In the beginning.
When early settlers first discovered virgin
prairie land, they were pleased to find highly productive soils. This was
largely due to the fact that these lands had never been plowed which resulted
in large amounts of organic matter that released nitrogen into the first
crops. However, as time progressed, organic matter declined along with
nitrogen output, and this resulted in a decrease of crop yields. The settlers
assumed that the soil was worn out and moved onto other land or let the
unproductive land rest, which allowed organic matter to build up again.
As the years passed and the settlers gained knowledge of soil health and
productivity, they discovered that nitrogen levels could be regained with
legumes, manures, and later with commercial fertilizers.
Much like the early settlers, today’s farmers
want healthy soil and improved productivity. Many have turned to
conservation tillage which is a way of growing plants that keeps the soil
from blowing or washing off fields. Conservation tillage can conserve
natural resources, optimize crop productivity through controlled erosion,
reduce soil compaction, increase water use efficiencies, and reduce energy
costs. Extensive research in the sandy soils of the Southern Coastal Plain
indicate that conservation tillage is a promising and fruitful technology
for the health of our soil and higher crop yields.
The long term benefits.
Many farmers practicing conservation tillage
alternate with conventional tillage. Conservation Agronomist Gene Hardee
of the USDA-Natural Resources Conservation Service (NRCS) agrees that this
alternation system can, “provide the farmer with several benefits such
as saved time and erosion control.” “However, to noticeably improve soil
quality, conservation tillage should be practiced continuously.” Jack Gibbs
agrees. “We didn’t see much difference until about five years. The first
year we did see some decrease in soil erosion, but crop yields were the
same and soil health too. But, after we had done it for awhile, we noticed
the moisture that built up in the soil and the overall improvement in the
soil health was obvious. It is definitely something you have to wait for
to get results, but it’s worth it.”
Conventional vs. Conservation.
Studies have shown that tillage of the soil
accelerates the decomposition of soil organic matter much like fanning
a fire. NRCS District Conservationist Louis Jackson from Sumter County
confirms that, “One disking reduces the organic matter to levels similar
to those in a conventional tillage system.” There is a big difference in
comparison of organic matter and distribution with the plow (conventional)
versus no-till systems (conservation). The plow inverts soil and places
crop residue deep below the surface. This results in an increase in soil
surface temperature and oxidation rates, thus accelerating organic matter
decay. Results indicate that plowed soil will lose from 20 to 50 percent
of its soil carbon content as a result of plowing. However, conservation
tillage leaves at least 30 percent of the field covered with residue from
previous crops after planting. Corn stalks, wheat, or soybean stubble help
hold the soil in place and reduce erosion by 50 percent of more. By adding
organic residues to the surface and leaving the existing organic matter
unharmed, the amounts of organic matter increases in the upper few inches
of the soil. This is beneficial because as soil organic matter increases,
soil health is improved partly because soil particles are glued together
into larger, more stable aggregates (Soil Quality-Agronomy Technical Note
No. 9, Soil Quality Institute, Auburn, Alabama). This increase in aggregation
and stability has the following effects:
The proof is in
the data.
A study performed in Indiana in 1992 illustrated
that after five years of continuous conservation tillage corn, aggregation
in the top two-inches of soil had increased by 120 percent for no-till.
After five years, the field was plowed and the aggregation index returned
to its original level.
Other studies have documented the long-term
effects of conservation tillage, thus proving the benefits of continuous
systems. A long-term study conducted at the Pee Dee Research and Education
Center near Florence, SC, was started in 1979 that set out to determine
if conservation tillage could increase the carbon content (organic matter)
of a Norfolk loamy sand with a cropping system of corn, cotton, soybeans,
and wheat. In the beginning of the experiment the carbon content remained
stable. But, in years nine to 14, the carbon content was nearly doubled.
Save time and money.
Conservation tillage can cut down on tractor
trips across the field, save money, and lessen the potential for soil compaction.
No-till is the purest form of conservation tillage in which there is no
mechanical soil preparation before planting. Gibbs has experimented with
the new equipment and chemicals available for conservation tillage and
has used his technical skills and imagination to create his own unique
devices. “I bought a rig designed for no-till and made a few minor adjustments
to fit my needs. Other farmers have asked me about my equipment and my
success with no-till and I tell them the same thing everytime—it works.
“ Conservation tillage has become a way of life for Gibbs and was passed
down to him from his uncle. It is a way of life that has benefited the
Gibbs family, like many other farmers have discovered, and it also benefits
our environment. Continuous conservation tillage systems build organic
matter in the soil which improves food productivity and will also protect
water quality and enhance wildlife habitat. If you would like to learn
more about conservation tillage, contact your local USDA Service Center.