Water-based enzyme assays are more sensitive than buffer-based assays to tillage and site in the U.S. Corn Belt

Authors: LOPEZ, ROSA - University Of Illinois Urbana-Champaign; WADE, JORDAN - Syngenta; VILLAMIL, MARIA - University Of Illinois; CULMAN, STEVE - Oregon State University; Cavigelli, Michel; Fischel, Matthew; Maul, Jude; DAVIS, MORGAN - University Of Missouri; ABERLE, EZRA - North Dakota State University; MARGENOT, ANDREW - University Of Illinois

Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2025
Publication Date: 10/6/2025
Citation: Lopez, R.E., Wade, J., Villamil, M.B., Culman, S., Cavigelli, M.A., Fischel, M.H., Maul, J.E., Davis, M.P., Aberle, E., Margenot, A.J. 2025. Water-based enzyme assays are more sensitive than buffer-based assays to tillage and site in the U.S. Corn Belt. Geoderma. 462. Article 117518. https://doi.org/10.1016/j.geoderma.2025.117518.
DOI: https://doi.org/10.1016/j.geoderma.2025.117518

Interpretive Summary: Plants and bacteria produce chemicals called enzymes to help them absorb soil nutrients. However, no standard method exists to extract enzymes from soils, and different techniques may yield varying results. This manuscript compares the soil enzymes from a water extraction and buffer extraction in soils from six sites across the U.S. to determine if the extraction method and the soil management influence the enzyme results. The results show that the water extraction was more effective in collecting soil enzymes and that tillage and location also influenced the enzymes present. This manuscript will help scientists by providing a standard method to extract soil enzymes and lead to improved research outcomes for soil health, benefiting farmers and policymakers in deciding which agricultural management techniques lead to the most impactful improvements in soil health.

Technical Abstract: Assay methodology can influence the sensitivity of soil enzyme activities to agroecosystem management practices. Using soils from long-term tillage experiments across six U.S. states, we tested the hypothesized greater sensitivity of acid phosphomonoesterase (AC-PME), alkaline phosphomonoesterase (AK-PME), ß-glucosidase (BG), N-acetyl-ß-D-glucosaminidase (NAG), and arylsulfatase (SUL) activities to tillage practices (conventional vs none) and site measured by water-based assays relative to buffer-based assays. To explain enzyme activity sensitivity differences between assay methodologies, we assessed (1) relative differences in activities measured with buffer- rather than water-based assays, (2) differences between soil and assay pH, and (3) activities on a soil versus soil organic carbon (SOC) basis. On a soil mass basis, enzyme activities were ˜2-fold more sensitive to tillage and to site using water- relative to buffer-based assays. Water-based NAG activity was most sensitive to tillage and site, whereas buffer-based SUL activity was least sensitive to tillage and buffer-based AK-PME activity least sensitive to site. Differences between assay and soil pH were 1.5- to 6-fold lower with water-based assays, though pH divergences did not fully explain differences between water- and buffer-based activities. Buffer-based assays produced lower AC-PME (-32%) and AK-PME (-53%) activities but higher BG (+23%), NAG (+43%) and SUL (+87%) activities relative to water-based assays. Tillage effects on activities were primarily driven by SOC, except for water-based BG and buffer-based AK-PME activities. However, water-based activities maintained an enhanced sensitivity to site. We recommend the use of water-based assays to maximize the sensitivity of soil enzyme activities to tillage and to site.