Detecting spatial variability of soil compaction using soil apparent electrical conductivity and maize traits

Soil compaction is one of the main limiting factors for sustainable agriculture. Efficient methods for detecting the distribution of soil compaction at a field scale are urgently needed in precision agriculture. We evaluated the possibility to detect soil compaction from measurements of apparent electrical conductivity (ECa) by using electromagnetic induction (EMI) and maize traits at a similar to 1 ha field parcel. The soil was Luvisol, and soil compaction-related properties, such as bulk density (BD), penetration resistance (PR), soil texture, soil salinity, soil moisture and maize traits, were measured at ten locations across the field based on ECa variability. In this site-specific study, no good correlation between soil compaction properties (i.e. BD and PR) and ECa was found but soil clay content was positively related to ECa in the sublayer (P = 0 .08). The variation in the unmanned aerial vehicle (UAV)-derived maize canopy height was significantly negatively correlated with soil compaction and a negative relationship between dry above-ground biomass and BD and PR existed at 25-50 cm layer. In addition, ECa and UAV-derived maize canopy height was negatively correlated (Spearman's rank correlation coefficients of -0.67 in the 0-25 cm layer) under the rather dry conditions prevailing during this study. Overall, as could be expected, detecting soil compaction with ECa was challenging under heterogeneous terrains, while maize traits had a better correlation with spatial variability of soil compaction. Owing to its sensitivity to the integral variation of multiple soil properties, ECa was a good indicator of maize canopy height.