Progress 06/01/21 to 05/31/25
Outputs
Target Audience:A peer-reviewed journal article in review with Geoderma - The Global Journal of Soil Science, which will primarily target an academic audience. Results have also been presented at regional meetings with private industry and extension, in both oral and poster format. Results have also been disseminated through talks at project (co)-PIs' University sponsoredfield days, including the UIUC Agronomy Day. Changes/Problems:This project underwent a host of changes and problems. The initial problem arose due to the COVID-19 pandemic. Sample collection was delayed. The project then underwent a change as the original PI Dr. Jordon Wade took a position at the University of Missouri. The project Lead was assigned to the University of Missouri. In 2023, Dr. Wade left Academia and project stewardship was past to Dr. Morgan Davis. Due to these changes have requested a 12 month no cost extension through May of 2025. Project objectives are now complete. A research article entitled, "Water-based assays maximize the sensitivity of soil enzyme activities to tillage and site relative to buffer-based assays across six U.S. states: A comparison of paranitrophenyl-based methods" was submitted on February 28, 2025, to Geoderma for publication and is currently under review. NIFA's support was acknowledged in this publication submission; this article will be put in Agpub if it is published. Citation: Rosa Elena López, Jordon Wade, María B. Villamil, Steve Culman, Michel A. Cavigelli, Matthew H.H. Fischel, Jude E. Maul, Morgan P. Davis, Ezra Aberle, and Andrew J. Margenot. 2025. Water-based assays maximize the sensitivity of soil enzyme activities to tillage and site relative to buffer-based assays across six U.S. states: A comparison of paranitrophenyl-based methods Geoderma. What opportunities for training and professional development has the project provided?The Post-Doctoral Student located at the University of Illinois continues to obtain valuable resources and professional development from this project. A publication has also been submitted in conjunction with this project. Furthermore, there has been continued collaboration between the PIs at The University of Missouri and The University of Illinois. How have the results been disseminated to communities of interest?Results from this project have been complied in a manuscript and are currently in review at Geoderma - The Global Journal of Soil Science. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
To meet the project goals we quantified the sensitivity of soil enzyme activities to tillage and site using water-based assays (Daughtridge et al., 2021; Klose et al., 2003; Margenot et al., 2018) versus buffer-based assays (Dick, 2011; NRCS, 2019; Tabatabai & Bremner, 1969). Using soils from replicated, long-term (>15 y) conventional tillage and no-till experiments at six locations across the U.S., we assayed acid phosphomonoesterase (AC-PME), alkaline phosphomonoesterase (AK-PME), β-glucosidase (BG), N-acetyl-β-D-glucosaminidase (NAG) and arylsulfatase (SUL) activities. To explain potential differences in the sensitivity of enzyme activities to tillage and site by assay methodology, we evaluated relative differences between water- and buffer-based activities, assessed the extent to which assay pH aligned with soil pH, evaluated the role of SOC in driving differences in activity sensitivity to tillage and site. We hypothesized that by virtue of assay pH aligning with soil pH, soil enzyme activities measured by water-based assays would be more sensitive to tillage and site than those measured using buffer-based assays. Finally, we hypothesized that the magnitude and directionality of relative differences between buffer- and water-based activities would depend on the enzyme being assayed, and would be influenced by tillage and site. Soils from contrasting long-term (>15 y) tillage experiments were sampled at six locations:Monmouth, IL, Chariton, IA, Wooster, OH, Lexington, KY, Beltsville, MD, and Carrington, ND,USA (Table 1). Soils are Mollisols (IA, IL, ND), Alfisols (KY, OH) and Ultisols (MD) (USDA SoilTaxonomy). Across sites, mean annual temperature (MAT) ranged 2.8-fold from 4.8 °C (ND) to13.5 °C (MD) while mean annual precipitation (MAP) ranged 2.4-fold from 528 mm (ND) to 12666 mm (KY). At each experiment, we sampled soils at 0-15 cm depth of 126 replicate plots of no-till(NT) and conventional (e.g. chisel plow) tillage (T) treatments in a randomized complete blockdesign. Experiments were maize (Zea mays)-based cropping systems, as continuous maize(IL), continuous maize with cereal rye (Secale cereale) between seasons (KY), maize-soybeanrotations (Glycine max) (IA and OH), or maize-soybean-wheat (Triticum aestivum) rotations (MDand ND). Soil organic carbon (SOC) ranged 2.4-fold from 9.2 to 22.1 g C kg-1 soil and was onaverage 1.0- to 1.8-fold greater in NT than in T plots. When averaged across tillage treatmentsfor a given site, SOC decreased in the order of IL (19.9 ± 1.9 g kg-1) > ND (19.5 ± 0.6 g kg-1) >IA (18.5 ± 1.4 g kg-1) > KY (16.4 ± 4.7 g kg-1) > OH (13.0 ± 0.8 g kg-1) > MD (11.2 ± 1.1 g kg-1). Soil pH ranged from 5.2 to 7.2. Soils were sampled in May-June 2022 following the maize phase in the preceding year. Three replicate plots per tillage treatment (n = 36 plots total) were sampled as one composite soil sample per plot. Composite soil samples (0-15 cm depth) were collected by a 2.5 cm diameter hand auger randomly across the plot (n = 15-20). Samples were placed in polypropylene bags and transported on ice to the laboratory for air-drying (25 °C) and sieving (<2 mm). Although air drying samples can change the absolute values of measured enzyme activities, relative differences in enzyme activities across soils and treatments are preserved (Bandick & Dick, 1999; Wallenius et al., 2010; Zornoza et al., 2006). As air-drying allows for greater sample homogeneity and