Canadian Forest Service Publications
Sample storage-induced changes in the quantity and quality of soil labile organic carbon. 2015. Sun, S.-Q.; Cai, H.-Y.; Chang, S.X.; Bhatti, J.S. Scientific Reports 5:17496.
Issued by: Northern Forestry Centre
Catalog ID: 36519
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Effects of sample storage methods on the quantity and quality of labile soil organic carbon are not fully understood even though their effects on basic soil properties have been extensively studied. We studied the effects of air-drying and frozen storage on cold and hot water soluble organic carbon (WSOC). Cold- and hot-WSOC in air-dried and frozen-stored soils were linearly correlated with those in fresh soils, indicating that storage proportionally altered the extractability of soil organic carbon. Air-drying but not frozen storage increased the concentrations of cold-WSOC and carbohydrate in cold-WSOC, while both increased polyphenol concentrations. In contrast, only polyphenol concentration in hot-WSOC was increased by air-drying and frozen storage, suggesting that hot- WSOC was less affected by sample storage. The biodegradability of cold- but not hot-WSOC was increased by air-drying, while both air-drying and frozen storage increased humification index and changed specific UV absorbance of both cold- and hot-WSOC, indicating shifts in the quality of soil WSOC. Our results suggest that storage methods affect the quantity and quality of WSOC but not comparisons between samples, frozen storage is better than air-drying if samples have to be stored, and storage should be avoided whenever possible when studying the quantity and quality of both cold- and hot-WSOC.
Plain Language Summary
This paper addresses an important issue for researchers studying the carbon content of soil, which is key to carbon cycling and global carbon modelling. Studies of soil carbon commonly measure water-soluble organic carbon (WSOC). In most studies, soil samples are stored for a period because they cannot be analyzed immediately or because they are shipped long distances to labs. It is not clear whether different ways of storing soil samples affect WSOC. If so, results of studies using different storage methods could have different results and be difficult to compare. The paper reports on the effects of sample storage methods (freezing and air drying) on the measurement accuracy of soil organic carbon. Samples of fresh, frozen and air-dried soil were extracted by cold and hot water methods. Concentrations, properties and quality of stored samples were measured and compared, and the change in organic carbon was assessed.Results show that the effects of the sample storage method differ for different properties of soils. The authors recommend that researchers select a sample storage method based on the soil property that is being researched. In general, storage affects the quantity and quality of WSOC, but not comparisons between samples. Freezing is better than air-drying if samples have to be stored, but storage should be avoided whenever possible when studying the quantity and quality of WSOC.