Sorption of Microbial Enzymes on Biochar and Manure Amendments in Agricultural Soils.

Building soil fertility with organic amendments may help alleviate the stress of climate variability on agricultural systems. Biochar and manure both provide organic matter that builds soil structure, increasing soil moisture, and alters microbial habitat. In a maize study in Northern Colorado, organic amendments including manure and pine biochar increased soil moisture similarly. However, the manure increase microbial biomass and had no impact on nutrient cycling extracellular enzymes, while biochar did not impact microbial abundance, but had wide ranging impacts on enzymatic activity levels. To test the mechanisms behind these interactions, we added four purified enzymes to the soils and amendments alone and in combination for a one hour incubation. We used a Bradford protein assay and then calculated the amount of protein sorbed to the soil-amendment matrices. By testing the sorption of the amendments and soils, we analyzed one potential mechanism of enzyme-soil-amendment interaction and found all matrices sorbed approximately 70% phosphatase, and 30% B-glucosidase. This leads to new questions revolving around enzyme activity and stabilization after sorption. By assessing these relationships, we can better predict the outcome of adding organic amendments to specific soils to best promote soil health.