Effects of Soil Storage at Freezing Temperatures on Soil Enzymatic Activities

Soil enzyme activities are good indicators of soil health. It has been hypothesized that soil storage before analysis might affect microbial function. The objective of the present study was to determine if soil storage at -20 and -80°C affects soil enzymatic activities. Soil samples were collected and stored for four weeks at -20 and -80°C. Activities of nine enzymes were measured in fresh samples and every two weeks during storage. Overall, nine enzymes were targeted including β-Glucosidase (BG), Cellobiohydrolase (CBH), β-N-Acetylglucosaminidase (NAGase), Aryl Sulfatase (AS), Acid Phosphatase (AP), Alkaline Phosphatase (AlP), Glycine Aminopeptidase (GAP), Leucine Aminopeptidase (LAP) and Peroxidase (PER). With the exception of GAP and LAP, no significant differences were observed between samples stored at -20°C for 2 weeks compared to controls. Storage at -80°C for two weeks resulted in a decrease in all the enzyme activities except for PER, BG, and LAP. With the exception of PER, storage at -20 and -80°C decreases the activities of all the enzymes tested after four weeks of storage. These changes varied with specific enzyme targeted. Further studies should be conducted to determine how these low storage temperatures affect microbial diversity and abundance.