Minimizing Soil Disturbance

Driving through a landscape allows you to observe fields with and without soil disturbance. Physical disturbance or tillage is the easiest to see. Biological soil disturbance or limited photosynthetic time and limited plant diversity, along with chemical soil disturbance or pesticide use are more difficult to see.  Let’s look at a few terms listed below in a rough chronological order to better understand US agriculture; and yes, they do overlap. These last 80 years will vary from region to region and even from farm to farm with the US.

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Tillage – Tillage is as old as crop production and is well recorded in historical documents.  Now we fast forward to the present and ask ourselves a simple question. How much soil loss can we tolerate per acre or per bushel?  For myself as a long-time conservationist the answer is zero.  The reasons listed for tillage are lengthy, but usually have little to do with managing wind and water erosion, water quality and quantity, building soil aggregates, or carbon. Early Best Management Practices for erosion control consisted of strip cropping, contour cropping, windbreaks, terraces, diversions, and waterways, to name a few. These were attempts to slow soil degradation with narrow fields and structural practices.  Basically, treating symptoms instead of the problem.  For example, installing a waterway to heal water erosion versus improving the drainage area infiltration.  That said, it was the early start of natural resource conservation. Biological disturbance was lower during this period, as we had more plant diversity, perennials, and livestock on the landscape.  Chemical disturbance was lower during this period too but was starting to increase.  Overall soil degradation was significant during this time period.

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Conservation Tillage – This agricultural term was commonly used for decades.  Usually, this effort consisted of tillage implements which left more residue on the soil surface and used less plowing. Field size expanded and tractor speeds increased. Biological disturbance increased due to a loss of plant diversity, perennials and livestock; resulting in less photosynthesis and less plant exudate diversity. Chemical disturbance increased also, with more fertilizer and pesticide use. However, it was a step in the right direction from the viewpoint of emphasizing the importance of conservation. Soil degradation slows but continues.

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No-till – We started to see a significant drop in erosion and related natural resource concerns. My first monitored soil organic matter gain was recorded in an early 1990’s no-till cropping system, more farms soon followed. Thanks to the work of scientists like Dr Dwayne Beck, Retired Research Manager at Dakota Lakes Research Farm in Pierre, South Dakota; we also started to understand that no-till systems are designed to work with diversified crop rotations. While physical disturbance decreased, biological and chemical disturbance continued to increase. Simplified crop rotations used chemical disturbance to offset limited plant diversity. Now conservation was partnered with the no-till planting concept. Another step in the right direction.

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Soil Health – Dynamic Soil Properties became important indicators. For example, soil aggregates, infiltration, soil organic matter, water and nutrient holding capacity, and bulk density to name a few.   Plant physiology helped further unravel the carbon cycle.  Soil demonstrations like slake, wind erosion model, and the rainfall simulator were commonplace. Again, physical disturbance decreased, biological disturbance decreased with the use of cover crops which returned photosynthesis activity and plant diversity, while chemical disturbance continued to increase.  Now conservation was partnered with soil health.

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Regeneration – Greenhouse gases (carbon dioxide, methane, and nitrous oxide) are in the forefront. Soil Health Principles are used to rebuild our soils.  Focusing on carbon (the food) for example, and asking is more carbon coming into our systems than is leaving?  Understanding an overall balance is needed to regenerate or rebuild a soil.  More emphasis is placed on nutrient density, both in crop production and grass finishing meat proteins. Realizing that Agriculture is an extraction business and asking what we are willing to do to offset nutrient export.  Physical disturbance improves, biological disturbance improves, and chemical disturbance has improved with some pesticide use reduction.  

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