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

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.