Follow these simple steps to optimal gardening in difficult soil.
The ideal soil, which is loam, has 20% clay particles, 35% silt and 45% sand. Clay holds water better, retaining moisture through drought conditions. Clay soil particles (colloids) have a negative charge (anions) giving them special physical properties. They attract positive charges (cations) that many elements in soil carry. This benefits plants by providing many cation nutrients like ammonium-nitrogen, copper, iron, maganese, potassium and zinc.
Healthy roots require a balanced soil pore space where they can uptake water and nutrients while maintaining enough airflow. An abundance of clay blocks air movement, pore spaces fill with water, soil becomes waterlogged and the plant root system suffocates.
An added problem is that clay soils compact very easily. When soil space and size are reduced, water and air cannot move through the soil. During wet conditions water pools on the surface. When conditions are dry, the soil may crack and dry into hard impenetrable lumps.
The Perk Test:
This test can be done at home in your yard to determine good drainage throughout your garden! In this test you are checking for drainage over a 24-hour period. Dig a hole 12 inches deep and fill it with water.
- Water drains 3 to 4 hours = good drainage
- Water drains 5 to 12 hours = moderate drainage
- Water drains in 12 to 24 hours = poor drainage
The most important thing you can do for your soil is to add organic material. In the areas with heavy clay soil, remove the top 12-18 inches of clay and replace with loose amended soil.
Compost: breaks up clay particles, helps increase aeration, increase the activity of microorganisms, feeds earthworms, prevent soil erosion, modifies pH and improves soil structure. Such as: Well- rotted animal manure from cattle, sheep, chicken, pig and horse. Home made compost: garden materials including leaves, grass clippings, green garden plant, and kitchen food waste.
Peatmoss: is very acidic helping to lower pH of alkaline soil.
Sand: Caution must be taken if adding sand. Some types of sand can create a cement-like substance when mixed with clay. It must be sharp or coarse like builders’ sand.
Peatmoss mixed with compost makes a wonderful soil amendment. Work this into your soil on a yearly basis to maintain a loose and friable soil that any plant would want to sink its roots into.
Plant Material for Your Soil:
Trees tolerant of clay soil include:
- Paper Birch- Betula papyrifera
- Manchurian Ash- Fraxinus mandshurica
- Black Ash- Fraxinus nigra
- Green Ash- Fraxinus pennsylvanica
- Poplar Brooks # 6- Populus ‘Brooks # 6’
- Poplar-Northwest- Populus ‘Northwest’
- Poplar-Tower- Populus canescens ‘ Tower’
- Laurel Leaf Willow- Salix pentandra
- Trembling Aspen- Populus tremuloids
Shrubs tolerant of clay soil include:
- Autumn Magic Chokeberry- Aronia melanocarpa
- Caragana cultivars- Caragana cv.
- Dogwood various cultivars- Cornus alba
- Honeysuckle cultivars- Lonicera cv.
- Alpine Currant- Ribes odoratum
- Willow- Salix
- Blue Fox Willow- Salix brachycarpa ‘Blue Fox’
- Coyote Willow- Salix exigua
- Dwarf Arctic Willow- Salix purpurea ‘Nana’
- Creeping Willow- Salix repens
- Polar Bear Willow- Salix sadicola ‘Polar Bear’
- Snowberry- Symphoricarpos albus
- Lilac cultivars- Syringa cv
- False Spirea- Sorbaria sorbifolia