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I’ve been an advocate of soil testing for years. I recently did a soil test on one of my rose beds. Boy, did I get a surprise when I opened the envelope.
A gardener growing plants without getting a soil test is like a surgeon performing an operation with a blindfold on.
Soil pH is a basic property that affects many chemical and biological activities in the soil.The degree of acidity or alkalinity is known as the soil pH. The scale runs from 0 which is highly acidic to 14.0 which is pure alkaline. A soil with a pH of 7.0 is termed to be neutral.
Each plant has its own requirements as far as pH and minerals in the soil. Most plants will do well if the pH range falls between 6.0 and 7.5.
However certain plants will not thrive if the pH falls outside of the desirable range of that particular plant. For example azaleas, hydrangeas, and rhododendrons prefer a pH in the 5.0-5.5 range. On the other hand clematis, delphiniums prefer soil with a pH in the 7.5-8.0 range.
Have you ever been disappointed with the performance of your vegetables or flowers, even though you gave them the best care you could? Truth is, pH might have been the problem. Plant roots absorb minerals such as nitrogen and iron only when they are dissolved in water. Now if this soil "soup" solution (the mixture of water and nutrients in the soil) is too acid or alkaline, some nutrients won't be dissolved, and as a result, they are unavailable to plants. They are said to be "locked up."
To put it another way, if the pH isn’t close to what these plants require, some nutrients, such as phosphorus, calcium and magnesium, can’t be dissolved in water. And since plants drink their food instead of eating it, if the nutrients aren’t dissolved first, the plant can’t absorb them. Thus, your corn, lettuce, roses and geraniums won't grow or produce to their full potential.
Most nutrients that plants need are readily available when the pH of the soil solution ranges from 6.0 to 7.5. Below a pH of 6.0 (acid): Some nutrients such as nitrogen, phosphorus, and potassium are less available.
Above a pH of 7.5 (very alkaline): Iron, manganese, and phosphorus are less available.As an avid rose grower; I had heard several years ago that if you add a handful of Epsom salts (Magnesium sulfate) to each plant when you fertilize it will give the roses a boost. I should have known better but I’ve been adding Epsom salts to my roses for the past 3-4 years. I was quite shocked when I recently received the results of a soil test that I had done on my rose beds. The Magnesium levels were on the very high side of the scale.
I contacted the owner of one of the better rose nurseries in the area. She indicated that in this area (SE Michigan) the natural Magnesium levels are adequate for plants and no additional Magnesium is needed. She went on to say that the excess Magnesium itself should not hurt the plants, but it could prevent the roses from taking up other vital nutrients. This might explain why the performance of my roses was not up to par this past season.
You can purchase home soil test kits at most garden centers; however I recommend that for a few cents more you can get a much more through test from your county extension office.It will give you your pH as well as Phosphorus, Potassium, and Magnesium levels. More importantly if will give you fertilizer recommendation tailored to your specific garden and the crops that you are growing. For example in my case it recommends that I apply soil sulfur at a rate of 15 pounds per 1000 square feet to acidify my soil into the range that roses prefer.
For those of you wondering why soil tests don’t give you nitrogen readings. Nitrogen is transit in soil, that is it moves through the soil quickly and levels change at a rapid pace.
One last note, soil tests will also give you the amount of organic material in your soil. One thing that you can never get too much of is compost. Please, before adding any chemicals or fertilizers, get you soil tested to see what you have and what you need for the crop that you are growing.
By the way, fall is the perfect time to get your soil tested, the labs are far less busy than in the spring and early summer.
DON’T GUESS, SOIL TEST
About Paul Rodman
Paul Rodman has been gardening for over 40 years. He is an Advanced Master Gardener, and American Rose Society Consulting Rosarian. He is currently president of the Western Wayne County Master Gardener Association in Wayne County, Michigan.
Rodman is the garden columnist for The News Herald newspaper, in Southgate, Michigan. He has also written for the OrganicGardening.com web site.
He has lectured on various gardening topics throughout southeastern Michigan.
His favorite pastime is teaching children about gardening. For the past several years he has conducted classes for second grade students teaching them about subjects ranging from vermi-composting to propagation.
Posted by SunnyMich (from Linden, MI) on November 26, 2007 at 11:39 AM:
I put all new organic soil in my garden last year. I didn't put in any compost or other fertilizers. My tomatoes were extremely dissappointing. My peppers were fine and wouldn't stop producing. My greenbeans had bugs on leaves and beans.
