Development of mechanical soil stability in an initial homogeneous loam and sand planted with two maize (Zea mays L.) genotypes with contrasting root hair attributes under in-situ field conditions

Purpose Soil structure evolving from physical and biological processes is closely related to soil mechanical characteristics and texture. We studied the influence of substrate and genotype on the initial development of mechanical traits, differences between depths, and changes over the course of two years in the field. Methods Plots were homogeneously filled with a loam and a sand and planted with two maize (Zea mays L.) genotypes (wild type (WT) and rth3 mutant) with contrasting root hair attributes. Undisturbed soil cores were taken in 2019 and 2020 at 14 and 34 cm depth. Confined uniaxial compression tests were performed to determine pre-compression stress (sigma(pc)), compressibility (C-c, C-s) and elasticity index (EI). Mechanical energy was calculated based on penetration resistance (PR) tests with a penetrometer needle resembling root geometries. Results sigma(pc), C-c and C-s were significantly higher in loam as compared to sand, whereas the factor genotype proved to be negligible. Over time, sigma(pc) increased and C-c decreased in loam from 2019 to 2020 and C-s declined in both substrates. Higher mechanical energies were observed in loam and partially in WT. Required energy was higher at 14 cm than at 34 cm depth and decreased from 2019 to 2020 in sand. Airdry sand samples required four times as much energy than those at matric potential (psi(m)) of -50 kPa. Conclusion For the development of the mechanical traits examined texture proved to be the dominating factor and changes in soil stability could be observed within a short period of time.