Soil Testing - Why Bother?

I've fallen in love with soil testing ever since I learned how to do a few of the tests myself.




The process of collecting a couple of cupfuls of soil and preparing to do the tests puts you in touch with your garden and it's foundation, in a very intimate way.

So what do you need to know? What is reasonable for you to test yourself? What would be better sent to a lab for analysis?

For now we are focusing on the mineral particles that make up your soil. Here there are three aspects that need attention:

  • Physical Characteristics - things like texture, structure and drainage.
  • Uptake Factors - the acid/alkaline measured by pH and the salinity measured by Electrical Conductivity. These affect whether or not your plants can get the nutrients in the soil.
  • Nutrient Levels - As far as we know plants need 18 elements in order to grow in a healthy way. Three of them - hydrogen, oxygen and carbon - are present and absorbed in the air and water. The others - nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, copper, chlorine, iron, manganese, molybdenum, zinc, nickel, and cobalt - are derived mostly from the soil.
There is one other huge factor for soil. It's the other half of the soil equation - the organic matter and the life it supports. This is the soil biology or soil food web. It's what makes the nutrients in the soil truly available for plants. A whole section of this website is devoted to this here. The organic matter of the soil is replenished by compost. In fact, for most soil problems adding compost will help.

Preparing Your Soil Sample

It's simple to get your soil sample. Just dig down about 4 inches or 10 cm and take a shovel, cup or trowel full of soil. If you have a large area you might want to sample several spots and mix them together to get an average of your soil.

Don't mix or collect your samples in a galvanized bucket. This will add zinc to the mix and change your soil results. Use a plastic bucket or bag to collect your sample.

Finding a Soil Testing Lab

It's totally okay to simply dig up a few cups of soil and send them off to a lab for analysis. Indeed some of the tests for soil that a lab does would be way too expensive for the average person to equip themselves to do.

There are many good labs throughout the world specializing in agricultural and garden soil testing. To find a local lab just Google soil testing and your area and you are sure to come up with a number of decent labs.

I did that for the area where I live in High River, Alberta, Canada. I can drop off or mail samples to a lab in Calgary which is only about 44 km or 25 miles from here.

The testing is not that expensive. A full analysis including the major soil nutrients - Nitrate, Phosphorus, Potassium, Sulfate, Magnesium, Calcium, Sodium and Chloride; some micro-nutrients - Iron, Zinc, Boron, Copper and Manganese; and soil properties including pH, Electrical Conductivity, and Organic Matter - would cost $61 at the lab I contacted.

You can add a Texture test, which only needs to be done once - texture doesn't change much over time - for another $20.

Doing Your Own Soil Tests

You can do many soil tests by yourself. Some of them require nothing more than a jar and distilled water. Others need some chemical agents used to measure nutrient or pH levels.

I'd highly recommend doing at least a few of your own soil tests - just because it's so much fun. It's kind of like being a CSI. Kids will find the process very exciting and it will bring them to the garden for at least the soil testing phase.

Soil Texture - What it is and How to Test It

Soil Drainage - What it is and How to Test It

Soil pH - What it is and How to Test It

Soil NPK - What it is and How to Test It - Coming Soon

Soil Salinity or Electrical Conductivity EC - What it is and How to Test It - Coming Soon

Soil Micro Nutrients - What they are and How to Test for them - Coming Soon



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