Soil cone index in relation to soil texture, moisture content, and bulk density for no-tillage and conventional tillage

Soil cone index (CI) is a widely used soil mechanical property to assess soil strength in tillage research. In this study, literature data relating CI to tillage practices are compiled into two datasets, one for no-tillage and the other for conventional tillage. Each dataset is analyzed to examine how CI varies with soil depth, textural parameters, bulk density, and moisture content. The results showed that for both no-tillage and conventional tillage, values of CI decrease with the increase in clay fraction, and increase with the increase in sand and silt fractions of soil. Similarly, higher bulk density and greater soil depth result in higher CI value, while higher moisture content reduces CI. Based on the literature data, regression equations were obtained to estimate CI under no-tillage and conventional tillage systems. In those regression equations, values of CI were linear functions of the other soil variables such as soil textural parameters and moisture content. Those regression equations were validated with field data collected from different sites in Manitoba, Canada. Over half of the results from the regression equations had good agreement with the field measurements, indicated by their relative errors of 20% or lower; however, greater discrepancies were noticed in some cases.