Alain F. Plante

University of Pennsylvania | UP · Department of Earth and Environmental Science

Iron (Fe)-bearing mineral phases contribute disproportionately to adsorption of soil organic matter (SOM), due to their elevated chemical reactivity and specific surface area (SSA). However, the spectrum of Fe solid-phase speciation present in oxidation-reduction-active soils challenges analysis of SOM-mineral interactions and may induce differenti...

Simultaneous thermal analysis [i.e., thermogravimetry (TG) and differential scanning calorimetry (DSC)] is frequently used in materials science applications and is increasingly being used to study soil organic matter (SOM) stability. Yet, important questions remain, especially with respect to how the soil mineral matrix affects TG-DSC results, whic...

In calcareous soils, two methods for measuring soil organic carbon (SOC) have been traditionally used: 1) wet oxidation, and 2) dry combustion in which SOC is measured either directly by removing soil inorganic carbon (SIC) from samples through an acid pretreatment, or indirectly by subtracting SIC measured by a calcimeter from total soil C. These...

Organic carbon (C) associated with fine soil particles (<20 μm) is relatively stable and accounts for a large proportion of total soil organic C (SOC). The soil C saturation concept proposes a maximal amount of SOC that can be stabilized in the fine soil fraction, and the soil C saturation deficit (i.e., the difference between current SOC and the m...

Volcanic ash‐derived soils are naturally deficient in the essential micronutrient B, but they also have maximum adsorption capacities (bB) that are as much as 40 times greater than in non‐volcanic soils, further exacerbating B availability. Because short‐range‐order (SRO) aluminosilicates (allophane and imogolite) and iron (Fe) oxyhydroxides are ma...

The global carbon cycle is strongly modulated by organic carbon (OC) sequestration and decomposition. Whereas OC sequestration is relatively well constrained, there are few quantitative estimates of its susceptibility to decomposition. Fjords are hot spots of sedimentation and OC sequestration in marine sediments. Here, we adopt fjords as model sys...

Iron (Fe) (oxyhydr)oxides represent a significant phase for the organic carbon (OC) stabilization. Due to their high surface areas, short-range-ordered Fe minerals, like ferrihydrite, show a higher ability to stabilize OC than crystalline secondary minerals, like lepidocrocite, goethite, and magnetite. However, how Fe phases and their crystallinity...

Alluvial riparian soils act as a filtration system, improving the environmental quality of downstream soils and waters. In areas affected by coal mining, alluvial soils also serve as a modern “sink” of fossil carbon (C). To date, little research has been done on ecosystem services provided by alluvial landscapes (i.e., river islands and tributary d...

This study assessed the applicability of artificial neural networks (ANNs) as a tool to identify compounds contributing to compositional differences in coal-contaminated soils. An artificial neural network model was constructed from laser desorption ionization ultrahigh-resolution mass spectra obtained from coal contaminated soils. A good correlati...

Extreme rainfall events in the humid-tropical Luquillo Mountains, Puerto Rico export the bulk of suspended sediment and particulate organic carbon. Using 25 years of river carbon and suspended sediment data, which targeted hurricanes and other large rainstorms, we estimated biogenic particulate organic carbon yields of 65 ± 16 tC km−2 yr−1 for the...

The soils in urban greenery provide essential ecosystem services. However, only a few studies have assessed urban soil quality based on a comprehensive view of ecosystem services and soil multi-functionality. In this study, we suggest an urban soil quality index (uSQI) to evaluate soil status in various spatial types of urban greenery. Our objectiv...

Understanding the controls on the amount and persistence of soil organic carbon (C) is essential for predicting its sensitivity to global change. The response may depend on whether C is unprotected, isolated within aggregates, or protected from decomposition by mineral associations. Here, we present a global synthesis of the relative influence of e...

How land-use and soil depth affect soil organic carbon (SOC) quality and stability, properties that are key to the long-term storage of C, is poorly understood in agroforestry systems. We examined the effects of land-use (forest vs. annual cropland) and soil depth (0–10 vs. 10–30 cm) on the quality (availability of C for decomposition), structural...

