@article{harrison2024methane,
  title = {Methane and nitrous oxide emissions during biochar-composting are driven by biochar application rate and aggregate formation},
  author = {Harrison, Brendan P and Gao, Si and Thao, Touyee and Gonzales, Melinda L and Williams, Kennedy L and Scott, Natalie and Hale, Lauren and Ghezzehei, Teamrat and Diaz, Gerardo and Ryals, Rebecca A},
  journal = {Global Change Biology Bioenergy},
  volume = {16},
  number = {1},
  pages = {e13121},
  doi = {10.1111/gcbb.13121},
  pdf = {https://onlinelibrary.wiley.com/doi/epdf/10.1111/gcbb.13121},
  year = {2024},
  sort-word = {biochar, agroecology}
}

Aims\{To investigate the physiological responses of groundnut (Arachis hypogea) and pearl millet (Penisetum glaucum) that were intercropped with the native evergreen woody shrubs Piliostigma reticulatum (D.C.) Hochst and Guiera senegalensis J.F. Gmel compared to control crops throughout two growing seasons at two sites with contrasting climate and soil types in Senegal.Methods\\Shrubs grown in groundnut and millet fields at higher than native density were coppiced annually with aboveground biomass returned to the soil and no additional fertilizer. Crop leaf area index (LAI), handheld normalized difference vegetation index (NDVI), leaf water potential, and soil moisture and temperature were monitored in 2012–2013.Results\\At the drier site, the presence of shrubs reduced soil temperature at 5 cm depth by up to 5 °C during early crop growth. Shrub presence increased LAI by up to 266%, NDVI by up to 217% and increased groundnut leaf water potential throughout the day at the wetter site. Shrub effects on crop physiology were stronger overall at the drier site.Conclusions\\These results improve the understanding of how this unique agroforestry system alters the growing environment and the physiological response of associated crops throughout the season.

@article{p2019-Bogie-et-al-c,
  author = {Bogie, N.A. and Bayala, R. and Diedhiou, I. and Dick, R. and Ghezzehei, T.A.},
  doi = {10.1007/s11104-018-3882-4},
  journal = {Plant and Soil},
  status = {published},
  volume = {1-2},
  pages = {143–159},
  month = jan,
  sort-word = {agroecology},
  mendeley = {https://www.mendeley.com/catalogue/621c9e9c-8372-3721-b62a-c5169e03047a/},
  pdf = {https://link.springer.com/content/pdf/10.1007/s11104-018-3882-4.pdf},
  title = {Intercropping With Two Native Woody Shrubs Improves Water Status and Development of Interplanted Groundnut and Pearl Millet in the Sahel},
  year = {2019}
}

Scarcity of plant available water is a major challenge for rainfed agriculture throughout the Sahel. At two long-term experiments in Central and Southern Senegal, optimized intercropping with native woody shrubs, Piliostigma reticulatum (DC.) Hochst or Guiera senegalensis J.F. Gmel, (elevated densities and annual coppiced biomass returned to soils) have shown significant improvement of soil-plant-water relations, nutrient availability, and crop yields. The objective was to investigate soil physical properties to develop a mechanistic understanding for the observed improvement of water dynamics due to optimized shrub intercropping. The field experiments had a split-plot factorial design with shrubs as the main factor and fertilizer rate (0, 0.5, 1.0. 1.5 times the recommended addition of N-P-K fertilizer) as the subplot factor. This experiment was carried out at the sites of Keur Matar Arame (Keur Matar) with G. senegalensis and Nioro du Rip (Nioro) with P. reticulatum. Water retention characteristic, unsaturated hydraulic conductivity, surface evaporation, and surface infiltration were measured in the zero fertilizer treatment. At Keur Matar samples were collected from crop + shrub plots near (<0.5 m) the shrub canopy (CSn), crop + shrub plots far (>1 m) from the canopy (CSf) and in crop only plots (CO). At Nioro samples were taken in CSn, CSf, CO, and also from bare soil with no crops or shrubs growing (BS). Infiltration in CO plots compared to CSn plots was 75% and 28% higher at Keur Matar and Nioro, respectively. At Keur Matar water retention was significantly higher at wilting point (−1.5 MPa) in the CSn treatment than in the CSf treatment with values of 0.030 and 0.016 m3 m−3, respectively. At Nioro there was no significant difference in wilting point water content between treatments. These results indicate that shrubs slow down soil water as it infiltrates in the sandy soils and that the large additions of shrub biomass over a ten year period has had a small but significant effect on water retention at wilting point. This study highlights the role that shrub presence and biomass additions play in altering centimeter-scale soil properties.

@article{p2018-Bogie-et-al,
  author = {Bogie, N and Bayala, R. and Diedhiou, I. and Dick, R.P. and Ghezzehei, T. A.},
  doi = {10.1016/j.still.2018.05.010},
  status = {published},
  journal = {Soil and Tillage Research},
  keywords = {Soil structure, Sahel, Agroforestry},
  month = may,
  pages = {153--163},
  sort-word = {agroecology},
  title = {Alteration of soil physical properties and processes after ten years of intercropping with native shrubs in the Sahel},
  volume = {182},
  year = {2018},
  bdsk-url-1 = {https://doi.org/10.1016/j.still.2018.05.010}
}

Hydraulic redistribution (HR) by woody vegetation has been proposed as a potential water source for crops in intercropped systems. The native woody shrub, Guiera senegalensis J.F. Gmel, grows in the fields of farmers across the African Sahel and has shown profound yield benefits to associated pearl millet (Pennisetum glaucum) crops, especially in drought years. We tested whether this benefit resulted from the shrubs performing hydraulic redistribution (HR) with pearl millet using some of this HR water. During an experimentally imposed drought, an enriched deuterium (2H) water tracer applied to 1 m deep roots of G. senegalensis shrubs was detected (2H ≥ +300‰) in aboveground stems of intercropped millet within 12–96 h of tracer introduction. The only viable path for the 2H-enriched H2O into millet was via HR by the shrubs, which confirmed active HR during the time when growing millet was under severe drought stress. Millet biomass production when intercropped with shrubs was over 900% greater than crops grown without shrubs present. Improvement of growing conditions previously found near shrubs cannot fully account for the benefit to associated millet under extreme drought stress without considering the positive impact of the transfer of HR water. This finding illuminates HR and water transfer as an important mechanism in a successful agroforestry system in a region where food security is a serious issue.

@article{p2018-Bogie-et-al-b,
  author = {Bogie, NA and Bayala, R and Diedhiou, I and Conklin, MH and Fogel, M and Dick, R and Ghezzehei, TA},
  doi = {10.3389/fenvs.2018.00098},
  status = {published},
  journal = {Frontiers in Environmental Science: Agroecology \& Land Use Systems},
  pages = {98},
  pdf = {http://www.readcube.com/articles/10.3389/fenvs.2018.00098},
  sort-word = {agroecology},
  title = {Hydraulic Redistribution by Native Sahelian Shrubs: Bioirrigation to Resist In-Season Drought},
  volume = {6},
  year = {2018},
  bdsk-url-1 = {https://doi.org/10.3389/fenvs.2018.00098}
}

Soil water infiltration is a critical process in the soil water cycle and agricultural practices, especially when wastewater is used for irrigation. Although research has been conducted to evaluate the changes in the physical and chemical characteristics of soils irrigated by treated wastewater, a quantitative analysis of the effects produced on the infiltration process is still lacking. The objective of this study is to address this issue. Field experiments previously conducted on three adjacent field plots characterized by the same clayey soil but subjected to three different irrigation treatments have been used. The three irrigation conditions were: non-irrigated (natural conditions) plot, irrigated plot with treated wastewater for two years, and irrigated plot with treated wastewater for five years. Infiltration measurements performed by the Hood infiltrometer have been used to estimate soil hydraulic properties useful to calibrate a simplified infiltration model widely used under ponding conditions, that were existing during the irrigation stage. Our simulations highlight the relevant effect of wastewater usage as an irrigation source in reducing cumulative infiltration and increasing overland flow as a result of modified hydraulic properties of soils characterized by a lower capacity of water drainage. These outcomes can provide important insights for the optimization of irrigation techniques in arid areas where the use of wastewater is often required due to the chronic shortage of freshwater.

@article{p2020-Albalasmeh-et-al,
  title = {Using Wastewater in Irrigation: The Effects on Infiltration Process in a Clayey Soil},
  author = {Albalasmeh, Ammar A. and Gharaibeh, Mamoun A. and Alghzawi, Ma’in Z. and Morbidelli, Renato and Saltalippi, Carla and Ghezzehei, Teamrat A. and Flammini, Alessia.},
  doi = {10.3390/w12040968},
  pdf = {https://www.mdpi.com/2073-4441/12/4/968/pdf},
  sort-word = {CO2 flux, Soil respiration, Soil Carbon, aggregation, modeling,biogeoscience},
  journal = {Water},
  status = {published},
  volume = {12},
  number = {4},
  pages = {968},
  year = {2020}
}

Most soil hydraulic information used in Earth System Models (ESMs) is derived from pedo-transfer functions that use easy-to-measure soil attributes to estimate hydraulic parameters. This parameterization relies heavily on soil texture, but overlooks the critical role of soil structure originated by soil biophysical activity. Soil structure omission is pervasive also in sampling and measurement methods used to train pedotransfer functions. Here we show how systematic inclusion of salient soil structural features of biophysical origin affect local and global hydrologic and climatic responses. Locally, including soil structure in models significantly alters infiltration-runoff partitioning and recharge in wet and vegetated regions. Globally, the coarse spatial resolution of ESMs and their inability to simulate intense and short rainfall events mask effects of soil structure on surface fluxes and climate. Results suggest that although soil structure affects local hydrologic response, its implications on global-scale climate remains elusive in current ESMs.

