MADISON, WI, NOVEMBER 17, 2008 —
One of the biggest threats to today’s farmlands is the loss of soil
organic carbon (SOC) and soil organic matter (SOM) from poor
land-management practices. The presence of these materials is essential
as they do everything from providing plants with proper nutrients to
filtering harmful chemical compounds to the prevention of soil erosion.
Sustainable management practices for crop residues are critical for
maintaining soil productivity, but being able to measure a loss in the
quality of soil can be difficult.
In an article published in the Soil Science Society of America Journal,
a team of USDA-Agricultural Research Service (ARS) scientists detail a
method of measuring soil quality using a new model. The researchers
combined their knowledge of crop, soil, and climatic data to predict
long-term SOM and SOC changes to evaluate the effect of an array of
management practices, including crop residue removal, on long-term SOC
levels by using this new model. CQESTR, pronounced “sequester,” a
contraction of “C sequestration” (meaning carbon storage), is a
process-based model developed by ARS scientists at the Columbia Plateau
Conservation Research Center in Pendleton, OR.
Four long-term experiments with several management
systems were selected to examine the ability of the model to simulate
the long-term effects of management practice on SOC dynamics. These
management systems included crop rotations, tillage practices, and
organic amendments, as well as crop residue removal. The results showed
success in predicting both SOC depletion and sequestration.
At a time when the role of agriculture is expanding
to include many different roles in society, including the production of
cellulosic ethanol, the ability to predict the loss of SOC and SOM is
essential to maintaining productive crops. The model can be used to
consider a wide range of scenarios before making recommendations or
implementing proposed changes to management practices. In conjunction
with the local conditions, the model can guide planning and development
of sustainable crop and soil management practices.
“The development of soil management practices that
maintain adequate SOM for nutrient cycling, soil structure stability,
and sufficient biomass to prevent erosion is essential for decisions on
land use for food, fiber, feed, and bioenergy,” says Hero Gollany, one
of the article’s authors and an ARS soil scientist.
The model has great potential to be used by all land
managers to guide the amount of crop residue that can be sustainably
harvested as feedstock for biomass ethanol and bio-based products
without degrading the soil resource, environmental quality, or
productivity. More studies are still needed to evaluate the model’s
performance in predicting the amount of crop residue required to
maintain the SOM concentration in different soils under a range of
management and climatic conditions.
The Soil Science Society of America (SSSA)
is a progressive, international scientific society that fosters the
transfer of knowledge and practices to sustain global soils. Based in
Madison, WI, and founded in 1936, SSSA is the professional home for
6,000+ members dedicated to advancing the field of soil science. It
provides information about soils in relation to crop production,
environmental quality, ecosystem sustainability, bioremediation, waste
management, recycling, and wise land use.