Investigating the effectsof various agricultural management systems on soil hydraulic properties in long-term field experiments allows farmers to evaluate their efficacy in mitigating the effects of droughts and floods, which are expected to intensify in the coming decades. This study's main objective was to quantify soil structural and hydraulic p...

Abstract: Terrestrial ecosystems in Iceland have undergone tremendous alterations and degradation ever since the Norse first settled there in 870 C.E. Soon after recognizing the value of their land, the Norse tried to restore the damage they had done. Initial environmental protection efforts like these eventually gave way to a deep-rooted Icelandic...

Terrestrial ecosystems in Iceland have undergone tremendous alterations and degradation ever since the Norse first settled there in 870 C.E. Soon after recognizing the value of their land, the Norse tried to restore the damage they had done. Initial environmental protection efforts like these eventually gave way to a deep-rooted Icelandic environme...

Nature-based tourism is a general term for travel activities in which people interact with land separate from humanity’s daily movements. Despite untouched land being the ideal locale, tourists also desire modern amenities and curated products. There is a tension between what level of development is idealized and desired, as development itself is c...

The magnitude of carbon (C) loss to the atmosphere via microbial decomposition is a function of the amount of C stored in soils, the quality of the organic matter, and physical, chemical, and biological factors that comprise the environment for decomposition. The decomposability of C is commonly assessed by laboratory soil incubation studies that m...

Radiocarbon is a critical constraint on our estimates of the timescales of soil carbon cycling that can aid in identifying mechanisms of carbon stabilization and destabilization and improve the forecast of soil carbon response to management or environmental change. Despite the wealth of soil radiocarbon data that have been reported over the past 75...

Soil organic matter (SOM) concentration and enzyme activity are important biochemical indicators of soil health for assessing the sustainability of agricultural management practices. However, little is known about the long-term effects of tillage and crop residue management on SOM and enzyme activities in soil particle-size fractions on the Loess P...

How weathering affects the physiochemical properties of biochar and its long-term carbon (C) sequestration potential remains unclear. In this study, we measured changes in biochar recalcitrance and solubility after 7 years of weathering in a cultivated field. Biochar recalcitrance and biodegradability of weathered and unweathered hardwood biochar m...

Abstract. The magnitude of carbon (C) loss to the atmosphere via microbial decomposition is a function of the amount of C stored in soils, the quality of the organic matter, and physical, chemical and biological factors that comprise the environment for decomposition. The decomposability of C is commonly assessed by laboratory soil incubation studi...

Soil profiles are rarely homogeneous. Resource availability and microbial abundances typically decrease with soil depth, but microbes found in deeper horizons are still important components of terrestrial ecosystems. By studying 20 soil profiles across the United States, we documented consistent changes in soil bacterial and archaeal communities wi...

While most bacterial and archaeal taxa living in surface soils remain undescribed, this problem is exacerbated in deeper soils owing to the unique oligotrophic conditions found in the subsurface. Additionally, previous studies of soil microbiomes have focused almost exclusively on surface soils, even though the microbes living in deeper soils also...

Radiocarbon is a critical constraint on our estimates of the timescales of soil carbon cycling that can aid in identifying mechanisms of carbon stabilization and destabilization, and improve forecast of soil carbon response to management or environmental change. Despite the wealth of soil radiocarbon data that has been reported over the past 75 yea...

Iron oxide surfaces can preserve soil organic matter (SOM) through the formation of mineral–organic associations (MOAs). Warming climates can affect SOM dynamics through altering the formation and stability of MOAs. We conducted batch sorption experiments from 15 to 35 °C using hematite and soil humic and fulvic acids to assess the stability of MOA...

Extensive sample preparation procedures are required to analyze natural organic matter (NOM) in soil and sediment samples due to the mineral matrix. The preparation procedure not only requires a large amount of sample (typically more than 50 mg) but also incomplete extraction of the organic can be done. In this study, 2–5 μg solid NOM or 500 μg unp...

Physical and chemical stabilization, environmental conditions, and organic matter composition all play vital roles in determining the persistence of soil organic matter (SOM). Fundamentally, SOM stability depends on the balance of microbial bioenergetics between the input of energy needed to decompose it (i.e., activation energy; Ea) and the net en...

