Spectrophotometric methods for lignin and cellulose in forest soils as predictors for humic substances

Abstract

Summary The origin and fate of humus, a soil organic matter fraction that is most resistant to decomposition, are not yet completely understood. Humus derives mainly from plant structural components; that is, lignin and cellulose, together with several other primary and secondary compounds. There are several methods to estimate lignin and cellulose in plant material; however, the applications to soil are limited and usually complicated and expensive. Conversely, humus can be estimated in soil by chemical titration methods, which estimate the carbon linked to humic and fulvic acids (HAC and FAC). Therefore, we carried out analyses that aimed to compare, within beech forest soils, spectrophotometric data for lignin and cellulose with those of HAC and FAC. We used soil samples from six different beech woods in Italy, sampling in four layers from 0–5 to 30–40 cm. The relations between spectrophotometric cellulose and lignin and HAC and FAC were tested by linear mixed models. Our results showed that both lignin and cellulose were significant predictors for HAC and FAC, even if cellulose had a larger conditional coefficient of determination (R2c). The best fit was between cellulose and the sum of HAC and FAC (R2c = 0.675). Our novel approach proved that spectrophotometric lignin and cellulose provide reliable results in both organic and mineral beech forest soils, even though lignin had a greater random variation than cellulose. Thus, spectrophotometric lignin and cellulose provide reliable and rapidly obtained predictors of humic substances in beech forest soils, with appropriate conversion factors to estimate HAC and FAC. Highlights Humic substances are of pivotal importance in the global carbon cycle. There is a need for simple and rapid methods to estimate humic substances. Spectrophotometric methods provide fast results for cellulose and lignin in soils. Lignin and cellulose function as good predictors for humic substances in forest soils.

Co-culture of Vel1-overexpressed Trichoderma asperellum and Bacillus amyloliquefaciens: An eco-friendly strategy to hydrolyze the lignocellulose biomass in soil to enrich the soil fertility, plant growth and disease resistance

“…Soil organic matter (SOM) was estimated gravimetrically by the loss‐on‐ignition technique and expressed as mg −g dry weight as suggested by Danise et al [ 42 ]. Total organic carbon (TOC) was calculated using the results of SOM with 2 as a conversion factor from SOC to TOC [ 42 ]. Total nitrogen (TN) was estimated using the Kjeldahl method [ 43 ].…”

Effect of Stand Age on Fine Root Biomass, Production and Morphology in Chinese Fir Plantations in Subtropical China

“…The linear mixed-effect analysis was performed using restricted maximum likelihood estimation with the lme4 package. To ensure the normality and homoscedasticity, a Box-cox transformation was applied to all dependent variables with λ = 0.15 [22,23]. Comparison of fine root biomass and morphological variables in the Chinese fir plantation in different ages were analyzed by one-way ANOVA, the method of multiple comparisons used the least significant difference (LSD).…”

Co-culture of Vel1-overexpressed Trichoderma asperellum and Bacillus amyloliquefaciens: An eco-friendly strategy to hydrolyze the lignocellulose biomass in soil to enrich the soil fertility, plant growth and disease resistance

“…Determination of soil organic matter, total organic carbon, lignin, cellulose, and C/N ratio Soil organic matter (SOM) was estimated gravimetrically by the loss-on-ignition technique and expressed as mg -g dry weight as suggested by Danise et al [42]. Total organic carbon (TOC) was calculated using the results of SOM with 2 as a conversion factor from SOC to TOC [42]. Total nitrogen (TN) was estimated using the Kjeldahl method [43].…”

“…C:N ratio was calculated using the results TOC and TN. lignin and cellulose content of the soil was estimated using the Updegra and acetylbromide spectrophotometric technique, respectively as suggested by Danise et al [42].…”