Soil carbon mineralization in response to nitrogen enrichment in surface and subsurface layers in two land use types

• Published in: PeerJ (San Francisco, CA) Vol. 7; p. e7130
• Main Authors: Perveen, Nazia, Ayub, Mariam, Shahzad, Tanvir, Siddiq, Muhammad Rashid, Memon, Muhammad Sohail, Barot, Sébastien, Saeed, Hamid, Xu, Ming
• Format: Journal Article
• Language: English
• Published: United States PeerJ. Ltd 08.07.2019; PeerJ, Inc; PeerJ; PeerJ Inc
• Subjects: Agricultural land; Agricultural Science; Agriculture; Biochemistry; Biology; Biotechnology; C sequestration; Carbon; Climate change; Computer Science; Environmental Impacts; Environmental science; Grasslands; Land use; Land use controls; Land use types; Microbiology; Mineralization; Nitrogen; Nitrogen enrichment; Organic soils; Phenolphthalein; Respiration; Soil c mineralization; Soil carbon; Soil profiles; Soil Science; Soil sciences; Soils; Studies; Subsurface soil C; Lahore Pakistan; Pakistan; China; Loess Plateau; Nitrogen enrichment; Soil c mineralization; Land use types; Subsurface soil C; C sequestration; Subjects Agricultural Science; Soil Science; Microbiology; Environmental Impacts Soil c mineralization
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.7130

Atmospheric nitrogen (N) deposition increases N availability in soils, with consequences affecting the decomposition of soil carbon (C). The impacts of increasing N availability on surface soil C dynamics are well studied. However, subsurface soils have been paid less attention although more than 50% soil C stock is present below this depth (below 20 cm). This study was designed to investigate the response of surface (0–20 cm) and subsurface (20–40 cm and 40–60 cm) C dynamics to 0 (0 kg N ha −1 ), low (70 kg N ha −1 ) and high (120 kg N ha −1 ) levels of N enrichment. The soils were sampled from a cropland and a grass lawn and incubated at 25 °C and 60% water holding capacity for 45 days. Results showed that N enrichment significantly decreased soil C mineralization (Rs) in all the three soil layers in the two studied sites ( p  < 0.05). The mineralization per unit soil organic carbon (SOC) increased with profile depth in both soils, indicating the higher decomposability of soil C down the soil profile. Moreover, high N level exhibited stronger suppression effect on Rs than low N level. Rs was significantly and positively correlated with microbial biomass carbon explaining 80% of variation in Rs. Overall; these results suggest that N enrichment may increase C sequestration both in surface and subsurface layers, by reducing C loss through mineralization.