Microbial respiration gives early indication of soil health improvement following cover crops

Authors: CROOKSTON, BRADLEY - Utah State University; YOST, MATT - Utah State University; BOWMAN, MARIA - National Corn Growers Association; Veum, Kristen; STEVENS, JOHN - Utah State University

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2022
Publication Date: 5/25/2023
Citation: Crookston, B.S., Yost, M.A., Bowman, M., Veum, K.S., Stevens, J.R. 2023. Microbial respiration gives early indication of soil health improvement following cover crops. Journal of Soil and Water Conservation. 78(3):272-281. https://doi.org/10.2489/jswc.2023.00015
DOI: https://doi.org/10.2489/jswc.2023.00015

Interpretive Summary: The demand for soil health testing and interpretation has highlighted our limited understanding of how soil health indicators respond to management practices across climates and soils. This study evaluated the short-term (< four years) effects of cover crops on 12 soil health indicators and three popular soil health interpretation tools. In collaboration with Midwestern U.S. corn and soybean producers, on-farm data was collected by the Soil Health Partnership from 2015-2019. In this study, management, climate, and soils information was obtained from 35 farmer fields representing 45 site years across ten states. A measure of four-day soil respiration and the composite score from a well-known tool called the “Comprehensive Assessment of Soil Health” were the only soil health values that were sensitive to the short-term cover crop treatment. In addition, the baseline soil health levels did not affect the ability to detect the influence of cover crops. This information will benefit producers by providing a better understanding of the sensitivity and utility of soil health indicators as cover crop conservation practices are initiated on crop land and will contribute to improved soil health interpretations for landowners.

Technical Abstract: Farmer participatory research in soil health is crucial to evaluating soil conservation practices like cover crops. The Soil Health Partnership (SHP) was a large farmer-led network conducting wide-scale assessments of soil health indicators, scores, and crop yield from on-farm research with consistent methods across site-years. Data from SHP were used to study the effect of one to four years of cover crops on 12 soil health indicators, three soil health assessment composite scores, and two crop yields. Data were collected from 35 SHP sites, composed of 45 site-years from 2015 to 2019, that applied single or mixed species winter cover crops in corn (Zea mays L.) and soybean (Glycine max L.) rotations. Baseline soil health measurements were included as a covariate in the analysis. Soil microbial respiration (C mineralization) and the composite Comprehensive Assessment of Soil Health score responded to cover crops. The impact of cover crops on soil health indicators or scores was not influenced by the baseline levels. These results demonstrate that regardless of initial soil health values, soil respiration might be a helpful soil health indicator to monitor short-term soil health changes within one to four years following the adoption of cover crop practices across the Midwestern U.S.