Tag Archives: Potassium

Soil Testing…Why Bother?

soil testI have been an avid backyard gardener for the last 7 years or so.  For the first 5 years or more, I had no idea what I was doing.  It was all a big science experiment.  My yard and my veggies were my subjects.  Some years it worked out and some years it didn’t.  The blueberries did well (I had advice from my uncle who has grown blueberries for 40+ years).  The carrots were hit and miss. Some years they did great, but  other years they did not grow at all or the roots were small (that is when I learn about thinning seedlings).  For years I planted garlic in the Spring.  I finally found out that it needs to be planted in the Fall in the climate where we live outside Chicago.  All of my gardening knowledge was obtained via books, Google, talking to other gardeners and trial and error.

Lately, however, I have been learning more about my edible gardening passion as I study to become a University of Illinois Extension Master Gardener Volunteer.  Through these classes and volunteer opportunities  I have realized that I have been doing a lot of things correctly, but even more things incorrectly.  The biggest mistake I believe I have made is never getting a soil test.  I was well aware of the possibilities of lead laden soil around my almost 100 year old home, so I built raised beds.  Yet, beyond lead, I never thought of having my soil tested.  For years I happily added compost, leaves, manure, mushroom compost and occasionally handfuls of organic fertilizers with abandon.  It was a rite of Spring and sometimes for good measure, a rite of Fall, too.   I never considered if my beds actually needed the amendments or what nutrients the soil and ultimately, my plants, required.

Fast forward to last week.  After spending a morning at the Cook County Farm Bureau  and hearing about their fantastic services, I decided it was time to get my soil tested.  The Farm Bureau has an arrangement with the University of Illinois Extension so if you sign a consent, your results will be shared with the Master Gardener volunteers that run the plant clinic . Then, as a free service, the Master Gardeners  will be available to help you interpret your results.  It is a great service and it is likely that you will need help with the interpretation (at least I did).  As part of my training, I am learning to interpret these results, so if you happen to get me on the phone when you call for help, I apologize in advance.

This is how it works:

  1. Obtain a soil testing kit.  There are a few labs across the country that do soil testing but many university extension offices will help you get your samples to their preferred lab.  Here in Illinois, the U of I Extension office has a list of labs that they will provide for you to contact.  I found it easier to go through the Cook County Farm Bureau instead of contacting a lab directly because they provide you with a package all put together with everything you need.  They gave me an educational packet of information,  a pre-paid label with a box, proper collection bags and the paperwork that needs to go with your sample.  They are also very friendly.  I had to pay the sample fee when I picked up the packet (they also mail them to you, but I happen to be there) so be sure to figure out how many samples you plan to take before you call.  Each sample cost me $20 because I am a CCFB member.  I believe it is $30/sample for non members.   Lead testing is a different fee.
  2. Fill out the forms with basic information like Name/address, etc.  Then, answer a few questions such as  “What will you be growing here?”,  ” Have you applied fertilizer?  If so, When? ” ,”Have you added organic matter?”, etc.    There are about 6 or 7 questions on the form and you need to fill one out for each area of your yard/garden that you are sampling.
  3. Take your samples.  There is a diagram that explains how to take the samples.  If you have a veggie bed, you can take multiple cores from that bed and included it as one sample.  In my case, I took 3 samples.  One from each of my two veggie beds and one from my blueberry patch.  In retrospect, I probably could have taken cores from each raised veggie bed and mixed those into one sample.
  4. Put your samples in the box they give you with the prepaid UPS label and call UPS for a pickup as soon as possible (or drop it off at a UPS location).  The sample should not sit around or it will dry out and alter the results.
  5. I received my results in PDF form in about a week via email. It was that simple!

What the results show you:

There is a lot of information on the documents they send you back, but the most important items for home gardeners are the pH of your soil, the % of organic matter, and levels of nutrients such as Phosphorus (P1), Potassium (K), Magnesium (Mg) and Calcium (Ca) and some fertilizing recommendations.  It also give you a measurement of your soil’s Calculated Cation Exchange Capacity (CEC).  You can view a slide show explaining CEC here, but CEC basically deals with the availability of nutrients in your soil.  All of this information can be helpful in determining which plants will do well in your soil and how to amend your soil to support the plants you wish to grow .  Keep in mind that changes to soil can take time so it is best to get a soil test the year before you are going to plant.  Of course, most of us do not plan that far in advance.  I am, in fact, 7 years too late to do that. So, I will leave you with one word of caution…

It is always better to plant  things that will grow well in your soil and in your environmental conditions than to try to drastically alter your soil!  If your soil cannot easily support what you want to grow, consider using raised beds or pots.

I hope to post some details about what my report actually showed for my garden and the actions I took.  What do you think?  Will you get a soil test this year?