Analysis of Soil Variability Measured With a Soil Strength Sensor

In the context of precision agriculture, the knowledge of soil strength variability at the field scale may be useful for improving site-specific tillage. Moreover, rapid and accurate sensing methods for soil physical properties determination would favourably replace labour-intensive, time-consuming and expensive soil sampling and analysis. This study aims at validating conclusions of a previous study which was conducted to develop and test a soil strength sensor in field conditions. The coupled acquisition of the sensor's signals and the corresponding DGPS positions allowed establishment of maps for the three measured outputs, namely the horizontal force (F _x ), the vertical force (F _z ) and the moment (M _y ). In order to study the relationships between measured forces and soil physical parameters, a series of soil properties were measured on soil cores collected in 10 reference plots. Significant correlations were found between F _x and the average resistance to cone penetration at 25 cm depth (r = 0.95) and between F _x and average soil moisture at 30 cm depth (r = –0.95). These relationships were similar to those found in the first study. This sensing method proved its capability to characterise within-field soil variability.