Submitted to: Pacific Northwest Direct Seed Conference Proceedings
Publication Type: Other
Publication Acceptance Date: 1/12/2005
Publication Date: 1/13/2005
Citation: Qiu, H., Wu, J., Williams, J.D., Oviatt, H.S., Wuest, S.B. 2005. Using the shaw model to evaluate the effects of treatments on seed-zone temperature and moisture. Pacific Northwest Direct Seed Conference Proceedings. (Poster)
Technical Abstract: No-till farming has long been recommended as an agricultural best management practice (BMP) for dryland farming in the Pacific Northwest. In general, no-till systems increase water infiltration, reduce surface runoff and erosion, and improve soil quality. Continuous no-till systems facilitate the development of macropores through bioturbation by soil organisms and plant roots, thus increasing hydraulic conductivity and infiltration capacity of soil. No-till residue management practices may also reduce evaporation. The objective of this study was to use the Simultaneous Heat and Water (SHAW) model to evaluate the effects of different conservation management practices on seed-zone moisture and temperature in a relatively flat research site. SHAW requires weather data, soil properties and management information to predict soil moisture and temperature. Two residue management scenarios were evaluated and compared: no-till with heavy surface residue, and residue incorporation representing lighter residue. Field data and model results show that surface residue has evident effects on seed-zone soil temperature and moisture. The heavy residue in no-till insulates the soil surface and damps soil temperature and soil water fluctuations, thus providing better temperature and moisture conditions for seeding than the incorporated residue treatment. In summary, precipitation that infiltrates into soil is subject to evapo-transpiration; managed with no-till practices, the heavy residue cover provides sufficient insulation to effectively reduce evaporative loss.