PS 28-139
Heterogeneous row-crop soil environments to harbor diverse, system-stabilizing mycorrhizal fungi

Tuesday, August 6, 2013
Exhibit Hall B, Minneapolis Convention Center
Patrick M. Ewing, Agronomy and Plant Genetics, University of Minnesota, Saint Paul, MN
Nicholas R. Jordan, Agronomy and Plant Genetics, University of Minnesota, Saint Paul, MN
Sheri C. Huerd, Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN
Yi Lou, Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Urbana, IL
Anthony C. Yannarell, Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Urbana, IL
Background/Question/Methods

Row crop agriculture in the US Corn Belt is under the dual pressures of an increasingly variable climate and a need to improve regional environmental quality.  Arbuscular mycorrhizal fungal (AMF) provide plant- and ecosystem-benefitting services that could help agriculture face these pressures.  AMF communities in intensively-managed agroecosystems, however, generally are considered to be low-diversity and low-functioning.  This phenomenon is attributed to the major land management choices of monocropping, tillage, and broadcast fertilization, which all have the same effect of homogenizing the soil environment at the sub-20cm scale.  Recent evidence suggests that niche partitioning and competitive exclusion play a major role in structuring AMF communities.  Therefore, re-introducing heterogeneity to the soil environment through a tilling management class called precision zonal management (PZM) could restore the beneficial services that AMF provide.  We hypothesize that PZM-induced soil heterogeneity diversifies the composition of surface AMF communities in corn and soybean fields in southern Minnesota and central Illinois.  We further predict that subsurface communities will act as a pool of diversity that restores surface community composition and function. 

Results/Conclusions

Initial results support our hypotheses.  Differences (Bray-Curtis dissimilarity) between ridge and furrow communities in PZM systems for both bacterial (r2 = 0.387) and fungal (r2 = 0.564) communities increases as fields age, while nonmetric multidimensional scaling shows fungal communities in Minnesota cluster by PZM or chisel plow management.  Additionally, T-RFLP analysis shows multiple AMF taxa as deep as 40-60 cm that could potentially colonize surface environments.