Soil health, microbial communities, and annual ryegrass yield under contrasting management practices

Authors: GONZALEZ-MATEU, MARTINA - Oregon State University; DOMNARIU, HORIA - University Of Budapest; MOORE, AMBER - Oregon State University; Trippe, Kristin

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2024
Publication Date: 11/2/2023
Citation: Gonzalez-Mateu, M., Domnariu, H., Moore, A., Trippe, K.M. 2023. Soil health, microbial communities, and annual ryegrass yield under contrasting management practices. Agronomy Journal. 116(1):380-393. https://doi.org/10.1002/agj2.21484.
DOI: https://doi.org/10.1002/agj2.21484

Interpretive Summary: Soil health, defined as “the capacity of soil to function as a vital living system” is measured using physical, biological, and chemical indicators. Over the past few decades, soil health indicators have been used to understand how land management practices impact soil function. Generally, conservation practices like no-till and returning of crop residues improve soil health compared to fields under conventional management practices, however, the relationship between management-driven impacts to soil health and yield is not well understood. The goal of this study was to explore the relationships between management practices, soil health metrics, and plant yield in annual ryegrass. To determine if improvements in soil health improvements led to increased yields, we collected soils from fields that either had a history of conservation or conventional practices and used them to grow annual ryegrass under controlled conditions. Prior to planting, soil health metrics were assessed. After the ryegrass was grown for five months, the above ground biomass was harvested. We found that conservation management led to improved soil health by increasing carbon cycling indicators in silt loam-textured soils, but not in silty clay loam- textured soil. Soil health related improvements in silt loams did not lead to greater yield. Conversely, in silty-clay loam textured soils, conservation management practices led to higher yields, but these improvements were not related to improvements in soil health. To determine if yield increases were related to soil microbial community structure, we examined the microbial community structure, Contrasting management practices resulted in distinct microbial communities, and the composition of these communities were positively associated with both soil health and plant metrics. These results highlight the complex interplay between microbial communities, soil health, and plant growth and the importance of considering inherent soil properties like texture.

Technical Abstract: Biological soil health indicators are often used to evaluate improvements to the soil made by conservation practices. However, which indicators are the most appropriate to assess changes in soil health after implementation of conservation practices, and how these relate to crop yield, remains unclear. The goal of this study was to explore the relationships between management practices, soil health metrics, plant yield, and soil microbial communities in annual ryegrass under normalized greenhouse conditions. A greenhouse experiment was set up using soils from annual ryegrass fields under contrasting managements (till/bale and no-till/straw). Soil health metrics were assessed. Annual ryegrass was grown for 5 months after which biomass was harvested and soil microbial communities analyzed using amplicon sequencing. Conservation management had texture-dependent effects on soil health and improved most carbon cycling metrics in silt loams, but not in silty clay loams. Soil health improvements in silt loams did not lead to greater yield; instead, plants in silty clay loams had higher aboveground biomass under conservation management. Contrasting management practices resulted in distinct microbial communities, making them sensitive indicators of changes in soil abiotic conditions, and both soil health and plant metrics were positively associated with the microbial communities from soils under conservation management. Biological soil health indicators (active and total carbon, and '-glucosidase) were negatively correlated to most plant parameters. These results highlight the complex interplay between microbial communities, soil health, and plant growth and the importance of considering inherent soil properties like texture.