Nitrogen deposition alters nitrogen cycling and reduces soil carbon content in low-productivity semiarid Mediterranean ecosystems

• Published in: Environmental pollution (1987) 2013-08, Vol.179, p.185-193
• Main Authors: Ochoa-Hueso, Raúl, Maestre, Fernando T., de los Ríos, Asunción, Valea, Sergio, Theobald, Mark R., Vivanco, Marta G., Manrique, Esteban, Bowker, Mathew A.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Air Pollutants - analysis; Air Pollutants - toxicity; ammonification; Applied sciences; beta-glucosidase; Biological and medical sciences; C and N cycling; carbon; Carbon - analysis; carbon nitrogen ratio; Carbon Sequestration; Chemical, physicochemical, biochemical and biological properties; Communities; Cyanobacteria; Deposition; Ecosystem; Ecosystems; emissions; Enzyme activities; Exact sciences and technology; Extant N gradient; Fertilization; Fertilization experiment; field experimentation; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Generalities; mineralization; Nitrification; nitrogen; Nitrogen - analysis; Nitrogen - toxicity; Nitrogen Cycle - drug effects; Nitrogen fertilization; nitrogen fertilizers; nitrogen fixation; Nitrogen, phosphorus, potassium fertilizations; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Pollution; Pollution abatement; semiarid soils; semiarid zones; Soil (material); Soil - chemistry; Soil and sediments pollution; Soil cyanobacteria community; soil fertility; Soil Microbiology; Soil organic C and N content; soil organic carbon; Soil science; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Spain; Stores
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2013.03.060

Anthropogenic N deposition poses a threat to European Mediterranean ecosystems. We combined data from an extant N deposition gradient (4.3–7.3 kg N ha−1 yr−1) from semiarid areas of Spain and a field experiment in central Spain to evaluate N deposition effects on soil fertility, function and cyanobacteria community. Soil organic N did not increase along the extant gradient. Nitrogen fixation decreased along existing and experimental N deposition gradients, a result possibly related to compositional shifts in soil cyanobacteria community. Net ammonification and nitrification (which dominated N-mineralization) were reduced and increased, respectively, by N fertilization, suggesting alterations in the N cycle. Soil organic C content, C:N ratios and the activity of β-glucosidase decreased along the extant gradient in most locations. Our results suggest that semiarid soils in low-productivity sites are unable to store additional N inputs, and that are also unable to mitigate increasing C emissions when experiencing increased N deposition. •Soil organic N does not increase along the extant N deposition gradient.•Reduced N fixation is related to compositional shifts in soil cyanobacteria community.•Nitrogen cycling is altered by simulated N deposition.•Soil organic C content decrease along the extant N deposition gradient.•Semiarid soils are unable to mitigate CO2 emissions after increased N deposition. N deposition alters N cycling and reduces soil C content in semiarid Mediterranean ecosystems.