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United States Department of Agriculture

Agricultural Research Service

Research Project: SUSTAINABLE AGRO-ECOSYSTEMS THAT CONTROL SOIL EROSION AND ENHANCE THE ENVIRONMENT

Location: Wind Erosion and Water Conservation Research

Title: Soil Fungal Distribution and Functionality as Affected by Grazing and Vegetation Components of Integrated Crop-Livestock Agroecosystems

Authors
item Davinic, Marko -
item Moore-Kucera, Jennifer -
item Acosta-Martinez, Veronica
item Allen, Vivian -
item Zak, John -

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 23, 2013
Publication Date: April 1, 2013
Repository URL: http://www.sciencedirect.com/science/article/pii/S0929139313000401
Citation: Davinic, M., Moore-Kucera, J., Acosta Martinez, V., Allen, V.G., Zak, J. 2013. Soil fungal distribution and functionality as affected by grazing and vegetation components of integrated crop-livestock agroecosystems. Applied Soil Ecology. 66:61-70.

Interpretive Summary: Agriculture in the Texas High Plains has been largely dependent on irrigation water from the Ogallala aquifer, however, the region is experiencing significant reductions in the water available from this aquifer. For the past 16 years, an interdisciplinary research team from Texas Tech University, Texas AgriLife, High Plains Underground Water Conservation District No. 1 and USDA-ARS has being evaluating the sustainability of integrated crop and livestock (ICL) production systems according to their economic profitability, energy requirements and effects on soil quality and functioning. The ICL agroecosystems are characterized by a mixture of perennial or annual vegetation grazed by livestock and annual harvested crops, which has been suggested to conserve water and to achieve other environmental and economic goals compared with monoculture cotton production. This current study focused on soil fungi as they play an essential role in the transformation of organic matter and nutrients and soil structure stabilization; however their specific role in organic matter transformations in ICL agroecosystems had not been studied. The study evaluated mycorrhizal and saprophytic fungal populations and saprophytic fungal functionality under a continuous cotton system and two ICL agroecosystems: 1) a non-irrigated system with a paddock for native grasses (old world bluestem; OWB) and a paddock for a cotton and foxtail millet rotation; and 2) a deficit irrigated system with a paddock for OWB and a paddock for bermudagrass. Abundance of both saprophytic and mycorrhizal fungal populations were higher under ICLs compared to the continuous-cotton system at 0–5 cm. Overall, vegetation impacted the distribution of the fungal FAME markers, whereas the fungal saprophytic functionality was more sensitive to grazing (vs. non-grazed areas available in both ICLs). Perennial vegetation (grasses) of ICLs was associated with an increase in fungal markers (saprophytic and mycorrhizal) as well as increased soil organic matter content. Among the grazed perennial vegetation, bermudagrass showed the highest fungal abundance and functional diversity values. These fungal improvements were also reflected in the highest organic matter content under this grass, potentially indicating improved sustainability under the ‘WW-B. Dahl’ old world bluestem and bermudagrass agroecosystem.

Technical Abstract: Integrated crop and livestock (ICL) agroecosystems are characterized by a mixture of perennial or annual vegetation grazed by livestock and annual harvested crops. Compared to annual crops, ICLs hold the potential to enhance soil organic matter (OM) inputs, carbon sequestration, nutrient cycling, and water conservation. Soil fungi play an essential role in the transformation of OM and nutrients and soil structure stabilization; however their specific role in OM transformations in ICL agroecosystems has not been studied. This study evaluated mycorrhizal and saprophytic fungal populations (via fatty acid methyl ester profiles; FAME) and saprophytic fungal functionality (via FungiLog analysis) under two ICL agroecosystems and a continuous cotton (Gossypium hirsutum L.) system in the Southern High Plains of the U.S. The first ICL system included non-irrigated perennial native grasses, an annual cotton and foxtail millet (Setaria italica) rotation and deficit-irrigated ‘WW-B. Dahl’ old world bluestem (Bothriochloa bladhii; OWB). The second ICL agroecosystem consisted of deficit-irrigated OWB and bermudagrass (Cynodon dactylon). The effect of grazing by cattle was evaluated via grazing exclusion areas. Abundance of saprophytic fungal FAMEs (10–26% of total FAMEs) and mycorrhizal FAMEs (2–24% of total FAMEs) were higher under ICLs compared to the continuous-cotton system at 0–5 cm. Overall, vegetation impacted the distribution of the fungal FAME markers, whereas the fungal saprophytic functionality was more sensitive to grazing. Perennial vegetation of ICLs was associated with an increase in fungal markers (saprophytic and mycorrhizal) as well as increased soil OM content. Greater utilization of multiple C sources and increased saprophytic fungal functional indices were found under cotton, non-grazed perennial vegetation (with exception of bermudagrass) and the rotation under millet. Among the grazed perennial vegetation, bermudagrass showed the highest fungal FAMEs abundance and functional diversity values. These fungal improvements were also reflected in the highest OM content under this grass, potentially indicating improved sustainability under the OWB and bermudagrass agroecosystem.

Last Modified: 9/20/2014