Effects of winter wheat roots on recovery of bulk density, penetration resistance and water-stable aggregation of sandy loam Eutric Cambisol and clayey loam Vertic Cambisol after compaction

The objectives of the experiment were to: (1) evaluate the effects of ground contact pressures of 0.051, 0.103 and 0.154 MPa on physical properties of sandy loam Eutric Cambisol and clayey loam Vertic Cambisol, and (2) assess the effects of winter wheat roots on the recovery of physical properties of the compacted soils. A 49day pot experiment included treatments with winter wheat (Triticum aestivum L.) growing until the BBCH 10 growth stage. The ground contact pressures were created by a hand-operated hydraulic compressor equipped with a manometer. As a reference, pots with uncompacted soils without plants were also included in the experiment. At the end of the experiment, bulk density, penetration resistance, total amount of water-stable aggregates (WSA), their size fractions and weight of dry roots in the whole 0-15 cm layers of both soils were determined. The ground contact pressures resulted in significantly higher mean values of bulk density in the 0-15 cm layers for both soils without plants compared to the uncompacted soils. Winter wheat roots contributed to a decrease in the mean values of bulk density of the clayey loam by 1.4, 3.8 and 4.9 %, but caused the increase in those of the sandy loam by 6.2, 5.1 and 1.8 % at the ground contact pressures of 0.051, 0.103 and 0.154 MPa, respectively. The ground contact pressures caused mostly a significant increase in the mean penetration resistance of the 0-5 cm layer in the clayey loam and sandy loam without plants compared to the uncompacted soils. The roots did not contribute to any significant change in the mean magnitudes of penetration resistance of both soils at the three studied levels of compaction. Total amount of WSA of the two soils significantly decreased after the compaction by all the applied ground contact pressures. Winter wheat roots contributed mainly to a partial recovery of the total amount of WSA in both compacted soils compared to those of the uncompacted soils.