@article{p2020-Fatichi-et-al,
  title = {Soil structure is an important omission in Earth System Models},
  author = {Fatichi, Simone and OR, Dani and Walko, Robert and Vereecken, Harry and Young, Michael H. and Ghezzehei, Teamrat A. and Hengl, Tomislav and Kollet, Stefan and Agam, Nurit and Avissar, Roni},
  doi = {10.1038/s41467-020-14411-z},
  sort-word = {CO2 flux, Soil respiration, Soil Carbon, aggregation, modeling,biogeoscience},
  journal = {Nature Communications},
  status = {published},
  pdf = {https://www.nature.com/articles/s41467-020-14411-z.pdf},
  data = {https://static-content.springer.com/esm/art%3A10.1038%2Fs41467-020-14411-z/MediaObjects/41467_2020_14411_MOESM3_ESM.zip},
  mendeley = {https://www.mendeley.com/catalogue/47459482-43dc-319e-95bf-b9110c277f4e/},
  volume = {11},
  pages = {522},
  year = {2020}
}

Increasing soil organic carbon (SOC) stocks in agricultural soils can contribute to stabilizing or even lowering atmospheric greenhouse gas (GHG) concentrations. Cover crop rotation has been shown to increase SOC and provide productivity benefits for agriculture. Here we used a split field design to evaluate the short-term effect of cover crop on SOC distribution and chemistry using a combination of bulk, isotopic, and spectroscopic analyses of size-and density-separated soil aggregates. Macroaggregates (>250 µm) incorporated additional plant material with cover crop as evidenced by more negative δ13C values (−25.4‰ with cover crop compared to −25.1‰ without cover crop) and increased phenolic (plant-like) resonance in carbon NEXAFS spectra. Iron EXAFS data showed that the Fe pool was composed of 17–21% Fe oxide with the remainder a mix of primary and secondary minerals. Comparison of oxalate and dithionite extractions suggests that cover crop may also increase Fe oxide crystallinity, especially in the dense (>2.4 g cm−3) soil fraction. Cover crop δ13C values were more negative across density fractions of bulk soil, indicating the presence of less processed organic carbon. Although no significant difference was observed in bulk SOC on a mass per mass basis between cover and no cover crop fields after one season, isotopic and spectroscopic data reveal enhanced carbon movement between aggregates in cover crop soil

@article{p2020-Schaefer-et-al,
  title = {Effect of Cover Crop on Carbon Distribution in Size and Density Separated Soil Aggregates},
  author = {Schaefer, Michael V and Bogie, Nathaniel A and Rath, Daniel and Marklein, Alison R and Garniwan, Abdi and Haensel, Thomas and Lin, Ying and Avila, Claudia C and Nico, Peter S and Scow, Kate M and Brodie, Eoin L. and Riley, William J. Riley and Fogel, Marilyn L. and Berhe, Asmeret Asefaw and Ghezzehei, Teamrat A. and Parikh, Sanjai and Keiluweit, Marco and Ying, Samantha C.},
  doi = {10.3390/soilsystems4010006},
  sort-word = {CO2 flux, Soil respiration, Soil Carbon, aggregation, modeling,biogeoscience},
  journal = {Soil Systems},
  status = {published},
  volume = {4},
  number = {1},
  pages = {6},
  year = {2020},
  publisher = {Multidisciplinary Digital Publishing Institute}
}

Soil water status is one of the most important environmental factors that control microbial activity and rate of soil organic matter decomposition (SOM). Its effect can be partitioned into effect of water energy status (water potential) on cellular activity, effect of water volume on cellular motility and aqueous diffusion of substrate and nutrients, as well as effect of air content and gas-diffusion pathways on concentration of dissolved oxygen. However, moisture functions widely used in SOM decomposition models are often based on empirical functions rather than robust physical foundations that account for these disparate impacts of soil water. The contributions of soil water content and water potential vary from soil to soil according to the soil water characteristic (SWC), which in turn is strongly dependent on soil texture and structure.The overall goal of this study is to introducea physically based modelling framework of aerobic microbial respiration that incorporates the role of SWC under arbitrary soil moisture status.The model was tested by compariing it with published datasets of SOM decomposition under laboratory conditions.

@article{p2019-Ghezzehei-et-al,
  author = {Ghezzehei, Teamrat A. and Sulman, Benjamin and Arnold, Chelsea L. and Bogie, Nathaniel A. and Berhe, Asmeret Asefaw},
  doi = {10.5194/bg-16-1187-2019},
  data = {10.6084/m9.figshare.7749332},
  pdf = {https://bg.copernicus.org/articles/16/1187/2019/bg-16-1187-2019.pdf},
  sort-word = {CO2 flux, Soil respiration, Soil Carbon, aggregation, modeling,biogeoscience},
  journal = {Biogeosciences},
  status = {published},
  volume = {16},
  pages = {1187-1209},
  month = mar,
  title = {On the role of soil water retention characteristic on aerobic microbial respiration},
  mendeley = {https://www.mendeley.com/catalogue/4b76b8fa-36d3-3812-bd2f-086f3faaab4f/},
  year = {2019}
}

Low-severity wildfires and prescribed burns have been steadily increasing for over three decades, currently accounting for more than half of total burned area in the Southwestern United States. Most observations immediately after low-severity burns report little adverse impacts on soil properties and processes. In a few studies, however, significant deterioration of soil structure has been observed several months after such fires. Here we show that rapid vaporization of pore water during low-severity burns raises pneumatic gas pressure inside large aggregates (20-30 mm) to damaging levels; on the order of aggregate tensile strength and high-enough to cause visco-plastic deformation. However, the impact on soil structure was not immediately perceptible. This suggests that other natural forces, such as wetting-drying and thermal cycles, are required to disrupt the weakened aggregates. Thus, adverse consequences of the suggested mechanism on soil processes and services (e.g., infiltration, erodibility, and organic matter protection) are likely overlooked.

@article{p2018-Jian-Berli-Ghezzehei,
  author = {Jian, Mathew and Berli, Markus and Ghezzehei, Teamrat A.},
  data = {10.6084/m9.figshare.6349469.v1},
  date-added = {2018-05-27 06:01:51 +0000},
  date-modified = {2018-11-14 14:17:28 -0800},
  doi = {10.1029/2018GL078053},
  journal = {Geophysical Research Letters},
  status = {published},
  month = may,
  number = {5553-5561},
  sort-word = {soil structure, aggregation},
  title = {Soil Structural Degradation during Low-severity Burns},
  volume = {45},
  year = {2018},
  bdsk-url-1 = {https://doi.org/10.1029/2018GL078053}
}

Peatlands are garnering much attention for their greenhouse gas feedback potential in a warming climate. As of yet, the coupled biogeochemical and hydrological processes that control the amount and timing of soil organic matter (SOM) mineralization and, ultimately, whether peatlands will be sinks or sources of atmospheric CO 2 are not fully understood. Soil structure is a key feature of soils that mediates the coupling between biogeochemical and hydrological processes. However, we know very little about how soil structure responds when soils are exposed to wettingedrying cycles outside their normal range. In order to better understand how high elevation peatlands will respond to increasingly dry years, we incubated soils from high elevation meadows in the Sierra Nevada at 5 different water potentials and measured the CO 2 flux for over one year. We found that the cumulative carbon mineralization had a U-shaped pattern, with the greatest mineralization at the wettest (À0.1 bar) and driest (À4 bar) water potentials, across all hydrologic regions of the meadow. We propose a conceptual model that reproduces a similar pattern by incorporating the concept of dual porosity medium, with two distinct pore-size populations representing inter-and intra-aggregate porosity. Availability of water and oxygen to the two pore-size populations depends on the soil’s equilibrium water potential. The model and the data suggest that the decomposition rates of intra-aggregate SOM may increase due to prolonged drought events that lead to accelerated release of C from previously untapped pool.

@article{p2015-Arnold-Ghezzehei-Berhe,
  author = {Arnold, Chelsea and Berhe, Asmeret Asefaw and Ghezzehei, Teamrat A.},
  doi = {10.1016/j.soilbio.2014.10.029},
  journal = {Soil Biology and Biochemistry},
  status = {published},
  keywords = {CO2 flux, Soil respiration, Hydrology, Meadows, Climate extremes, Soil structure},
  month = sep,
  pages = {28-37},
  researchgate = {https://www.researchgate.net/publication/268630795_Decomposition_of_distinct_organic_matter_pools_is_regulated_by_moisture_status_in_structured_wetland_soils},
  sort-word = {aggregation, biogeoscience},
  title = {Decomposition of distinct organic matter pools is regulated by moisture status in structured wetland soils},
  volume = {81},
  year = {2015}
}

This study deals with deformation of small pores in wet soils of relatively high bulk density such as in the final settlement phase of tilled or disturbed soils. Pore deformation was modeled by volume reduction of spherical voids embedded in a homogenous soil matrix. External constant stress and overburden were considered as steady stresses because the change in interaggregate contact stress under overburden is slow compared to the associated strain rate. In contrast, stress due to passage of farm implements was considered as transient because the rate of change of interaggregate stress is comparable with the strain rate. Rheological behavior of the soil matrix under steady and transient stresses was obtained from independent rheological measurements. Experimental data from the literature were used to illustrate the model. Model predictions of relative density compared favorably with experimental data for constant stress application as well as for constant strain rate experiments. Results showed that the rate of densification decreased as the relative density approached unity (complete pore closure) and the relative stress required for driving densification increased exponentially with increasing relative density.

@article{p2003-Ghezzehei-Or-b,
  author = {Ghezzehei, Teamrat A. and Or, Dani},
  date-modified = {2018-05-27 19:55:55 +0000},
  journal = {Water Resources Research},
  status = {published},
  month = mar,
  number = {3},
  sort-word = {aggregation},
  title = {Stress-induced volume reduction of isolated pores in wet soil},
  doi = {10.1029/2001wr001137},
  volume = {39},
  year = {2003}
}

Tillage causes soil fragmentation thereby increasing the proportion of interaggregate (structural) pore space. The resulting tilled layer tends to be structurally unstable as manifested by a gradual decrease in interaggregate porosity until a new equilibrium has been reached between external loads and internal capillary forces at a rate governed by the soil rheological properties. The soil pore-size distribution (PSD) will change accordingly with time. We have previously applied the Fokker-Planck equation (FPE) to describe the evolution of the PSD as the result of drift, dispersion, and degradation processes that affect the pore space in unstable soils. In this study, we provide closed-form solutions for PSD evolution, which can be used to predict temporal behavior of unsaturated soil hydraulic properties. Solutions and moments of the PSD were obtained in case: (i) drift and degradation coefficients depend on time and the dispersivity is constant and (ii) drift and dispersivity are also linearly related to pore size. Both solutions can model the reduction in pore size during the growing season while the second solution can account for a reduction in the dispersion of the PSD. The solutions for PSD were plotted for a mathematically convenient expression for the drift and degradation coefficients and for an expression derived from a model for soil aggregate coalescence. Experimental data on the settlement of a Millville (coarse-silty, carbonatic, mesic Typic Haploxeroll) silt loam during wetting and drying cycles were used to determine time-dependent drift and degradation coefficients according to this coalescence model. The solution for the PSD was used to independently predict the water retention curve, which exhibited a satisfactory agreement with experimental retention data at the end of two drying cycles.

