Comparison of Surface Energy Balance Components between a Tilled and an Un-Tilled Bare Soil.

The partitioning of surface energy balance components is important to both water and energy budgets in agricultural ecosystems. The disturbance and alteration of the surface can have substantial impacts on the way in which the components of the surface energy balance (net radiation, soil heat flux, sensible heat flux, and latent heat flux) are partitioned. Few studies have investigated the influence of tillage and subsequent soil re-settling on the partitioning of the surface energy balance with time.

The objective of this study is to compare surface energy balance components of a tilled and un-tilled bare soil surface during a series of rainfall-wetting and evaporative-drying cycles. Measurements are performed on a silty clay loam soil in central Iowa. Net radiation is measured at a height of 1 m above the surfaces and soil heat flux is determined by combining measurements with a soil heat flux plate at a 6 cm depth with the change in heat storage in the 0-6 cm soil layer. Sensible and latent heat fluxes are derived from micro-Bowen ratio measurements of water vapor concentration and air temperature at 1 and 6 cm heights. Energy fluxes of the two treatments most differ just after tillage but become more similar over time as the number of wetting-drying cycles increases. Quantified values of the surface energy balance components for the two treatments will be reported.