A team of Chinese scientists has discovered a link between plant traits and the rhizosphere priming effect (RPE), which is the change in soil organic matter decomposition caused by roots and microbes.

The researchers studied six common grassland plants with and without nitrogen fertilizer, and found that RPE varied across species and was influenced by nitrogen addition. The most important plant traits that explained the interspecific variation were specific rhizosphere respiration (SRR) and root nitrogen concentration, both of which had a positive correlation with the RPE. SRR is the amount of carbon dioxide released per unit root biomass per day, and it reflects the root metabolic activity and exudation. Root nitrogen concentration indicates the nutrient status and quality of roots. The researchers suggested that these two traits represent the carbon input and output of plants to the rhizosphere, which affect the microbial activity and soil organic matter decomposition.

They found that root traits explained more variation in RPE than leaf traits, and that nitrogen fertilization affected RPE through its interaction with plant traits and soil processes.

Their findings suggest that plant traits can help predict soil carbon dynamics under global change, which is important for understanding the feedbacks between plants, soils, and climate. Their study was published in Functional Ecology entitled "Linking plant traits to rhizosphere priming effects across six grassland species with and without nitrogen fertilization".