Report reading is an important skill when using soil tests

Without skill in report reading, a soil test can be just a confusing jumble of numbers. One of the most important advantages with tests from SWEP Laboratories is that they help you by organizing the information into sections according to how you will go about improving the soil:

1. Tests for soil structure and friability
2. Tests for plant health and nutrition
3. Tests for soil biological activity

1. Soil structure

The results in this section include the levels of the five major soil cations - Calcium, Magnesium, Sodium, Potassium and Hydrogen - together with their desirable levels and their respective percentages of the Adjusted CEC. For effective report reading it is essential to understand Cation Exchange and its adjustment according to the organic matter percentage.

In this section, effective report reading also includes developing an appreciation of the importance of measures like the Exchangeable Sodium Percentage (ESP) and the Calcium Magnesium ratio.

These measures are used in assessing the likely problems that may arise from a particular set of cation percentages. We refer to this as the soil cation balance.

For additional information to assist report reading about cation balancing:

The actions of Lime, Dolomite and Gypsum
These materials are not fertilizers. In fact they need to be used well ahead of any planned fertilizer application.

Follow these 5 steps to reliably improve your soil.
This is a simple strategy that applies the principles of the Mikhail System to improve any soil.

2. Balanced Plant Nutrition

In this section, report reading includes all the essential plant nutrients, which are dealt with according to the amounts required by plants generally:

1. Major nutrients
• Nitrogen (N)
• Phosphorus (P)
• Potassium (K)
• Sulphur (S)
2. Available cations
• Calcium (Ca)
• Magnesium (Mg)
• Sodium (Na)
3. Trace elements
• Copper (Cu)
• Zinc (Zn)
• Iron (Fe)
• Manganese (Mn)
• Cobalt (Co)
• Molybdenum (Mo)
• Boron (B)

You will see that the available cation results are given in parts per million (ppm), while the exchangeable cations are in milli-equivalents per 100g of soil (me/100g). This is not a mistake, they really are different. The available cations include both exchangeable and soluble forms and are given in ppm to assist their conversion to fertilizers (if required).

Also, Potassium actually fits into two sections - Major Nutrients and Available cations, but it is generally included as a Major nutrient due to the amounts needed by most plants.

For additional information to help with report reading in this section:

Convert nutrients into fertilizer
Only a percentage of any fertilizer is made up of actual nutrient elements. This is how you can work out how much to apply and how to compare different fertilizers.

Is organic fertilizer the best?
What is the best sort of fertilizer to use and why?

3. Soil Biology

This is only a recent inclusion as research has only recently shown how biology can be effectively integrated with the other soil components. For this reason, biology is covered on a page of its own.

There is also good information now available on effective use of bio-active materials like kelp, humic acid and fish emulsion.

Further Reading:

There is also a lot of good information available on the SWEP Laboratories website, including:

Understanding the recommendations on a SWEP soil test.

Tips on applying soil improvement treatments