Dryland regions, covering nearly half of the Earth’s terrestrial surface, are increasingly threatened by climate change (Prăvălie, R. (2016)). Rain-fed agriculture in these systems, depends on unpredictable rainfall, and is therefore highly vulnerable to water scarcity. Beyond immediate impacts of droughts can create a persistent “legacy effect” that influence soil processes and plant performance across seasons (Müller, L. M., & Bahn, M. (2022)).
We conducted a two-season field experiment at the Migda Experimental Farm using three naturally occuring species: Avena sterilis(wild oat), Stipa capensis (native grass), and Glebionis segetum (broad leaved-forb). In the first season, plants grew under natural conditions. In the second, we applied soil and species-interchange treatments with 5 replicates to simulate crop rotation and evaluate how past plant identity and water stress affect soil plant interactions.
Treatments significantly influenced infiltration time(p=0.035) and soil organic matter (SOM) (p=0.022). Infiltration times ranged from ~145 ± 18 s in Avena soils to ~440 ± 55s in Stipa soils. SOM peaked when Avena was grown on broad leaved soil (2.78 ± 0.12%), compared to ~2 ± 0.1% in other combinations. Moistured depth, hydraulic conductivity and aboveground biomass showed no significant differences. Biomass trends favored Stipa on broad-leaved plots (~100 ± 15 gm-2), but production was likely constrained by the second consecutive drought year, when rainfall dropped from 173 mm and then 93 mm ~ 45% of the site’s long term annual average.
Multivariate analysis confirmed strong treatment driven shifts in community composition (Wilks’ λ=0.216, p< 0.001). Overall, previous plant identity and drought history exert measurable legacies on SOM, infiltration and community structure even when biomass remains stable.
