Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands

Aim: To compare Australian dryland soils with dryland soils globally. Location: Australian and global drylands. Methods: We used data from standardized surveys of soil properties (C, N, and P content and stoichiometry, and pH) and microbes (diversity, composition, and correlation networks) from Australian and global drylands, which occupy three-quarters of the Australian land mass and are the largest biome on Earth. Results: We found that Australian dryland soils were different, exhibiting characteristics of ancient weathered soils. They had lower pH, total and available P, and total N, and greater C:N and C:P ratios than global dryland soils. Australian soils had distinctive microbial community composition and diversity, with more Proteobacteria and fewer Basidiomycota than global dryland soils, and promoted the abundance of specific microbial phylotypes including pathogens, mycorrhizae, and saprobes. Main conclusions: Australian dryland soils are clearly different from dryland soils elsewhere. These differences need to be considered when managing dryland soils to avoid unreasonable expectations about plant productivity and carbon stocks, or when predicting likely changes in ecosystem processes resulting from global environmental change.