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Soil Tech Note 14A- Residue Accumulation

Residue Accumulation

PROBLEM:   “I don’t know, seems like none of my residue is breaking down.  It just piles up on the surface.  Is that Bt corn fault?”

 

PROBLEM OF INCOMPLETE RESIDUE BREAKDOWN: 

  • Lack of proper kind and number of microorganisms in the surface layer. 
  • Excess tillage has sealed off the surface layer from the microbes below.
  • Yes, Bt corn residue is somewhat more difficult to decompose but will break down with time and right microbes.
  • Soil surface is remaining wet or even saturated.  Anaerobic conditions exist. Compaction can be more of a problem in the surface layer. 

 

WHAT DAMAGE IS CAUSED BY EXCESSIVE RESIDUE ACCUMULATION: 

  • Residue needs to be decomposed to release the organic nutrients that are being held by the residue.  If no decomposition occurs, no organic nutrients become available.
  • Causes surface to remain wet which increases anaerobic microbes and decreases aerobic ones.   Soil respiration decreases more under these conditions.
  • Soil picks up an acidic or “sour” smell as anaerobic microbes dominate now.
  • If surface soil now remains wet longer, even light tillage can increase compaction.   

 

POSSIBLE SOLUTIONS TO CONTROL EXCESS RESIDUE: 

  • Proper mix of cover crops can increase the porosity of the soil.  More pores, more air which can lead to more aerobic microbes which will increase residue breakdown. 
  • In some cases, vertical tillage or minor mixing of thick surface residues will increase the soil-to-residue contact which will help the microbes reach and destroy the residue.