Ag Instructor Vic Martin: Life Below the Surface

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Great Bend Tribune
Published September 20, 2020

The Drought Monitor shows little change from last week, however, the dry/droughty areas will likely expand west from the Colorado border counties with the forecast for the week.  As of this report, our area is not even listed as abnormally dry regarding soil moisture.  There is moisture present in most area soils near the surface for wheat planting, however, with temperatures forecast in the eighties and as of today, slim chances for rain, things could become a bit touchy.  On the plus side the forecast is pretty ideal for drying down and harvesting fall crops.  The six to ten day outlook (September 23 to 27) has well-below normal precipitation and above normal temperatures for the region.  Looking out eight to fourteen days (September 25 to October 1) indicates essentially more of the same.  Not a bad forecast for bringing in the fall harvest but less than ideal for establishing the 2021 wheat crop.

Currently, there are articles and reports out everywhere regarding what to do planting wheat this fall.  Instead of focusing on that, let’s turn our attention to what we can’t easily see but is vital in crop production – life below the soil surface.

Space won’t allow for an in depth discussion of the soil environment so let’s hit the high points.

  • We tend to focus on the negative aspects of what is going on underground, insects, diseases, etc., however, the same types of micro and macro invertebrates, and microorganisms are critical to a positive soil environment for crop growth.  And these beneficial organisms thrive in the same type of physical and chemical environment as our common crop plants.  So, in general terms, what are they and what do they do?
  • Microorganisms such as bacteria, nematodes, and protozoa are thought of as detrimental and a small group are, however, most are benign or beneficial.  Many nematodes, microscopic round worms, are predators feeding on insect larvae, fungi and other microorganisms.  Bacteria help with decomposition of organic matter and in the process create stable organic matter and release plant nutrients. Certain bacteria are able to fix nitrogen, convert nitrogen gas to plant available nitrogen, in the soil.  Other invade the roots of legumes such as soybean and alfalfa and provide them with nitrogen.  Protozoans are predators feeding on bacteria. 
  • While we think of fungi as strictly negative, they play a vital role in breaking down organic matter, cycling nutrients, and some species infect plant root systems and essentially provide a “shadow’ root system that enhances plant water and nutrient uptake.  Some plants can’t survive without this association.  Remember they are also the source of antibiotics.
  • Earthworms aid in soil mixing of organic matter and soil amendments while also helping create a stable macropore system for aeration and plant root exploration.
  • Termites and ants also help break down organic matter.  Certain ant species are also predatory. 
  • Interestingly, the soil environment most ideal for crop growth, favors these beneficial organisms.  And a poor soil environment favors the negative species.
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