Nutrient Management Research Database

Reducing emissions of greenhouse gases (GHG) from agriculture is related to increasing and protecting soil organic matter (SOM) concentration. Agricultural soils can be a significant sink for atmospheric carbon (C) through increase of the SOM concentration. The natural ecosystems such as forests or prairies, where C gains are in equilibrium with losses, lose a large fraction of the antecedent C pool upon conversion to agricultural ecosystems. Adoption of recommended management practices (RMPs) can enhance the soil organic carbon (SOC) pool to fill the large C sink capacity on the world’s agricultural soils. This article collates, reviews, and synthesizes the available information on SOC sequestration by RMPs, with specific references to crop rotations and tillage practices, cover crops, ley farming and agroforestry, use of manure and biosolids, N fertilization, and precision farming and irrigation. There is a strong interaction among RMPs with regards to their effect on SOC concentration and soil quality. The new equilibrium SOC level may be achieved over 25 to 50 years. While RMPs are being adapted in developed economies, there is an urgent need to encourage their adoption in developing countries. In addition to enhancing SOC concentration, adoption of RMPs also increases agronomic yield. Thus, key to enhancing soil quality and achieving food security lies in managing agricultural ecosystems using ecological principles which lead to enhancement of SOC pool and sustainable management of soil and water resources.

• Increasing levels of soil organic carbon (SOC) by careful agricultural management benefits grower and environment alike.
• Increase SOC improves soil structure, water holding capacity, and infiltration rates.
• Agricultural soils present an opportunity for significant carbon sequestration.
• Carbon sequestration is a process where the greenhouse gas carbon dioxide (CO2) is removed from the atmosphere, and stored in organic compounds within the soil.
• This review paper examines an array of management practices that can stimulate soil carbon sequestration.

The following topics are covered in this review:

Tillage

• Tillage can disturb soil aggregates, resulting in the depletion of SOC and release of CO2 into the atmosphere. This process is essentially the reverse of carbon sequestration.
• Conservation tillage and no-tillage practices can increase levels of SOC.

Crop Rotation

• Utilizing a series of differing crops, as opposed to a continuous system of a single crop, can help retain soil C.
• The rate of SOC sequestration depends on the specific crop rotation utilized.

Crop Residue Incorporation

• About 45% of crop residue is C, so incorporation of non-harvested crop biomass represents a source of new SOC. 
• Retaining crop residues on the soil surface, as in no-till systems, can reduce the rate of SOC decomposition.