My squash got bores My eggplant never got big enough to pick.
I know now that I needed to add compost and manure. I started a compost this year. When do I put the compost in the garden and do I till it in with the old plant life left in the garden?
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Posted by paulgrow (from Allen Park, MI) on November 26, 2007 at 3:30 PM:
The first thing I would do us to get a soil test. The extension office is located on West Pasadena, in Flint. Tel# 810-244-8523.
That will tell you what you have and what you might need.
Compost can be added at amy time.
I just top dressed my garden with about 3" of compost. I'll let it lie there all winter and turn it under in the spring.
You can never get to much organic material in your garden.
Paul
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Subject: Soil Testing
Posted by telarsteve (from Miramar Beach, FL) on November 20, 2007 at 12:37 AM:
What is the best technique for collecting soil for testing? 1. Amount? What part of Garden? How deep? Thanks
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Posted by paulgrow (from Allen Park, MI) on November 20, 2007 at 7:08 AM:
Instructions are usually inculded in the kits.
You want to take samples from several locations throughout the garden.about 6" deep.
Paul
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Subject: magnesium
Posted by rosa18 (from Bartlett, IL) on November 19, 2007 at 11:19 AM:
Hello Paul,
In early fall I had a soil test done. I live in zone 5a Chicago suburbs. My Magnesium levels we're off the charts. I grow 55 roses, all flowered and look well, but I would like to try and correct the magnesium levels. Will sulfur do the trick?
Thanks for any help
Jill
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Posted by paulgrow (from Allen Park, MI) on November 19, 2007 at 2:26 PM:
I'm not sure, what was the pH on your test?
Adding sulfur will make it more acidic.
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Posted by rosa18 (from Bartlett, IL) on November 20, 2007 at 10:17 AM:
My ph was 7.2- Also our water is softened, do you think this add's to the high magnesium levels?
Jill
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Posted by paulgrow (from Allen Park, MI) on November 20, 2007 at 12:30 PM:
You're just slightly on the alkaline side, how you adjust the pH will depend on what you want to grow. A little sulfur wouldn't hurt if you're growing roses.
I'm going to do some more checking on the magnesium levels and see if I can find out if they'll disapate on their own.
I'll let you know. BTW did you add epsom salts?
Paul
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Posted by rosa18 (from Bartlett, IL) on November 24, 2007 at 9:57 AM:
No, I didn't add any epsom salt, that is why it is so puzzling to me. I know you shouldn't water with softened water, but the bypass is so hard to turn on the softener, so if my husband isn't home to adjust it for me, I just go ahead and water.
I tried to find information on watering with softened water and the effects but I didn't have much luck. Someone advised growing a cover crop to leach out the magnesium, but that would be a big mess in my mind.
Thanks for your help.
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Posted by paulgrow (from Allen Park, MI) on November 24, 2007 at 10:00 AM:
IWe don't need a water softener but I would think that softened water it would be high in sodium not magnesium.
I'm, still checking into this.
Paul
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Subject: soil testing
Posted by dun1kirk (from Berkeley, CA) on November 15, 2007 at 12:14 PM:
Yes, it's been on my list for a LONG time. I'll do it this month. Can you refer me to a company that will provide a complete test?
Thanks.
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Posted by paulgrow (from Allen Park, MI) on November 15, 2007 at 12:19 PM:
Check with your county extension office, most od them do testing.
Paul
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Posted by dun1kirk (from Berkeley, CA) on November 15, 2007 at 12:23 PM:
I've tried that. Believe it or not, they told me to just obtain a home test. So, if you know of a reputable company to refer me, I would appreciate it.
Thanks
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Posted by paulgrow (from Allen Park, MI) on November 15, 2007 at 12:47 PM:
Her's a link to a company, I've never used them but a couple of folks have and been happy with the results.
Posted by wgnkiwi (from Burlingame, CA) on November 15, 2007 at 1:02 PM:
The county extension offices here in the San Francisco Bay Area don't offer soil testing. I believe we are one of the very few areas in the country that are missing out on this service. I've made attempts to have my soil tested before but the fees charged by the private laboratories make it prohibitive. Thanks for the link to MidWest Labs - they are offering a free first time test and their prices are great.