@article{p2002-Leij-Ghezzehei-Or-b,
  author = {Leij, Feike J. and Ghezzehei, Teamrat A. and Or, Dani},
  date-modified = {2018-05-31 01:37:35 +0000},
  journal = {Soil Science Society of America Journal},
  status = {published},
  number = {4},
  pages = {1104},
  pdf = {https://www.researchgate.net/publication/37450945_Analytical_Models_for_Soil_Pore-Size_Distribution_After_Tillage},
  doi = {10.2136/sssaj2002.1104},
  sort-word = {aggregation},
  title = {Analytical Models for Soil Pore-Size Distribution After Tillage},
  volume = {66},
  year = {2002}
}

Tillage modifies the soil structure to create conditions favorable for plant growth. However, the resulting loose structure is susceptible to collapse by internal capillary forces and external compactive stresses with concurrent changes in soil hydraulic properties. Presently, limited understanding of these complex processes often leads to consideration of the soil plow-layer as a static porous medium. Our objective is to provide a review of recent progress in modeling soil structural dynamics at the pore-scale, based on soil mechanical and rheological properties. The basic geometrical framework of the models was a cubic arrangement of monosized spherical aggregates (other arrangements are discussed). The process of soil aggregate rejoining by capillary forces was modeled by considering the rate of energy dissipation due to viscous deformation of wet soil, and corresponding energy release due to reconfiguration of water capillary menisci. The model was complemented by independent rheological characterization of soil that provides control on the rate as well as the onset and termination of aggregate coalescence. The model was also adapted for consideration of steady stress (such as overburden) acting upon the unit cells. Unlike steady stress, transient stress (such as traffic) is applied for too short of a period to allow for total energy dissipation by viscous deformation. Hence, a portion of the deformation is elastic (with a recoverable portion of the applied energy). Rheological characterization under transient (oscillatory) stress provided coupled elastic and viscous properties under several loading frequencies. Effects of transient stresses on the geometrical model were modeled by considering a combination of (i) Hertzian-type elastic strain and (ii) viscous flow of soil at the contacts. Application of the models is demonstrated using illustrative examples and rheological measurements of Millville silt loam soil. Finally, we provide an outlook for upscaling the unit cell results to an aggregate bed scale.

@article{p2002-Or-Ghezzehei,
  author = {Or, D and Ghezzehei, T. A.},
  date-modified = {2018-05-31 01:36:51 +0000},
  journal = {Soil and Tillage Research},
  status = {published},
  keywords = {Rheology, Soil-structure, Compaction, Aggregate},
  number = {1-2},
  pages = {41-59},
  researchgate = {https://www.researchgate.net/publication/222697340_Modeling_post-tillage_soil_structural_dynamics_A_review},
  sort-word = {aggregation},
  title = {Modeling post-tillage soil structural dynamics: a review},
  volume = {64},
  year = {2002}
}

Soil tillage often results in a structurally unstable soil layer with an elevated inter-aggregate porosity that is gradually decreased by the interplay of capillary and rheological processes. We have previously proposed to describe the evolution of the pore-size distribution (PSD) with the Fokker–Planck equation (FPE). The coefficients of this equation quantify the drift, dispersion, and degradation processes acting upon the PSD. An analytical solution for the PSD is presented for the case where drift and degradation coefficients depend on time, and the dispersion coefficient is proportional to the drift coefficient. These coefficients can be estimated from independent measurements of the PSD or (surrogate) water retention data or from mechanistic models. In this paper, we illustrate the application of the pore-size evolution model for: (i) a generic drift coefficient, (ii) static water retention data for soils under different tillage regimes, and (iii) dynamic hydraulic data for a soil subject to a sequence of wetting and drying cycles. These applications show the viability of our approach to model pore-size evolution. However, the development and application of the model is hampered by a lack of definitive data on soil structural and hydraulic dynamics.

@article{p2002-Leij-Ghezzehei-Or,
  author = {Leij, FJ and Ghezzehei, TA and Or, D},
  date-modified = {2018-05-31 01:36:25 +0000},
  journal = {Soil and Tillage Research},
  status = {published},
  keywords = {Soil hydraulic properties, Compaction, Wetting, Drying, Pore-size distribution, Analytical solution},
  number = {1-2},
  pages = {61-78},
  researchgate = {https://www.researchgate.net/publication/222696315_Modeling_the_dynamics_of_the_soil_pore-size_distribution_Soil_Tillage_Reseach},
  pdf = {https://www.sciencedirect.com/science/article/pii/S0167198701002574/pdfft?md5=4b527e89a8a8936c6acaf6c4e53e2470&pid=1-s2.0-S0167198701002574-main.pdf},
  doi = {10.1016/S0167-1987(01)00257-4},
  sort-word = {aggregation},
  title = {Modeling the dynamics of the soil pore-size distribution},
  volume = {64},
  year = {2002}
}

Tilled agricultural soils are in a constant state of change induced by variations in soil strength due to wetting and drying and compaction by farm implements. Changes in soil structure affect many hydraulic and transport properties; hence their quantification is critical for accu- rate hydrological and environmental modeling. This study highlights the role of soil rheology in determining time-dependent stress–strain relationships that are essential for prediction and analysis of structural changes in soils. The primary objectives of this study were (i) to extend a previously proposed aggregate-pair model to prediction of compaction under external steady or transient stresses and (ii) to provide experimentally determined rheological information for the above models. Rheological properties of soils and clay minerals were measured with a rotational rheometer with parallel-plate sensors. These measurements, under controlled steady shear stress application, have shown that wet soils have viscoplastic behavior with well-defined yield stress and nearly constant plastic viscosity. In contrast, rapid transient loading (e.g., passage of a tractor) is often too short for complete viscous dissipation of applied stress, resulting in an elastic (recoverable) component of deformation (viscoelastic behavior). Measured viscoelastic properties were expressed by complex viscosity and shear modulus whose components denote viscous energy dissipa- tion, and energy storage (elastic). Results show that for low water contents and fast loading (tractor speed), the elastic component of deformation increases, whereas with higher water contents, viscosity and shear modulus decrease. Steady and oscillatory stress application to an aggregate pair model illustrates potential use of rheological properties towards obtaining predictions of strains in soils.

@article{p2001-Ghezzehei-Or,
  author = {Ghezzehei, Teamrat A. and Or, Dani},
  date-modified = {2018-05-30 21:37:12 +0000},
  journal = {Soil Science Society of America Journal},
  status = {published},
  number = {3},
  pages = {624},
  pdf = {https://www.researchgate.net/publication/37450913_Rheological_Properties_of_Wet_Soils_and_Clays_under_Steady_and_Oscillatory_Stresses},
  sort-word = {aggregation, mechanics},
  title = {Rheological Properties of Wet Soils and Clays under Steady and Oscillatory Stresses},
  doi = {10.2136/sssaj2001.653624x},
  volume = {65},
  year = {2001}
}

Tillage operations disrupt surface layers of agricultural soils, creating a loosened structure with a substantial proportion of interaggregate porosity that enhances liquid and gaseous exchange properties favorable for plant growth. Unfortunately, such desirable soil tilth is structurally unstable and is susceptible to change by subsequent wetting and drying processes and other mechanical stresses that reduce total porosity and modify pore size distribution (PSD). Ability to model posttillage dynamics of soil pore space and concurrent changes in hydraulic properties is important for realistic predictions of transport processes through this surface layer. We propose a stochastic modeling framework that couples the probabilistic nature of pore space distributions with physically based soil deformation models using the Fokker‐Planck equation (FPE) formalism. Three important features of soil pore space evolution are addressed: (1) reduction of the total porosity, (2) reduction of mean pore radius, and (3) changes in the variance of the PSD. The proposed framework may be used to provide input to hydrological models concerning temporal variations in near‐surface soil hydraulic properties. In a preliminary investigation of this approach we link a previously proposed mechanistic model of soil aggregate coalescence to the stochastic FPE framework to determine the FPE coefficients. An illustrative example is presented which describes changes in interaggregate pore size due to wetting‐drying cycles and the resulting effects on dynamics of the soil water characteristic curve and hydraulic conductivity functions.

@article{p2000-Or-etal,
  author = {Or, D and Leij, FJ and Snyder, V and Ghezzehei, T. A.},
  date-modified = {2018-05-30 21:36:47 +0000},
  journal = {Water Resources Research},
  status = {published},
  month = jul,
  number = {7},
  pages = {1641-1652},
  researchgate = {https://www.researchgate.net/publication/37450896_Stochastic_model_for_post-tillage_soil_pore_size_evolution},
  sort-word = {aggregation},
  title = {Stochastic model for posttillage soil pore space evolution},
  volume = {36},
  year = {2000},
  doi = {10.1029/2000WR900092}
}

The desired soil structure following tillage of agricultural soils is often unstable and susceptible to coalescence of aggregates and reduction of interaggregate porosity due to wetting and drying cycles. This process of aggregate rejoining was modeled by equating the rate of work done by liquid‐vapor menisci, to the rate of energy dissipation due to viscous deformation of a pair of spherical aggregates. The nonlinearity of wet soil viscous flow behavior was accounted for by introducing a Bingham rheological model. A natural outcome of the analysis was the formulation of a mathematical condition for the onset and termination of coalescence based on soil strength at specified water content. The condition states that sufficient energy in excess of soil strength (yield stress) must be available for coalescence to proceed. The rate of aggregate coalescence is proportional to available energy and is inversely related to the coefficient of plastic viscosity. Transport of wet soil to the periphery of the interaggregate contact by viscous flow leads to smoothing of the neck, resulting in pore closure, on the one hand, and restricting the minimum matric potential that can be achieved, on the other. The interplay between rheology and geometry prevent coalescence from proceeding indefinitely. Independently determined soil rheological properties were used to illustrate the use of the model. Coalescence under constant water content and during wetting‐drying cycles was calculated. Comparison of data from experiments on one‐dimensional, aggregate bed settlement has shown reasonable agreement with the model predictions.

