A scanner-based approach to soil profile-wall mapping of root distribution

Root distribution sampling techniques are often inaccurate, time consuming and costly. We present an inexpensive approach to soil profile-wall mapping using a desktop scanner that allowed us to spend reduced time in the field. The scanner was pressed onto the vertical surface of a 1 x 1m soil pit and images of the roots were taken in situ. In a common garden planting of eleven, 30-year-old conifer and hardwood tree species in Poland, we compared root counts (number of roots cm(-2)) obtained by this method with independent measurements of root length density (RLD) obtained from soil cores. We found a positive correlation (Spearman rank correlation r=0.93; P<0.001) suggesting general agreement of the two approaches in ranking among the species. Soil coring as well as grid mapping with plastic overlays took a longer total time for quantifying root distribution than the scanning procedure. The desktop scanner approach we developed is an inexpensive, time efficient and accurate way of quantifying root distribution and abundance that allows a unique coupling of root data to soil properties.