Engineering Commons^™

Effects Of Calcium Silicate Treatment On The Composition Of Forest Floor Organic Matter In A Northern Hardwood Forest Stand, Ankit Balaria, Chris E. Johnson, Peter M. Groffman, Melany C. Fisk

Civil and Environmental Engineering

Calcium amendment can help improve forest sustainability in stands that have been impacted by chronic acid deposition. An important component of this improvement is the stimulation of the microbial activity that supports ecosystem nutrient cycling processes. To test the hypothesis that Ca treatment alters the structure and solubility of organic matter substrates, an important driver of microbial activity, we investigated the effect of wollastonite (CaSiO₃) treatment on soil organic matter (SOM) and hot-water-extractable organic matter (HWEOM). We found a decrease in the HWEOM content of forest floor soils within two years of treatment with a high dosage of …

Compositional Characterization Of Soil Organic Matter And Hot-Water Extractable Organic Matter In Organic Horizons Using A Molecular Mixing Model, Ankit Balaria, Chris E. Johnson

Civil and Environmental Engineering

Purpose Microbial decomposition of soil organic matter (SOM) is generally believed to be heterogeneous, resulting in the preferential loss of labile compounds such as carbohydrates and proteins and the accumulation of recalcitrant compounds such as lipids and lignin. However, these fractions are difficult to measure directly in soils. We examined patterns in the biomolecular composition of SOM and hot-water-extractable organic matter (HWEOM) by using a molecular mixing model (MMM) to estimate the content of carbohydrates, protein, lipids, and lignin.

Materials and methods Organic-horizon soils from Spodosols at the Hubbard Brook Experimental Forest in New Hampshire, USA were analyzed for this …

A 13c Nmr Study Of Decomposing Logging Residues In An Australian Hoop Pine Plantation, Chris E. Johnson, Timothy J. Blumfield, Sue Boyd, Zhihong Xu

Civil and Environmental Engineering

Purpose Residue retention is important for nutrient and water economy in sub-tropical plantation forests. We examined decomposing hoop pine (Araucaria cunninghamii Ait. Ex D. Don) residues – foliage, branches and stem wood – to determine the changes in structural chemistry that occur during decomposition.

Materials and methods Residues were incubated in situ using 0.05-m² microplots. We used solid-state ¹³C nuclear magnetic resonance (NMR) spectroscopy to determine the structural composition of harvest residues in the first 24 months of decomposition.

Results and discussion The spectral data for branch and stem residues were generally similar to one another and …