Agricultural management practices impact soil properties more than soil microarthropods

Authors: REILLY, KEELIN - Johns Hopkins University; Cavigelli, Michel; SZLAVECZ, MICHEL - Johns Hopkins University

Submitted to: Pedobiologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2023
Publication Date: 7/4/2023
Citation: Reilly, K., Cavigelli, M.A., Szlavecz, M.A. 2023. Agricultural management practices impact soil properties more than soil microarthropods. Pedobiologia. https://doi.org/10.1016/j.ejsobi.2023.103516.
DOI: https://doi.org/10.1016/j.ejsobi.2023.103516

Interpretive Summary: Agricultural management impacts soil biological communities, which are critical to regulating many soil health properties such as nutrient cycling and soil structure. However, soil health tests generally do not include direct measures of soil biological communities, due to their complexity and our limited knowledge of how soil biological communities relate to current measures of soil health and respond to agricultural management. An ARS researcher, collaborating with colleagues from Johns Hopkins University, used soil microarthropod communities, which are often used to assess environmental stress, to evaluate the impacts of agricultural management on soil biology and some standard soil health metrics. Among the three long-term agricultural systems evaluated--two conventional systems, one tilled and one using no-till, and one organic system--standard soil health metrics (soil organic carbon, nutrients) were highest in the organic system. However, microarthropod communities were similar among the three agricultural systems, confirming the challenge of linking standard and biological measures of soil health. However, soil microarthropod populations were more numerous and communities more diverse in a nearby forest soil used as a comparison. Lower soil bulk density in the forest than the three agricultural systems seems to favor the more diverse soil microarthropod communities and suggests that improving soil biological aspects of soil health in agricultural soils could focus on practices that reduce soil bulk density. These results will be of interest to farmers and scientists interested in improving soil health in agricultural systems.

Technical Abstract: Soil biology is a fundamental aspect of soil quality; thus, it is imperative to understand how agricultural management impacts soil organisms. Among soil biota, microarthropods such as mites (Acari) and springtails (Collembola) act at multiple trophic levels, influencing soil microbial communities and nutrient dynamics. We investigated how agricultural management influences soil microarthropods at the U.S. Department of Agriculture (USDA) Agricultural Research Service Farming Systems Project (FSP), a long-term study comparing the sustainability and productivity of conventional and organic agriculture, in Beltsville, Maryland. We sampled soil and soil microarthropods from plots under conventional management—tilled and no till—and under organic management. Though soils managed using organic practices had significantly higher values for organic matter and several key nutrients, we found no significant differences in microarthropods among systems. Plots under organic management had, numerically, the most abundant microarthropod communities and highest soil quality (as indicated by the QBS-ar index), but all agricultural plots scored lower in both metrics than undisturbed areas evaluated for comparison. Thus, differences in abiotic soil factors do not necessarily translate into differences in the biotic community. These results demonstrate the utility of the QBS-ar index in evaluating impacts of agricultural management on biological components of soil quality, specifically soil arthropod communities.