Soil Organic Matter

Go beyond T - Manage for C

The goal of reducing soil erosion to T (tolerable soil loss rates) generated remarkable improvements in the nation’s natural resources (Figure 2). We can achieve a new level of soil conservation by focusing on building soil organic matter or soil carbon (C).

• By emphasizing organic matter management technology, soil loss can be reduced on those lands that still suffer excessive erosion.
• Even moderate erosion rates can harm air quality, water quality, and wildlife habitat. Improving soil organic matter levels can further stabilize soil within fields and protect environmental quality (Figure 3).
• Keeping soil in place is only the beginning of soil conservation. Soil also has to function well. It must hold nitrogen, phosphorus, and pesticides in place and keep them out of surface water. Soil must deliver nutrients and water to plants as they need them. Soil should minimize the effects of floods and droughts. Organic matter helps soil perform all these functions.

Figure 2. National annual soil loss.

The pace of erosion control has slowed as we approach the goal of managing to T. However, 1.8 billion tons of soil are still lost from cropland annually, and 120 million acres of cropland are eroding at a rate greater than T.

Figure 3. Managing for soil organic matter can save more soil than managing for T.

If all cropland were managed to T, annual soil loss would decline by 0.85 billion tons. If all cropland were managed for C (SCI>0), soil loss would decline by 1.29 billion tons. Thus, conservation efforts could save an additional $8.2 billion worth of soil annually by managing for C instead of managing to T. Reaching this higher standard is possible by focusing on different conservation tools and benefits.

What does this mean for conservation?

Managing for C means using well-known technology in a new way. By addressing conservation issues from the perspective of soil organic matter instead of erosion, the focus is on enhancing the soil as opposed to managing for tolerable degradation. The full potential of cover crops, crop rotations, and reduced tillage can be exploited to address conservation concerns. Moreover, managing for C provides additional on-site benefits and incentives for the landowner, creating greater motivation for the person making the ultimate decisions about managing the Nation’s natural resources.

> Go to "How Organic Matter Works"