New medicine for soil restoration: biological soil crust capsules facilitate native plant and soil microbe establishment

Introduction: Restoration in drylands is challenging because of harsh climates, requiring creative methods and organisms like biocrusts for restoration of degraded lands. Biocrusts are thin, coherent soil surface layers prevalent in drylands, engineered, and inhabited by communities of organisms including mosses, lichens, and cyanobacteria. Objectives: Biocrusts are critical to dryland ecosystem recovery, enhancing soil stability and fertility, capturing dust, and sometimes enhancing native plant establishment. We tested the efficacy of biocrust capsules—a novel, cost-effective biocrust delivery method using commercially available pill capsules filled with biocrust inoculum—as a method for biocrust restoration in four experiments. Methods: We evaluated the compatibility of multiple capsule types with: field-collected and cultivated biocrusts from different sources (Sonoran, Mojave and Sonoran cultivated), native seeds, anti-herbivory agents (diatomaceous Earth alone and with: habanero powder, coyote urine, pectin, or bergamot oil), and water-holding additives (activated charcoal and hydrogel, alone or together) in four experiments. We watered by hand in the greenhouse, monitoring breakdown rate, biocrust activity, and seed germination. Results: Biocrust capsule types broke down at different rates. Tapioca and vegetable cellulose types were compatible with all biocrust sources, including cultivated inoculum. Capsule breakdown and biocrust activity varied by biocrust source and capsule material. Capsules did not inhibit native seed germination. Anti-herbivory additives had little effect on herbivory, suggesting that encapsulated biocrusts may not be appealing to some herbivores. Conclusions: Biocrust capsules show significant promise as a scalable, practical method for biocrust distribution.