Scaling of root length density of maize in the field profile

Root length density is an important parameter in crop growth simulation and in evaluating consequences of root pattern on crop water and nutrient uptake. In this study, a scaling model was presented for estimating the profile distribution of root length density of maize (Zea mays L.). The model inputs are root length data of a reference profile and bulk densities of soil layers, as well as root length data in the first soil layer of a field profile to be investigated. Using the root length data of 10 soil profiles investigated over 2 years, the model was examined. The results show that the proposed scaling approach is effective in estimating the root length density of each layer of soil in the field profile. The relative root mean square error (RRMSE) of the developed scaling model was 25.28%, while that of the traditional exponential model was 39.53%. The scaling approach would facilitate determination of heterogeneous distributions of root length densities in the field.