|Morris, Lesley -|
Submitted to: Conservation Research Report
Publication Type: Other
Publication Acceptance Date: December 17, 2010
Publication Date: December 21, 2010
Citation: Morris, L., Monaco, T.A. 2010. Land-use legacies from dry farming in the Park Valley area of Box Elder County. Conservation Research Report. 1:1. Technical Abstract: Last fall in this newsletter, we reported on the initiation of a study on the land-use legacies of dry farming in the Park Valley area. Land-use legacies are the long lasting impacts of historic land uses; such as, cultivation for dry farming. The Park Valley area and Box Elder County experienced a "land boom" beginning in 1910s due to dry-farming homesteads and land purchases. To establish a dry farm, land was first cleared of sagebrush and other vegetation, plowed 7 to 10 inches deep, and then "harrowed" with a wide frame, fixed with large teeth or spikes to pulverize the soil. The legacy of this soil disturbance can still be seen in many places today nearly a century after these fields were first cultivated. We began analysis on the differences between dry-farmed lands and adjacent noncultivated areas by measuring vegetation cover and species composition differences. We found less cover of sagebrush in the old fields even though they had not been cultivated for nearly a century. Greasewood and rabbitbrush, two shrubs that grow well in disturbed areas, had more cover inside old fields. There was also less cover of native forbs (flowering plants) and more cover of weedy forbs. We were surprised by the differences in grass cover because we expected to find more of the invasive annual cheatgrass in the old fields. Instead, the cover of grasses inside these old fields was mostly squirreltail. Finally, we also found evidence that historic cultivation can change the composition of shrubs in old fields. For example, at one of our study sites, the edge of the old field (See arrow in Figure A) was recognizable by the vegetation shift from a mix of shrubs to dominance of only big sagebrush (See Figure B). We also evaluated the physical aspects of the soils inside the old fields versus noncultivated adjacent land. Oral historics from people who lived and dry farmed in Park Valley in the early 1900s reported that wind erosion of soils off the cleared fields was severe. We tested the particle sizes of the soils to see if there was still any indication of top soil erosion. When soil is eroded by wind, the smallest and lightest soil particle size, called silt, is picked up and carried away as dust. The larger and heaviest particle size, called sand, is not as easily removed by wind. Therefore, highly wind eroded soils will have lower silt ad higher sand content. This is exactly what we found in the soils of the old fields. There was even more rock on the soil surface in the old fields, indicating just how much of the top soil had been lost. Finally, cultivation appears to have compacted the soil inside the old fields, creating higher bulk densities, and has hardened the soil surface making it difficult for seeds to germinate and water to infiltrate. Seeing how much this legacy had impacted the natural re-vegetation of these old fields, we wondered if it had also impacted directed re-vegetation efforts like rangeland seedings. The next phase of the project looks at how these legacies impact rangeland reseeding efforts. This summer, we collected similar measures of vegetation and soils in areas that were dry farmed historically and then reseeded in the past 2 to 30 years. We have also planted different grasses and flowering plants in the old fields and in noncultivated land to learn which species perform better. We look forward to providing a research update on the results of that study in future newsletters.