Plant litter quality affects the accumulation rate, composition, and stability of mineral-associated soil organic matter

Córdova, S. Carolina; Olk, Dan C.; Dietzel, Ranae; Mueller, Kevin E.; Archontouilis, Sotirios V.; Castellano, Michael J.

doi:10.1016/j.soilbio.2018.07.010

Cited by 154 publications

(86 citation statements)

References 68 publications

(94 reference statements)

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“…The carbon to nitrogen (C:N) ratio of roots, which is critical to predict soil organic matter (SOM) dynamics, also varies across environments and growth stages. Root C:N ratio is the primary indicator of crop residue quality, which influences nutrient availability and SOM stabilization (Gentile et al, 2011b;Córdova et al, 2018) in the shortand long-term (Gentile et al, 2011a;Cotrufo et al, 2013;Sprunger et al, 2019). Although low C:N ratios are often assumed to promote nutrient release and SOM stabilization, results are inconsistent (Castellano et al, 2015) and a previous study indicated that the formation and stabilization of SOC is more affected by the quantity of residue inputs and their interaction with soil matrix than the quality of residue inputs (Gentile et al, 2011b).…”

Section: Introductionmentioning

confidence: 99%

Root to shoot and carbon to nitrogen ratios of maize and soybean crops in the US Midwest

Ordóñez

Archontoulis

Martinez-Feria

et al. 2020

European Journal of Agronomy

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Root traits are important to crop functioning, yet there is little information about how root traits vary with shoot traits. Using a standardized protocol, we collected 160 soil cores (0−210 cm) across 10 locations, three years and multiple cropping systems (crops x management practices) in Iowa, USA. Maximum root biomass ranged from 1.2 to 2.8 Mg ha−1 in maize and 0.86 to 1.93 Mg ha−1 in soybean. The root:shoot (R:S) ratio ranged from 0.04 to 0.13 in maize and 0.09 to 0.26 in soybean. Maize produced 27 % more root biomass, 20 % longer roots, with 35 % higher carbon to nitrogen (C:N) ratio than soybean. In contrast, soybean had a 47 % greater R:S ratio than maize. The maize R:S ratio values were substantially lower than literature values, possibly due to differences in measurement methodologies, genotypes, and environment. In particular, we sampled at plant maturity rather than crop harvest to minimize the effect of senescence on measurements of shoots and roots. Maximum shoot biomass explained 70 % of the variation in root biomass, and the R:S ratio was positively correlated with the root C:N measured in both crops. Easily-measured environmental variables including temperature and precipitation were weakly associated with root traits. These results begin to fill an important knowledge gap that will enable better estimates of belowground net primary productivity and soil organic matter dynamics. Ultimately, the ability to explain variation in root mass production can be used to improve C and N budgets and modeling studies from crop to regional scales.

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Section: Introductionmentioning

confidence: 99%

Root to shoot and carbon to nitrogen ratios of maize and soybean crops in the US Midwest

Ordóñez

Archontoulis

Martinez-Feria

et al. 2020

European Journal of Agronomy

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“…First, plant tissue chemistry determines the availability of plant derived C that could be stabilized by physicochemical interactions in mineral soils . Plant tissue chemistry regulates decomposition rates of plant litter, substrate use efficiency by soil microbes, and the inherent “recalcitrance” and reactivity of plant biomolecules (e.g., Castellano, Mueller, Olk, Sawyer, & Six, ; Córdova et al, ; Mueller, Polissar, Oleksyn, & Freeman, ; Mueller et al, ). Thus, the stability of total SOM in mineral soils beneath different tree species could be positively correlated with indices of those species’ litter quality (e.g., low lignin to nitrogen ratios), because correspondingly high rates of litter decomposition and high substrate use efficiency by microbes would result in greater proportional retention of microbial C in SOM pools that are stabilized by organo‐mineral interactions (both of which would increase the proportion of stable SOM within total SOM).…”

Section: Introductionmentioning

confidence: 99%

Soil organic carbon stability in forests: Distinct effects of tree species identity and traits

