SPECTRAL-ANALYSIS OF CONE PENETROMETER DATA FOR DETECTING SPATIAL ARRANGEMENT OF SOIL CLODS

Tillage changes the spatial distribution of the soil structural units and clods and consequently the soil physical and mechanical properties. A recording cone penetrometer was used to determine soil strength along transects, prior to and after deep ploughing (40 cm) and deep ploughing followed by shallow secondary tillage (duckfoot cultivator and rototiller). The data were analysed geostatistically to compare power spectra of the resistance data. Distinct periodic variations in soil structural arrangements were found under a freshly ploughed plot, which conformed to the dimensions and possible spatial positioning of the clods. Aggressive secondary tillage (rototilling) obliterated some of the periodic pattern. But the basic periodic variations conforming to clod dimensions could still be detected. © 1990.