Keep Soil Covered

posted in: Soil health principles | 0

Part one in a series of short articles on the soil health principles by Mark J. Kopecky, New Mexico State Agronomist,
United States Dept. of Agriculture/ Natural Resources Conservation Service (USDA/NRCS)

Apple orchard in Dixon, New Mexico, with permanent ground cover. Photo: NRCS NM

Looking at the basics of soil health, I’d like to focus on the soil health principles that form the framework of our efforts. As a starting point, let’s consider the definition of soil health: 

The continued capacity of the soil to function as a vital living ecosystem that sustains plants, animals, and humans.

To accomplish this, we follow a few simple principles that guide our management:

  1. Maximize soil cover.
  2. Minimize disturbance.
  3. Maximize living plants (roots)
  4. Maximize biodiversity
  5. Integrate livestock (for simplicity, and to accommodate the illustration below, we often include this principle in Number 4).

This illustration shows how the four basic principles divide neatly into the right half  (protecting the soil) and the left (feeding the soil):

Let’s start our review of the basic principles in the lower right quadrant: 

Maximize Soil Cover. Here in New Mexico, I think this is one of the most important steps toward achieving a healthy soil. 

Soil cover provides a great number of benefits for protecting and enhancing soil life:

  • Protecting the soil from erosion (both wind and water).
  • Increasing the infiltration of both air and water—this helps to get more of our precious rainfall actually into the soil, rather than just running off to the nearest arroyo or stream.
  • Moderating the temperature of the soil– this helps to reduce evaporation (wasted water loss) and helps to preserve the microbial life and plant roots in the upper few inches of soil.
  • Providing habitat and food for surface-feeding soil organisms like earthworms, arthropods, and others.
  • Reducing physical compaction from machinery and livestock—this reduces penetration resistance for better plant root growth and protects soil aggregation, porosity, infiltration, and soil microbial habitat.

For a dramatic illustration of how helpful soil cover can be for moderating temperatures, this slide below shows what a huge effect soil cover has on surface temperature, with some of the implications for its effects on covered vs. uncovered soil.

At NRCS, a lot of our work focused on conservation practices with established guidelines.  Some of the practices we use that help to maximize soil cover include:

  • Cover Crop (340)
  • Residue and Tillage Management (329 and 345)
  • Conservation Cover (327)
  • Mulching (484)
  • Controlled Traffic (334)
  • Forage and Biomass Planting (512)
  • Prescribed Grazing (528)
Six-way cover crop mix of crimson clover, common vetch, fava, winter barley, phacelia, and Balansa clover.
A sunflower crop mulched with litter/crop residue.

Explore the next principle of soil health!

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