Dr Charles Rice1, Dr. Marcos  Sarto1, mr. Carlos Pires1, Mr. James Lin1

1Kansas State University, Manhattan, United States

Central USA was dominated by tallgrass prairie across a large precipitation gradient broadly representative of both current and future precipitation regimes. Much of the prairie is now under cultivation. Much research has focused on the role of the soil microbiome in the global C cycle, given soils can serve as a sink or source of greenhouse gases. These microbial functions are strongly influenced by microbial resource limitations and available moisture. Microbes also influence soil structure. Soil aggregation mediates soil chemical, physical, and biological properties and improves soil quality and sustainability. Identifying drivers of the long-term persistence of soil organic C represents another challenge for projecting future interactions between soil properties, water, and soil microbial behavior.  The aim of this study was to investigate the soil biophysical properties across a precipitation gradient with different land uses.  Soil profiles were sampled to 1m for soil C and N, aggregate structure, and microbial community composition by phospholipid fatty acid (PLFA) analysis. Microbial biomass C (MBC) in the native prairie and agriculture were not significantly affected by the precipitation gradient.  Large aggregates (>2 mm) were higher in the native prairie at central> west and east. Large aggregates (>2 mm) were higher in the native prairie relative to agriculture.

Total PLFA was higher in the native prairie with greater precipitation. Total PLFA was higher in the native prairie relative to agriculture.  Higher AMF content was found under greater precipitation regime in all land uses. The aggregate structure was highly correlated to fungal and mycorrhizal fungi biomass. Relations with C, depth, and microbial community composition are being explored.


Charles (Chuck) Rice is a University Distinguished Professor and holds the Vanier University Professorship at Kansas State University.  He is a Professor of Soil Microbiology in the Department of Agronomy.

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