longer storage times relative to field-fresh samples (Dick, 2011; Lopes et al.,2015), the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) (NRCS, 2019) and the Soil Science Society of America (Dick, 2011) recommend assays be standardized by using air-dried soils. Data analysis and visualizations were performed in RStudio v. 2022.12.0.353 in R 4.3.0 (Posit Team, 2022; R Core Team, 2022). To compare the sensitivity of enzyme activities to tillage and site across assay methodologies (e.g. water-based vs buffer-200 based), we calculated F-values for enzyme activity as a response variable for each of the experimental factors (i.e., tillage, site, tillage × site) using the anova() command in the car package (Fox & Weisberg, 2018). A greater F-value indicates greater sensitivity for a given experimental factor, and differences among F values are quantitative. Site was treated as a fixed effect to assess differences in soil enzyme activity across sites and to directly compare activity sensitivity to differences in site based on assay methodology. The use of site as a fixed effect was unique to this study's aims, but would not be a common analytical decision in future implementations of enzyme assays. Therefore, to test if sensitivity differences to tillage by assay methodology persisted across multiple random effect structures, an additional model with two random effects--site and of block nested within site--was assessed using lmer() in the lme4 package (Bates et al., 2015). Normality of residuals was tested using Shapiro-Wilk's test and homogeneity of variances was visually assessed using check_model() in performance (Lüdecke et al., 2021). If assumptions were not met, Box-Cox transformation was performed using the boxcox() command in MASS (Venables & Ripley, 2002). To help explain site-specific differences in activity, relationships between soil enzyme activities on a SOC basis and soil pH were assessed using lm() in the stats package. To assess how closely assay pH aligned with soil pH for each assay methodology, we performed unpaired Wilcoxon rank-sum tests (with exact p-values) using wilcox.test() in stats. This non-parametric approach was selected due to the non-normality of residuals despite several transformations. Specifically, we evaluated potential discrepancies between median pH values of assays and soils (i.e., assay pH - soil pH) for water-based and buffer-based assays. We determined relative differences in activity across assay methodologies using the following equation: ???????????????? ????????????????????(%) = ???????????????????????????? - ?????????????????????????? A????????????????????????× 100 Where ???????????????????????????? is enzyme activity measured using buffer-based assays and ??????????????????????????is enzyme activity measured using water-based assays. Water-based activities were used asthe reference since we hypothesized that soil enzyme activities would be more sensitive totillage and site effects when measured using water- rather than buffer-based assays. Thus,relative differences signify the extent to which activity values deviate when buffer-based assaysare employed instead of water-based assays. Relative activity differences across sites andtillage practices were assessed via two-way ANOVA, followed by Tukey's honest significantdifference test using HSD.test() in agricolae (De Mendiburu Delgado, 2009). Data visualizationwas performed using the ggplot2 package (Wickham, 2016).
Publications
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Progress 06/01/23 to 05/31/24
Outputs
Target Audience:The findings from Objectives 1 through 4 will be disseminated in three ways, each targeting a different audience. First, we anticipate a peer-reviewed journalarticles from Objectives 1 through 4, which will primarily target an academic audience.Publication outlets will be focused based on results and include Soil Biology &Biochemistry, Geoderma, and Biogeochemistry. Second, results will be presented atregional meetings with private industry and extension, in both oral and poster format. Results from Objective 4 would likely be of primary interest, although Objective 2 and 3may also be of interest. Anticipated regional meetings include the North-CentralIndustry-Extension Conference, the annual National No-Till Conference Third, the No-Till on the Plains Conference, and the NCERA-13 meeting. These presentations wouldtarget agricultural professionals and consultants as well as regional extensionspecialists. Resources have been allocated in years 2 and 3 of the project for travel. Third, results will be disseminated through talks at project (co)-PIs' University sponsoredfield days, including the UIUC Agronomy Day and OSU's Small Grains FieldDay. This task will be performed in Q2, Q3, and Q4 of 2023 and Q1 of 2024. Changes/Problems:This project has undergone a host of changes and problems. The initial problem arose due to the COVID-19 pandemic. Sample collection was delayed. The project them underwent a change as the original PI Dr. Jordon Wade took a position at the University of Missouri. The project Lead was assigned to the University of Missouri. In 2023, Dr. Wade left Academia and project stewardship was past to Dr. Morgan Davis. Due to these changes have requested a 12 month no cost extension through May of 2025. What opportunities for training and professional development has the project provided?The Post-Doctoral Student located at the University of Illinois continues to obtain valuable resources and professional development from this project. Furthermore, there has been continues collaboration between the PIs at The University of Missouri and The University of Illinois. How have the results been disseminated to communities of interest?Results are still pending to disseminate. What do you plan to do during the next reporting period to accomplish the goals?We plan to finish this project and have a manuscript submitted for publication.
