BY VINCENT J. ZAZUETA
Although it is hot and muggy, mid-summer is the ideal time to prepare the soil for our fast approaching fall planting season. For organic gardening/food systems, everything starts with building healthy soil.
It is important to understand two terms used in basic soil science: soil texture and soil structure.
Soil is classified and named according to the relative proportion of sand, silt and clay. This is known as soil texture. In the Imperial Valley, the United States Department of Agriculture (USDA) Soil Conservation Service has classified and named over fifty types of soil. To describe soil texture, names such as Holtville silty loam, Imperial silty clay and Niland fine sand are used.
One cannot change soil texture. If your soil type is Imperial silty clay, which is the soil type in El Centro, you will always have a clay soil. This is the parent material that was left in place by the ebb and flow of the Colorado River over millions of years. It is like the genes given to us by our parents, which also cannot be changed.
On the other hand, soil structure, which is the arrangement of sand, silt and clay particles in the soil profile, can be changed or modified. It is like our lifestyle, which also can be changed for the better by eating less, exercising, and eating more fruits and vegetables.
The soil structure determines the soil’s ability to absorb water and the circulation of air through the soil. Soil particles can be arranged into small groups that form “aggregates.” In a good soil, the aggregates are clumped together into larger groups that allow water, air and roots to move easily through the soil. This is referred to as the soil having a good “crumb structure”, or good tilth, this means that the soil is easy to “work.”
As stated earlier, one cannot change the soil texture. However, you can greatly improve the soil structure by adding plentiful amounts of organic matter to your soil. Organic matter can be aged barnyard manure (horse, goat, sheep, rabbit, chicken and cow), and grass clippings, which are readily available, and most importantly, compost.
Adding organic matter to heavy clay soils improves drainage and aids in better root penetration. Added to sandy soils, organic matter helps absorb water and stores nutrients.
I add organic material to my soil on a regular basis, at least two to three times per year. For example, I add two wheel barrow loads of compost to a 4-foot-by10-foot garden bed and plant carrots in October. I harvest the carrots in February and then add two more wheel barrow loads of compost to the harvested garden bed and plant basil into the same bed. Other garden beds that will stay fallow during the summer months will be put to “sleep/lie dormant” and covered with alternating layers of aged barnyard manure and grass clippings. This process is known as “sheet composting.” I will elaborate more on composting in future articles.
If you decide to start a garden anywhere in the desert southwest, be diligent about adding organic matter. Plan on incorporating an 8 to 12- inch layer of organic material into the soil before each planting season. I cannot overemphasize the importance of adding organic matter to garden soils. This is the most important thing you can do to create healthy, living soil. Everything we eat comes from the soil, and healthy soil produces healthy plants, healthy people and healthy communities. If you want more information on this garden topic or any other gardening concerns, e-mail me or better yet, come to a garden workshop I will be hosting at the Harding Elementary School Garden at the corner of Hamilton Avenue and Seventh Street in El Centro. The workshop will be on Saturday, September 23, from 8 a.m. to 10 a.m.
Vincent J. Zazueta is a Garden-Based Community Educator and earned a Bachelor of Science Degree in Agricultural Systems and Environment from UC Davis and a Secondary Science Teaching Credential from San Diego State University. He learned the love of gardening from his Grandma Josefa. He lives in El Centro and can be reached at firstname.lastname@example.org