A Glossary of Garden Soil Terms

Summary: A “dirt” glossary! Well, sort of glossary of terms for garden soils to help you while reading through some of the articles at BestPlants.com. Some words are older and seldom used and others we find used in our everyday “plant” vocabulary. We’ll be adding more and updating.

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Complete Fertilizer

A complete fertilizer is one containing all the significant elements—nitrogen, phosphorus, and potassium, and in some cases, many of the trace elements. Three-figure symbols—such as 5-10-5, 4-8-4, and 2-5-7 are generally used to indicate the proportions of these constituents in a given fertilizer.

The first figure is always the percentage of nitrogen, the second the percentage of phosphoric acid, and the last the percentage of potassium or potash. Thus, a 5-10-5 mixture is one containing 5 percent nitrogen, 10 percent phosphoric acid, and 5 percent potash.


Compost is manure made up of various fermented or decomposed materials adaptable to use as a fertilizer.

Compost results from the making of a compost pile. Which is generally composed of alternate layers of manure and absorbent vegetable refuse such as garbage, lawn clippings, leaves, sod, rubbish, etc.

An excellent source of humus, it is the best “filler” or base to use in the distribution of commercial fertilizers. It is a valuable fertilizer and soil conditioner safe for all garden plants.


A soil conditioner is the same as an amendment. Soil conditioners improve the texture of clay or sandy soils (which are deficient in natural chemicals) by linking the exceedingly tiny soil particles into aggregates. They have no food value.

Cover Crop

A cover crop is a temporary crop sown at the close of the growing season to cover the ground until early spring.

A cover crop prevents erosion and the leaching away of plant nutrients, checks perennials’ growth, and helps harden or ripen them by using up some of the soil food. When turned over in spring, a cover crop adds valuable organic material to the soil.


A soil crust is a surface layer of brittle, hardened soil that forms on many grounds as they dry out – particularly after very thorough wettings.



In the soil sense, the term cultivation includes all tillage operations from the pre-planting preparation of soil by digging or plowing through all the many after-planting stirrings of surface soil until crop harvest.

Most gardeners, however, use the term to refer only to the after-planting tillage of surface soil, which serves to kill weeds, break up a hard crust, aerate the ground and establish a dust mulch.


Damping-off is a condition that produces wilting and death, not a disease of seedlings. It occurs just before or after the seedlings emerge from the soil and is caused by many fungous parasites.

Once a seedling is affected, there’s no cure. However, damping-off can be prevented by ventilating and drying the seedbed and by pre-planting the treatment of seeds or soil with heat or chemicals.


Drainage is natural or artificial filtering or channeling of excess water through the ground slope, open ditches, and subsurface drainage using unique porous tiles.

Drainage of small, waterlogged plots can often be improved by adding coal cinders, sand, or organic matter. Drainage requirements for potted subjects always include a hole in the pot bottom.


Erosion is the wearing away of land by the action of water, wind, or other force.


Fallowing is the soil-management practice of allowing land to rest, without any crop, for one or more seasons.

The only cultivation during this period is surface tillage to discourage weeds. The purpose of fallowing is to afford soil the benefits of the uninterrupted play of sun, wind, rain, and frost on it, which builds up soil’s productive capacity and water-storing ability and serves to starve out any existing soil pests, diseases, and weeds.


A fertile soil has a good physical structure and the nutrient elements essential to plant growth – but no toxic or harmful components.

It must have the ability to retain sufficient water to support plants yet not hold an excessive amount. It must also be well aerated.


A fertilizer is any material—organic or inorganic—that, when added to the soil, hastens the growth of plants, improves their quality, increases their size or yield, and improves the soil.


A friable soil can be easily cultivated or dug. It crumbles readily in the fingers.

Green Manure

The term green manure applies to any crop grown for the sole purpose of being plowed under and thereby improving the soil by adding organic matter.


Hardpan is any hardened ‘ or cemented layer of soil which prohibits the penetration of plant roots and the filtration of water.


Heaving is the alternate rising and falling of plants in the ground caused by successive freezings and thawings. A light, well-drained sandy soil heaves only slightly. A lump of heavy clay or silt soil may throw sufficiently to lift some plants out of the ground or tear the crowns of others away from their roots.

Heavy Soil

Heavy soil is predominantly clay or silt. Its soil particles are so fine they prevent the easy flow of water and retain an excess, becoming muddy in wet weather.


Soil horizons are the several distinct layers of soil lying approximately parallel to the land surface and produced through the operation of soil-building processes. Each horizon has more or less well-defined characteristics and colors.

The upper horizon is usually dark and contains leaves, decomposed roots, and dead and decaying matter of all kinds. This surface soil with its organic residues is usually the most fertile layer.

The B Horizon, lighter in color, is made of finely ground rock particles and contains some plant roots. The third or C Horizon is composed of the original rock.