Agriculture by Irrigation Modifies Microbial Communities and Soil Functions Associated With Enhancing C Uptake of a Steppe Semi-Arid Soil in Northern Patagonia

FRENE JP; FAGGIOLI V; COVELLI J; REYNA D; GABBARINI L; SOBRERO P; FERRARI A; GUITIERREZ M; WALL LG

Frontiers in Soil Science

Frontiers

Lugar: Lausanne; Año: 2022

The transformation of the semiarid steppe soil after 5 years of intensive irrigatedagriculture in Northern Patagonia was analyzed in an on-farm study. The private growerventure used conservative practices, including no-till to maintain soil structure, high croprotation and cover crops. To characterize steppe soil changes by irrigated agriculture,we analyzed the enzymatic activities involved in the biogeochemical cycles (carbon,nitrogen, phosphorus and sulfur), the whole soil fatty acids profile, the state of soilaggregation, and the bacterial and fungal microbiota through DNA sequencing methods.After 5 years of management, irrigated agriculture soil increased organic matter (25?33%), enzymatic activities -Cellobiose-hydrolase (60?250%), Phosphatase (35?60%),Xylanase (101?185%), Aryl-sulphatase (32?100%), Chitinase (85%), b-Glucosidase(61?128%), Leucine-aminopeptidase (138%)?depending on soil series, and macroaggregateformation at the expense of the abundance of micro-aggregates in the first0?5 cm of soil. Whole soil fatty acids profiles changed, enhancing mono-unsaturated,branched, cyclic and methylated fatty acids. Microbial communities showed significantdifferences between irrigated agriculture sites and pristine valleys. The richnessbasedalpha-diversity established increased bacterial communities but decreased fungalcommunities in cultivated soil. Indicators selected using the LEfSe method revealedthe bacterial taxa Acidothermus, Conexibacter and Thermoleophilum, associated withsemiarid steppe soil while Asticcacaulis, Aquicella and Acromobacter with irrigatedagriculture. Ascomycota Phylum changed its community composition, being bothtaxa Aspergillus and Alternaria reduced while Stagonospora and Metarhizium wereenhanced in irrigated agriculture. Taxa belonging to Acidobacteria, Chloroflexi, andBetaproteobacteria, that were enriched in irrigated agriculture soils, were associated withhigher capture of C but smaller values of aggregation, while taxa abundant on steppesoils belonging to Actinobacteria, Alphaproteobacteria, and Firmicutes were positivelyassociated with soil aggregation but negatively with C uptake.