Test Your Soil! 1st Rule of Gardening.

With gardening you learn something new every year. I am an avid reader of gardening blogs, YouTube, and garden Web forums.  So, when I hear add eggs shell, Epsom salt, and everything under the sun to to my soil, it peeks my interest.  I too want a HUGE harvest.  Last year for some unknown reason, I decided to test my soil.   When I got my results I started shutting off all of the noise and realized that adding the kitchen sink to my soil was a waste of time and it could actually hurt my efforts. So, remember, test your soil.  It is the 1st rule of gardening.

Seriously, Anna.  Everyone adds Epsom salt to their tomatoes.  

In my master gardener’s class, I learned that soil is tricky.  It is all about balance.

And then there is something called wasting money.  Why buy this product or that product if your soil test says your soil has an A+ rating?

Again, test your soil, and stop wasting  money.

My Soil Test

When you test your soil, you must specify on the soil testing questionnaire what part of the garden you are testing.  For example, I tested my fruit trees, bramble bushes, perennials, lawn, and vegetable garden.  Yes.  5 different soil tests.  Each group of plants has different needs.

Just to give you some context, before we built our house, the land was a timothy hay field.  I recall years ago when we did some soil test for the lawn that we needed phosphorus.  In New Jersey, you can no longer add it to your lawn unless you need it.  Excess phosphorous causes algae bloom in the nearby lakes and streams.

The years have flown by but I do recall we applied several rounds of corn gluten to combat the crabgrass. Corn gluten has a lot of nitrogen.

But, the lawn  was just a big green weed fest.   Other priorities came before the lawn.

Now to give you further context about the rest of the property:

• My garden has raised beds and perennials in the ground.  The garden received compost every year.  The beds were comprised of store bought top soil and compost.  I also did a special test for the vegetable garden to find out the organic matter content of the beds.  It is called a Soil/plant Suitability test.
•  There are several perennial beds that were installed 10 years ago that never received any special treatment.
• We discussed the lawn above.
• The brambles (blueberries, raspberries and blackberries) received a lot of compost before planting. Note, you must do a separate test for blueberries because they like a much lower pH then other fruit bearing bushes. So, I had to do 2 different fruit bush soil tests.

Instead of boring you with the details of all the separate soil tests, I will focus on the vegetable garden.  Here is my test:

pH is the measure of the acidity or alkalinity of the soil.  A pH of 7.0 is neutral.  Most vegetables like a pH of  5.8 to 6.5.  (Notice my soil is a little high.) The Division of Agriculture and Research Extension at the University of Arkansas states:

“Roses, turf-grasses, fruits, and nuts like a pH of 5.5 to 5.8. Blueberries like a pH below 5.5.  Based upon your results, you will need to add lime to increase the pH or elemental sulfur to decrease the pH.”

During my Master Gardening class, I learned that applying leaf based compost will increase your pH over time.  I use a grass/leaf compost that I buy form the county.  I just can’t make enough for my garden.

If I had used my own compost, which is basically food compost and leaves, I probably would not see that result. (I am the lazy composter. I just throw it in and hope it turns into compost.)

This is the special test that I did:

Lastly, here are the fertilizer requirements.

But before we go into what I need–what does those 3 little numbers mean–NPK?

The first one is nitrogen which makes your plants grow.  Note, there isn’t a test for your nitrogen levels.

According to the Division of Agriculture and Research Extension at the University of Arkansas,

“Nitrogen is normally the most limiting nutrient for optimum plant growth. Soil tests that estimate soil N availability are not currently used because soil N exists in many forms which may change with time and influence plant availability.”

So recommendations for the amount of nitrogen are based upon the particular plant.

The second number is phosphorous.

The third number is potassium.

According to University of Massachusetts at Amherst, phosphorous is basically the plant’s fuel.  They state,

“[P]hosphorus provides plants with a means of using the energy harnessed by photosynthesis to drive its metabolism. A deficiency of this nutrient can lead to impaired vegetative growth, weak root systems, poor fruit and seed quality, and low yield; however, excessive soil phosphorus levels are a concern due to the potential negative impact on surface water quality. Most phosphorus losses occur with runoff, but where soil levels are extremely high, subsurface losses can occur. Phosphorus enrichment is a leading source of water quality impairment of many lakes, streams, and rivers in New England.

Remember the algae bloom I talked about above?

The plants need potassium to be able to use the nitrogen and water supplied to them. If the soil doesn’t have enough potassium, then the plant are more susceptible to disease.

Then there is calcium, magnesium, and other micro-nutrients that I won’t go into in this article.    If you want to read about those minerals, click HERE and HERE.

My target fertilizer is 1-0-0, which means 1 for Nitrogen, 0 for phosphorus, and 0 for potassium.  This is where science and fertilize manufacturers do not see eye to eye.

I couldn’t find any fertilizer remotely close to this recommendation.  My Agriculture extension officer suggested I use alfalfa meal as a fertilizer since it is 2.8-.24-2.4.

How about the other tests?

As for the other tests,

• the blueberries’ pH was way too high and I have been applying elemental sulfur.
• The lawn failed miserably for low phosphorous. We had to use a lawn company to apply starter fertilizer to the lawn since you can’t use any fertilizer with phosphorous in NJ.
• The perennial beds also had low phosphorous but not as bad as the lawn.
• Finding a high OMRI approved phosphorous based fertilizer is very hard. Down to Earth was the only company I could find that had a phosphorous based fertilizer.  They are based on the west coast.

How do you test your soil?

Go get a kit from your county extension or university.  Sure, you can buy one online but it isn’t going to be as accurate unless you are sending it to a lab.

Watch my video below to get an idea of how to  create a soil sample.  Depending on the test, you will need to take soil from different areas of the planting bed you are testing.  Then you combine all the soil, and then take a portion for your sample.

You don’t need to take notes.  Most soil tests will give you instructions.

It is best to take soil samples in the fall so that you can prepare your beds instead of playing catch up in the spring.

I strongly urge you to take soil tests every few years since it will save you money and a lot of headaches from failed crops.

Join the Conversation:

Do you get a soil test for your garden?

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