Identifying water availability with maize phytoliths in Range Creek Canyon, Utah

Abstract

In arid and semi-arid regions, systems of water management and irrigation are crucial for successful crop production, and therefore provide valuable information regarding human behavior and the environmental constraints under which they operated. Unfortunately, structural evidence of irrigation can be difficult to locate, prompting various studies to evaluate the utility of phytolith analysis as a means of identifying past water availability. Evidence suggests the ratio of long-cell to short-cell phytoliths is an effective measure of relative water availability in some important economic crops such as wheat, barley, and sorghum. Expanding on this, the present research applies a similar method of analysis to determine the utility of maize (Zea mays) phytoliths for understanding past water availability. Experimental maize crops receiving different amounts of irrigation were grown in Range Creek Canyon, Utah, a canyon in the northern Colorado Plateau occupied by Fremont populations most heavily from around 800-1100BP. The production of long-cell and short-cell phytoliths from maize leaves, husks, and tassels is analyzed using statistical modeling. Results suggest the ratio of long-cell to short-cell phytoliths in maize increases as a function of increased water availability. The statistical models indicate maize phytoliths are an effective tool for inferring past water availability. By examining maize phytolith assemblages from archaeological contexts, analyzing the inferred available water, and comparing to relative climate and precipitation records, systems of irrigation can be identified and better understood.