Elevated [CO2] enhanced soil respiration and amf abundance in a semiarid peanut agroecosystem

Authors: LAZA, HAYDEE - Texas Tech University; Acosta-Martinez, Veronica; CANO, AMANDA - Texas Tech University; Baker, Jeffrey; Mahan, James; Gitz, Dennis; Emendack, Yves; SLAUGHTER, LINDSEY - Texas Tech University; Lascano, Robert; TISSUE, DAVID - Western Sydney University; Payton, Paxton

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2023
Publication Date: 5/30/2023
Citation: Laza, H., Acosta Martinez, V., Cano, A., Baker, J.T., Mahan, J.R., Gitz, D.C., Emendack, Y., Slaughter, L., Lascano, R.J., Tissue, D., Payton, P.R. 2023. Elevated [CO2] enhanced soil respiration and AMF abundance in a semiarid peanut agroecosystem. Agriculture, Ecosystems and Environment. 355. https://doi.org/10.1016/j.agee.2023.108592.
DOI: https://doi.org/10.1016/j.agee.2023.108592

Interpretive Summary: Continued increase in atmospheric carbon dioxide [CO2] is predicted to have significant effects on ecosystem productivity as a result of altered plant growth and changes in microbial communities. Carbon sequestration by plants and soils serves to buffer the negative effects of increasing [CO2] but our knowledge of the long-term impact of elevated [CO2] on crop production and soil microbes is limited. Further, the dynamics of the interactions between the plants and microbes, both good and bad, is unknown. Most legumes, including peanut, form a valuable symbiotic relationship with fungi and bacteria that allow for the utilization of atmospheric nitrogen as fertilizer. This relationship is critical for peanut crop production and also a key part of both the global nitrogen and carbon cycles and soil health. We studied the impact of elevated [CO2] on peanut production and the below-ground changes in soil respiration and soil microbe communities. Elevated [CO2] resulted in a significant shift in the community structure, increasing specific types of fungi, while reducing others. Additionally, microbial respiration and growth appeared to be unaffected by periodic drought conditions compared to control plots grown under ambient [CO2]. These findings suggest that in future climates, soil respiration, soil fungal populations, and nutrient availability are most likely to increase in semi-arid peanut agroecosystems where periodic drought is common. Further, the increases in soil microbial activity may improve crop resilience to these periodic drought conditions. This work lays the foundation for future studies to examine how these changes in soil microbe populations might affect soil health, soil carbon sequestration, and crop productivity under increased [CO2].

Technical Abstract: Rising atmospheric carbon dioxide concentration ([CO2]) and intensification of drought are expected to significantly alter the soil respiration rate in many crop production systems. However, the below-ground responses of the soil microbiome in response to elevated [CO2] (EC) conditions is poorly understood especially in a semi-arid production systems like the southwestern US, many of which can host both rhizobia and arbuscular mycorrhizal fungi that support plant resilience to water deficit stress and aid in nutrient uptake. This study investigated the effect of EC on the soil respiration and the microbial component during two successive growing seasons in a deficit irrigation peanut production system on the US Southern Great Plains. We evaluated the soil microbial community size and composition using ester-linked fatty acid methyl ester (EL-FAME) profiling and changes in soil metabolic activity by measuring soil respiration and ß-glucosidase activity. The 2 year-study mean showed that EC shifted the soil microbial community composition by 46% towards greater arbuscular mycorrhizal (AMF) markers compared to ambient [CO2] (AC) conditions. Soil respiration was increased by 82% in EC conditions during the soil water-deficit periods, however, there were no significant changes in ß-glucosidase activity, the enzyme involved in the rate-limiting step of cellulose degradation. Our results show that EC increased the soil organic carbon, indicating that the soil nutrient availability at limited soil moisture. These findings suggest that in future climates, soil respiration, AMF populations, and nutrient availability are most likely to increase in semiarid peanut agroecosystems. Therefore, understanding how these changes will affect soil ecology and the climate feedbacks is critical.