title: [Assessment of humic and fulvic acids in black soils using near-infrared reflectance spectroscopy].
abstract: The organic carbon content and optical densities of humic acids in black soils of China were predicted and assessed using near infrared spectroscopy technique. The contents of humic acid (HA) and fulvic acid (FA) in 136 black soil samples in China were analyzed and the NIR spectra were collected using a VECTOR/22 (Fourier transform infrared spectroscopy). Partial least squares (PLS) regression with cross validation was used to develop prediction models with reference data and soil NIRS spectra, and the model was validated using an independent set of samples. NIRS well predicted (HAC+FAC), HAC and FAC contents, with R2 = 0.92, 0.92 and 0.86, RPD = 3.66, 3.82 and 2.69, and high correlation coefficients between predicted and measured values (r = 0.90, 0.85 and 0.82). Predictions for the E4 values of HA and FA were also good (R2 = 0.85, 0.85; RPD = 2.88, 2.65; r = 0.92, 0.80). Predictions for optical densities of HA and FA at 665 nm (E6) was acceptable. Generally, NIRS showed a good potential to predict C content and optical densities of humic acid and fulvic acid in blacks soils and may reveal information on SOC quality.
authors.affiliation: Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130012, China. fanruqin2007@126.com
authors.forename: Ru-Qin
authors.initials: RQ
authors.lastname: Fan
authors.forename: Yan
authors.initials: Y
authors.lastname: Shen
authors.forename: Xue-Ming
authors.initials: XM
authors.lastname: Yang
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Zhang
authors.forename: Ai-Zhen
authors.initials: AZ
authors.lastname: Liang
authors.forename: Shu-Xia
authors.initials: SX
authors.lastname: Jia
authors.forename: Xue-Wen
authors.initials: XW
authors.lastname: Chen
authors.forename: Shou-Cai
authors.initials: SC
authors.lastname: Wei
mesh_terms: D001578:Benzopyrans / Q000032:analysis*; D002244:Carbon / Q000032:analysis; D006812:Humic Substances / Q000032:analysis*; D016018:Least-Squares Analysis; D009930:Organic Chemicals / Q000032:analysis; D012987:Soil / Q000737:chemistry*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D001578:Benzopyrans; D006812:Humic Substances; D009930:Organic Chemicals; D012987:Soil; D002244:Carbon; C005023:fulvic acid