The emerging view of soil organic matter (SOM) persistence asserts that SOM exists as a continuum of organic material, continuously processed by the decomposer community from large biopolymers to small monomers and with increasing oxidation and solubility, protected from decomposition through mineral aggregation and adsorption. Microbial community...

Our study tests the emerging paradigm that biochemical recalcitrance does not affect substantially long-term (50 years) SOC persistence. We analyzed the molecular composition of SOC in archived soils originating from four European long-term bare fallow experiments (Askov, Rothamsted, Versailles and Ultuna). The soils had been collected after variou...

Soil organic matter (SOM) turnover increasingly is conceptualized as a tension between accessibility to microorganisms and protection from decomposition via physical and chemical association with minerals in emerging soil biogeochemical theory. Yet, these components are missing from the original mathematical models of belowground carbon dynamics an...

While the contribution of iron (Fe)-bearing minerals to organic carbon (C) stabilization in terrestrial systems is well-described, the influence of Fe solid-phase speciation on organomineral associations is unclear in highly-dynamic, oxidation-reduction (redox)-active soils. In humid tropic forest soils, fluctuations in redox state accelerate weath...

Changes in global soil carbon stocks have considerable potential to influence the course of future climate change. However, a portion of soil organic carbon (SOC) has a very long residence time ( > 100 years) and may not contribute significantly to terrestrial greenhouse gas emissions during the next century. The size of this persistent SOC reservo...

Changes in global soil carbon stocks have considerable potential to influence the course of future climate change. To implement sequestration strategies and evaluate their efficiency it is essential to estimate the soil organic carbon (SOC) that is mineralized over a relatively short period of time (e.g., 20 years). Nonetheless, models of SOC dynam...

Changes in global soil carbon stocks have considerable potential to influence the course of future climate change. However, a portion of soil organic carbon (SOC) has a very long residence time (> 100 years) and may not contribute significantly to terrestrial greenhouse gas emissions during the next century. The size of this persistent SOC reservoi...

Improved quantification of the factors controlling soil organic matter (SOM) stabilization at continental to global scales is needed to inform projections of the largest actively cycling terrestrial carbon pool on Earth, and its response to environmental change. Biogeochemical models rely almost exclusively on clay content to modify rates of SOM tu...

Calcareous soils where lithogenic and secondary carbonates are important constituents of the soil mineral matrix abound in many arid and semiarid areas. Soil carbonates have been described as an organic matter stabilization agent, mainly due to chemical stabilization mechanisms. In this chapter, we focus on the role of carbonates as indirect agents...

Tropical forest soils contribute disproportionately to the poorly-characterized and persistent deep soil carbon (C) pool. These soils, highly-weathered and often extending one to two meters in depth, may contain an abundance of iron-(Fe) bearing mineral phases. Short-range-order (SRO) minerals are of particular interest due to their high reactive s...

Soil organic matter (SOM) plays a critical role in the global terrestrial carbon cycle, and a better understanding of soil processes involved in SOM stability is essential to determine how projected climate-driven changes in soil processes will influence carbon dynamics. We used ¹⁴C signature, analytical thermal analysis, and ultrahigh resolution m...

Process-based models are a powerful approach to test our understanding of biogeochemical processes, to extrapolate ground survey data from limited plots to the landscape scale, and to simulate the effects of climate change, nitrogen deposition, elevated atmospheric CO2, increasing natural disturbances, and land-use change on ecological processes. H...

The organic carbon reservoir of soils is a key component of climate change, calling for an accurate knowledge of the residence time of soil organic carbon (SOC). Existing proxies of the size of SOC labile pool such as SOC fractionation or respiration tests are time consuming and unable to consistently predict SOC mineralization over years to decade...

Droughts, which can strongly affect both hydrologic and biogeochemical systems, are projected to become more prevalent in the tropics in the future. We assessed the effects of an extreme drought during 2015 on stream water composition in the Luquillo Mountains of Puerto Rico. We demonstrated that drought baseflow in the months leading up to the stu...

