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The soil is a complex ecosystem
Dr. Victor Martin

The drought monitor report as of Feb. 13 shows marked improvement from the prior week. We are at 49% of the state completely out of dry conditions, up 13% from the prior while a year ago that number was seven percent. None of the state is now in exceptional or extreme drought, only two percent in severe drought. This is an extremely significant change from a year ago at this time. The six to ten-day outlook (Feb. 20 to 24) indicates a 70 to 80% chance of above normal temperatures and a 33 to 40% chance of leaning below normal for precipitation. The eight to 14-day outlook (Feb. 22 to 28) indicates a 60 to 70% chance of above normal temperatures and near normal precipitation. On average by the end of February, precipitation amounts start to increase.

Today, as we head towards spring, and all that it means for agriculture, let’s take time to discuss the soil as an ecosystem. An ecosystem is defined as: “the complex of a community of organisms and its environment functioning as an ecological unit.” We most often think of the soil as the mineral component, the plant community, as an anchor for plants, and a source of water and nutrients. It has an environment connected to and influenced by the terrestrial ecosystem, yet has its own unique characteristics. An example is an atmosphere higher in humidity, lower in oxygen, and higher in carbon dioxide that what we breathe. While it has daily and seasonal temperature changes as we experience, these changes are slower and as you go deeper into the soil, the daily temperature changes and extremes decrease. These are just some of the differences between where we exist and the soil ecosystem. However, let’s briefly focus on a part of the soil playing a critical part in the health of the soil, plant life, and really all life on earth – soil microorganisms.  

• Here we are referring to fungi, bacteria, nematodes, and viruses as the microbial community. There are certainly negative species of these present in all soils but they are overall a small fraction of what is present. As we briefly mention these important functions, keep in mind that our goal in agriculture is to promote and protect these beneficial organisms as they are critical to economical, environmentally sound crop production.

• Perhaps the most important function of fungi and bacteria is the breakdown and recycling of organic residue. It may be plant residue, manures, animal carcasses, the remains of living organisms and their byproducts. Without them, we would be buried in a sea of organic residue. They use these materials as a carbon and nutrient source, breaking them down into smaller fragments until we are left we humus, stable organic matter important in soil structure along with water and nutrient holding capacity.  Further as they decompose this material, they will release nutrients such as nitrogen and sulfur in to the soil and make it plant available. Another example is fungi that can form a symbiotic relationship with plant roots. Some plants can grow without this relationship. Or bacteria infecting the roots of legumes and provide the plant with nitrogen – think soybeans and alfalfa.

Next week:  How can we improve the soil microbial environment.

Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207, or