@article{p2000-Ghezzehei-Or,
  author = {Ghezzehei, T. A. and Or, D.},
  date-modified = {2018-05-30 21:21:45 +0000},
  journal = {Water Resources Research},
  status = {published},
  month = feb,
  number = {2},
  pages = {367-379},
  researchgate = {https://www.researchgate.net/publication/37450893_Dynamics_of_soil_aggregate_coalescence_governed_by_capillary_and_rheological_processes},
  sort-word = {soil structure, aggregation},
  title = {Dynamics of soil aggregate coalescence governed by capillary and rheological processes},
  volume = {36},
  year = {2000},
  doi = {10.1029/1999WR900316}
}

@article{harrison2024methane,
  title = {Methane and nitrous oxide emissions during biochar-composting are driven by biochar application rate and aggregate formation},
  author = {Harrison, Brendan P and Gao, Si and Thao, Touyee and Gonzales, Melinda L and Williams, Kennedy L and Scott, Natalie and Hale, Lauren and Ghezzehei, Teamrat and Diaz, Gerardo and Ryals, Rebecca A},
  journal = {Global Change Biology Bioenergy},
  volume = {16},
  number = {1},
  pages = {e13121},
  doi = {10.1111/gcbb.13121},
  pdf = {https://onlinelibrary.wiley.com/doi/epdf/10.1111/gcbb.13121},
  year = {2024},
  sort-word = {biochar, agroecology}
}

Soil water infiltration is a critical process in the soil water cycle and agricultural practices, especially when wastewater is used for irrigation. Although research has been conducted to evaluate the changes in the physical and chemical characteristics of soils irrigated by treated wastewater, a quantitative analysis of the effects produced on the infiltration process is still lacking. The objective of this study is to address this issue. Field experiments previously conducted on three adjacent field plots characterized by the same clayey soil but subjected to three different irrigation treatments have been used. The three irrigation conditions were: non-irrigated (natural conditions) plot, irrigated plot with treated wastewater for two years, and irrigated plot with treated wastewater for five years. Infiltration measurements performed by the Hood infiltrometer have been used to estimate soil hydraulic properties useful to calibrate a simplified infiltration model widely used under ponding conditions, that were existing during the irrigation stage. Our simulations highlight the relevant effect of wastewater usage as an irrigation source in reducing cumulative infiltration and increasing overland flow as a result of modified hydraulic properties of soils characterized by a lower capacity of water drainage. These outcomes can provide important insights for the optimization of irrigation techniques in arid areas where the use of wastewater is often required due to the chronic shortage of freshwater.

@article{p2020-Albalasmeh-et-al,
  title = {Using Wastewater in Irrigation: The Effects on Infiltration Process in a Clayey Soil},
  author = {Albalasmeh, Ammar A. and Gharaibeh, Mamoun A. and Alghzawi, Ma’in Z. and Morbidelli, Renato and Saltalippi, Carla and Ghezzehei, Teamrat A. and Flammini, Alessia.},
  doi = {10.3390/w12040968},
  pdf = {https://www.mdpi.com/2073-4441/12/4/968/pdf},
  sort-word = {CO2 flux, Soil respiration, Soil Carbon, aggregation, modeling,biogeoscience},
  journal = {Water},
  status = {published},
  volume = {12},
  number = {4},
  pages = {968},
  year = {2020}
}

Most soil hydraulic information used in Earth System Models (ESMs) is derived from pedo-transfer functions that use easy-to-measure soil attributes to estimate hydraulic parameters. This parameterization relies heavily on soil texture, but overlooks the critical role of soil structure originated by soil biophysical activity. Soil structure omission is pervasive also in sampling and measurement methods used to train pedotransfer functions. Here we show how systematic inclusion of salient soil structural features of biophysical origin affect local and global hydrologic and climatic responses. Locally, including soil structure in models significantly alters infiltration-runoff partitioning and recharge in wet and vegetated regions. Globally, the coarse spatial resolution of ESMs and their inability to simulate intense and short rainfall events mask effects of soil structure on surface fluxes and climate. Results suggest that although soil structure affects local hydrologic response, its implications on global-scale climate remains elusive in current ESMs.

@article{p2020-Fatichi-et-al,
  title = {Soil structure is an important omission in Earth System Models},
  author = {Fatichi, Simone and OR, Dani and Walko, Robert and Vereecken, Harry and Young, Michael H. and Ghezzehei, Teamrat A. and Hengl, Tomislav and Kollet, Stefan and Agam, Nurit and Avissar, Roni},
  doi = {10.1038/s41467-020-14411-z},
  sort-word = {CO2 flux, Soil respiration, Soil Carbon, aggregation, modeling,biogeoscience},
  journal = {Nature Communications},
  status = {published},
  pdf = {https://www.nature.com/articles/s41467-020-14411-z.pdf},
  data = {https://static-content.springer.com/esm/art%3A10.1038%2Fs41467-020-14411-z/MediaObjects/41467_2020_14411_MOESM3_ESM.zip},
  mendeley = {https://www.mendeley.com/catalogue/47459482-43dc-319e-95bf-b9110c277f4e/},
  volume = {11},
  pages = {522},
  year = {2020}
}

Increasing soil organic carbon (SOC) stocks in agricultural soils can contribute to stabilizing or even lowering atmospheric greenhouse gas (GHG) concentrations. Cover crop rotation has been shown to increase SOC and provide productivity benefits for agriculture. Here we used a split field design to evaluate the short-term effect of cover crop on SOC distribution and chemistry using a combination of bulk, isotopic, and spectroscopic analyses of size-and density-separated soil aggregates. Macroaggregates (>250 µm) incorporated additional plant material with cover crop as evidenced by more negative δ13C values (−25.4‰ with cover crop compared to −25.1‰ without cover crop) and increased phenolic (plant-like) resonance in carbon NEXAFS spectra. Iron EXAFS data showed that the Fe pool was composed of 17–21% Fe oxide with the remainder a mix of primary and secondary minerals. Comparison of oxalate and dithionite extractions suggests that cover crop may also increase Fe oxide crystallinity, especially in the dense (>2.4 g cm−3) soil fraction. Cover crop δ13C values were more negative across density fractions of bulk soil, indicating the presence of less processed organic carbon. Although no significant difference was observed in bulk SOC on a mass per mass basis between cover and no cover crop fields after one season, isotopic and spectroscopic data reveal enhanced carbon movement between aggregates in cover crop soil

@article{p2020-Schaefer-et-al,
  title = {Effect of Cover Crop on Carbon Distribution in Size and Density Separated Soil Aggregates},
  author = {Schaefer, Michael V and Bogie, Nathaniel A and Rath, Daniel and Marklein, Alison R and Garniwan, Abdi and Haensel, Thomas and Lin, Ying and Avila, Claudia C and Nico, Peter S and Scow, Kate M and Brodie, Eoin L. and Riley, William J. Riley and Fogel, Marilyn L. and Berhe, Asmeret Asefaw and Ghezzehei, Teamrat A. and Parikh, Sanjai and Keiluweit, Marco and Ying, Samantha C.},
  doi = {10.3390/soilsystems4010006},
  sort-word = {CO2 flux, Soil respiration, Soil Carbon, aggregation, modeling,biogeoscience},
  journal = {Soil Systems},
  status = {published},
  volume = {4},
  number = {1},
  pages = {6},
  year = {2020},
  publisher = {Multidisciplinary Digital Publishing Institute}
}

Soil water status is one of the most important environmental factors that control microbial activity and rate of soil organic matter decomposition (SOM). Its effect can be partitioned into effect of water energy status (water potential) on cellular activity, effect of water volume on cellular motility and aqueous diffusion of substrate and nutrients, as well as effect of air content and gas-diffusion pathways on concentration of dissolved oxygen. However, moisture functions widely used in SOM decomposition models are often based on empirical functions rather than robust physical foundations that account for these disparate impacts of soil water. The contributions of soil water content and water potential vary from soil to soil according to the soil water characteristic (SWC), which in turn is strongly dependent on soil texture and structure.The overall goal of this study is to introducea physically based modelling framework of aerobic microbial respiration that incorporates the role of SWC under arbitrary soil moisture status.The model was tested by compariing it with published datasets of SOM decomposition under laboratory conditions.

@article{p2019-Ghezzehei-et-al,
  author = {Ghezzehei, Teamrat A. and Sulman, Benjamin and Arnold, Chelsea L. and Bogie, Nathaniel A. and Berhe, Asmeret Asefaw},
  doi = {10.5194/bg-16-1187-2019},
  data = {10.6084/m9.figshare.7749332},
  pdf = {https://bg.copernicus.org/articles/16/1187/2019/bg-16-1187-2019.pdf},
  sort-word = {CO2 flux, Soil respiration, Soil Carbon, aggregation, modeling,biogeoscience},
  journal = {Biogeosciences},
  status = {published},
  volume = {16},
  pages = {1187-1209},
  month = mar,
  title = {On the role of soil water retention characteristic on aerobic microbial respiration},
  mendeley = {https://www.mendeley.com/catalogue/4b76b8fa-36d3-3812-bd2f-086f3faaab4f/},
  year = {2019}
}

Soil aggregate degradation during medium and high severity fires is often identified as the main mechanism that leads to loss of soil organic matter due to fire. Low severity fires, however, are considered not to cause aggregate degradation assuming that temperatures <250º C, as occurring during low-severity burns, have only limited effects on the stability of the soil organic binding agents. Recent studies suggest that low severity burns may cause soil aggregate degradation due to rapid vaporization of soil pore water that can induce pressure on the soil aggregates beyond their yield stress. Such pressure-driven degradation of soil aggregates may expose physically protected organic carbon to decomposition. Our study investigated the effect of a low-severity fire on soil organic matter, water extractable organic C and N as well as respiration for two initial soil moisture conditions undergoing three "heating regimes" using aggregates from a California forest and Nevada shrubland soil. We found that initially moist soil aggregates that were rapidly heated up degraded the most, showing increased cumulative carbon mineralization when compared to aggregates that were not heated, aggregates that were dry before being heated , and initially moist soil aggregates that were slowly heated. Our results suggest that exposure of previously physically protected organic carbon within the soil aggregates to oxidative conditions was the most likely cause of increased rates of decomposition of organic matter after low-intensity burns. Additionally, we show that for a shrubland soil, aggregates with relatively low organic carbon content, low severity burns increased cumulative carbon mineralization. We hypothesized that this was due to decomposition of cytoplasmic material from lysed microbes. Our results suggest that low severity burns can accelerate decomposition of soil organic carbon protected in soil aggregates.

