Soil Erosion and Agriculture Sustainability

As Southeastern Colorado enters the third consecutive year of drought, the threat of soil erosion caused by wind is increased.  Drought affects soil moisture, plant growth and the amount of crop residue left after harvesting.  Although farmers and ranchers have adopted soil conservation practices over the years, wind erosion remains one of the most serious problems impacting agricultural productivity and sustainability in this area.

Wind erosion adversely affects soil productivity by selective removal of the finer soil particles which contain plant nutrients and organic matter.  With time, this leads to degradation of soil structure (compaction of the soil and poor tilth), loss of water-holding capacity and reduced uniformity of soil conditions within a field.  Soil productivity is the capability of soil for producing a specified crop or sequence of crops under a defined set of management practices. Once the topsoil within a given soil productivity potential has been lost, the remaining soil is of much lower productivity and will have to be treated to restore its full productivity.

Before attempting to restore productivity of eroded soils, the production limitations must be identified. Some soils can be restored simply by replenishing lost fertility, other soils require more drastic restorative measures and some soils may never be fully restored.

Controlling further erosion is an extremely important part of the restoration process.  There are three primary means to control or reduce erosion or damage from wind:

Decrease the distance across a field that receives no shelter from the wind.
Form ridges with appropriate tillage equipment on the soil surface at right angles to the prevailing erosive winds.
Protect the soil surface with a covering of plant residue or growing plants.

Increasing the organic matter content is one of the most effective and practical ways to help restore the productivity of eroded soils.  The organic matter content can be increased through several soil-management practices.  These include manure additions, adequate fertilization, return of crop residues to the soil, and most importantly, conservation tillage coupled with intensive cropping systems and rotations.

Restoring organic matter over time may eventually return most of the physical properties to near their original condition, with the exception of soil texture. As the organic matter content increases, the degree of aggregation and the stability of the aggregates also increase. This in turn increases porosity, lowers bulk density, increases infiltration and increases water-recharge potential. Increasing organic matter generally increases the total water-holding capacity as well as the water-supplying capacity of the soil which is a major factor in restoring the production potential to erosion-damaged soils, especially under rain-fed water management.

Achieving soil restoration is sometimes more complex than simply adding organic amendments. However, organic amendments can be viewed as a first step for farmers and ranchers in transitioning to long-term sustainable use of degraded agro-ecosystems. Certainly, organic matter would contribute to minimizing further erosion and could also play a positive role in climate change mitigation by soil organic carbon sequestration, which in turn can reverse the processes of soil degradation.

For more information on restoration of eroded soil contact your local Colorado State University Extension Offices or visit us at: www.ext.colostate.edu/.  Also, contact your local Natural Resource Conservation Service County Offices or online at: www.nrcs.usda.gov/wps/portal/nrcs/site/national/home/

By Wilma Trujillo
Southeast Area Agronomist
Phone: (719) 336-7734
wilma.trujillo@colostate.edu