Do caliche nodules in loessial profiles affect root growth?

Background Caliche nodules, the product of the leaching and deposition of calcium carbonate in the soil, are widely distributed in loessial profiles on the Loess Plateau in China. Their presence leads to complex interactions between plant roots and the soil. Aims and Methods We studied the interactions between caliche-nodule and water content and their effects on the biomass, morphology and vertical distribution of roots of Caragana ( Caragana korshinskii Kom.) for two years using a soil-column experiment. Four root parameters (biomass, diameter, length density and surface-area density) in various diameter classes were compared and analyzed. Results Water and caliche-nodule contents significantly affected root biomass and morphology. Both coarse- and fine-root biomasses were highest at a nodule content of 30%, did not differ significantly from those in fine earth (nodule-free) but were significantly higher than at the other two nodule contents. The nodules affected fine-root biomass when water content was