Nutrient management and bioaugmentation interactively shape plant–microbe interactions inMiscanthus × giganteus

Abstract

Marginal lands are an untapped source of agricultural potential, particularly regarding high‐yielding, low‐input bioenergy crops like Miscanthus × giganteus (Miscanthus). Miscanthus is of specific interest because it can be productive and sequester carbon in soil even under the stressful conditions present on some degraded lands. A key component of these abilities is the interaction of Miscanthus with its soil and root microbiome. Microbial functions depend on the nutrient status of soil, and hence are sensitive to fertilization regimes. Nevertheless, little is known about how fertilization strategies affect the partnership of Miscanthus with its microbial associates. Here, we tested the individual and interactive effects of nutrient addition and bioaugmentation (i.e., the addition of microbial communities) on Miscanthus performance and microbiome function in marginal soil. We found that the effect of nutrient addition on Miscanthus biomass yield depended on nutrient addition type (i.e., organic or inorganic nutrients) and whether bioaugmentation was also applied. Some microbial functions, like free‐living nitrogen fixation and carbon use efficiency, were sensitive to nutrient addition depending on whether bioaugmentation was also applied. On the other hand, arbuscular mycorrhizal fungus colonization of roots decreased with fertilization regardless of bioaugmentation. These results imply that managing microbial communities may regulate the effect of nutrient addition on plant–microbe interactions that in part determine system productivity and environmental impact.

Metagenomic insights into the alteration of soil N‐cycling‐related microbiome and functions under long‐term conversion of cropland toMiscanthus

“…Miscanthus cultivation can enhance microbial functions of soil N‐cycling, facilitating N absorption and improving the N using efficiency of Miscanthus (Ma et al, 2021). Interestingly, several reports have evidenced that Miscanthus cultivation, even in the first year (Keymer & Kent, 2014), can recruit the N fixers to provide nonnegligible N to meet Miscanthus growth demand (Kane et al, 2022; Zhao et al, 2021), especially under N deficiency conditions (Liu & Ludewig, 2019). We herein, together with our previous report (Zhao et al, 2021), strongly supported this point in different Miscanthus species and stand ages (10 and 15 years) based on a LCMC.…”

Roots selectively decompose litter to mine nitrogen and build new soil carbon

“…All roots that were inside of the cores were separated from soils and washed in the lab. Dry root biomass was measured, and microbial biomass C was measured from a subsample of soil from each core using chloroform slurry fumigations (Witt et al., 2000) followed by persulfate digestion to CO 2 (Doyle et al., 2004; Kane et al., 2022). In brief, soils were extracted in potassium sulfate with and without chloroform for 4 h. Filtered supernatant was digested in persulfate solution, where dissolved C was oxidized to CO 2 .…”

“…The extent to which roots and mycorrhizal fungi facilitate SOM formation or loss in agricultural ecosystems may be modulated by fertilization. For example, some N‐limited plants can dynamically shift C allocation belowground to root exudation and mycorrhizal symbionts to stimulate microbial decomposition in the rhizosphere and increase N acquisition (Brzostek et al., 2014; Kane et al., 2022). When N limitation is alleviated by fertilization, plants can also reduce belowground C allocation, suppressing SOM decomposition (Eastman et al., 2021; Frey et al., 2014).…”

Roots prime microbes to extract nitrogen and stabilize soil organic matter

“…All roots that were inside of the cores were separated from soils and washed in the lab. Dry root biomass was measured, and microbial biomass C was measured from a subsample of soil from each core using chloroform slurry fumigations (Witt et al, 2000) followed by persulfate digestion to CO 2 (Doyle et al, 2004;Kane et al, 2022). In brief, soils were extracted in potassium sulfate with and without chloroform for 4 hrs.…”

“…The extent to which roots and mycorrhizal fungi facilitate SOM stabilization or destabilization in agricultural ecosystems may be modulated by fertilization. For example, some N-limited plants can dynamically shift C allocation belowground to root exudation and mycorrhizal symbionts to stimulate microbial decomposition in the rhizosphere and increase N acquisition (Brzostek et al, 2014;Kane et al, 2022). When N limitation is alleviated by fertilization, plants can also reduce belowground C allocation, suppressing SOM decomposition (Eastman et al, 2021;Frey et al, 2014).…”