Measured and Estimated Soil Hydraulic Conductivity In Continuous Corn and Reconstructed Prairie.

Soil hydraulic properties which impact the movement of water and chemicals in soil are affected by factors such as soil texture, soil structure, soil bulk density, and porosity.  These factors are influenced by plants and by human activities such as tillage and traffic compaction.  The conversion of crop lands to reconstructed prairies for the production of biomass feedstocks can potentially have a significant impact on soil hydraulic properties.  In order to anticipate the effect of land conversion on the movement of water and chemicals in soil, accurate estimates of soil hydraulic properties are needed.  The objective of this study is to evaluate soil hydraulic conductivity using numerical inverse analysis of field observations and pedotransfer functions.  Tension infiltrometer measurements are made in a reconstructed prairie and in different management zones of a continuous corn system.  Soil hydraulic conductivity is calculated from the cumulative infiltration data using the multiple tension method. Saturated hydraulic conductivity (K_sat) in the traffic interrow management zone of the continuous corn system is 93% lower than K_sat in the non-traffic interrow management zone.  In the prairie, K_sat is more than 2.3 times larger than the K_sat of the wheel traffic interrow management zone.  However, at water tensions of 15-cm soil hydraulic conductivity is larger in the traffic interrow management zone than in the non-traffic interrow management zone and reconstructed prairie.  In addition to the field measurements, estimates of hydraulic conductivity are estimated numerically using field measured data.  Pedotransfer functions utilizing selected soil properties are also used to estimate soil hydraulic conductivity.  The advantages and disadvantages of each method are evaluated.