Introduction

1. Paper No: B33B-0396A & Impact of land use change on wind erosion and dust emission: Scenarios from the central US John Tatarko, USDA-ARS, Manhattan, KS (John.Tatarko@ars.usda.gov) Gregory S. Okin, UCLA, Los Angeles, CAJeff Herrick, USDA-ARS, Las Cruces, NMJunran Li, UCLA, Los Angeles, CA Methods The Wind Erosion Prediction System (WEPS), developed by the USDA-Agricultural Research Service, is a processed-based, daily time step wind erosion model that simulates hydrology, plant growth and decomposition, land management, and soil surface erodibility to simulate wind erosion soil loss (total, suspension, and PM10 sizes) as affected by stochastically simulated local weather. The WEPS Hydrology submodel can also simulate water use for land management systems. WEPS was applied to the following land use scenarios for a 160 acre loamy fine sand field in Dallam County, TX to simulate their effects on soil loss by wind and water use. Tolerable (sustainable) loss for this soil is 1.1 kg/m2/yr (5 t/ac/yr) . As expected, the WW-F scenario, similar to that used during the Dust Bowl shows excessive wind erosion/dust emission. Changing to native short grass, as was done in response to the Dust Bowl significantly reduces soil loss on these soils as does land planted to tall grass species for the CRP. However, as CRP contracts expire, converting these lands to croplands or harvesting the biomass shows erosion potentials greater than tolerable amounts if residues removed exceed certain levels. Water use is also affected by land use. Evaporation amounts increase with amounts of plant material (i.e., mulch) removed, while transpiration is dependent on the amount of live leaf area. The WW-F scenario is the most conserving of total water use since every other year, the fallow period has a high residue mulch and no transpiring plants. The short and tall grass scenarios exhibit relative low water use while irrigated corn requires almost twice that of other land uses, mostly the result of irrigation and increased transpiration demands. Conclusions Conversion of range or CRP lands to cropland or biomass harvesting run the risk of excessive erosion/dust emission if insufficient biomass is left on the soil. The results indicate that policy and economic forces shaping land use decisions can have significant effects on wind erosion and, importantly, dust emission with local and regional consequences. In addition, water use results show the potential effects of land use changes on this precious resource which is a limiting factor in much of the central US, particularly in the western Great Plains states. Introduction Land degradation is threatening the world’s food supply. Significant land use changes are expected throughout the central United States (US) in the coming years, particularly resulting from climate change, changes in US rangeland/farm policy, and increasing exploitation of land-intensive sustainable energy sources. These land use changes have potential to further degrade soil, air, and water resources. The water limited central US has historically undergone drought and land use changes, most notably during and following the Dust Bowl period of the 1930’s when large areas ravaged by wind erosion were converted to grasslands in an effort to reduce soil loss. More recently, additional highly erodible lands were planted to grass under the Conservation Reserve Program (CRP) to further reduce wind erosion. However, farm policy changes will force much of the current CRP acres out of the program. In addition, there is increased interest in the conversion of traditional crops to production of biofuels such as cellulosic ethanol.The purpose of this study was to investigate potential land use change scenarios on wind erosion, dust emission, and water use. By simulating various past and future land use scenarios, the effects of land use changeon wind erosion and dust emissions as well as water use can be evaluated. Results