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Organic Materials
Topsoil and Subsoil
Improving Soil
Inorganic Materials
Lawn Soil
Acidity and Alkilinity
Composts, Mulch
Mulch Benefits
Fertilizers
Organic Fertilizers
Foliar Feeding
Soil Maintenance
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What You Should Know about Organic Materials
The term organic material refers to living
organisms or their remains, as opposed to inorganic or nonliving rock and its decomposed
forms. Thus fallen leaves, twigs and stems, and corpses of animals are all organic. In
speaking of the organic content of soils we assume that the material is at least partially
decayed; the result of such decomposition is a black substance with a woodsy smell called
humus.
Some gardeners practically worship organic matter, while others may not appreciate it
enough. A little in the soil is almost essential for pleasant gardening; a lot is probably
a luxury, more important to you than to the soil.
In nature, soils range from the nearly organic-less desert soils and coastal sands, to the
nearly all-organic mucks of low lying areas. There is no set organic content that makes a
garden soil good. The best prairie soils seldom have more than a few percent organic
content, which is a clear indication that small quantities have great influence. It takes
only a few percent of organic matter to make any soil friable and more responsive. By and
large, inland soils contain less organic matter than coastal ones, because where
temperatures are generally higher, all biological activity is speeded up, including
decomposition.
Most of the humus in soils has accumulated through the ages from plants and animals that
have died. However, Man adds organics when he spreads manure, compost, processed wastes,
forest residues such as redwood compost or shredded barks, and agricultural residues such
as rice hulls and seed meals. All of these materials return to the soil essentially the
same elements that were extracted from it to make the plants or animals that fed upon
them. As an additional good point, organics also provide food for the many microorganisms
in the soil that are on the whole beneficial to its structure and fertility.
With so many seeming advantages, it is easy to overestimate the importance of organic
materials. The fact is, that crops can be grown year after year on the same soil without
the addition of organic material. Of course, ample fertilizer is used. Some of the most
expensive, productive land in the country--the Central Valley and other irrigated soils of
our State and Arizona--yield excellent harvests though the soil is almost devoid of
organic content! With enough fertilizer and constant soil management practices you can
grow a lawn and garden on almost any soil. But you cannot necessarily make the soils easy
and pleasant to dig into without plenty of organic material.
NEXT: The
Differences Between Topsoil and Subsoil |
