College News

Ag Instructor Vic Martin: Soil Organic Matter – How?

Great Bend Tribune
Published October 3, 2021

As of September 30, our area is again essentially unchanged.  Moderate to severe drought is continuing to creep further into the northwest corner of the state and along the border with Oklahoma.  These recent rains aren’t reflected in this report.  Fall crop harvest is well underway, however, these recent rains have at least temporarily halted progress.  It’s the same story for wheat but these rains are just what the 2021 wheat crop ordered.  The six to ten-day outlook (October 6 to 10) indicates above normal temperatures (greater than 50% chance) and below-normal precipitation.  The eight to fourteen-day outlook (October 5 to 14) indicates more of the same with a 50 to 60% chance of above-normal temperatures and normal precipitation.  Last week we discussed the value and need to increase organic matter.  This week, how can we increase organic matter levels in the soil?

First, remember for humus to develop, it will take time and won’t happen in a year or but over decades.  However, even surface residues and partially decomposed organic matter will help.

  • Soil test to make sure soils aren’t too acid as this affects microbial populations degrading organic matter.  They should be above a pH of 6.0.
  • As much as practical, rotate crops with differing growth habits (tap root vs. shallow fibrous root for example).  Try to include crops higher in nitrogen in the residue such as soybeans.  If you can include a crop such as alfalfa into a rotation, the lack of soil disturbance coupled with a deep taproot system helps, especially if you don’t till the crop up before the next crop.
  • Consider cover crops and green manures, especially legumes such as clovers and vetch.  Plants such as turnips and tillage radishes also help.
  • Try to minimize or eliminate tillage as it allows residue to accumulate of the soil surface, provides a better soil temperature and moisture environment while protecting the soil for wind and water erosion so you won’t lose the organic matter you already have.
  • Don’t forget manures and other animal waste.  These greatly enhance microbial activity and fairly rapidly increase organic matter.  Care should be taken with poultry manure as it can contain enough ammonia to make it “hot” for biological activity.  Composted manure is fine but you lose some of the benefits to the microbial population.  When using uncomposted manure or bringing in other uncomposted materials, it pays to be cautious.  They can harbor weed seed and in some cases plant diseases and insects.