@article{p2018-Jian-et-al,
  author = {Jian, Mathew and Berhe, Asmeret Asefaw and Berli, Markus and Ghezzehei, Teamrat A.},
  date-added = {2018-05-27 04:59:20 +0000},
  date-modified = {2018-06-27 20:51:02 +0000},
  doi = {10.3389/fenvs.2018.00066},
  journal = {Frontiers in Environmental Sciences-Soil Processes},
  status = {published},
  month = jun,
  sort-word = {biogeoscience, structure},
  title = {Vulnerability of physically protected soil organic carbon to loss under low severity fires},
  year = {2018},
  bdsk-url-1 = {https://doi.org/10.3389/fenvs.2018.00066}
}

Peatlands are garnering much attention for their greenhouse gas feedback potential in a warming climate. As of yet, the coupled biogeochemical and hydrological processes that control the amount and timing of soil organic matter (SOM) mineralization and, ultimately, whether peatlands will be sinks or sources of atmospheric CO 2 are not fully understood. Soil structure is a key feature of soils that mediates the coupling between biogeochemical and hydrological processes. However, we know very little about how soil structure responds when soils are exposed to wettingedrying cycles outside their normal range. In order to better understand how high elevation peatlands will respond to increasingly dry years, we incubated soils from high elevation meadows in the Sierra Nevada at 5 different water potentials and measured the CO 2 flux for over one year. We found that the cumulative carbon mineralization had a U-shaped pattern, with the greatest mineralization at the wettest (À0.1 bar) and driest (À4 bar) water potentials, across all hydrologic regions of the meadow. We propose a conceptual model that reproduces a similar pattern by incorporating the concept of dual porosity medium, with two distinct pore-size populations representing inter-and intra-aggregate porosity. Availability of water and oxygen to the two pore-size populations depends on the soil’s equilibrium water potential. The model and the data suggest that the decomposition rates of intra-aggregate SOM may increase due to prolonged drought events that lead to accelerated release of C from previously untapped pool.

@article{p2015-Arnold-Ghezzehei-Berhe,
  author = {Arnold, Chelsea and Berhe, Asmeret Asefaw and Ghezzehei, Teamrat A.},
  doi = {10.1016/j.soilbio.2014.10.029},
  journal = {Soil Biology and Biochemistry},
  status = {published},
  keywords = {CO2 flux, Soil respiration, Hydrology, Meadows, Climate extremes, Soil structure},
  month = sep,
  pages = {28-37},
  researchgate = {https://www.researchgate.net/publication/268630795_Decomposition_of_distinct_organic_matter_pools_is_regulated_by_moisture_status_in_structured_wetland_soils},
  sort-word = {aggregation, biogeoscience},
  title = {Decomposition of distinct organic matter pools is regulated by moisture status in structured wetland soils},
  volume = {81},
  year = {2015}
}

By the end of the 20th century, the onset of spring in the Sierra Nevada mountain range of California has been occurring on average three weeks earlier than historic records. Superimposed on this trend is an increase in the presence of highly anomalous “extreme years, where spring arrives either significantly late or early. The timing of the onset of continuous snowpack coupled to the date at which the snowmelt season is initiated play an important role in the development and sustainability of mountain ecosystems. In this study, we assess the impact of extreme winter precipitation variation on aboveground net primary productivity and soil respiration over three years (2011 to 2013). We found that the duration of snow cover, particularly the timing of the onset of a continuous snowpack and presence of early spring frost events contributed to a dramatic change in ecosystem processes. We found an average 100% increase in soil respiration in 2012 and 2103, compared to 2011, and an average 39% decline in aboveground net primary productivity observed over the same time period. The overall growing season length increased by 57 days in 2012 and 61 days in 2013. These results demonstrate the dependency of these keystone ecosystems on a stable climate and indicate that even small changes in climate can potentially alter their resiliency.

@article{p2014-Arnold-Ghezzehei-Berhe,
  author = {Arnold, Chelsea and Ghezzehei, Teamrat A. and Berhe, Asmeret Asefaw},
  data = {10.6084/m9.figshare.1113179.v19},
  date-modified = {2018-05-27 21:16:54 +0000},
  doi = {10.1371/journal.pone.0106058},
  journal = {PLoS ONE},
  status = {published},
  keywords = {Ecosystems, Seasons, Soil respiration, Productivity, Spring, Winter, Carbon dioxide, Ecosystem functioning},
  month = sep,
  number = {9},
  pages = {e106058},
  researchgate = {https://www.researchgate.net/publication/265509769_Early_Spring_Severe_Frost_Events_and_Drought_Induce_Rapid_Carbon_Loss_in_High_Elevation_Meadows},
  sort-word = {biogeoscience},
  title = {Early Spring, Severe Frost Events, and Drought Induce Rapid Carbon Loss in High Elevation Meadows},
  volume = {9},
  year = {2014}
}

@article{wang2023soil,
  title = {Soil physics matters for the land--water--food--climate nexus and sustainability},
  author = {Wang, Gang and Liu, Ying and Yan, Zhifeng and Chen, Dingjiang and Fan, Jun and Ghezzehei, Teamrat A},
  journal = {European Journal of Soil Science},
  volume = {74},
  number = {6},
  pages = {e13444},
  doi = {10.1111/ejss.13444},
  pdf = {https://bsssjournals.onlinelibrary.wiley.com/doi/epdf/10.1111/ejss.13444},
  year = {2023},
  sort-word = {editorial}
}

Soil carbohydrates play a vital role in maintaining the health of soil and ensuring that ecosystems function properly. The method used in this study for measuring carbohydrate content in soil is quick, effective and easy. The investigation involved using three techniques to extract 45 soil samples of different soil texture; hot water, cool water and classical methods. The extracted samples were then analyzed for carbohydrates using two techniques; the widely accepted Phenol Sulfuric Acid method and the newly developed Sulfuric Acid UV method. The results revealed that the hot water extraction method consistently yielded higher levels of carbohydrates compared to the other methods. Interestingly the newly developed Sulfuric Acid UV method consistently produced similar results to those obtained from the well established Phenol Sulfuric Acid method. These results suggest that the novel Sulfuric Acid UV method, which relies on absorption in the ultraviolet region to analyze soil carbohydrate content is indeed a viable approach. This has allowed scientists and researchers to have an alternative means of determining soil carbohydrate levels.

@article{albalasmeh_novel_2024,
  title = {A novel approach for determining soil carbohydrates using {UV} spectrophotometry},
  issn = {1658077X},
  doi = {10.1016/j.jssas.2024.01.004},
  language = {en},
  urldate = {2024-02-09},
  journal = {Journal of the Saudi Society of Agricultural Sciences},
  author = {Albalasmeh, Ammar A. and Mohawesh, Osama and Gharaibeh, Mamoun A. and Ghezzehei, Teamrat A.},
  month = feb,
  year = {2024},
  pages = {S1658077X24000109},
  sort-word = {method}
}

Determination of saturated hydraulic conductivity, Ks, and the van Genuchten water retention curve θ(h) parameters is crucial in evaluating unsaturated soil water flow. The aim of this work is to present a method to estimate Ks, α and n from numerical analysis of an upward infiltration process at saturation (Cap0), with (Cap0 + h) and without (Cap0) an overpressure step (h) at the end of the wetting phase, followed by an evaporation process (Evap). The HYDRUS model as well as a brute-force search method were used for theoretical loam soil parameter estimation. The uniqueness and the accuracy of solutions from the response surfaces, Ks–n, α–n and Ks–α, were evaluated for different scenarios. Numerical experiments showed that only the Cap0 + Evap and Cap0 + h + Evap scenarios were univocally able to estimate the hydraulic properties. The method gave reliable results in sand, loam and clay-loam soils.

@article{p2017-Pena-Sancho-et-al,
  author = {Pe{\~{n}}a-Sancho, C. and Ghezzehei, T.A. and Latorre, B. and Gonz{\'{a}}lez-Cebollada, C. and Moret-Fern{\'{a}}ndez, D.},
  date-modified = {2018-11-14 14:03:19 -0800},
  doi = {10.1080/02626667.2017.1343476},
  journal = {Hydrological Sciences Journal},
  status = {published},
  keywords = {soil hydraulic properties, inverse methods, HYDRUS},
  month = jul,
  number = {10},
  pages = {1683--1693},
  sort-word = {method},
  title = {Upward infiltration{extendash}evaporation method to estimate soil hydraulic properties},
  volume = {62},
  year = {2017},
  bdsk-url-1 = {https://doi.org/10.1080%2F02626667.2017.1343476},
  bdsk-url-2 = {http://dx.doi.org/10.1080/02626667.2017.1343476},
  bdsk-url-3 = {https://doi.org/10.1080/02626667.2017.1343476}
}

Determination of saturated hydraulic conductivity, Ks, and the shape parameters α and n of the water retention curve, θ(h), is of paramount importance to characterize the water flow in the vadose zone. This work presents a modified upward infiltration method to estimate Ks, α and n from numerical inverse analysis of the measured cumulative upward infiltration (CUI) at multiple constant tension lower boundary conditions. Using the HYDRUS‐2D software, a theoretical analysis on a synthetic loam soil under different soil tensions (0, 0–10, 0–50 and 0–100 cm), with and without an overpressure step of 10 cm high from the top boundary condition at the end of the upward infiltration process, was performed to check the uniqueness and the accuracy of the solutions. Using a tension sorptivimeter device, the method was validated in a laboratory experiment on five different soils: a coarse and a fine sand, and a 1‐mm sieved loam, clay loam and silt‐gypseous soils. The estimated α and n parameters were compared to the corresponding values measured with the TDR‐pressure cell method. The theoretical analysis demonstrates that Ks and θ(h) can be simultaneously estimated from measured upward cumulative infiltration when high (>50 cm) soil tensions are initially applied at the lower boundary. Alternatively, satisfactory results can be also obtained when medium tensions (<50 cm) and the Ks calculated from the overpressure step at the end of the experiment are considered. A consistent relationship was found between the α (R^2 = 0.86, p < 0.02) and n (R^2 = 0.97, p < 0.001) values measured with the TDR‐pressure cell and the corresponding values estimated with the tension sorptivimeter. The error between the α (in logarithm scale) and n values estimated with the inverse analysis and the corresponding values measured with pressure chamber were 3.1 and 6.1%, respectively.

