Short‐Term Improvement in Soil Physical Properties of Cultivated Histosols through Deep‐Rooted Crop Rotation and Subsoiling

Core Ideas Short rotations showed small hydraulic conductivity improvement the year of rotation. Effects vanished the year after termination of the rotational crops. Pore continuity appears to be disrupted by tillage operations.The formation of a compacted layer in cultivated organic soils reduces water infiltration and can lead to the formation of a perched water table. To test the hypothesis that integrating deep‐rooted crops in a short‐term rotation could improve soil physical properties, a 3‐yr trial was conducted on two Histosols. A lettuce ( Lactuca sativa L.) control and three crops combinations—corn ( Zea mays L.) and common vetch ( Vicia sativa L.), sorghum [ Sorghum bicolor (L.) Moench] and faba bean ( Vicia faba L.), and a mix of tillage radish ( Raphanus sativus L.), ryegrass ( Lolium perenne L.) and crimson clover ( Trifolium incarnatum L.)—were planted for 2 yr, on subsoiled and not subsoiled plots. Then, lettuce was reintroduced on all plots the third year of the experiment. Measurements of soil penetration resistance (SPR), saturated hydraulic conductivity ( K s and K fs ), water table level, and matric potential were performed over time. K fs improved in the compacted layer during the second year of the rotation compared with the lettuce control. Subsoiling improved SPR, K s , and K fs in some cases. Once tillage was used to reestablish lettuce in the third year, those effects disappeared quickly (<3 mo), likely due to tillage. No treatment differences in water table levels or soil matric potentials were observed at that time, indicating that the short‐term increase in K fs did not improve deep drainage. Despite short‐term changes in the top horizons, the general drainage pattern was controlled mainly by the deeper organic layers rather than the shallow compacted layer originally identified.