Divergent belowground carbon allocation patterns of winter wheat shape rhizosphere microbial communities and nitrogen cycling activities. (February 2022)

• Record Type: Journal Article
• Authors: Kelly, Courtland; Haddix, Michelle L.; Byrne, Patrick F.; Cotrufo, M. Francesca; Schipanski, Meagan; Kallenbach, Cynthia M.; Wallenstein, Matthew D.; Fonte, Steven J.
• Is Part Of: Soil biology and biochemistry. Volume 165(2022)
• Publication Date: 2022-02
• Subjects: Crop genotype -- Rhizodeposition -- Root architecture -- Stable isotopes -- Triticum aestivum; Soil biochemistry -- Periodicals; Soil biology -- Periodicals; Sols -- Biochimie -- Périodiques; Sols -- Biologie -- Périodiques; Sols -- Microbiologie -- Périodiques; Bodembiologie; Biochemie; 631.46
• DOI: 10.1016/j.soilbio.2021.108518
• Languages: English
• ISSNs: 0038-0717

Abstract

Abstract: Plant roots add carbon (C) -rich rhizodeposits to the soil, which can alter microbial activity and nitrogen (N) cycling with implications for N availability and uptake by plants. We evaluated root architecture, rhizodeposit C, and microbial community structure and function across a breeding gradient of twelve winter wheat genotypes and examined how these rhizosphere traits were related to the availability and uptake of N from fresh cover crop residues in the soil. We traced wheat-derived C into soil and microbial pools using continuous isotopic labelling ( 13 C–CO2 ) and applied 15 N labelled plant residues to quantify plant and microbial uptake of residue-derived N. Wheat genotypes differed in root C allocation patterns, influencing N cycling. Thicker roots released more C into soil, which enhanced N mineralization through stimulation of the microbial biomass. Microbial biomass increased N-cycling enzyme activity and residue N-uptake by wheat. Microbial communities did not differ between wheat genotypes but were strongly related to patterns in root C allocation, and several genera showed strong relationships with root C deposition and N uptake. The microbial community associated with extractable root-derived C was structurally different from the community associated with residue N uptake, indicating that N-cycling and mineralization was not necessarily carried out by the same microbial community members as those stimulated by rhizosphere C inputs. Our results indicate that differential patterns of rhizodeposition and associated belowground C allocation strategies in winter wheat can alter microbial communities and influence cycling and plant availability of residue N. Ecologically-based nutrient management in agricultural systems should consider the role of crop root traits and associated microbiomes to optimize soil nutrient dynamics. Highlights: Wheat with short, coarse roots had the highest C rhizodeposition and enzyme activity. Soil N-cycling enzyme activity was stimulated by the release of wheat-derived C. Microbial biomass C was related to increased cover crop N uptake and N cycling activity. Rhizosphere microbial communities and taxa were associated with specific C and N pools, but not wheat genotype.