Composted sewage sludge can improve the physiological properties of Betula schmidtii grown in tailings

We investigated how the application of composted sewage sludge to tailings affects the physiological response of woody plants growing on abandoned coal-mining sites. Twenty seedlings of Betula schmidtii were transplanted to pots containing various combinations of artificial soil plus nursery soil, tailings, composted soil, or tailings amended with composted soil. Dry weights, shoot to root ratios, relative growth rates (RGR), chlorophyll content and fluorescence, and carbohydrate concentrations were assessed at the end of the experiment. Growth responses differed significantly among soil types. For example, dry weights were greatest for seedlings grown in composted soil and smallest for plants raised in pure tailings. Shoot to root ratios were higher for seedlings in composted soil compared with those in either tailings or nursery soil. Leaf chlorophyll content was twice as high for seedlings from composted soil than for those in the nursery soil or tailings; chlorophyll fluorescence (Fv/Fm) was lower for seedlings in either nursery soil or tailings than for those in composted soil. In contrast, plants grown in either nursery soil or tailings had higher starch concentrations in their stems, whereas the carbohydrate allocation of seedlings in composted soil was highest in the leaves, followed by stems and roots. Overall, the carbohydrate content was highest in the leaves, except for seedlings treated with tailings. Therefore, we believe that composted soil can improve the physiological and biochemical properties of trees growing in tailings when appropriate nutrients are supplemented.