@article{p2016-Moret-Fernandez-et-al,
  author = {Moret-Fern{\'{a}}ndez, D. and Latorre, B. and Pe{\~{n}}a-Sancho, C. and Ghezzehei, T.A.},
  date-modified = {2018-05-27 19:55:55 +0000},
  journal = {Hydrological Processes},
  status = {published},
  month = apr,
  number = {17},
  pages = {2991--3003},
  publisher = {Wiley},
  sort-word = {method, infiltration},
  title = {A modified multiple tension upward infiltration method to estimate the soil hydraulic properties},
  volume = {30},
  year = {2016}
}

A new method was developed to measure soil consolidation by capillary suction in organic soils. This method differs from previous methods of measuring soil consolidation in that no external load is utilized and only the forces generated via capillary suction consolidate the soil matrix. This limits the degree of consolidation that can occur, but gives a more realistic ecological perspective on the response of organic soils to desiccation in the field. This new method combines the principles behind a traditional triaxial cell (for measurements of volume change), a pressure plate apparatus, (to facilitate drainage by capillary suction), and the permeameter, (to measure saturated hydraulic conductivity), and allows for simultaneous desaturation of the soil while monitoring desiccation induced volume change in the soil. This method also enables detection of historic limit of dryness. The historic limit of dryness is a novel concept that is unique to soils that have never experienced drying since their formation. It is fundamentally equivalent to the pre-compression stress of externally loaded soils. This method is particularly important for forecasting structural and hydrologic changes that may occur in soils that were formed in very wet regimes (e.g., wet meadows at the foot of persistent snow packs and permafrost peats) as they respond to a changing climate.

@article{p2015-Arnold-Ghezzehei,
  author = {Arnold, Chelsea and Ghezzehei, Teamrat A.},
  data = {10.6084/m9.figshare.1243716.v1},
  doi = {10.1002/2014WR015745},
  journal = {Water Resources Research},
  status = {published},
  keywords = {Ecosystems, Seasons, Soil respiration, Productivity, Spring, Winter, Carbon dioxide, Ecosystem functioning},
  month = sep,
  number = {1},
  pages = {e106058},
  pdf = {https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1002/2014WR015745},
  researchgate = {https://www.researchgate.net/publication/267875649_A_method_for_characterizing_desiccation-induced_consolidation_and_permeability_loss_of_organic_soils},
  sort-word = {method, mechanics},
  title = {A method for characterizing desiccation-induced consolidation and permeability loss of organic soils},
  volume = {51},
  year = {2015}
}

A new UV spectrophotometry based method for determining the concentration and carbon content of carbohydrate solution was developed. This method depends on the inherent UV absorption potential of hydrolysis byproducts of carbohydrates formed by reaction with concentrated sulfuric acid (furfural derivatives). The proposed method is a major improvement over the widely used Phenol-Sulfuric Acid method developed by DuBois, Gilles, Hamilton, Rebers, and Smith (1956). In the old method, furfural is allowed to develop color by reaction with phenol and its concentration is detected by visible light absorption. Here we present a method that eliminates the coloration step and avoids the health and environmental hazards associated with phenol use. In addition, avoidance of this step was shown to improve measurement accuracy while significantly reducing waiting time prior to light absorption reading. The carbohydrates for which concentrations and carbon content can be reliably estimated with this new rapid Sulfuric Acid-UV technique include: monosaccharides, disaccharides and polysaccharides with very high molecular weight.

@article{p2013-Albalasmeh-Berhe-Ghezzehei,
  author = {Albalasmeh, Ammar A. and Berhe, Asmeret Asefaw and Ghezzehei, Teamrat A.},
  date-modified = {2018-05-31 13:28:00 +0000},
  doi = {10.1016/j.carbpol.2013.04.072},
  journal = {Carbohydrate Polymers},
  status = {published},
  number = {2},
  pages = {253-61},
  researchgate = {https://www.researchgate.net/publication/255176344_A_new_method_for_rapid_determination_of_carbohydrate_and_total_carbon_concentrations_using_UV_spectrophotometry},
  sort-word = {method},
  title = {A new method for rapid determination of carbohydrate and total carbon concentrations using UV spectrophotometry},
  volume = {97},
  year = {2013},
  bdsk-url-1 = {https://doi.org/10.1016/j.carbpol.2013.04.072}
}

Direct characterization of hysteresis in water retention (WR) is typically cumbersome and time consuming. Thus, such data are scarce, and even when available are typically ignored in unsaturated flow modeling. One reason for disregard of this ubiquitous and significant feature of WR is lack of a universally applicable index for the degree of hysteresis that allows a priori assessment of its effect on flow. In this note we show that the mismatch between the hydraulic capacity functions of the primary drainage and imbibition curves can serve as generalized index for degree of hysteresis (H). Moreover, we showed that hysteresis indices of a broad range of soils are linearly related with the natural-logarithm of the van Genuchten n parameter (r^2 = 0.73). This model allows predicting the degree of hysteresis and the missing hysteresis branch using only wetting or drying water retention data. The robustness of the proposed index was illustrated by comparing it with error in simulated moisture redistribution in a horizontal column that arises from ignoring hysteresis.

@article{p2011-Gebrenegus-Ghezzehei,
  author = {Gebrenegus, Thomas and Ghezzehei, Teamrat A.},
  date-modified = {2018-05-30 21:20:08 +0000},
  doi = {10.2136/sssaj2011.0082N},
  journal = {Soil Science Society of America Journal},
  status = {published},
  number = {6},
  pages = {2122-2127},
  researchgate = {https://www.researchgate.net/publication/274221936_An_Index_for_Degree_of_Hysteresis_in_Water_Retention},
  sort-word = {method},
  title = {An Index for Degree of Hysteresis in Water Retention},
  volume = {75},
  year = {2011},
  bdsk-url-1 = {https://doi.org/10.2136/sssaj2011.0082N}
}

Application of time domain reflectometry (TDR) in soil hydrology often involves the conversion of TDR‐measured dielectric permittivity to water content using universal calibration equations (empirical or physically based). Deviations of soil‐specific calibrations from the universal calibrations have been noted and are usually attributed to peculiar composition of soil constituents, such as high content of clay and/or organic matter. Although it is recognized that soil disturbance by TDR waveguides may have impact on measurement errors, to our knowledge, there has not been any quantification of this effect. In this paper, we introduce a method that estimates this error by combining two models: one that describes soil compaction around cylindrical objects and another that translates change in bulk density to evolution of soil water retention characteristics. Our analysis indicates that the compaction pattern depends on the mechanical properties of the soil at the time of installation. The relative error in water content measurement depends on the compaction pattern as well as the water content and water retention properties of the soil. Illustrative calculations based on measured soil mechanical and hydrologic properties from the literature indicate that the measurement errors of using a standard three‐prong TDR waveguide could be up to 10%. We also show that the error scales linearly with the ratio of rod radius to the interradius spacing.

@article{p2008-Ghezzehei,
  author = {Ghezzehei, Teamrat A.},
  date-modified = {2018-05-31 13:28:50 +0000},
  doi = {10.1029/2007WR006502},
  journal = {Water Resources Research},
  status = {published},
  keywords = {TDR, water content, compaction, measurement error},
  number = {8},
  pdf = {https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2007WR006502},
  sort-word = {method},
  title = {Errors in determination of soil water content using time domain reflectometry caused by soil compaction around waveguides},
  volume = {44},
  year = {2008},
  bdsk-url-1 = {https://doi.org/10.1029/2007WR006502}
}

Cavities excavated in unsaturated geological formations are important to activities such as nuclear waste disposal and mining. Such cavities provide a unique setting for simultaneous occurrence of seepage and evaporation. Previously, inverse numerical modeling of field liquid-release tests and associated seepage into cavities were used to provide seepage-related large-scale formation properties, ignoring the impact of evaporation. The applicability of such models was limited to the narrow range of ventilation conditions under which the models were calibrated. The objective of this study was to alleviate this limitation by incorporating evaporation into the seepage models. We modeled evaporation as an isothermal vapor diffusion process. The semiphysical model accounts for the relative humidity (RH), temperature, and ventilation conditions of the cavities. The evaporation boundary layer thickness (BLT) over which diffusion occurs was estimated by calibration against free-water evaporation data collected inside the experimental cavities. The estimated values of BLT were 5 to 7 mm for the open underground drifts and 20 mm for niches closed off by bulkheads. Compared with previous models that neglected the effect of evaporation, this new approach showed significant improvement in capturing seepage fluctuations into open cavities of low RH. At high relative-humidity values (>85%), the effect of evaporation on seepage was very small.

@article{p2004-Ghezzehei-et-al,
  author = {Ghezzehei, T. A. and Trautz, R. C. and Finsterle, S. and Cook, P. J. and Ahlers, C. F.},
  date-modified = {2018-05-27 20:09:29 +0000},
  doi = {10.2136/vzj2004.0806},
  journal = {Vadose Zone Journal},
  status = {published},
  month = aug,
  number = {3},
  pages = {806--818},
  researchgate = {https://www.researchgate.net/publication/236570656_Modeling_coupled_evaporation_and_seepage_in_ventilated_tunnels},
  sort-word = {nuclear waste},
  title = {Modeling Coupled Evaporation and Seepage in Ventilated Cavities},
  volume = {3},
  year = {2004}
}

Water dripping into subterranean cavities within fractured porous media is studied in order to improve estimates of dripping rates, drop sizes, and chemical composition of droplets that could affect long‐term integrity of waste disposal canisters placed in caverns. Steady state liquid flux in fracture surfaces supported by flow in partially liquid‐filled grooves and liquid films in adjacent planes was calculated as a function of the matric potential (vapor pressure) of the fracture. At an intersection of a vertical fracture with a wider cavity the liquid flux feeds a growing pendant drop that eventually detaches. Equilibrium state size and approximate shape of liquid drops suspended from the cavity ceiling were determined from lateral and vertical force balance considering capillarity, gravity, and hydrostatic pressure. A one‐dimensional, viscous extension model with appropriate gravitational and surface tension components was employed to determine dripping rate from specified fracture roughness geometry as a function of matric potential (flux). The effect of evaporation from drop surface during drop formation was incorporated; the resulting alterations in drop volume, dripping rate, and drop solute concentration were determined. To facilitate experimental testing of the proposed model, a decoupled solution that considers independently controlled flux and evaporation is presented. Under evaporative conditions, dripping in finite period is possible only when volumetric flux exceeds evaporative demand. Calculations indicate that dripping rate and solute concentration are extremely sensitive to ambient matric potential. The results of this work may be extended to study other phenomena including formation and growth of stalactites and rivulet flow in cave ceilings.

