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Soil Organic Matter
National trends in soil organic matter management
The amount of cropland managed using methods that improve soil organic matter
increased by 46 million acres between 1982 and 1997 (Figure 6). An additional 48
million acres, formerly with degrading organic matter trends, were taken out of
production. Organic matter levels can be improved without taking land out of
agricultural production.
What can you do?
Go beyond T - Manage for C
Land managers can focus on management practices that build soil carbon and enhance soil function
across the landscape. Practice standards important to organic matter management
include: Conservation Crop Rotation (328), Cover Crop (340), Residue and
Tillage Management (345, 329 & 346), and Residue Management-Seasonal (344), and
Prescribed Grazing (528) when used to improve the health and vigor of pasture
plant communities and to improve soil condition. In addition, appropriate irrigation technology may be important to increasing
plant vigor and biomass production.
Crop Residue Removal for Biomass
Energy Production discusses the effects on soil when crop residues are
harvested rather than leaving them in place to protect soil and build soil
organic matter.
Expect a transition period and learning curve associated with management
changes. Soil biological and physical properties will improve before increased
soil organic matter is noticeable.
Avoid single-bullet solutions
No single practice works alone to enhance soil function, and no single set of
practices works everywhere. Aim to improve soil organic matter and soil
function, rather than to implement a particular set of practices. Well-managed, continuous no-till may be the most cost effective practice in many
places, but even no-till may not stand alone. No-till should be combined with
compaction prevention, a diverse and high-biomass rotation, and other locally
relevant practices. In some areas, such as on wet and clayey soils, strip
tillage or other variations are preferable.
Protect the investment
In many parts of the country, every tillage event can reduce soil organic
matter. Occasional tillage can destroy all of the organic matter gained during
several years of no-till. Read more about the effects of crop residue removal
![The acres of cropland managed for good soil organic matter increased from 1982 to 1997.](images/fig6.jpg) |
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Figure 6. Trends in soil organic matter management.
* A positive Soil Conditioning Index (SCI)
indicates a cropping system that is likely to
result in increasing levels of soil organic
matter. |
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