There is no cook book recipe for creating the ideal soil environment (good aeration, drainage, ability to hold adequate moisture and nutrients). Start by examining soil compaction and drainage. If drainage is not adequate, determine if the soil has been compacted due to construction traffic. Deep cultivation may be necessary to loosen the soil. Corrective measures may be needed to improve surface or internal drainage. This could include redirecting surface water, installing drainage tile, or incorporating materials into the soil, i. e. pine bark mulch.

In situations of heavily compacted soil or severe soil erosion, it may seem easier to buy topsoil and start over. Unfortunately they are no standards on what is sold as topsoil. You do not know what you are getting and what new problems you may be purchasing, i. e. weeds, chemical residuals. You may also encounter some additional water drainage problems. When water moves from one layer of soil and encounters another distinct layer or type of soil, it may not be able to move freely into it.

The primary problem with clay soil is excessive water retention, ease of soil compaction, and limited soil aeration. Never dig or cultivate when the soil is excessively moist. Minimize soil compaction by reducing traffic when the soil is wet. Adding sand to improve drainage seems logical, but can actually decrease drainage. The combination of large sand particles and the small clay particles often creates a soil that has less aeration and drainage. Adding peat moss will only increase the moisture holding capacity which is already high. The primary problem with sandy soil is a low capacity to hold water and nutrients. Frequent applications of both fertilizer and water may be needed. Adding organic matter to sandy soils will improve nutrient and water holding capacity.

Organic amendments such as compost, manures, and pine bark are more effective and economical than vermiculite, peat moss, sand, topsoil, or perlite. Apply a 3 to 6 inch layer of organic material and incorporate. The organic matter must be decomposed before plants can use the nutrients. The rate of decomposition of organic matter by soil organisms is affected by moisture, temperature, particle size, the carbon to nitrogen ratio, and nitrogen availability. The proper balance of carbon and nitrogen is needed for rapid decomposition as well as warm temperatures and adequate moisture. When using straw, leaves, or sawdust (which are high in carbon) you will need to add nitrogen fertilizer while the material is decomposing. Nitrogen is used by soil microbes during decomposition and may become deficient for your intended plants.


Consumer Horticulture | Quick Reference

© Erv Evans, Consumer Horticulturist
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