soil sealing: what it is and why it’s important

soil sealing2

Soil. A living, breathing fundamental component of the world.  Without it, we would not be able to grow food. There would be no trees and plants growing to provide us with the delicious oxygen so necessary to our existence. Our water would not be purified. We would more or less just be screwed. Yet, we continue to cover this valuable resource with impermeable materials like asphalt and concrete in an effort to build housing, roads, factories and parking lots.

Sure, we need those things too. There is no denying it. But, there are alternatives to impervious materials.They may cost a bit more, but how much exactly is clean water worth? To those without it, it is invaluable or at least much more valuable than a new parking lot. What is the value of a house that has not been destroyed by flooding? Certainly much less than one that is floating down a river towards the ocean in pieces because it was destroyed by flash flooding.

The main perpetrators of this crime against nature are suburban sprawl, a rapidly growing population, and increases in transportation demands. The rapid migration to urban areas is exacerbating this issue.

surface sealing

Some soils are naturally prone to sealing – like those in Southwest USA. However, this is often the result of  poor soil quality (issues with aggregation). There are also issues with soil sealing as a result of poor agricultural practices, such as driving large farm equipment over wet soils and leaving large tracts of land bare of vegetation which would typically improve the structure of the soil and mitigate issues created by rainfall.

Regardless of the source of sealing (although it is usually the fault of humans), the consequences of soil sealing are many including, but certainly not limited to:

  • Increased flood risks
  • Reduced groundwater recharge
  • Increased water pollution (caused by runoff)
  • Loss of biodiversity as a result of habitat fragmentation
  • Disrupted gas, water and energy fluxes

To deal with the issue of soil sealing, many steps can be taken.

The best option is to stop engaging in practices that lead to soil sealing. This means using land more efficiently and intelligently, as well as using existing infrastructure. However, we as humans sometimes have a difficult time changing our habits. This may require that alternatives to impervious concrete and asphalt be more widely used (as alternatives already exist.  see: http://www.perviouspavement.org).

In regards to agricultural causes, crop rotations should be employed, heavy machinery should not be used on wetlands, and cover crops should be planted to encourage aggregate formation and water absorption.

Should we as a species work to address the issue of soil sealing (or even take preventative measures), a myriad of negative consequences could be mitigated. Then maybe one less family will lose everything because of a flood, one less crop will be destroyed taking us one step closer to food security, and mother nature can continue to do her thing – something we can all appreciate (even if we don’t know it).

sources:

http://www.agprofessional.com/news/soil-sealing-crusting-water-erosion-and-poor-soil-health
http://www.concretenetwork.com/pervious/
http://ec.europa.eu/environment/soil/pdf/guidelines/pub/soil_en.pdf