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Wednesday, February 11, 2015

PIMP MY SOIL!!! - MI Lake Home Garden Edition

The information for this article comes from the MSU Master Gardener Volunteer Class.

Often, when people have difficulty growing plants, they forget to consider their soil.  They will say, “Well, I gave it plenty of water!  There’s plenty of sun!  I dumped some fertilizer on it!  I don’t see any insects!  I don’t know what’s wrong...”

This person may seem to have been on the right track when they said that they “Dumped some fertilizer on it.”  But did they add the right amount or type of fertilizer?  What about the soil texture?  Is the soil loose enough for the roots to grow?  Is there enough living matter in the soil? Is the soil pH right for the plant?

To have a healthy garden, the composition of the soil needs to be right for the plants in the garden. So... LET’S PIMP YOUR SOIL! 

Soil Texture:

The ideal composition of soil should be: 45% mineral, 5% organic, 25% water and 25% air. 

There are 3 basic types of soil: sand, silt and clay.  Sand has the largest particle size and clay the smallest.  Sand drains well and dries out quickly.  Clay clings to moisture and can become thick and difficult to dig through. 
Sandy, gravely Michigan soil  can be seen between the rows on this Romeo Farm.

You might think that you can improve either type of soil by simply mixing sand and clay together. DO NOT DO THIS!  You will end up with cement!  Instead, add organic matter.  You may have to do this every year until you build up a nice layer of topsoil.  Organic matter is most readily available in the form of compost, leaf mold, peat or animal manure.  Combine the organic matter with the soil by hoeing it in.  You can also use a tiller, but be careful not to over-till.  When you till, leave clumps. Do not create an even powdery soil, or the soil will either wash away or compact back into cement.  Also welcome earthworms to your garden.  These invertebrates will carry organic matter down into the native soil for you.

A healthy soil with enough organic matter will be dark in color – almost black.  It will hold together if you squeeze it tight, but will crumble again if you gently tap it or push at it with your finger.

Organic matter also encourages living things to make a home in your soil.  These include bacteria, fungi, mycorrhizae, lichens, protozoa, invertebrates, and vertebrates. May of these organisms help to keep the soil fertilized, help to break down organic matter and some even have symbiotic relationships with the plants in the garden.  Remember, healthy soil is living soil!

You can buy organic matter at your local nursery or super store.  You can also make it yourself by composting.   Simply keep and contain your food scraps, grass clippings, and leaves in a bin or pile.  If you want to speed the composting process, turn the material over with a shovel or spading fork once in a while.  This material will break down and will be ready to apply to your garden when it looks like crumbly black soil.

For the sake of health safety, do not add meat, pet manure or human manure to the compost pile.  These may contain unhealthy bacteria that can cause sickness when applied to vegetable gardens.  Pet and human manure are not considered useful as compost until they have broken down for at least 10 years.  Most of us cannot wait that long! 

Most soils can be improved enough to grow plants well simply by adding organic material to improve soil structure.  So, always add organic matter to improve the soil first.  If you have tried this, and your plants are still struggling, please read on. 
Dark soil under this rose is high in organic matter.

Fertilizer and Plant Food:

Sometimes people think that fertilizing is the only way to improve soil, and the more the better!  NOT TRUE!

You cannot just dump fertilizer on a plant and expect it to grow.  Different plants require different amounts of nutrients.  Also, the soil contains most of the nutrients that a plant needs.  It is possible that your soil is lacking in a particular nutrient, but do you know which one?

To find out, get a soil test!  You can send soil to your local extension office.  They will return a report to you that states exactly which nutrients your soil contains, and will recommend an amount and type of fertilizer for you.  If you live in Michigan, you can send for a soil test here:

There are 17 mineral nutrients that plants typically require.  These are: Hydrogen (H), Oxygen (O), Phosphorus (P), Potassium (K), Nitrogen (N), Sulfur (S), Calcium (Ca), Iron (Fe), Carbon (C), Boron (B), Magnesium (M), Chlorine (Cl), Manganese (Mn), Molybdenum (Mo), Copper (Cu), Zinc (Zn), and Cobalt (Co).

When you get a bag of fertilizer, you will typically see 3 numbers listed on the front of the bag.  These represent the 3 most commonly required plant nutrients: N-P-K  (Nitrogen, Phosphorus, Potassium).  When you get your soil test results, the report will tell you what levels of these nutrients your soil requires and how much to apply per square foot. Please follow the directions EXACTLY! Adding more is not better.  When you add too much fertilizer, it can just wash away into the water systems.  This results in algae blooms that kill off fish and generally pollute the water system. It also costs more to buy more fertilizer than you need, and is of no benefit to the plants.  In addition, over-use of fertilizer can build up chemical salts within the soil and ultimately poison future plants.  So, just as you would when taking medicine for yourself, use the correct prescribed dose!

Remember the old saying, “Enough is enough, and too much is poison!”

Soil pH:

pH is a way to measure how acidic or alkaline (base) your soil is. If you recall from high school biology or chemistry class, 0 is the most acidic on the scale and 14 is the most alkaline/base.  Acids are generally sour in taste (lemon juice, vinegar), alkaline/bases are generally bitter in taste (baking soda). Acids and bases create chemical reactions together that result an a neutral substance and gasses (bubbles).  (Remember building that volcano in elementary school buy mixing vinegar and baking soda together?  No?)

battery acid            vinegar                 water                          ammonia                        Lye
0                                     <----Acid         7        Alkaline/Base ---->

You can test the pH of your soil buy purchasing a soil pH test at any garden center.  Please follow the directions on the package exactly.

Most plants grow best at a pH between 6.0 and 7.0.   However, there are a few others that require different levels of pH.  For example, azaleas and blueberries require acidic soil with a pH around 5.0, whereas alfalfa thrives at a neutral to alkaline pH around 6.5 to 7.5.  It is important to research your plants and to know what pH level they need to survive.

Some of the topsoil in Michigan is acidic, primarily in areas where the soil has not been disturbed much.  In suburban and urban areas, the soil is primarily alkaline because it has been churned up by construction.  Construction companies often remove the acidic top soil and pull the alkaline bedrock lime to the surface.

It is best to test the pH before choosing plants.  While the pH can be adjusted somewhat within a small area such as a raised garden bed or a pot, it is nearly impossible to change the pH of an entire field for the extended period of time needed to grow a plant.

So, if you live in an area where the soil is acidic, do not try to farm alfalfa or asparagus!  If you live in an area where the soil is alkaline, do not take up blueberry or cranberry farming!  Find the right site for your growing needs.

To adjust the soil pH in a small area (for example a pot), you can put additives into the soil. 
  • To make soil more alkaline you can add: lime, calcium oxide, calcium hydroxide, marl, slags, or wood ashes. 
  • To make soil more acidic you can add sulfur.

When adding either of these products, first test the soil pH.  Then, follow the instructions on the product bag exactly.  Again, more is not better.

Also, you do not need to lime your lawn if your soil is already alkaline.  This will make your grass less healthy rather than more healthy.  Add only what your soil requires! 

I hope that you find this information useful.  Now, get out there and PIMP YOUR SOIL!!

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