It's the Soil

Allen Hirst displays one of the tools he used to demonstrate
ways of learning about garden soil.                                       

Below, I'll first pass on a short summary of the education moment during the February meeting of the Reno County Extension Master Gardeners.  Allen Hirst, our oldest active member, and a veteran teacher, was the presenter and summary writer.

Summary

Allen presented a program entitled ITS (It's the Soil).  He first presented how you need to test the soil.  Then by following the process to separate the soil you can determine the type of soil that you have.  Then he presented the instruments and the importance of testing the soil for proper temperature, moisture, and pH.  These factors are essential for the best production from your soil.

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Here are further details that Allen referred to in his presentation.

Soil Separation

Any soil suitable for gardening will be a mixture of clay, sand, and silt.  During the meeting, Allen provided a handout that gave instructions for determining the exact percentages of each of these soil components in a soil sample. Depending on what the process reveals, soil from the sample can be further described as a medium loam soil or some other loam combination such as sandy loam, silty loam, or clay loam.  Medium loam is usually considered ideal, but many other kinds of soil will work well for gardening, if the gardener uses appropriate compensations for less-than-ideal soil composition.  

Initially, the soil should be gathered from many sites within the square footage of the testing site.  The soil should then be dried and pulverized.  Allen used the rolling pin that belonged to his wife Eva to pulverize the soil he used for his sample, acknowledging that she would hardly have approved this use of the rolling pin that she inherited from her great grandmother.  

Three-fourths cup of the dry soil should then be mixed with 3 1/2 cups of water and five tablespoons of powdered dishwashing soap.  Putting the mixture into a tightly sealed straight-sided jar works well, and shaking it thoroughly (for five minutes) is the next step.  The various soil components will settle into clearly distinguishable layers over time, and the thickness of the layers can be measured.  These measurements will be used in some mathematical calculations, with the results entered on a diagram that shows which kind of loam is present.   

Soil Temperature

To determine soil temperature, Allen used another kitchen tool, a meat thermometer with a probe.  Since most seeds will germinate most quickly within a specific (but fairly narrow) temperature range, it pays to avoid planting when soil temperatures are too far outside this range.  Most garden seeds germinate well between 75 and 85 degrees.  Spinach can germinate best at 70 degrees, and many vine crops germinate best at 85 degrees or higher.  These are some of the outliers in germination temperatures.

Soil Moisture

Garden plants will wilt when they lack the necessary moisture.  "Wilt point" is the term when a plant transitions from having adequate moisture to having too little.  While plants vary somewhat in how much moisture they require to avoid wilting, wilting is never a good thing, and using a moisture meter can reveal when the wilting level is approaching.  Irrigating ahead of the wilting point is necessary if rainfall is insufficient.  

The kind of moisture meter Allen showed is a palm-sized instrument "box" attached to a probe.  The probe goes into the soil and senses the amount of moisture, which is then displayed on the outside of the instrument "box."  The readout can be either in the form of a dial or a digital display.  

Soil pH

Soil that is extremely acidic or extremely alkaline will not be suitable for growing most garden plants.  On a scale of 1 (extremely acidic) to 14 (extremely alkaline), most plants will grow well at a pH of about 6.5.  Only potatoes, eggplant, and watermelons may need a lower pH.  

Soil pH affects the availability of various minerals in the soil.  In other words, a plant cannot take up certain minerals if the pH is outside of a certain range.  The range varies for individual kinds of plants.

In general, adding lime is the remedy for soil that is too acidic.  Sulfur can correct soil that is too alkaline.  

Soil pH can be tested using color-changing strips that are available in a local hardware store.

Light

While this is more of a site consideration than a soil consideration, the amount of light available also affects plant growth.  A light meter can reveal whether sufficient light is present for growing garden crops, or whether light is limited enough to grow plants that prefer shade.  Light meters are available in local building supply stores.