Spectrophotometric Determination of Biopolymers in Alabama Benchmark Soils

Biopolymers are organic polymers synthesized by biological organisms. Cellulose, lignin, and proteins are important soil biopolymers known to bind soil particles to improve or strengthen soil structures and support agricultural productivity. In this study, we spectrophotometrically determined the amount of soil cellulose, acetyl bromide lignin, and autoclaved citrate extractable protein in soils in relation to other soil properties. Results showed acetyl bromide lignin > cellulose > autoclaved citrate extractable protein. High clay soils have relatively higher amounts of cellulose and lignin but have lower protein content. The coefficient of variation (CV) of the three biopolymers in the soils studied was autoclaved citrate extractable protein (56.8%), >cellulose (55.2%), >acetyl bromide lignin (44.7%). Pearson correlation analysis showed that soil cellulose was significantly related to cation exchange capacity (CEC), total nitrogen, soil organic matter, and available phosphorus. An increase in soil acetyl bromide lignin suggested an increase in soil organic matter and lower soil available phosphorus. Soil autoclaved citrate extractable protein was significantly correlated with extractable acidity. However, cellulose, acetyl bromide lignin, and autoclaved citrate extractable protein were not significantly correlated with permanganate oxidizable carbon (POxC), electrical conductivity (EC), and C:N ratio. We assume that the concentrations of biopolymers in soils are an intrinsic soil characteristic and contribute to general soil health and productivity.