How to Amend a Large Lot With Clay Soil
Plants grow best in well-drained, fertile, sandy loam soils. These soils, when well-supplied with organic matter, are easily cultivated and produce quality plants. Unfortunately, many garden soils are less than ideal. Gardeners faced with dense clay soils must modify the soil for growing success. Organic amendments and extensive tillage will remedy problems caused by gardening in clay. Does this Spark an idea?
Instructions
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Test the soil. Dig holes for random sampling in a checkerboard pattern across the lawn or garden plot. Dig a hole 6 to 8 inches deep. Disregard the soil from the hole. Move back 1 inch from the hole and take a clean 1-inch slice of soil. Place the slice in a plastic bucket. Repeat the process, taking a slice from the remainder of the test holes. Put each slice in the bucket. When all are collected, mix well, removing clumps, roots and debris. Spread out the test soil on newspaper to dry, then place about 1 pint of the soil in an sealable plastic bag for submitting to a testing laboratory. Soil tests are available from the agricultural department of colleges and universities, commercial labs and from your local county extension office.
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Review the results of the soil test and plan to amend the soil as recommended. Add dolomite (calcium and magnesium) if pH levels are less than ideal. An application of 5 lbs. of dolomite per 100 square feet will raise pH levels by 1 point.
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Till the soil to a depth of 8 to 10 inches. Repeat tillage in alternate directions across the landscape to break up clods and aerate the soil. As you till remove rocks and roots. Tillage is the most important step in improving clay soil as it promotes permeability and oxygen diffusion within the soil. This provides a viable structure for seedling growth and root development. You can accomplish this task more easily by renting a garden tractor or cultivator from a home and garden center or equipment rental business.
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Till the soil late in the summer when the ground is as dry as possible. Clay soils are often dark brown, yellow or grayish in color. Gray clay is an indicator of poor drainage. Clay has a plastic-like, sticky consistency when wet. If worked when wet, it forms clods and becomes compacted.
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Add gypsum to the soil. Broadcast 50 lbs. of gypsum per 1,000 square feet. Gypsum, an ideal soil amendment, is nontoxic to both humans and animals and will not burn plants. It can be obtained from home and garden centers and applied throughout the year. Follow manufacturer's label instructions for subsequent applications.
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Cover the soil with 8 to 10 inches of aged, non-treated sawdust or small wood chips. Till into the soil as deeply as possible, multiple times, covering both the width and the depth of the plot. Large amounts of these materials are required to to improve soil permeability and drainage.
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Add organic compost to the soil to supplement its nutrient content. Apply a thick layer (12 to 18 inches) of compost and till it into the soil. Repeat tillage multiple times until the compost is worked in and the soil is crumbly and loose.
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Cover the soil with a heavy layer (8 to 12 inches) of organic mulch. Use aged manure from herbivores (sheep, horses, cows, lamas or goats), straw, dead leaves, shredded newspaper or cardboard, pine needles, grass clippings, or kitchen and garden scraps. Water until the soil is thoroughly saturated. If feasible, cover the entire area with heavy black landscape plastic, which traps the heat of the sun and retains moisture to accelerate decomposition. Allow the land to rest until spring.
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In spring, remove the plastic, allow the soil to dry, then till the mulch layer into the soil. Again, repeated tillage is the secret to creating loamy soil. The land is now ready for planting, rich with the nutrients required to produce a bountiful harvest.
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Tips & Warnings
Do not till or drive heavy equipment on wet clay soil.
Repeated tillage is time consuming and labor intensive. Nevertheless, do not skimp on this step as it's vital to soil enhancement and plant production.
References
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