Abstract
Soil management techniques play an important role in limiting root competition and improving soil structure, biodiversity and nutrient richness, aiming for optimal root growth and activity. In a high-density apple orchard (Malus ×domestica), four different soil management techniques were applied both in the tree row and the drive alley: turfgrass (Festuca sp.); multi-species ground cover (Festuca sp., Polygonum fagopyrum, Medicago sativa); shallow tillage; and shallow tillage plus compost amendment. Averaged across treatments, 60% of observed roots were localized between 0.1 to 0.3 m soil depths. Tillage effectively contained herbaceous root growth and, together with the compost amendment, induced a shift of root allocation to deeper soil layers and increased average root diameter. Multi-species ground cover inhibited apple root growth during the first year of the experiment. The strongest inhibition was recorded during the two peaks of apple root growth in late spring and early autumn. The same periods were also characterized by the highest rate of ground cover root production. The understorey ground cover did not compromise above ground plant performance measured either as shoot growth or as yield and fruit quality.