ST. LOUIS (KMOX) - I want to give you the scoop on soil.
I’m in a Master Gardener Course with the University of Missouri Extension, this past week we learned about soil management. By the end of the three and a half hour lecture I was pining to get home, dig a hole and count my worms. Worms, those wonderful creatures that aerate the soil, break down organic matter and leave behind wonderful fertilizer. How many you have can be an indicator of the health and productivity of your soil.
And, they’re all part of this highly complicated and connected ecosystem that is right under our feet.
Justin Keay was our speaker, he’s a University of Missouri Extension Field Specialist in Horticulture for St. Louis and St. Charles and sort of a local soil guru. He fell in love with the soil, or at least began to really appreciate it, after he started his own organic vegetable farm in Florissant. He said he had three acres of beautiful, rich soil, full of everything his crops needed. However, after a few years of heavy tilling he said his land was taking a turn for the worse and that is when he began to dive into soil management.
Keay realized he was tilling his land too often and breaking down the natural formation of soil aggregates. Soil aggregates are groupings of soil particles, bound together by organic matter, organisms and plant roots. Keay explained, “When tilling an area multiple times, those little aggregates are broken down, reducing pore space, and creating a compacted layer below the tilled soil. After a heavy rainfall event I noticed that the water would no longer infiltrate deeply into the soil” After a while, water begins to pond on the soil surface, and when the soil finally dries much of the fluffiness of the tilled soil has been lost. The pore space of the soil has collapsed, reducing the amount of air and water the soil can hold, and plant roots can access.
Think of the soil as a beautifully made lasagna… the more layers the better the lasagna, but instead of different types of cheeses, meats, and sauce it’s layered half with sand, silt, clay, organic matter and the other half is pore space, which is a mix of air and water.
Keay said often times after new construction or in urban areas the soil has been disturbed. "The soil is compressed like concrete, making it very difficult for roots to get established. Heavy equipment traffic and removal of topsoil during construction creates challenges down the road"
Keay says the best way to begin improving the soil after over tilling is to find ways to minimize tillage and add organic matter. Keay said when it comes to organic matter, “Think about things from the home that you can turn into compost like grass clippings, those piles of leaves from last fall, the vegetable scraps from the kitchen. Organic matter acts as a glue that holds the particles together, forming those important soil aggregates.” Keay says that fresh organic matter should always be composted before it is added to soils, but things like leaves and grass clippings can be used fresh as a surface mulch.”
Keay did reassure the class that some tilling is ok, but it can easily be overdone. He said if you're trying to get rid of weeds, use leaves or mulch around your plants for weed control. In the fall you can cover your garden with cardboard or leaves, in the spring you can simply remove the coverings, let your soil dry, and you're ready to plant. Tarps work well too.
Keay highly recommends soil testing. The twenty-five dollars a test can save you time and money when you don’t have to purchase unnecessary fertilizers. Most of our Missouri soils are acidic and may need lime, which works as a neutralizer, but Keay says don’t just blindly start adding things to your lawn and garden, get the test first. Acidic soil isn't bad, some plants like blueberries and azaleas thrive on the acidic soil, but roses, dogwoods and tomatoes do well in a more neutral environment. Bottom line, you'll never know exactly where your soil stands on the pH scale if you don't get it tested.
Most fertilizers contain a mix of nitrogen, phosphorous and potassium, the primary macronutrients plants find in the soil. However, thirteen other elements are considered essential to plant growth, and when the soil gets too much or too little of one of the macronutrients, it can affect how the plants are able to access the other vital nutrients. Keay said, “excessive phosphorous and potassium can’t be removed, too much phosphorous can bind up iron and zinc, making these vital micronutrients unavailable to plants.” The three numbers on the fertilizer bag represent the weight of each of the primary nutrients. A 50-pound bag of 20-0-10 contains 10 lbs of Nitrogen, 0 lbs of Phosphorous and 5 lbs of potassium. A soil test will help you know exactly what kind of fertilizer you need to add, if any at all.
Over-fertilizing is not just a waste of money, but also bad for the environment.
Keay said that when consumers use excessive amounts of fertilizers, after a big rain they can run off into local streams and rivers and contribute to those devastating algal blooms in the Gulf of Mexico. “Both agricultural and urban runoff contribute to nutrient pollution and the environmental problems associated with it.”
Keay told us that the soil is an incredibly complex ecosystem, and that we continue to learn about the symbiotic relationships between all the living organisms that make the soil their home. And remember, it’s not just dirt in your yard… it’s beautiful soil!
From March 2-7, the University of Missouri Extension is having a soil testing blitz in the St. Louis region. Some local nurseries will be accepting soil samples for the University of Missouri Extension.
Cost for a soil test is $25. Drop your soil off during the soil testing blitz and receive a free class on "Understanding your soil test report for lawn and garden success" an April 7th and 20th.* Brightside (St. Louis City)* Crabapple Cove Nursery (Mehlville)* Hummert International (Maryland Heights)* Garden Heights (Richmond Heights)* Gateway Greening (St. Louis City)* Greenscape Gardens (Ballwin)* St. Louis Composting (Florissant or Valley Park)
You can check out more information and locations here.