Angst

Mueller

Eissenstat

et al. 2019

Global Change Biology

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Rising atmospheric CO2 concentrations have increased interest in the potential for forest ecosystems and soils to act as carbon (C) sinks. While soil organic C contents often vary with tree species identity, little is known about if, and how, tree species influence the stability of C in soil. Using a 40 year old common garden experiment with replicated plots of eleven temperate tree species, we investigated relationships between soil organic matter (SOM) stability in mineral soils and 17 ecological factors (including tree tissue chemistry, magnitude of organic matter inputs to the soil and their turnover, microbial community descriptors, and soil physicochemical properties). We measured five SOM stability indices, including heterotrophic respiration, C in aggregate occluded particulate organic matter (POM) and mineral associated SOM, and bulk SOM δ15N and ∆14C. The stability of SOM varied substantially among tree species, and this variability was independent of the amount of organic C in soils. Thus, when considering forest soils as C sinks, the stability of C stocks must be considered in addition to their size. Further, our results suggest tree species regulate soil C stability via the composition of their tissues, especially roots. Stability of SOM appeared to be greater (as indicated by higher δ15N and reduced respiration) beneath species with higher concentrations of nitrogen and lower amounts of acid insoluble compounds in their roots, while SOM stability appeared to be lower (as indicated by higher respiration and lower proportions of C in aggregate occluded POM) beneath species with higher tissue calcium contents. The proportion of C in mineral associated SOM and bulk soil ∆14C, though, were negligibly dependent on tree species traits, likely reflecting an insensitivity of some SOM pools to decadal scale shifts in ecological factors. Strategies aiming to increase soil C stocks may thus focus on particulate C pools, which can more easily be manipulated and are most sensitive to climate change.

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“…As an extension, biochemically recalcitrant inputs would preferentially accumulate as POM (Castellano, Mueller, Olk, Sawyer, & Six, 2015). While this hypothesis has been tested and often confirmed in the laboratory (Córdova et al, 2018;Haddix et al, 2016;Lavallee et al, 2018) field experiments are still limited and largely performed in natural forest or grassland systems (Bird, Kleber, & Torn, 2008;Bird & Torn, 2006;Sokol et al, 2018;Soong et al, 2016). Understanding how differences in litter chemistry impact the decomposition and resultant SOM formation of root vs shoots is going to be critical to informing agricultural management, particularly in bioenergy production systems.…”

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confidence: 99%

Pathways of soil organic matter formation from above and belowground inputs in a Sorghum bicolor bioenergy crop

Fulton-Smith

Cotrufo

2019

GCB Bioenergy

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When aboveground materials are harvested for fuel production, such as with Sorghum bicolor, the sustainability of annual bioenergy feedstocks is influenced by the ability of root inputs to contribute to the formation and persistence of soil organic matter (SOM), and to soil fertility through nutrient recycling. Using 13C and 15N labeling, we traced sorghum root and leaf litter‐derived C and N for 19 months in the field as they were mineralized or formed SOM. Our in situ litter incubation experiment confirms that sorghum roots and leaves significantly differ in their inherent chemical recalcitrance. This resulted in different contributions to C and N storage and recycling. Overall root residues had higher biochemical recalcitrance which led to more C retention in soil (27%) than leaf residues (19%). However, sorghum root residues resulted in higher particulate organic matter (POM) and lower mineral associated organic matter (MAOM), deemed to be the most persistent fraction in soil, than leaf residues. Additionally, the overall higher root‐derived C retention in soil led to higher N retention, reducing the immediate recycling of fertility from root as compared to leaf decomposition. Our study, conducted in a highly aggregated clay‐loam soil, emphasized the important role of aggregates in new SOM formation, particularly the efficient formation of MAOM in microaggregate structures occluded within macroaggregates. Given the known role of roots in promoting aggregation, efficient formation of MAOM within aggregates can be a major mechanism to increase persistent SOM storage belowground when aboveground residues are removed. We conclude that promoting root inputs in S. bicolor bioenergy production systems through plant breeding efforts may be an effective means to counterbalance the aboveground residue removal. However, management strategies need to consider the quantity of inputs involved and may need to support SOM storage and fertility with additional organic matter additions.

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Plant litter quality affects the accumulation rate, composition, and stability of mineral-associated soil organic matter

Cited by 154 publications

References 68 publications

Root to shoot and carbon to nitrogen ratios of maize and soybean crops in the US Midwest

Root to shoot and carbon to nitrogen ratios of maize and soybean crops in the US Midwest

Soil organic carbon stability in forests: Distinct effects of tree species identity and traits

Pathways of soil organic matter formation from above and belowground inputs in a Sorghum bicolor bioenergy crop

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