Impacts
What was accomplished under these goals?
To meet the project goals we quantified the sensitivity of soil enzyme activities to tillage and site using water-based assays (Daughtridge et al., 2021; Klose et al., 2003; Margenot et al., 2018) versus buffer-based assays (Dick, 2011; NRCS, 2019; Tabatabai & Bremner, 1969). Using soils from replicated, long-term (>15 y) conventional tillage and no-till experiments at six locations across the U.S., we assayed acid phosphomonoesterase (AC-PME), alkaline phosphomonoesterase (AK-PME), β-glucosidase (BG), N-acetyl-β-D-glucosaminidase (NAG) and arylsulfatase (SUL) activities. To explain potential differences in the sensitivity of enzyme activities to tillage and site by assay methodology, we evaluated relative differences between water- and buffer-based activities, assessed the extent to which assay pH aligned with soil pH, evaluated the role of SOC in driving differences in activity sensitivity to tillage and site. We hypothesized that by virtue of assay pH aligning with soil pH, soil enzyme activities measured by water-based assays would be more sensitive to tillage and site than those measured using buffer-based assays. Finally, we hypothesized that the magnitude and directionality of relative differences between buffer- and water-based activities would depend on the enzyme being assayed, and would be influenced by tillage and site. Soils from contrasting long-term (>15 y) tillage experiments were sampled at six locations:Monmouth, IL, Chariton, IA, Wooster, OH, Lexington, KY, Beltsville, MD, and Carrington, ND, USA (Table 1). Soils are Mollisols (IA, IL, ND), Alfisols (KY, OH) and Ultisols (MD) (USDA Soil Taxonomy). Across sites, mean annual temperature (MAT) ranged 2.8-fold from 4.8 °C (ND) to13.5 °C (MD) while mean annual precipitation (MAP) ranged 2.4-fold from 528 mm (ND) to 12666 mm (KY). At each experiment, we sampled soils at 0-15 cm depth of 126 replicate plots of no-till(NT) and conventional (e.g. chisel plow) tillage (T) treatments in a randomized complete blockdesign. Experiments were maize (Zea mays)-based cropping systems, as continuous maize(IL), continuous maize with cereal rye (Secale cereale) between seasons (KY), maize-soybeanrotations (Glycine max) (IA and OH), or maize-soybean-wheat (Triticum aestivum) rotations (MDand ND). Soil organic carbon (SOC) ranged 2.4-fold from 9.2 to 22.1 g C kg-1 soil and was onaverage 1.0- to 1.8-fold greater in NT than in T plots. When averaged across tillage treatmentsfor a given site, SOC decreased in the order of IL (19.9 ± 1.9 g kg-1) > ND (19.5 ± 0.6 g kg-1) >IA (18.5 ± 1.4 g kg-1) > KY (16.4 ± 4.7 g kg-1) > OH (13.0 ± 0.8 g kg-1) > MD (11.2 ± 1.1 g kg-1). Soil pH ranged from 5.2 to 7.2. Soils were sampled in May-June 2022 following the maize phase in the preceding year. Three replicate plots per tillage treatment (n = 36 plots total) were sampled as one composite soil sample per plot. Composite soil samples (0-15 cm depth) were collected by a 2.5 cm diameter hand auger randomly across the plot (n = 15-20). Samples were placed in polypropylene bags and transported on ice to the laboratory for air-drying (25 °C) and sieving (<2 mm). Although air drying samples can change the absolute values of measured enzyme activities, relative differences in enzyme activities across soils and treatments are preserved (Bandick & Dick, 1999; Wallenius et al., 2010; Zornoza et al., 2006). As air-drying allows for greater sample homogeneity and longer storage times relative to field-fresh samples (Dick, 2011; Lopes et al., 2015), the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) (NRCS, 2019) and the Soil Science Society of America (Dick, 2011) recommend assays be standardized by using air-dried soils.
Publications
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