@article{p2000-Or-Ghezzehei,
  author = {Or, D and Ghezzehei, T. A.},
  date-modified = {2018-05-30 21:36:21 +0000},
  journal = {Water Resources Research},
  status = {published},
  month = feb,
  number = {2},
  pages = {381-393},
  researchgate = {https://www.researchgate.net/publication/37450895_Dripping_into_cavities_from_unsaturated_fractures_under_evaporative_conditions},
  sort-word = {nuclear},
  title = {Dripping into subterranean cavities from unsaturated fractures under evaporative conditions},
  volume = {36},
  year = {2000},
  pdf = {https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/1999WR900311},
  doi = {10.1029/1999WR900311}
}

The remarkable complexity of soil and its importance to a wide range of ecosystem services presents major challenges to the modeling of soil processes. Although major progress in soil models has occurred in the last decades, models of soil processes remain disjointed between disciplines or ecosystem services, with considerable uncertainty remaining in the quality of predictions and several challenges that remain yet to be addressed. First, there is a need to improve exchange of knowledge and experience among the different disciplines in soil science and to reach out to other Earth science communities. Second, the community needs to develop a new generation of soil models based on a systemic approach comprising relevant physical, chemical, and biological processes to address critical knowledge gaps in our understanding of soil processes and their interactions. Overcoming these challenges will facilitate exchanges between soil modeling and climate, plant, and social science modeling communities. It will allow us to contribute to preserve and improve our assessment of ecosystem services and advance our understanding of climate-change feedback mechanisms, among others, thereby facilitating and strengthening communication among scientific disciplines and society. We review the role of modeling soil processes in quantifying key soil processes that shape ecosystem services, with a focus on provisioning and regulating services. We then identify key challenges in modeling soil processes, including the systematic incorporation of heterogeneity and uncertainty, the integration of data and models, and strategies for effective integration of knowledge on physical, chemical, and biological soil processes. We discuss how the soil modeling community could best interface with modern modeling activities in other disciplines, such as climate, ecology, and plant research, and how to weave novel observation and measurement techniques into soil models. We propose the establishment of an international soil modeling consortium to coherently advance soil modeling activities and foster communication with other Earth science disciplines. Such a consortium should promote soil modeling platforms and data repository for model development, calibration and intercomparison essential for addressing contemporary challenges.

@article{p2016-Vereecken-et-al,
  author = {Vereecken, H. and Schnepf, A. and Hopmans, J.W. and Javaux, M. and Or, D. and Roose, T. and Vanderborght, J. and Young, M.H. and Amelung, W. and Aitkenhead, M. and Allison, S.D. and Assouline, S. and Baveye, P. and Berli, M. and Br{\"u}ggemann, N. and Finke, P. and Flury, M. and Gaiser, T. and Govers, G. and Ghezzehei, T. and Hallett, P. and Franssen, H.J. Hendricks and Heppell, J. and Horn, R. and Huisman, J.A. and Jacques, D. and Jonard, F. and Kollet, S. and Lafolie, F. and Lamorski, K. and Leitner, D. and McBratney, A. and Minasny, B. and Montzka, C. and Nowak, W. and Pachepsky, Y. and Padarian, J. and Romano, N. and Roth, K. and Rothfuss, Y. and Rowe, E.C. and Schwen, A. and {\v{S}}im{\r{u}}nek, J. and Tiktak, A. and Dam, J. Van and van der Zee, S.E.A.T.M. and Vogel, H.J. and Vrugt, J.A. and W{\"o}hling, T. and Young, I.M.},
  date-modified = {2018-05-27 19:55:55 +0000},
  journal = {Vadose Zone Journal},
  status = {published},
  keywords = {Akaike information criterion, Bayesian model evidence, Bayesian information criterion, Bayesian model averaging, CLM, Community Land Model, DEM, digital elevation model, EnKF, Ensemble Kalman Filter, ET, evapotranspiration, GHG, greenhouse gases, GIS, geographic information system, GPS, global positioning system, IC, information criteria, ISMC, International Soil Modeling Consortium, KIC, Kashyap information criterion, LIDAR, Light Detection and Ranging, MCMC, Markov chain Monte Carlo, MRI, magnetic resonance imaging, MW, microwave spectrum, MWIR, mid-wave infrared spectrum, NIR, near-infrared spectrum, OTU, operational taxonomic units, pdf, probability density function, PSS, proximal soil sensing, PTF, pedotransfer function, SAR, Synthetic Aperture Radar, SDA, sequential data assimilation, SVAT, soil--vegetation--atmosphere transfer, SWIR, short-wave infrared spectrum, TE, treated effluents, TIR, thermal infrared spectrum, UAV, unmanned air vehicles, μCT, microcomputed tomography, VIS, visible spectrum, VSP, virtual soil platform},
  number = {5},
  researchgate = {https://www.researchgate.net/publication/303017539_Modeling_Soil_Processes_Review_Key_Challenges_and_New_Perspectives},
  sort-word = {synthesis, review},
  title = {Modeling Soil Processes: Review, Key Challenges, and New Perspectives},
  volume = {15},
  doi = {10.2136/vzj2015.09.0131},
  year = {2016},
  bdsk-url-1 = {https://doi.org/10.2136%2Fvzj2015.09.0131},
  bdsk-url-2 = {http://dx.doi.org/10.2136/vzj2015.09.0131},
  bdsk-url-3 = {https://doi.org/10.2136/vzj2015.09.0131}
}

@article{p2008-Ghezzehei-b,
  author = {Ghezzehei, Teamrat A.},
  date-modified = {2018-05-27 20:01:54 +0000},
  journal = {Soil Science Society of America Journal},
  status = {published},
  number = {1},
  pages = {277},
  publisher = {Soil Science Society of America},
  title = {Book Review: Clay Swelling and Colloid Stability},
  volume = {72},
  sort-word = {review},
  year = {2008},
  bdsk-url-1 = {https://doi.org/10.2136%2Fsssaj2007.0024br},
  bdsk-url-2 = {http://dx.doi.org/10.2136/sssaj2007.0024br},
  bdsk-url-3 = {https://doi.org/10.2136/sssaj2007.0024br}
}

Abstract. In this paper, we present and analyze a global database of soil infiltration measurements, the Soil Water Infiltration Global (SWIG) database, for the first time. In total, 5023 infiltration curves were collected across all continents in the SWIG database. These data were either provided and quality checked by the scientists who performed the experiments or they were digitized from published articles. Data from 54 different countries were included in the database with major contributions from Iran, China, and USA. In addition to its global spatial coverage, the collected infiltration curves cover a time span of research from 1976 to late 2017. Basic information on measurement location and method, soil properties, and land use were gathered along with the infiltration data, which makes the database valuable for the development of pedo-transfer functions for estimating soil hydraulic properties, for the evaluation of infiltration measurement methods, and for developing and validating infiltration models. Soil textural information (clay, silt, and sand content) is available for 3842 out of 5023 infiltration measurements ( 76 %) covering nearly all soil USDA textural classes except for the sandy clay and silt classes. Information on the land use is available for 76 % of experimental sites with agricultural land use as the dominant type ( 40 %). We are convinced that the SWIG database will allow for a better parameterization of the infiltration process in land surface models and for testing infiltration models. All collected data and related soil characteristics are provided online in *.xlsx and *.csv formats for reference, and we add a disclaimer that the database is for use by public domain only and can be copied freely by referencing it. Supplementary data are available at doi:10.1594/PANGAEA.885492. Data quality assessment is strongly advised prior to any use of this database. Finally, we would like to encourage scientists to extend/update the SWIG by uploading new data to it.

