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Galveston Monthly

Soil and Mulch

May 03, 2019 08:04PM
According to the Master Gardener Handbook, soil is produced when a parent material (rock) is acted upon by climate and vegetation over a period of time. It consists of weathered rock fragments (minerals) and decaying remains of plants and animals (organic matter). It also contains varying proportions of air, water and microorganisms.

Soil is the primary source of water and nutrients for plants, and provides the physical anchor for the plant to stand upright. Managing it and water properly and applying appropriate fertilizers at the right time are basic to producing healthy plants.

Soil can be separated into parts. Humus is dark and moist and composed of bits of dead, rotting insects, animals, leaves, roots, sticks, and food. Humus adds the nutrients to soil that plants need to grow and live.

Clay holds water and when wet feels slippery and slimy. Silt looks like fine grains of rock and sand is soil that is coarse and that drains quickly while gravel is visible rock particles.

One often reads of the importance of soil testing. The purpose of a soil test is to supply you with enough information to make a wise choice with regard to applications of soil amendments and fertilizers. A soil test conducted by the Agricultural Extension Service will provide information on texture, pH, salt content, lime content and available nitrogen, phosphorus, potassium and micronutrients.

 Some gardeners prefer to mix their own soil components thus ensuring that the soil is properlybalanced and amended to their liking. However you choose to begin, a basic recipe could start with one part garden soil, one part well-turned compost, and one part sand. Be sure to mix thoroughly for a uniform product.

The addition of sphagnum peat moss to soil will add bulk without adding weight and helps with water retention. Adding perlite to your recipe will improve drainage and allow excess water to drain away.

Nutrient sources are especially necessary when mixing your own soil; a combination of natural fertilizers will provide a long-term eco-friendly source of nutrients. Try a blend of alfalfa meal, blood, bone and fishmeal.

Soil Basics 101
First off, soil contains air, water, and humus (the decayed remains of dead animals and plants). It
is made from rocks that break apart or wear away over many years. This is referred to as weathering and may take one hundred to one thousand years to accomplish.

The tips of small plant roots move through the soil with a twisting screw-like motion. Mature trees can have as many as five million active root tips. Plants growing in a two-acre wheat field can have more than 30,000 miles of roots, greater than the circumference of the earth.

Although the soil surface appears solid, air moves freely in and out of it. The air in the upper eight inches of well-drained soil is completely renewed about every hour.

Earthworms move soil from lower strata up to the surface and move organic matter from the soil surface to lower layers. Where earthworms are active, they can turn over the top six inches of soil in ten to twenty years.

Mulching is a definitive technique to enhance and nourish that new landscape that we have spent time and precious funds to create. Mulch is defined as a protective covering, usually of organic matter such as leaves, straw, or peat, placed around plants to prevent the evaporation of moisture, freezing of roots, and growth of weeds.

The use of mulch was not a common practice until around the middle of the 20th century, when a popular gardening author, Ruth Stout, now considered the “Grande Dame of mulch” promoted the advantages of the use of mulch in her writings.

Previously, “dust mulch,” the surface layer of loose dirt left after the soil has been worked with a hoe was thought the best approach to conserve water by slowing evaporation. Years of continued use of organic mulches in home gardening have shown that the benefits of their use far outweigh the dust mulch theory.

There are two categories of mulch - organic mulch and inorganic mulch. Organic mulch is manure, compost, straw, or shredded bark chips. These bits and pieces will eventually rot, adding humus to the soil thus enriching its fertility. Inorganic mulch is the use of materials like pebbles or crushed rock.

There are many benefits of adding organic mulch to the gardens, trees and landscaping that we have recently planted.

Mulch prevents the loss of water through evaporation and reduces the growth potential
of weeds. Mulch keeps the soil at a more even temperature - cooler in summer and warmer in
winter. Decaying mulch adds nutrients to the soil and prevents soil compaction. Mulch adds color and texture to garden beds making them more attractive and interesting to the eye.

When applying mulch, spread it in a uniform thickness around plants. To add visual interest to your landscape try fine textured mulch to compliment a more formal garden, and rough textured mulch around trees.

Mulching is really nature’s idea and is one of the most important ways to maintain healthy landscape plants. Nature produces large quantities of mulch with fallen leaves, needles, twigs, pieces of bark, spent flower blossoms, fallen fruit, and other organic material. Why not take a cue from Mother Nature, and follow her example.