Predicting diurnal variations in water content along with temperature at the soil surface
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Under field conditions, much of the uncertainty regarding the magnitude of nitrogen loss as ammonia from surface-applied urea fertilizers arises from the interaction of short-term fluctuations in soil water and temperature with chemical processes. A mechanistic model to combine present knowledge of individual components of the volatilization process may provide insight into the variability. Thus, the ability to adequately predict fluctuations in surface water content and temperature is desirable. Diurnal fluctuations in soil surface water contents and temperatures were compared with predictions from a model based on the finite difference solution of the coupled soil water and heat flow equations and on simulated mass and energy balances at the soil surface. The measured values were taken over several weeks on Muir silt loam (fine-silty, mixed, mesic, Pachic Haplustolls) and Haynie very fine sandy loam (coarse-silty, mixed, mesic, Typic Udifluvents). Small diurnal fluctuations in the surface soil water content were simulated closely by the model for both soils. The fluctuations of soil temperature were simulated well by the model for both soils, even under overcast skies. Generally, there was good agreement (< 1.7°C average difference) between modeled and measured temperatures. © 1986.
author list (cited authors)
McInnes, K. J., Kanemasu, E. T., Kissel, D. E., & Sisson, J. B.