradicting both: owner of the main media outlet for “healthy grown food” – J.I. Rodale and “mainstream” agriculture advice (that was more and more controlled by agriculture companies, that had no business in farmers growing healthy, nutrient dense food, they business was in selling farmers artificial fertilizers that will increase plants yields and in pesticides that will later protect sickly plants) his legacy was almost forgotten.

Wheat protein content linked to soil fertility

Decline of the quality of food started some time ago. Please notice general lower protein content of the wheat grown in the east part of Kansas and how much protein content of wheat had declined in only 9 years. Scan from “Albrecht’s Papers”.

Please notice how annual precipitation influence the protein content of wheat…

Base Saturation

This great soil scientist over the years of experiments have found out that most plants grow the best and produce the highest quality cereal, fruit, vegetables and animal fodder if particular nutrients are in certain balance. According to Albrecht the soil should be saturated with “cations” or “bases” (hence “base saturation”) in a particular way to produce highest quality food. If the soil is not in balance the plants will not grow so well. By “not grow so well” I don’t mean that the plants will not produce high yields, but I mean the plants’ mineral content will not be as high as it could be and the plants will not produce as much protein (and of as good amino acids profile) as they could produce. The main “bases” we are talking about are:

  • Calcium (Ca2+)
  • Magnesium (Mg2+)
  • Potassium (K+)
  • Sodium (Na+)

The base saturation Wiliam Albrecht recommended is:
calcium 60-75% magnesium 10-20, potassium 2-5%, sodium 0.5-5.0%, and other cations (copper, zinc, manganese, iron, boron, tin, nickel and other positively charge trace elements) 5%. There’s also 10% left for hydrogen – acid cation that is not a plant nutrient, though it is beneficial to have it in the soil. What’s interesting to notice, is that this ratio will guarantee, that pH of your soil will be around 6,5. This is ideal pH for most plants (blueberries, cranberries, carnivores plants, rhododendrons etc. not included). Also most macronutrients, micronutrients and trace elements needed for plants are most available at this pH. It’s a sort of sweet spot for most plants…

 

pH nutrients availability

Soil ph nutrients availability chart

Cation Exchange Capacity

We know that we need certain base saturation of positively charged nutrients in the soil. But what is the thing that we are saturating them with? It’s Cation Exchange Capacity (CEC).

C. E.C. (or just CEC) is a value that tells us the soils ability to hold onto and provide nutrients. Usually sandy soils have very low CEC, between 1 (pure sand, without organic matter) and 9–10 (sandy soil with high organic matter content). Clay soils usually starts from 10, and they can go up to around 50, although most often they are between 10–25.Organic matter has relatively high CEC: 100-400. The CEC is being measure in milliequivalent of Hydrogen per 100 g of dry soil(meq+/100g), or the (newer) SI unit centi-mol per kg (cmol+/kg). Soil that has CEC of 1 can hold 1 meq+ of Hydrogen or 1meq of Calcium or 1meq+ of Magnesium or 1 meq+ of Sodium or 1meq+ of Potassium. In weight that will be (per 100 grams of soil of CEC 1):

20 mg of Calcium Ca++ (atomic weight 40)

12 mg of Magnesium Mg++ (atomic weight 24)

39 mg of Potassium K+ (atomic weight 39)

23 mg of Sodium Na+ (atomic weight 23)
Per Acre, to a depth of 6” to 7” (that’s the plough layer – the most important part in growing crops), 1 meq or ME:

20 lb Hydrogen H+

400 lb Calcium Ca++

240 lb Magnesium Mg++

780 lb Potassium K+

460 lb Sodium Na+

Per 1000 square feet, 6” to 7” depth (that’s the plough layer – the most important part in growing crops), 1 meq or ME=

O.46 lb of Hydrogen H+

9.2 lb of Calcium Ca++

5.5 lb or Magnesium Mg++

17.9 lb of Potassium K+

10.6 lb of Sodium Na+
Per Hectare, to a depth of 15cm to 17cm (that’s the plough layer – the most important part in growing crops), 1 meq or ME=

20 kg of Hydrogen H+

400 kg of Calcium Ca++

240 kg of Magnesium Mg++

780 kg of Potassium K+

460 kg of Sodium Na+

To convert hectares to 100 square meters move the decimal point 2 places to the left: 400
kg/ha = 4.0 kg/ 100m

How much calcium, magnesium, potassium and sodium should be in soil with CEC 1?

According to Albrecht, the ideal base saturation is:

  • 65% of calcium
  • 15% o magnesium
  • 4% of potassium
  • 2% of sodium

Your 1 CEC soil should have per hectare:

  • 135kg of Calcium
  • 18 kg of Magnesium
  • 15,5 kg of Potassium
  • 5kg of Sodium

or

  • 135 lbs of Calcium
  • 18 lbs of Magnesium
  • 15,5 lbs of Potassium
  • 5 bs of Sodium

per acre

If CEC of your soil is 14 your just need to multiply above numbers by 14, if CEC of your soil is 8 you multiply them by 8…

if you want to find out more, make sure to check out The Ideal Soil: A Handbook for the New Agriculture by Michael Astera.

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