K-Stater Studies Impact of Fort Riley Tank Maneuvers on Soil Quality

5/4/2004

From: Peg Althoff of the Kansas State University, 785-532-3780

MANHATTAN, Kan., May 4 -- When a 63-ton M1A1 Abrams tank rumbles across prairie earth, it has an environmental impact on the plants, the soil and the soil dwellers, too.

Just exactly what impact such tank training maneuvers have on the prairie is the subject of a new research project funded by Fort Riley's Integrated Training Area Management Program, or ITAM, and being conducted by Peg Althoff, a Kansas State University agronomy graduate student.

Fort Riley, a 100,656-plus-acre military reservation, has been a driver's ed training course for U.S. Army tank crews for decades. About 73,000 acres of the reservation are used for training maneuvers, and there are 127 miles of tank trails on the fort.

Such a huge and irreplaceable tract of land is an essential training facility for national preparedness, said Althoff, who pointed out that thousands of soldiers have been trained at Fort Riley for service aboard armored vehicles. "Managing the land at Fort Riley for the long haul is essential."

Her research could help determine the soil properties that would indicate to Fort Riley land stewards that a tank range is becoming over-used and degraded. Althoff works closely with range control officer Lee Breidenstein and Integrated Training Area Management Program coordinator Philip Woodford. K-State agronomy professor Stephen Thien is adviser to Althoff's project, and researchers from several departments are collaborating.

In personal correspondence, Breidenstein said that all areas of the ecosystem -- flora, fauna, soil, air, and water -- are impacted by the repeated exposure to tracked vehicles, rotary winged aircraft and by the troops. Recognizing that, the Army has established a protocol for long-term monitoring of military lands, the Land Condition Trend Analysis.

Since 1995, Phil Gipson, leader of the U.S. Geological Survey Cooperative Fish and Wildlife Research Unit in the K-State Division of Biology, and K-State statistics professor Jeff Pontius, have been assessing the plant and wildlife responses to military training exercises.

Althoff collected and analyzed data from one growing season and starts year two of her work in spring-summer 2004. "Anything we can say at this point is preliminary because we have only one season of data," she said. "Long-term research is what's needed in order to make accurate conclusions."

Althoff is evaluating physical, chemical and biological factors that might be impacted by repeated tank traffic - soil compaction, bulk density, soil texture, chemical elements, plant biomass, microbial diversity and the nematode and earthworms taxa.

She established 24 soil quality treatment plots on a less-used area of Fort Riley designated "Quebec." The study design calls for a fully loaded tank to circumscribe a figure-eight pattern five times on plots of silty clay loam and of silt loam, the two most prevalent soil types on the fort.

"Tank treatments" were carried out in 2003 after early spring rains and again at summer's end when the ground was very dry. Althoff took soil samples before and after tank maneuvers and analyzed the samples for various physical, biological and chemical factors, which are compared to similar data sets from control plots that had no tank traffic.

She collected grasses and forbs to get biomass data in order to determine rate of recovery and to watch for shifts in species composition. So far, tank maneuvers on wet soil conditions create statistically significant changes in two factors, soil bulk density and porosity.

Soil quality changes that might indicate ecosystem alteration are often quite subtle: for example, if compaction reduces soil aeration then the populations of soil-dwellers like nematodes or earthworms could decline, but the ramifications of that decline are not easy to predict, Althoff said.

Likewise, if soil changes resulting from tank maneuvers lead to shifts in the plant communities and the dominant, deep-rooted perennial prairie grasses become replaced by shallow-rooted annual plants, then soil degradations like accelerated erosion and a decline in soil-stored carbon may follow.

Althoff said the prairie ecosystem is both complex and resilient, making outcomes from this study difficult to predict.

Althoff presented the project at the Society for Range Management meeting in Salt Lake City in January 2004. She is a K- State graduate student in the crop, soil and range sciences program of the department of agronomy. If she pursues doctoral work, she plans to do three more years of data collection at Fort Riley. Althoff is a certified associate wildlife biologist. She has an associate degree in natural resources from Hocking Technical College, Ohio, and a bachelor's degree in interdisciplinary environmental science from Oglala Lakota College, South Dakota.