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Browsing Research Data by Author "Haddix, Michelle"

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    ItemOpen Access
    Dataset associated with the manuscript: “Divergent belowground allocation patterns of winter wheat shape rhizosphere microbial communities and nitrogen cycling activities”
    (Colorado State University. Libraries, 2021) Kelly, Courtland; Fonte, Steven; Haddix, Michelle
    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 (13C-CO2) and applied 15N 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 the N-cycling response to exudation 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.
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    ItemOpen Access
    Dataset associated with the manuscript: “Long-term compost amendment modulates wheat genotype differences in belowground carbon allocation, rhizosphere recruitment and nitrogen acquisition”
    (Colorado State University. Libraries, 2021) Kelly, Courtland; Fonte, Steven; Haddix, Michelle
    The implementation of soil health-promoting practices, such as cover crops and compost additions, has important implications for nutrient cycling regimes in agroecosystems. At the same time, plant belowground carbon (C) allocation patterns can influence nutrient cycling and availability in soil, but the effects may depend on the crop genotype and management practices in place. The relationship between root exudation, rhizosphere communities and the processes they regulate is likely influenced by a range of soil conditions, including soil organic matter (SOM) content, nutrient status, and overall soil biological activity, but such interactions remain poorly understood. To better understand the potential role of long-term soil management (that alters of SOM) and crop genotype in regulating rhizosphere microbial communities and associated nitrogen (N) cycling processes, we collected soils from two treatments in a 10-year field trial, one with high compost inputs (108.7 Mg ha-1 every 2 years) and a control (no nutrient inputs). We then used stable isotopes to measure belowground C allocation patterns in two genotypes of winter wheat (Triticum aestivum) with distinct rooting and exudation strategies. We also measured microbial community structure and function in the rhizosphere and quantified uptake of residue-derived N from 15N-labeled residues. We found an interactive effect between soil management and genotype, where the high-exudation genotype modified its exudation more in response to soil management and was relatively better at accessing residue N in the compost-amended soils than the low-exudation genotype. The high-exudation genotype also demonstrated selection of specific rhizosphere microbial taxa, with several taxa conserved across soil treatments. Our results suggest that the high-exudation strategy influences the microbial community, and this strategy is more successful in soils with higher SOM. Understanding the relationship between crop genotype, soil management, and microbial function can help inform crop production and breeding strategies in systems seeking to leverage improved soil health and biological nutrient cycling.