ARS | Publication request: Hunting Nutrients and Trapping Carbon

Submitted to: Workshop Proceedings
Publication Type: Proceedings/Symposium
Publication Acceptance Date: January 19, 2007
Publication Date: January 30, 2007
Citation: Nichols, K.A. 2007. Hunting Nutrients and Trapping Carbon. Meeting proceedings for the 11th Annual No-Till on the Plains Winter Workshop, Salina, KS, Jan. 30-31. pp. 66-69.

Interpretive Summary: Soil is home to many organisms that convert nutrients into plant available forms by processes such as organic matter decomposition and nitrogen fixation. Symbiotic organisms, like mycorrhizal fungi, deliver nutrients to plants in exchange for simple sugars that the plant produces in abundance by photosynthesis. The bodies of mycorrhizal fungi are thread-like filaments, called fungal hyphae, that grow beyond the nutrient depleted area around plant roots to deliver more nutrients to the root from the soil, especially immobile nutrients like phosphorus. The fungal hyphae also helps to improve soil structure by forming a hyphal `net¿ to trap soil particles and debris to form aggregates. Glomalin, found on the hyphae of arbuscular mycorrhizal fungi, protect hyphae from nutrient loss, acting like ¿PVC coating¿ on the cardboard tube (hyphae). Glomalin sloughs off into surrounding soil particles and contributes to the formation and stabilization of soil aggregates. Soil aggregation is the formation of a conglomeration of sand, silt, clay, organic matter, such as plant debris, and inorganic compounds like iron oxide. Glomalin provides a protective coating to aggregates to stop them from breaking apart into smaller, erodible particules. Aggregates increase the soil¿s stability against wind and water erosion, maintain soil pores, which provide air and water infiltration rates favorable for plant growth, improve soil fertility by holding nutrients in protected micro-sites near the plant roots, store carbon by protecting organic matter from decomposition, and assist in nutrient cycling.

Technical Abstract: Soil fertility is enhanced directly by arbuscular mycorrhizal fungi (AMF) efficiently absorbing the maximum amount of nutrients available and indirectly by formation of stabilized soil aggregates. Glomalin is sticky, not easily soluble substance, on AMF hyphae and provides a protective coating to bind aggregates together. In systems managed for improved soil quality, the amounts of water-stable aggregates and glomalin in the soil are high. Management for soil quality includes reduced or no tillage, continuous cropping, and reduced synthetic inputs.