Contrasting Organic Amendments Induce Different Short-Term Responses in Soil Abiotic and Biotic Properties in a Fire-Affected Native Mediterranean Forest in Chile

This study aimed to evaluate contrasting organic amendments as a strategy to promote the recovery of biotic and abiotic edaphic conditions central to the reestablishment of soil ecosystem functions at a site in south-central Chile affected by megafires in the 2016–2017 summer season. We analyzed the effects of the application of fresh (poultry and swine manure) and stabilized (compost of agricultural waste origin) organic amendments on microbial parameters, including basal respiration, microbial biomass, the carbon mineralization coefficient, and the microbial metabolic quotient, along with soil physicochemical properties related to soil fertility and stability. All organic amendments improved soil fertility and stimulated soil microbial activity. Fresh amendments, particularly swine manure, promoted the immediate recovery of the microbial conditions evaluated. However, greater mineralization rates and thus presumably shorter periods of carbon (C) source consumption were related to the application of such organic amendments. Soils treated with compost accumulated the most organic carbon and nitrogen, ensuring long-term nutrient release and thus long-term soil function recovery. Choosing the type of organic amendment to use to sustain ecosystem resilience will highly depend on the restoration goals over time.