Abstract

Plant growth depends on nitrogen bioavailability and the soil microbiome. In recycling of nitrogen participate archaean ammonium-oxidant communities (AOA) and bacterial (AOB) who perform the first stage of nitrification, whose relative contribution (AOA:AOB) responds to physicochemical conditions of the soil. The structure and bacterial community composition in a humiferous soil irrigated during 7 weeks with: grey water (GW), grey water treated in sand filter and vermifilter (SFW, VFW), and drinking water (DW) as a control, compared to the initial soil conditions. Physicochemical parameters were determined associated (n=17) with the quality of standard irrigation water and soil (pH, conductivity and total organic matter). The abundance of AOA and AOB communities and total bacteria was quantified by qPCR (amoA functional gene and 16S rRNA, respectively) and sequencing (iTag-16S rDNA). Grey water filtered by VFW showed a lower pH and conductivity, and a higher nutrient content compared to GW and SFW. However, VFW complied only with 58% of the parameters analyzed with respect to the ch standard. 1333. The AOA: AOB ratio decreased by all treatments except VFW, related to increased soil conductivity (Spearman r=-0.9, p=0.037). Sequencing results show an enrichment of Planctomycetes, Gammaproteobacteria, Nitrospirae, Chlorofexi in soils watered with gray water compared to DW. In total, our results indicate that irrigation alters the soil microbiome, including functional groups of the nitrogen cycle.