College News

Instructor Vic Martin: The Soil Ecosystem – Part 2

Great Bend Tribune
Published February 24, 2024

The drought monitor report as of February 20 is easy this week as the entire state is unchanged.  Especially good news for Southwest, and the majority South Central and much fo Northwest Kansas.  Wheat is greening up nicely overall and in much better condition than the last several years.  The six to ten-day outlook (February 27 to March 2) indicates a 60 to 70% chance of above normal temperatures and normal for precipitation.  The eight to fourteen-day outlook (February 29 to March 6) indicates a continued 60 to 70% chance of above normal temperatures and near normal precipitation.  Normal for the entire month of March is around 2.5 inches of liquid precipitation.

Last week, we briefly discussed the importance of soil microorganisms and some invertebrates in the soil ecosystem and their importance to plant communities.  Whether the native plant community, from grasslands and forests, or our crop plants.  This week, let’s briefly discuss some of the ways we can promote healthy fauna in our crop soils.

  • Depending on your location in the state, you may deal with acid soils.  Much of the western third of the state has soils with a pH above 7 and are basic, alkaline.  Much of the area south of the Arkansas River and especially as you head south/southeast does deal with acid soils, especially under long-term cereal grain and corn production.  Our crops, microbes, and earthworms prefer a pH above 6.2 (7 is neutral).  As pH goes below 5 and especially as it heads towards 4, beneficial microbes disappear and fungi, especially disease-causing fungi predominate.  And in certain soils, aluminum levels can damage crops and microbes.  Therefore, liming acid soils not only benefits your crop but the microbial community.
  • Beneficial microbes and earthworms, and your plant roots, need oxygen and a soil with a good mixture of pore sizes and continuity provide good oxygen levels and water storage and infiltration.  It also allows for better root growth and for earthworm activity.  This can be achieved by minimizing tillage, if possible no-tillage.  And allowing residue to accumulate at/near the soil surface. 
  • Microbes need food – a carbon source and preferably one with nutrients such as nitrogen, sulfur, etc.  This serves several purposes.  It is a food source to promote microbial activity.  As the fungi and bacteria decompose the organic matter (plant residue, manure, cover crops, and so on) release nutrients in inorganic forms available to plants.  It also provides humus, stable organic matter, which decreases bulk density, increase soil water and nutrient holding capacity, and increase beneficial soil structure.  This takes time and there are several ways to slowly improve organic matter levels.  First, minimize or even eliminate tillage.  Next plant crops where the residue is higher in nitrogen than cereal grains and corn.  Soybeans, alfalfa, and canola will work.  If it fits your operation, cover crops, especially those terminated while actively growing greatly boost microbial activity.  If available, uncomposted manures fit the bill nicely.  The one exception is chicken manure and with the relatively high ammonia levels, composting is recommended.

There’s more naturally, but this provides an idea of what to do do.