Map-based investigation of soil physical conditions and crop yield using diverse sensor techniques

Precision farming relies on diverse sensor techniques to collect site-specific information at field scale. To comprehend and interpret miscellaneous information referring to each specific soil, crop and weather conditions, different case studies are needed. This paper presents two case studies. A horizontal dielectric penetrometer, an EM38 (Geonics Ltd., Canada) and a yield sensor (RDS Technology Ltd., UK) were used. Several parameters, volumetric soil water content (VSWC), penetration resistance (PR), apparent electrical conductivity (ECa) and crop yield, were investigated. A case study (20 ha, Warleberg Farm, Kiel, Germany; crops: rapeseed (Brassica napus L.) in 2007/2008, winter wheat (Triticum aestivum L.) in 2008/2009) indicated that VSWC maps at a depth of 20 cm conformed to both ECa maps and yield maps over two years. Another case (7.7 ha, Dikopshof Experimental Farm, Bonn, Germany; crops: winter wheat (T. aestivum L.) in 2007/2008, winter barley (Hordeum vulgare L.) in 2008/2009) had similar results except a yield map of 2009. For soil strength distribution at the depth of 20 cm, a PR map at Warleberg Farm generally agreed to other maps (VSWC, ECa and yield), whereas the PR map from Dikopshof Experimental Farm only partly agreed to those. In brevity, this study concludes: (i) an assessment for the availability of the horizontal dielectric penetrometer applied at field scale; (ii) ECa pattern measured by EM38 can be viewed as a fingerprint within a field for predicting the distribution of soil water content and crop yield; (iii) PR pattern on top layer is relatively difficult to interpret than ECa pattern.