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Building Great Garden Soil

Note–The Madison County MU Extension Center announces its July Specialist of the Month, Donna Aufdenberg. Donna has been with Extension for 12 years and is the Horticulture Specialist serving Madison County. Her specialties include vegetable gardening, flower gardening, plant propagation and greenhouse growing, but she is an excellent resource for any horticulture topic. Her current projects include garden journaling to a better garden, vegetable grafting, and utilizing natives in the landscape. You may contact Donna directly at 573-238-2420 or aufdenbergd@missouri.edu.

Spring will be here before you know it and many of us are already thinking about gardening.  Soon we’ll begin working the soil in preparation for the spring planting season.  Working the soil provides an opportune time to add amendments and make improvements to your soil. 

In Missouri, many gardeners live in areas where soil conditions are not so great.  With either clay, rocky or sandy soils, many of us gardeners are left dreaming of a fertile, easy to work soil that will grow anything.   For those who do garden with great soil, a better soil is a work in progress.  Here are some tips for a road to a better garden soil:

  • First and foremost, soil test every 2-3 years.  Knowing what is in your soil, and what the possible problems are is a giant step toward a better soil.  A soil test will give the pH, phosphorus, potassium, calcium and magnesium levels.  
  • Limit your roto-tilling. Tillers can do a good job of incorporating old plant residues or amendments, and creating a good seed bed for planting; but tillers can be greatly overused. For starters, tilling brings dormant weed seeds to the surface where they will germinate. Secondly, it can destroy soil and cause crusting of the soil surface.  his will impede water infiltration, increase runoff, reduce germination rates of seedlings, and can lead to soil compaction.  Continual tillage at the same depth will also create a hard pan beneath the tilled surface of the soil.  This hard pan can become quite dense, reducing water and root movement downward through the soil, thus restricting plant growth. 
  • You should also be mindful of the soil conditions when you till.  If the soil is too wet, then clods can form. These clods are very dense and hard to break down once they dry out. Plus, tilling wet soil can lead to compaction. To make sure the soil is dry enough to till, take a handful of soil in your hand and squeeze it to form a ball. Then apply slight pressure to the soil ball with your thumb and finger. If the ball does not crumble easily, then the soil is too wet to till and you should wait until it dries further.
  • Spring provides a great time to add amendments to the soil. Organic amendments are a great way to improve your soil.  Adding organic matter improves water infiltration, soil tilth, increases drainage in clay soils, supplies plant nutrients and improves the physical conditions of the soil. There are a number of amendments to add to the soil:  peat moss, manure, humus, compost, grass clippings, leaves, etc.
  • Sand should not be used as a soil amendment. Instead of creating pore space, adding sand to clay will fill in the pores and you will end up with soil that resembles concrete. Choose an organic amendment instead.
  • During the growing season, take advantage of grass clippings, leaves, vegetable scraps, or any green or brown organic material that may come your way. Start your own compost pile that can be added to your garden soil at the end (or beginning) of the gardening year. Organic matter is the best thing you can add to make your soil a “Healthy Soil.”
  • Plant a cover crop.  Cover crops are plants that you sow in your garden when it is laying fallow.  After the crop gets about 6-10 inches high, it is incorporated into the soil or mowed to lay on top of the soil. For example, after removing cabbage and broccoli, instead of leaving the area empty, plant buckwheat.  At the end of the year when the plants are pulled, plant a cool season cover crop such as winter wheat or winter rye.  Cover crops cover the soil, prevent erosion, improve the soil tilth, aeration and structure, and much, much more. 

Building up “good” soil is a process that takes many years to accomplish and adding organic amendments is a key step in improving your soil.

Donna Aufdenberg, Horticulture specialist, MU Extension

Donna Aufdenberg, Horticulture specialist, MU Extension

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