Abstract
We evaluated a method of estimating the total length of roots in a space from the number of the cut ends of roots appearing on the soil profile, to estimate the length of plant roots in soil. The total length of the segments randomly distributed in a space, R, is shown by R=2nV/S; where, V is the volume of the space, S the surface area of the space and n the number of surface crossing of the lines. The total length of the fine roots of tea plants in the field was estimated using this formulas, and was compared with the root length actually measured after dug out. By using this method, the root length could be estimated with a high accuracy.