@article{p2018-Rahmati-et-al,
  author = {Rahmati, Mehdi and Weiherm{\"o}ller, Lutz and Vanderborght, Jan and Pachepsky, Yakov A. and Mao, Lili and Sadeghi, Seyed Hamidreza and Moosavi, Niloofar and Kheirfam, Hossein and Montzka, Carsten and Looy, Kris Van and Toth, Brigitta and Hazbavi, Zeinab and Yamani, Wafa Al and Albalasmeh, Ammar A. and Alghzawi, Ma{\&}amp$\mathsemicolon$apos$\mathsemicolon$in Z. and Angulo-Jaramillo, Rafael and Antonino, Ant{\^{o}}nio Celso Dantas and Arampatzis, George and Armindo, Robson Andr{\'{e}} and Asadi, Hossein and Bamutaze, Yazidhi and Batlle-Aguilar, Jordi and Bechet, Beatrice and Becker, Fabian and Bl{\~A}¶schl, G{\~A}¼nter and Bohne, Klaus and Braud, Isabelle and Castellano, Clara and Cerd{\`{a}}, Artemi and Chalhoub, Maha and Cichota, Rogerio and C{\'{\i}}slerov{\'{a}}, Milena and Clothier, Brent and Coquet, Yves and Cornelis, Wim and Corradini, Corrado and Coutinho, Artur Paiva and de Oliveira, Muriel Bastista and de Macedo, Jos{\'{e}} Ronaldo and Dur{\~{a}}es, Matheus Fonseca and Emami, Hojat and Eskandari, Iraj and Farajnia, Asghar and Flammini, Alessia and Fodor, N{\'{a}}ndor and Gharaibeh, Mamoun and Ghavimipanah, Mohamad Hossein and Ghezzehei, Teamrat A. and Giertz, Simone and Hatzigiannakis, Evangelos G and Horn, Rainer and Jim{\'{e}}nez, Juan Jos{\'{e}} and Jacques, Diederik and Keesstra, Saskia Deborah and Kelishadi, Hamid and Kiani-Harchegani, Mahboobeh and Kouselou, Mehdi and Jha, Madan Kumar and Lassabatere, Laurent and Li, Xiaoyan and Liebig, Mark A. and Lichner, Lubom{\'{\i}}r and L{\'{o}}pez, Mar{\'{\i}}a Victoria and Machiwal, Deepesh and Mallants, Dirk and Mallmann, Micael Stolben and de Oliveira Marques, Jean Dalmo and Marshall, Miles R. and Mertens, Jan and Meunier, F{\'{e}}licien and Mohammadi, Mohammad Hossein and Mohanty, Binayak P. and Moncada, Mansonia Pulido and Montenegro, Suzana and Morbidelli, Renato and Moret-Fern{\'{a}}ndez, David and Moosavi, Ali Akbar and Mosaddeghi, Mohammad Reza and Mousavi, Seyed Bahman and Mozaffari, Hasan and Nabiollahi, Kamal and Neyshabouri, Mohammad Reza and Ottoni, Marta Vasconcelos and Filho, Theophilo Benedicto Ottoni and Rad, Mohammad Reza Pahlavan and Panagopoulos, Andreas and Peth, Stephan and Peyneau, Pierre-Emmanuel and Picciafuoco, Tommaso and Poesen, Jean and Pulido, Manuel and Reinert, Dalvan Jos{\'{e}} and Reinsch, Sabine and Rezaei, Meisam and Roberts, Francis Parry and Robinson, David and Rodrigo-Comino, Jes{\'{u}}s and Filho, Otto Corr{\^{e}}a Rotunno and Saito, Tadaomi and Suganuma, Hideki and Saltalippi, Carla and S{\'{a}}ndor, Ren{\'{a}}ta and Sch{\~A}¼tt, Brigitta and Seeger, Manuel and Sepehrnia, Nasrollah and Moghaddam, Ehsan Sharifi and Shukla, Manoj and Shutaro, Shiraki and Sorando, Ricardo and Stanley, Ajayi Asishana and Strauss, Peter and Su, Zhongbo and Taghizadeh-Mehrjardi, Ruhollah and Taguas, Encarnaci{\'{o}}n and Teixeira, Wenceslau Geraldes and Vaezi, Ali Reza and Vafakhah, Mehdi and Vogel, Tomas and Vogeler, Iris and Votrubova, Jana and Werner, Steffen and Winarski, Thierry and Yilmaz, Deniz and Young, Michael H. and Zacharias, Steffen and Zeng, Yijian and Zhao, Ying and Zhao, Hong and Vereecken, Harry},
  data = {https://10.0.6.58/PANGAEA.885492},
  date-modified = {2018-06-27 20:51:14 +0000},
  doi = {10.5194/essd-2018-11},
  journal = {Earth System Science Data},
  status = {published},
  month = jun,
  pages = {1--42},
  sort-word = {synthesis},
  title = {Development and Analysis of Soil Water Infiltration Global Database},
  year = {2018},
  bdsk-url-1 = {https://doi.org/10.5194%2Fessd-2018-11},
  bdsk-url-2 = {http://dx.doi.org/10.5194/essd-2018-11},
  bdsk-url-3 = {https://doi.org/10.5194/essd-2018-11}
}

Advancing our understanding of Earth system dynamics (ESD) depends on the development of models and other analytical tools that apply physical, biological, and chemical data. This ambition to increase understanding and develop models of ESD based on site observations was the stimulus for creating the networks of Long-Term Ecological Research (LTER), Critical Zone Observatories (CZOs), and others. We organized a survey, the results of which identified pressing gaps in data availability from these networks, in particular for the future development and evaluation of models that represent ESD processes, and provide insights for improvement in both data collection and model integration. From this survey overview of data applications in the context of LTER and CZO research, we identified three challenges: (1) widen application of terrestrial observation network data in Earth system modelling, (2) develop integrated Earth system models that incorporate process representation and data of multiple disciplines, and (3) identify complementarity in measured variables and spatial extent, and promoting synergies in the existing observational networks. These challenges lead to perspectives and recommendations for an improved dialogue between the observation networks and the ESD modelling community, including co-location of sites in the existing networks and further formalizing these recommendations among these communities. Developing these synergies will enable cross-site and cross-network comparison and synthesis studies, which will help produce insights around organizing principles, classifications, and general rules of coupling processes with environmental conditions.

@article{p2018-Baatz,
  author = {Baatz, Roland and Sullivan, Pamela L. and Li, Li and Weintraub, Samantha and Loescher, Henry W. and Mirtl, Michael and Groffman, Peter M. and Wall, Diana H. and Young, Michael and White, Tim and Wen, Hang and Zacharias, Steffen and K{\~A}¼hn, Ingolf and Tang, Jianwu and Gaillardet, J{\'{e}}r{\^{o}}me and Braud, Isabelle and Flores, Alejandro N. and Kumar, Praveen and Lin, Henry and Ghezzehei, Teamrat and Gholz, Henry L. and Vereecken, Harry and Looy, Kris Van},
  date-modified = {2018-11-14 14:16:32 -0800},
  doi = {10.5194/esd-9-593-2018},
  journal = {Earth System Dynamics},
  status = {published},
  month = may,
  pages = {593-609},
  pdf = {https://www.earth-syst-dynam.net/9/593/2018/esd-9-593-2018.pdf},
  researchgate = {https://www.researchgate.net/publication/325313872_Steering_operational_synergies_in_terrestrial_observation_networks_opportunity_for_advancing_Earth_system_dynamics_modelling},
  sort-word = {synthesis},
  title = {Integration of terrestrial observational networks: opportunity for advancing Earth system dynamics modelling},
  volume = {9},
  year = {2018},
  bdsk-url-1 = {https://doi.org/10.5194%2Fesd-2017-94},
  bdsk-url-2 = {http://dx.doi.org/10.5194/esd-2017-94},
  bdsk-url-3 = {https://doi.org/10.5194/esd-9-593-2018}
}

The remarkable complexity of soil and its importance to a wide range of ecosystem services presents major challenges to the modeling of soil processes. Although major progress in soil models has occurred in the last decades, models of soil processes remain disjointed between disciplines or ecosystem services, with considerable uncertainty remaining in the quality of predictions and several challenges that remain yet to be addressed. First, there is a need to improve exchange of knowledge and experience among the different disciplines in soil science and to reach out to other Earth science communities. Second, the community needs to develop a new generation of soil models based on a systemic approach comprising relevant physical, chemical, and biological processes to address critical knowledge gaps in our understanding of soil processes and their interactions. Overcoming these challenges will facilitate exchanges between soil modeling and climate, plant, and social science modeling communities. It will allow us to contribute to preserve and improve our assessment of ecosystem services and advance our understanding of climate-change feedback mechanisms, among others, thereby facilitating and strengthening communication among scientific disciplines and society. We review the role of modeling soil processes in quantifying key soil processes that shape ecosystem services, with a focus on provisioning and regulating services. We then identify key challenges in modeling soil processes, including the systematic incorporation of heterogeneity and uncertainty, the integration of data and models, and strategies for effective integration of knowledge on physical, chemical, and biological soil processes. We discuss how the soil modeling community could best interface with modern modeling activities in other disciplines, such as climate, ecology, and plant research, and how to weave novel observation and measurement techniques into soil models. We propose the establishment of an international soil modeling consortium to coherently advance soil modeling activities and foster communication with other Earth science disciplines. Such a consortium should promote soil modeling platforms and data repository for model development, calibration and intercomparison essential for addressing contemporary challenges.

@article{p2016-Vereecken-et-al,
  author = {Vereecken, H. and Schnepf, A. and Hopmans, J.W. and Javaux, M. and Or, D. and Roose, T. and Vanderborght, J. and Young, M.H. and Amelung, W. and Aitkenhead, M. and Allison, S.D. and Assouline, S. and Baveye, P. and Berli, M. and Br{\"u}ggemann, N. and Finke, P. and Flury, M. and Gaiser, T. and Govers, G. and Ghezzehei, T. and Hallett, P. and Franssen, H.J. Hendricks and Heppell, J. and Horn, R. and Huisman, J.A. and Jacques, D. and Jonard, F. and Kollet, S. and Lafolie, F. and Lamorski, K. and Leitner, D. and McBratney, A. and Minasny, B. and Montzka, C. and Nowak, W. and Pachepsky, Y. and Padarian, J. and Romano, N. and Roth, K. and Rothfuss, Y. and Rowe, E.C. and Schwen, A. and {\v{S}}im{\r{u}}nek, J. and Tiktak, A. and Dam, J. Van and van der Zee, S.E.A.T.M. and Vogel, H.J. and Vrugt, J.A. and W{\"o}hling, T. and Young, I.M.},
  date-modified = {2018-05-27 19:55:55 +0000},
  journal = {Vadose Zone Journal},
  status = {published},
  keywords = {Akaike information criterion, Bayesian model evidence, Bayesian information criterion, Bayesian model averaging, CLM, Community Land Model, DEM, digital elevation model, EnKF, Ensemble Kalman Filter, ET, evapotranspiration, GHG, greenhouse gases, GIS, geographic information system, GPS, global positioning system, IC, information criteria, ISMC, International Soil Modeling Consortium, KIC, Kashyap information criterion, LIDAR, Light Detection and Ranging, MCMC, Markov chain Monte Carlo, MRI, magnetic resonance imaging, MW, microwave spectrum, MWIR, mid-wave infrared spectrum, NIR, near-infrared spectrum, OTU, operational taxonomic units, pdf, probability density function, PSS, proximal soil sensing, PTF, pedotransfer function, SAR, Synthetic Aperture Radar, SDA, sequential data assimilation, SVAT, soil--vegetation--atmosphere transfer, SWIR, short-wave infrared spectrum, TE, treated effluents, TIR, thermal infrared spectrum, UAV, unmanned air vehicles, μCT, microcomputed tomography, VIS, visible spectrum, VSP, virtual soil platform},
  number = {5},
  researchgate = {https://www.researchgate.net/publication/303017539_Modeling_Soil_Processes_Review_Key_Challenges_and_New_Perspectives},
  sort-word = {synthesis, review},
  title = {Modeling Soil Processes: Review, Key Challenges, and New Perspectives},
  volume = {15},
  doi = {10.2136/vzj2015.09.0131},
  year = {2016},
  bdsk-url-1 = {https://doi.org/10.2136%2Fvzj2015.09.0131},
  bdsk-url-2 = {http://dx.doi.org/10.2136/vzj2015.09.0131},
  bdsk-url-3 = {https://doi.org/10.2136/vzj2015.09.0131}
}