Organic inputs from plant establishment are part of the rehabilitation process in restoring coal minesoil function. Soil organic matter (SOM) content could therefore potentially be an indicator of rehabilitation success. Rehabilitated coal minesoils contain inherited coal and char that complicate the attribution of measured total C to recent SOM in...

We know little about how shifts in tree species distribution and increases in forest fire intensity could affect the formation of pyrogenic organic matter (PyOM) or charcoal, one of the most important and persistent soil organic matter pools. This limitation arises partly because the role of the precursor wood in controlling PyOM formation is uncle...

A large fraction of soil organic matter (OM) resists decomposition over decades to centuries as indicated by long radiocarbon residence times, but the mechanisms responsible for the long-term (multi-decadal) persistence are debated. The current lack of mechanistic understanding limits our ability to accurately predict soil OM stock evolution under...

Globally, soil respiration is one of the largest fluxes of carbon to the atmosphere and is known to be sensitive to climate change, representing a potential positive feedback. We conducted a number of field experiments to study independent and combined impacts of topography, watering, grazing and climate manipulations on bare soil and vegetated soi...

Soil C is a key component of climate change. Any alteration of the soil organic C (SOC) reservoir yields a rapid modification of the atmospheric CO 2 concentration. However, a part of the SOC reservoir will not contribute significantly to next century's land CO 2 emissions as its residence time exceeds this timescale. The size of the pluri-centenni...

This chapter presents an overview of the physiological strategies employed by soil microorganisms. To survive and grow, soil microbes require a carbon source, an energy source, and a means of transferring electrons. The biochemical transformations that soil microbes undertake are governed by the principles of redox reactions and chemical thermodyna...

This chapter includes a complete description of the mathematical expressions used to simulate the biological, chemical, and physical processes in existing models and a description of the computer models, which are currently being used to simulate soil carbon and nutrient cycling. The models range from analytical, substrate-enzyme-microbe, cohort, m...

Tropical subsoils contain large reservoirs of carbon (C), most of which is stored in soil organic matter (SOM). Subsoil OM is thought to be particularly stable against microbial decomposition due to various mechanisms and its position in the soil profile, potentially representing a long-term C sink. However, few experiments have explicitly investig...

Green stormwater infrastructure (GSI) is designed to capture stormwater for infiltration, detention, evapotranspiration, or reuse. Soils play a key role in stormwater interception at these facilities. It is important to assess whether contamination is occurring in GSI soils because urban stormwater drainage areas often accumulate elements of concer...

The accuracy of forest soil C and N estimates is hampered by forest soils that are rocky, inaccessible, and spatially heterogeneous. A composite coring technique is the standard method used in Forest Inventory and Analysis, but its accuracy has been questioned. Quantitative soil pits provide direct measurement of rock content and soil mass from a l...

A better understanding of how varying the proportion of different organic wastes affects humic acid (HA) formation during vermicomposting would be useful in producing vermicomposts enriched in HAs. With the aim of improving the knowledge about this issue, a variety of analytical techniques [UV-visible spectroscopic, Fourier transform infrared, fluo...

Agricultural soils are typically depleted in soil organic matter compared with their undisturbed counterparts, thus reducing their fertility. Organic amendments, particularly manures, provide the opportunity to restore soil organic matter stocks, improve soil fertility and potentially sequester atmospheric carbon (C). The application of the soil C...

Above- and belowground litter inputs in a temperate deciduous forest were altered for 20 yr to determine the importance of leaves and roots on soil C and soil organic matter (SOM) quantity and quality. Carbon and SOM quantity and quality were measured in the O horizon and mineral soil to 50 cm in five treatments (control, double litter [DL], no lit...

The response of soil organic matter dynamics to climate change will reflect the impact of warming and drying on several interrelated processes. The response is expected to be a net decrease in soil carbon stocks, representing a positive feedback to climate, though the magnitude of this change is still under debate.

Buried soils contain large reservoirs of organic carbon at depths that are not typically included in regional and global soil carbon inventories 1. One such palaeosol, the Brady soil of southwestern Nebraska, USA, is buried under six metres of loess. The Brady soil developed at the land surface on the late-Pleistocene-aged Peoria Loess in a period...