Effects of mechanical planting on establishment and early growth of willow

Commercial willow planting is mostly performed by machines, using long rods which are automatically pressed in the soil and cut. This procedure exerts a large mechanical impact on the cuttings, and may lead to damage, especially when planted in compacted soils. We studied cuttings and early growth performance of willow (in terms of produced shoot biomass, shoot height, leaf area, and number of shoots per cutting) after machine planting, in comparison to manually prepared and planted cuttings. To isolate the effect of mechanical planting from the effects of field variation after planting, we dug out cuttings from five different clones directly after machine planting in well prepared and compacted soil respectively and grew them under controlled conditions, together with a manually prepared control. We found that undamaged cuttings had a better growth performance than visibly damaged cuttings. Planting by machine on compacted soil resulted in a relatively large number of cuttings landing on the soil surface, instead of being planted vertically in the soil. Soil compaction and machine planting interacted with cutting dimensions, the poorer performance of thinner cuttings being more pronounced in compacted soil. To obtain a faster and more even establishment of willows, we recommend thorough soil cultivation prior to planting, further development of planting machines to minimize damage to cuttings at planting, and the use of cuttings with a diameter of at least 10-11 mm. (C) 2013 Elsevier Ltd. All rights reserved.