Central Region Mineral Resources Science Center

Soil geochemistry and microbial characteristics on cultivated/irrigated versus non-cultivated/nonirrigated (grassland) sites in western Nebraska

Task Objectives

Because of demands currently placed on soil ecosystems and because of the increased awareness of the possibility of bioterrorism aimed at the agricultural productivity of the nation, there is an increasing need for better understanding of the factors controlling soil health, biodiversity, and resilience, and of the interrelationships among these factors. The health of a soil is determined by many factors, among which three of the most important are: 1) the original composition of the soil; 2) the nature of the microbial community in the soil; and 3) land use management. We propose to determine the geochemical signature (including both total and partial extractions), mineralogy, and microbiological characteristics of both an irrigated agricultural site and a non-irrigated grassland site in Nebraska. We will conduct these studies on sites in Nebraska selected for investigation by the High Plains Study Unit of the USGS National Water Quality Assessment (NAWQA) Program.

This task focuses on the matrix of variables for relating geology, hydrology, soil type, soil geochemistry, land use, and microbial ecology. The study sites within the state of Nebraska have been selected with the intent of holding geologic setting, hydrology, and soil type constant while varying the land use (irrigated agricultural versus non-irrigated native grassland). We will focus on the following issues:

1. What is the microbiological variability between an agricultural and native grassland site with similar geology, geochemistry, and pedology?
2. What is the variability of geochemistry and microbiology among the Nebraska sites and sites of grossly different geologic setting and soil types in California and the northern Appalachian Basin?
3. What is the impact of irrigation, fertilization, and pesticide application on soil microbiology?

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