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Influence of the quality of organic amendments on Mediterranean agricultural soils following a drought episode

Year: 2025
Type: article
Abstract: Soil organic matter loss is a major concern in agricultural Mediterranean soils due to its influence on soil water retention and hence increased susceptibility to drought conditions. An experiment was conducted to study the influence of organic inputs' quality on the resistance of a C-poor soil to drought. Four organic materials were added to the soil in a mesocosm experiment: 1) leonardite; 2) earthworm humus; 3) biosolid compost; and 4) dry biomass of Vicia faba , simulating the incorporation of a legume cover crop. Pots were sown with a forage mixture ( Lolium perenne and Medicago polymorpha ), and 45 days following C-addition a drought episode (30 % reduction in water inputs) was simulated in half of the replicates. Soil resistance was evaluated by measuring soil chemical properties, biological activity (enzyme activities and respiration rate), biomass and the fungi:bacteria ratio in the microbial community, and plant productivity. With the exception of earthworm humus, organic-C addition had positive effects on soil chemical properties and water retention. V. faba biomass was the most effective material for enhancing water retention (16.5 % higher than in the non-amended soil), microbial activity and abundance (2.5 and 8.4 times greater bacterial and fungal abundances than in the non-amended soil, respectively), and soil N and P availability. Soils enriched with V. faba biomass also had the highest fungi:bacteria ratio by the end of the experiment. Drought reduced plant productivity, but all soil function indices showed a high resistance to drought, regardless of the organic matter quality or the fungi:bacteria ratio. • Organic C amendments of different quality were added to a degraded soil to increase its drought resistance. • Dry legume biomass was the most effective material for enhancing water retention, microbial activity and abundance. • Soils enriched with legume biomass also showed the highest fungi:bacteria ratio. • Drought reduced plant productivity, but all soil functions showed a high resistance to drought. • The resistance of soil functions to drought was not linked to the amendment quality or the fungi:bacteria ratio.
DOI: 10.1016/j.jenvman.2025.125093
Language: English
Subfield: Soil Science
Open Access status: hybrid
Estimated APC paid: $3,750
OpenAlex ID: W4408842532
FWCI: 3.012
Cites: 65
Cited by: 6
Related to: 10