Are you confused by the numbers and the percentages (%) ?  Don’t be- as they are rather easy to read and it’s even easy to understand what they are trying to report.

First of all, it is hoped that the same person collected all of the samples for the current tests and all previous tests.  It is also hoped that any tests to be compared to previous ones have been taken at the same time of year.  The depth of the probe needs to be consistent as does the physical amount of the “plug” that’s pulled from the field and dropped in the sample bag.

Base Saturation testing measures the minerals with the smallest amount of soil measurable called a colloid.  The base minerals are attracted to this colloid by the strength of their positive attraction to the negative colloid.  These minerals - Calcium (Ca), Magnesium (Mg), sodium (Na) and Potassium (K) - attach to the colloid through this mutual positive/negative attraction.

A definable range indicates a balanced soil condition which means spaces for air and water between the colloids (due to positive and negative natural forces). Thus, an environment is present for the soil bacteria to thrive, break down minerals, and make space for the roots to establish (resulting in optimum crop performance).   When the limits of the ranges are exceeded it indicates a problem and the plants growing in that soil will grow at a less than normal rate because the soil microbiology will not provide the necessary minerals for the plants. As the soil colloids react to this unbalanced situation, normal air and water functions of the soil change and as the living organisms decrease their function, the plants suffer the consequences.

This loss of space for air and water is called many things, but is generally noted as COMPACTION.  Yes, permanent compaction is caused by the lack of mineral balance in the soil and is only temporarily compacted by mechanical abuse.  Compaction can be temporarily relieved by aeration or deep plowing or other methods, but it will fall back together again because of the original problem.  Only by adding the necessary mineral(s) can the farmer control his compaction problem.

Numerous soil labs across the USA and Canada use Base Saturation soil testing. The generally accepted ranges for the minerals are Calcium (Ca) 65-75%, Magnesium (Mg) 12-18%, Potassium (K) 3-5% and Sodium (Na) <3%.  Hydrogen (H) also shows up when there are open spots on the colloid to be filled with the base minerals and will always show up if the PH is below 7 (usually indicating a need for Calcium). 

In this type of testing, the % numbers for these minerals (generally listed as Calculated Cation Saturation) will always add up to 100.  To me, this has always meant that when using the number 100 to define the sum of 4 “things”, then whatever has the highest percentage must be the most important.  For example, Calcium reading 65 – 75% would be the most important mineral in the soil and Magnesium reading 12 – 18% would be next and so on.

As Calcium gets lower, the % of Magnesium rises and this combination starts to tighten up the soil and thus puts the squeeze on the air and water spaces.  This creates compaction and makes the soil “sticky” (a soil with excess Magnesium sticks to and builds up on wheels and shoes).  This partial plugging of the soil begins to shut down the normal leaching process which gets rid of excessive Sodium, Sulfur and P and K.  As the Sodium builds up, the plant will take in Sodium instead of Potassium causing internal cell development and health of the plant to be affected along with disease control.

Check the Calcium saturation % first and if it’s low, there’s a good chance that the Sodium % will be elevated.  If the Sodium % is higher than the K% then your plants are already in trouble.  The sodium most generally comes from the granular fertilizer being used.  Muriate of Potash contains 40% Chloride and when that breaks down it creates Sodium Chloride (salt) and even some Chlorine (used to kill bacteria in water). Most mineral fertilizers (naturally occurring and thus mined) contain some salt.  An open soil is terribly important to the normal function of growth and regrowth.

Sulfur is a necessary trace mineral and it is used to help balance the soil minerals and in excess, it will be leached away naturally. Gypsum contains both Calcium and Sulfur is the preferred material to combat high Magnesium soils.  Ammonium Sulfate fertilizer is common and has 24 % Sulfur.  Excess Sulfur on a soil test usually points to the compaction problem.  Sulfur is a necessary nutrient that comes from many sources and keeps building up when the soil is compacted and won’t leach. If you don’t believe any other numbers believe this one ! 

Calcium comes from limestone.  Limestone is commonly known as AgLime and usually comes in bulk and is spread at 1-3 tons per acre.  Pelletized limestone is more expensive, but takes less per acre and breaks down immediately.  Liquid lime is a possibility also.  Calcium is a catalyst for Nitrogen and excessive use of nitrogen is what lowers the Calcium in the soil over the years.  When adding Calcium back to your soil you may find that you can cut nitrogen input immediately. It has always been interesting to me that where Anhydrous Ammonia is used, the soils get harder over the years and farmers will complain that they have to keep gearing down their tractor to pull a plow the next year !  Burn up the calcium and the soil tightens up !

If Magnesium is low, additional Magnesium can be found as Mag Sulfate.  This product is also known as Epsom Salts.  It can be dissolved and applied with a sprayer and sometimes an immediate response is seen (a green-up).  Just don’t forget to build the soil by applying the Magnesium Sulfate as granular.  Mg is important for the process of photosynthesis.

The problem of the Sodium getting into the plant instead of the Potassium can be lessened by adding more Potassium while dealing otherwise with the Sodium problem.  It is generally apparent on most soil tests that as the soil gets tighter, mineral availability decreases. Thus, additional minerals are needed to compensate (specifically K). 

CEC is Cation Exchange Capacity which is a measurement of the tightness of the soil.  Or it can be looked at as a measure of the mineral holding capacity of the soil.  Numbers below 5 are usually PGA greens and numbers over 40 can be found on many sod farms.  Normal soils are around 15-20.  If a mineral is adequately available with a CEC of 15, it won’t have nearly that availability at a CEC of 35 !  The warehouse in the soil needs to have additional materials to draw from as the numbers go up.

PH indicates the RESULT of the soil situation based on the mineral levels. It is a trailing indicator and shouldn’t be looked at to define the soil being tested unless the Base Saturation figures have been explored and understood. I’ve found that soils with high sodium % can’t be trusted to give an accurate PH.  So start working with what you know to be accurate.

Lastly, it’s important to note that Magnesium starts compacting the soil as Calcium drops below the 65% Saturation level.  The resultant compaction then begins to slow down mineral availability as noted before.  It is also important to understand that as Magnesium drops below its Saturation level the resultant higher Calcium creates the same darn compaction !    

Calcium and Magnesium are the keys to effective and efficient soil function.  Granular amendments are necessary to rebalance or maintain correct mineral levels.  Liquid amendments (soil and microbial stimulants, adjuvants, moisture retention materials and detox materials among others) can be very effective and part of a long term or a short term special package.  Combined with a granular program the results can be terrific and cost effective.

BUT, it takes time. Get your soil tested using Base Saturation methodology and start learning this week.

Here are some labs I have worked with in the past: 

Midwest Labs
Omaha, Nebraska
402-334-7770

A & L Plains Lab
Lubbock, Texas
806-763-4278

A & L Memphis
Memphis, Tenn
901-527-2790