Selecting a nitrogen availability index for understanding plant nutrient dynamics in rehabilitated bauxite-processing residue sand

• Published in: Ecological engineering 2013-09, Vol.58, p.228-237
• Main Authors: Goloran, J.B., Chen, C.R., Phillips, I.R., Xu, Z.H., Condron, L.M.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Availability; Bauxite-processing residue sand; Biological and medical sciences; Conservation, protection and management of environment and wildlife; Ecology; Environment and sustainable development; Environmental degradation: ecosystems survey and restoration; Fundamental and applied biological sciences. Psychology; Nitrate; Nitrogen availability index; Nutrients; Plant available nitrogen; Plants (organisms); Rehabilitation; Residues; Revegetation; Sand; Soil (material); Strategy
• ISSN: 0925-8574; 1872-6992
• DOI: 10.1016/j.ecoleng.2013.07.004

•Revegetated bauxite residue sand (BRS) areas were highly alkaline.•A range of soil N availability indices for BRS areas were assessed.•Pot trial and field survey revealed the dominance of extractable nitrate-N.•2M KCl extractable nitrate-N was the best indicator for plant N uptake. Understanding nutrient dynamics in non-typical soil materials such as bauxite-processing residue sand (pH>10; EC>30dSm−1) is critical for developing fertilizer strategies and evaluating ecological restoration performance. Indices relating nitrogen (N) concentration in soil to plant N uptake are well-established for natural soils but their application to non-typical soils has received little attention. This study investigated a range of soil-based methods [i.e. 2M KCl extractable inorganic N (NH4+, NO3−), potentially mineralizable nitrogen (PMN), and 0.01M CaCl2 extractable N] to identify their suitability for describing soil–plant N relations in highly alkaline bauxite-processing residue sand. Nitrogen availability indices were measured under laboratory (pot trial) and field conditions. Pot trial was established using residue sand that had been amended (10%, v/v, basis) with various organic (greenwaste compost, biochar and biosolids) and inorganic (zeolite) materials. Both the field study and pot trial showed that 2M KCl extractable NO3−-N was most highly correlated with plant biomass N compared with the other N availability indices. Findings from this study suggest that 2M KCl extractable NO3−-N can be used as a soil quality indicator in developing fertilizer management strategies and assessing ecological status of the residue storage areas.