Soil structure as an indicator of soil functions: A review

Soil, through its various functions, plays a vital role in the Earth's ecosystems and provides multiple ecosystem services to humanity. Pedotransfer functions (PTFs) are simple to complex knowledge rules that relate available soil information to soil properties and variables that are needed to parameterize soil processes. In this paper, we review the existing PTFs and document the new generation of PTFs developed in the different disciplines of Earth system science. To meet the methodological challenges for a successful application in Earth system modeling, we emphasize that PTF development has to go hand in hand with suitable extrapolation and upscaling techniques such that the PTFs correctly represent the spatial heterogeneity of soils. PTFs should encompass the variability of the estimated soil property or process, in such a way that the estimation of parameters allows for validation and can also confidently provide for extrapolation and upscaling purposes capturing the spatial variation in soils. Most actively pursued recent developments are related to parameterizations of solute transport, heat exchange, soil respiration and organic carbon content, root density and vegetation water uptake. Further challenges are to be addressed in parameterization of soil erosivity and land use change impacts at multiple scales. We argue that a comprehensive set of PTFs can be applied throughout a wide range of disciplines of Earth system science, with emphasis on land surface models. Novel sensing techniques provide a true breakthrough for this, yet further improvements are necessary for methods to deal with uncertainty and to validate applications at global scale.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1002/2017RG000581

Pedotransfer functions in Earth system science: challenges and perspectives

A review of the mechanical effects of plant roots on concentrated flow erosion rates

In this update, we review some of the more significant advances that have been made in the last decade in the study of preferential flow through the vadose zone as well as suggest some research needs in the coming years. We focus mostly on work that aims to improve understanding of the processes themselves and less on more applied aspects concerning the various consequences of preferential flow (e.g., for surface water and groundwater quality). In recent years, the research emphasis has shifted somewhat toward the two extremes of the scale continuum, the pore scale and the scale of management (field, catchments, and landscapes). This trend has been facilitated by significant advances in both measurement technologies (e.g., noninvasive imaging techniques and high frequency–high spatial resolution monitoring of soil moisture at field and catchment scales) and application of novel methods of analysis to large datasets (e.g., machine learning). This work has led to a better understanding of how pore network properties control preferential flow at the pore to core scales as well as some new insights into the influence of site attributes (climate, land uses, soil types) at field to landscape scales. We conclude that models do not at present fully reflect the current state of process understanding and empirical knowledge of preferential flow. However, we expect that significant advances in computational techniques, computer hardware, and measurement technologies will lead to increasingly reliable model predictions of the impacts of preferential flow, even at the larger scales relevant for management.

Understanding Preferential Flow in the Vadose Zone: Recent Advances and Future Prospects

/pdf/splash-erosion-a-review-with-unanswered-questions-2bp0d2mzu9.pdf

Splash erosion : A review with unanswered questions

https://biblio.ugent.be/publication/780994/file/793140.pdf

Effect of root density and vegetable garden compost mulch on erodibility of a loamy soil under simulated rain

Temporal and spatial variability in 3D soil macropore characteristics determined using X-ray computed tomography

Vegetative filter strip characteristics such as perenniality drive hydrology and subsequent ecosystem services. However, the extent and the potential for forage–biomass crops to improve water quality, provide fodder, and optimize nutrient cycling in multifunctional systems is unknown. We evaluated (a) how species, perenniality, and plant community composition are linked to water quality; and (b) the multiuse forage–biomass potential of filter strips. Whole plots were species [eastern gamagrass (Tripsacum dactyloides), Kernza [or intermediate wheatgrass (Thinopyrum intermedium)], silphium (Silphium integrifolium), switchgrass (Panicum virgatum), and winter wheat (Triticum aestivum)], with split-plots receiving 0 or 5.6 Mg ha−1 broiler litter. Rainfall simulations were conducted at 5 cm h−1 (until 30 min of continuous runoff) in summer and fall of 2019 and 2021 with dual forage and biomass harvests occurring 2019–2021. Kernza and silphium had the lowest biomass regrowth after forage harvests relative to native grasses, suggesting they would not be ideal multifunctional forage–bioenergy crops. Among all soil–plant–water variables, canonical correlations indicate poultry litter (.97), and soil phosphorus saturation (.77) were the most influential variables for water quality. Water quality score, FWQ, which is inversely related to runoff water quality, was lowest for switchgrass (0.03) and greatest (P ≥ .05) for eastern gamagrass and wheat (1.77 and 3.33, respectively), but not different from Kernza (0.98) and silphium (0.31). Therefore, switchgrass resulted in the best water quality scores and highest forage–biomass yields, with Kernza and silphium also showing promise for reducing sediment and nutrient loads following poultry litter applications in multifunctional filter strip systems. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/csc2.20878

Perenniality drives multifunctional forage‐biomass filter strips’ ability to improve water quality

Poultry litter is a useful product as a fertilizer, energy feedstock for thermochemical conversion, and a precursor for synthesis of adsorbents and catalysts. Detailed characterization of baseline properties is necessary for enhanced environmental and economic utilization of this valuable resource. Baseline physicochemical characterization was carried out at two broiler production facilities (Arkansas, PL1, and North Carolina, PL2). Greater concentrations of inorganic nitrogen, phosphorus, and potassium were obtained for PL1, suggesting greater nutrient value compared to PL2. PL2 had greater carbon content and water-holding capacity than PL1. X-ray photoelectron spectroscopy (XPS) of PL1 and PL2 indicated a similarity between litters in terms of the presence of carbon, nitrogen, and oxygen bonds. Both poultry litters had oxygen, nitrogen, sulfur, and phosphorous functional groups, as confirmed by infrared spectroscopy. Time of flight – secondary ion mass spectroscopy of negative ions also indicated similarity of the surface charge distribution between PL1 and PL2. Overall, poultry litters evaluated had similar surface chemistries, with nutrient composition varying based on rearing conditions, which has implications for downstream use in thermochemical conversion and other value-added products.

Poultry litter physiochemical characterization based on production conditions for circular systems

https://www.mdpi.com/2673-8783/2/4/14/pdf?version=1668153847

Sheela Katuwal

Papers

Effect of root density and vegetable garden compost mulch on erodibility of a loamy soil under simulated rain

Temporal and spatial variability in 3D soil macropore characteristics determined using X-ray computed tomography

Perenniality drives multifunctional forage‐biomass filter strips’ ability to improve water quality

Poultry litter physiochemical characterization based on production conditions for circular systems

Characterization of Poultry Litter Biochar and Activated Biochar as a Soil Amendment for Valorization