Everything You Wanted To Know About Dirt – Stockton, Ca

Written by Bill Stoermer on April 15th, 2014. Posted in Blog

A soil amendment is any material added to a soil to improve its physical properties, such as water retention, permeability, water infiltration, drainage, aeration and structure. The goal is to provide a better environment for plant roots.

To do its work, an amendment must be thoroughly mixed into the soil. If it is merely buried, its effectiveness is reduced, and it will interfere with water and air movement and root growth.

Amending a soil is not the same thing as mulching, although many mulches also are used as amendments. A mulch is left on the soil surface. Its purpose is to reduce evaporation and runoff, inhibit weed growth, and create an attractive appearance. Mulches also moderate soil temperature. Organic mulches may be incorporated into the soil as amendments after they have decomposed to the point that they no longer serve their purpose. Cheap, inexpensive mulches breakdown faster, fade in the sun and are usually made from cheaper products.

Quick Facts

In clay soils, soil amendments improve the soil aggregation, increase porosity and permeability, and improve aeration, drainage, and rooting depth.

In sandy soils, soil amendments increase the water and nutrient holding capacity.

Permeability โ€“ The ability of soil for fluids to flow through.

Infiltration โ€“ the process by which water on the surface enters the soil.

Aeration โ€“ the process by which air is circulated through soil.

Organic vs. Inorganic Amendments

There are two broad categories of soil amendments: organic and inorganic. Organic amendments come from something was ALIVE. Inorganic amendments are either mined or man-made. Organic amendments include sphagnum peat, wood chips, grass clippings, straw, compost, manure, biosolids, sawdust and wood ash. Inorganic amendments include vermiculite, perlite, tire chunks, pea gravel and sand.

Organic amendments increase soil organic matter content and offer many benefits. Over time, organic matter improves soil aeration, water infiltration, and both water and nutrient holding capacity. Many organic amendments contain plant nutrients and act as organic fertilizers. Organic matter is an important source for bacteria, fungi and earthworms that live in the soil.

Wood Products

Wood products tie up nitrogen in the soil and cause nitrogen deficiency in plants. Microorganisms in the soil use nitrogen to break down the wood. Over several months to years, as microorganisms complete the rapid decomposition process, the nitrogen is released and again becomes available to plants. This hazard is greatest with sawdust, because it has a greater surface area than wood chips.

Compost wood products before using them as soil amendments or allow Ace Hardware to provide you with products already composted! Do not use uncomposted wood products or sawdust as a soil amendment; it is slow to break down, ties up nitrogen, interferes with seedbed preparation, and interferes with soil and water movement through the soil profile.


Fresh manure can harm plants due to elevated ammonia levels. To avoid this problem, use only aged or composted manure.

Human pathogens, including E coli, are another potential problem with fresh manure, especially on vegetable gardens. Aged manure refers to manure that has been piled for at least six months. Excessive ammonia will have escaped; however salt levels may be higher as the salts concentrate in the decomposing material, or may leach out with high rainfall. Weeds will still be viable.

Commercially composted manure has been through multiple active heating cycles and turned mechanically in between. Heated above 145 degrees F, it will kill pathogens and weed seeds. In composted manure, the organic matter is stabilized (through the rapid decomposition process) making it an ideal soil amendment.

In Stockton, California? Learn more at Fremont Plaza Ace Hardware.

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