Influence of Local Topography on Precision Irrigation Management.

Precision irrigation management is currently accomplished using spatial information about soil properties through soil series maps or electrical conductivity (EC) measurements.  Crop yield, however, is consistently influenced by local topography, both in rain-fed and irrigated environments.  Utilizing a combination of both soil properties and local topography has been hypothesized to provide a more detailed description of crop yield patterns, thus influencing irrigation management.  A study was developed in Fall 2013 on two fields in Western, NE (both planted to wheat) and one field in Eastern, NE (planted to soybean) to investigate the respective roles of soil properties and local topography in determining crop yield.  Previously collected EC measurements along with local topography were used to guide sampling of 32 soil cores (100 cm deep) collected on each field.  Field Connect (Deere & Company, Moline, IL) systems were further installed to monitor soil moisture variability.  Combined with multi-year crop yield, data analysis suggests irrigation management can be improved by including local topography information.  We believe this has implications not only on irrigation application, but also for monitoring soil moisture variability.