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Posted by paulgrow (from Allen Park, MI) on November 15, 2007 at 2:11 PM:
Your welcome
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Posted by victorgardener (from Lower Hudson Valley, NY) on November 15, 2007 at 9:51 PM:
Paul, do you have a home test? I'm curious about their accuracy. I would like to see the results from the Extension vs. the home test. Thanks for the article.
Victor
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Posted by geneivy (from Kyle, TX) on November 15, 2007 at 11:05 PM:
Paul, do you have any knowledge of the "PH meters" for the hobbiest such as the Rapitest unit and are they of any value?
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Posted by paulgrow (from Allen Park, MI) on November 16, 2007 at 8:55 AM:
I've never used a home test.
For the low cost the extension charges plus the recommendations they provide I never saw a reason to try it my self.
Paul
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Posted by victorgardener (from Lower Hudson Valley, NY) on November 16, 2007 at 8:56 AM:
Thanks - our extension charge is not low.
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Posted by paulgrow (from Allen Park, MI) on November 16, 2007 at 10:04 AM:
How much do they charge?
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Posted by victorgardener (from Lower Hudson Valley, NY) on November 16, 2007 at 12:04 PM:
I haven't done it in a while but there were two tests available - a reasonably priced simple pH test and a more expensive (don't remember how much) nutrient analysis.
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Posted by geneivy (from Kyle, TX) on November 16, 2007 at 12:26 PM:
Paul, I know there are some VERY expensive PH meters but the "rapidtest" is about $30. We propagate plants, our native soil is very alkaline, and we use lots of raised beds. The extension service charges $12 for the kind of test you describe so it is cost prohibitive for as many beds as we would need to do. Thanks for your input. Gene
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Posted by KyWoods (from Melbourne, KY) on November 16, 2007 at 2:18 PM:
I wonder if Lowe's or Home Depot sell tests?
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Posted by paulgrow (from Allen Park, MI) on November 16, 2007 at 3:03 PM:
Probably in the spring and summer. Our Lowe's garden dept is all Christmas stuff now.
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Posted by KyWoods (from Melbourne, KY) on November 16, 2007 at 3:46 PM:
Ooooo, that's right--forgot about that! Haven't been in there for a while.
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Subject: Thank you Paul
Posted by Dyson (from Moneta, VA) on November 15, 2007 at 7:57 AM:
For an informative and important article.
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Posted by McGlory (from Southeast, NE) on November 15, 2007 at 7:43 PM:
Thanks, Paul! I never was too certain about the home tests, and never was sure about how important it is. Thank you for taking the time to explain all that. I, too, have contacted my extension service. The baggie, as they say, will be in the mail. Thanks again!
Lori
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Posted by KyWoods (from Melbourne, KY) on November 15, 2007 at 9:20 PM:
Great idea! Never thought of it before...thanks, Paul!
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Posted by michaeljo (from West Norriton, PA) on November 15, 2007 at 11:22 PM:
Thanks for pushing the soil test to the top of my list. Calling my extension service tomorrow.
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Posted by David_Paul (from Clinton, CT) on November 19, 2007 at 5:59 AM:
Quoted:
I had heard several years ago that if you add a handful of Epsom salts (Magnesium sulfate) to each plant when you fertilize it will give the roses a boost
Heard the same thing about tomatoes. Everyone, or it seems as if everyone, suggests tossing Epsom salts into the hole when planting out. Like you, I was suprised when my soil test came back--there is more than enough magnesium in the soil. Adding more would have been a waste of money and as you write, may have blocked the uptake of other elements. Right there I paid for the soil test several times over. My problem was phosophus (a common problem in CT). Only had 1 lb per acre. The lawn I was carving a garden out of looked OK but the soil was not at all suitable for tomatoes (pH of 5.7 and less than optimum K).
Might mention another reason for a soil test: lead.
If you're growing vegetable, it is only prudent to know the lead level. I thought mine might be high because of location and the age of the house but it was only slightly above background. The University of Connecticut provided information on how to mitigate the problem. had it been high.
Aluminum levels are likewise handy to know--both for growing food crops and hydrangeas.
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Posted by Islandshari (from Kwajalein
(Marshall Islands)) on November 19, 2007 at 1:04 PM:
A very good job of explaining a complicated subject in an easy to understand way. Great job Paul!
