Evaluation of aggregate stability methods for soil health

Authors: RIEKE, ELIZABETH - Soil Health Institute; BAGNALL, DIANNA - Soil Health Institute; MORGAN, CRISTINE - Soil Health Institute; GREUB, KELSEY - Soil Health Institute; BEAN, G - Soil Health Institute; CAPPELLAZZI, SHANNON - Soil Health Institute; COPE, MICHAEL - Soil Health Institute; LIPTZIN, DANIEL - Soil Health Institute; NORRIS, CHAROLETTE - Soil Health Institute; TRACY, PAUL - Soil Health Institute; Ashworth, Amanda; Baumhardt, Roland - Louis; Dell, Curtis; Derner, Justin; Ducey, Thomas; Fortuna, Ann Marie; Kautz, Mark; Kitchen, Newell; Leytem, April; Liebig, Mark; Moore, Philip; Osborne, Shannon; Owens, Phillip; Sainju, Upendra; Sherrod, Lucretia; Watts, Dexter

Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2022
Publication Date: 9/16/2022
Citation: Rieke, E.L., Bagnall, D.K., Morgan, C., Greub, K., Bean, G.M., Cappellazzi, S.B., Cope, M., Liptzin, D., Norris, C.E., Tracy, P.W., Ashworth, A.J., Baumhardt, R.L., Dell, C.J., Derner, J.D., Ducey, T.F., Fortuna, A., Kautz, M.A., Kitchen, N.R., Leytem, A.B., Liebig, M.A., Moore Jr., P.A., Osborne, S.L., Owens, P.R., Sainju, U.M., Sherrod, L.A., Watts, D.B., et al. 2022. Evaluation of aggregate stability methods for soil health. Geoderma. 428. Article 116156. https://doi.org/10.1016/j.geoderma.2022.116156.
DOI: https://doi.org/10.1016/j.geoderma.2022.116156

Interpretive Summary: Soil structure is the backbone of a soil’s ability to support processes vital to the health and productivity of plants, animals, and ecosystems. Soil structural units, or aggregates, form when fresh organic matter is decomposed by microbial community members into binding agents between mineral soil particles. Over the past few decades numerous methods have been developed to measure aggregate stability, although limited evaluations have been done on soil health based on management practices This study assessed four commonly used methods of measuring aggregate stability using data collected as part of the North American Project to Evaluate Soil Health Measurements on 124 locations across Canada, Mexico, and the United States. In addition, the influence of climate and inherent soil properties were analyzed in addition to indicator responses to rotation diversity, crop count, residue management, organic nutrient amendments, cover crops, and reduced physical disturbance. This North American Project to Evaluate Soil Health Measurements suggests all four aggregates stability methods were sensitive to climate and inherent soil properties between sites. In general, aggregate stability was improved with reduced tillage, cover cropping, increased residue retention, and organic amendments. Therefore, these best management practices are expected to improve soil structure and ultimately soil health throughout North America.

Technical Abstract: Aggregate stability is a commonly used indicator of soil health as increases in the measure are related to reduced erodibility and improved soil-water dynamics. Over the past few decades numerous methods have been developed to measure aggregate stability. Limited comparisons among the indicators have shown that methodological differences result in varied magnitudes of response to soil health management practices and varied influences of inherent soil properties and climate. It is not clear whether selection of an individual measurement method creates any advantage to the investigator. This study assessed four commonly used methods of measuring aggregate stability using data collected as part of the North American Project to Evaluate Soil Health Measurements. The methods included water stable aggregates using the Cornell Rainfall Simulator (WSACASH), wet sieved water stable aggregates (WSAARS), slaking captured with image recognition (STAB10), and the mean weight diameter of water stable aggregates (MWD). Influence of climate and inherent soil properties were analyzed in addition to indicator responses to rotation diversity, crop count, residue management, organic nutrient amendments, cover crops, and reduced physical disturbance. All four methods were sensitive to climate and inherent soil properties between sites. None of the indicators were sensitive to increases in rotation diversity or crop count, while all significantly recorded improved aggregate stability in systems with reduced tillage. Significant increases or positive trends were observed for all indicators in relation to cover cropping, increased residue retention, and organic amendments, except for STAB10, which expressed a slightly negative response to organic amendments. Considering the costs and availability of indicator measurements at commercial laboratories and the performance of the indicators in this study, STAB10 is the best suited indicator for measuring aggregate stability at commercial scales.