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Monday, January 16, 2017

War on Crop Residue

2017 marks my 40th year in the business of soil management. In 1977 when I started working s a soil scientist, there was still a big question as to the effects of conservation tillage on crop yields. Farmers led the way in proving that top yields could be had even with high surface residue. In the past year, I have noticed that there seems to be a war on residue.  Tours at John Deere and Greg Sauder's Yield Center 360 both unveiled tillage equipment that looks to imitate moldboard plowing without moldboard plowing.  Burying residue seems to be becoming accepted management.It was refreshing last week to attend the National No-Till conference and see that there are still people out there that are interested in leaving residue on the surfacefor soil health benefits and erosion control.

Last week I read an Article in October Prairie Farmer "Residue Impacts on Corn Yield". The Article list 5 problems with crop residue that I will attempt to debunk.

1. Residue saps moisture.  While residue sticking down into the planting slit can wick moisture, a well adjusted planter will overcome that issue easily. Residue other than in the planting slit covers the soil and conserves moisture. 

2. Insulation effect.  Residue can keep soil temperatures lower than bare soil. This issue can be overcome two ways.  One, light vertical tillage can cut up residue and get it to decompose a bit to get some bare soil.  Two, Row cleaners move trash away from the planting area allowing soil to warm up as needed when seeds are planted.  The added bonus of the insulation effect is that as temperatures rise into the summer, crop residues keeps ground and field temperatures closer to ideal.

3. Toxic Environment. They say that too much decomposing residue adds toxins to the soil.  Residue on the surface is not a problem.  Incorporated residue could be a problem, especially in a corn on corn situation.  Rotate to a different crop.

4. N and P Stealer.  There are lots of ways to overcome this. Adequate P levels in the soil will reduce P tie-up.  Nitrogen may be tied up, but once again. adequate fertilizer N will help to make nitrogen available when the crop needs it.  Residue on the surface is not the culprit.  Cover crops can also help. 

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