Impact of Tillage and Long-Term Irrigation on Dynamic Soil Properties and Taxonomy in Aridic Argiustolls of Western Kansas.

Soil health and the classification of soils can be affected by humans in different agricultural practices.  In western Kansas, most of the agricultural land is irrigated under strip tillage. This study will determine how intense agricultural practices affects the classification and the dynamic soil properties (DSPs) of a soil.  To understand how DSPs are affected by agriculture practices, nine sites in Sheridan County, Kansas mapped as Keith (fine-silty, mixed, superactive, mesic Aridic Argiustolls) will be described and sampled. Of the nine sites, five are under strip till, and four have been under no-till management ranging from four years to fifteen years.  All sites have been irrigated under center pivot systems since the 1970’s.  Soil samples of the A horizon were taken at each site to analyze total carbon, aggregate stability, bulk density, pH, soil microbiology, and particle size distribution.  Field investigations showed that sites under no-till management had a higher moisture status and showed a greater presence of soil fauna.  Additional lab analysis will be completed to determine how tillage affects DSPs.  Pedons were sampled from the strip till sites in the irrigated areas as well as outside the pivot track to represent dryland conditions.  By comparing the irrigated and non-irrigated pedons, the effects of long-term irrigation on the formation of argillic horizons can be determined.  Preliminary field investigations did not show differences in clay illuvation in irrigated vs non-irrigated pedons.  The micromorphology of thin-sections will show if the argillic horizons formed through a combination of clay illuviation and in-situ weathering of mica.  Understanding the formation of agrillic horizons and DSPs of Keith soils will determine how humans alter and change these soil forming processes.