Irrigation experiments on 12 instrumented field plots were used to assess the impact of dynamic soil crack networks on
infiltration and run-off. During applications of intensity similar to a heavy rainstorm, water was seen being preferentially
delivered within the soil profile. However, run-off was not observed until soil water content...
Vertisols and other vertic-intergrade soils are found all over the globe, including many agricultural and urban areas. These soils are characterized by their cyclical shrinking and swelling behaviors, where bulk density and porosity distribution both vary as functions of time and/or soil moisture. In turn, alterations in physical soil parameters...
n situ soil moisture monitoring networks are critical to the development of soil moisture remote sensing missions as well as agricultural and environmental management, weather forecasting, and many other endeavors. These in situ networks utilize a variety of sensors and installation practices, which confounds the development of a unified reference...
We explore selected aspects of J.-Y. Parlange’s contributions to hydrological transport of solutes and sediments, including both the laboratory and field scales. At the laboratory scale, he provided numerous approximations for solute transport accounting for effects of boundary conditions, linear and nonlinear reactions, and means to determine relevant parameters. Theory...
The movement of air in natural porous media is complex and challenging to measure. Yet gas transport has important implications, for instance, for the evolution of the seasonal snow cover and for water vapor transport in soil. A novel in situ multi-sensor measurement system providing high-resolution observation of gas transport...
The hierarchical organization of aggregates in soil is responsible for the presence of inter and intra-aggregate pores. This research aimed to investigate effects of soil surface liming, considering lime rates of 0, 10 and 15 t ha(-1), on the intra-aggregate porous system of soil aggregates with equivalent diameters of 2-4...
The perhumid coastal temperate rainforests of southeast Alaska contain an abundance of soil organic carbon (SOC) that has accumulated in a wet, cool climate where forest fire disturbance is minimal and organic matter decomposition rates are low. Coastal temperate rainforests are supported by carbon-rich soils that provide ecosystem services including...
Various soil tests are routinely used in the United States to predict soil lime requirement. New non-hazardous methods have recently been proposed for adoption in Oregon, however the accuracy of these methods for Oregon soils has not been established. The objectives of this investigation were: (a) to document and describe...
The effects of fire on above-ground forest systems have been extensively studied. However, research on fire effects on belowground processes is lacking. While the soil microbiome is understood to be vital to conifer growth and regeneration, the complexity of soils means that research on the topic has largely been accomplished...
Onion thrips (Thrips tabaci) are pests found in onion fields of the Treasure Valley, which is located in Eastern Oregon and Western Idaho. Thrips cause damage to this high value crop by feeding on the onion’s extracellular fluid, making photosynthesis more difficult to occur. The feeding from the thrips can...
Soil moisture is an essential climate variable influencing land–atmosphere interactions, an essential hydrologic variable impacting rainfall–runoff processes, an essential ecological variable regulating net ecosystem exchange, and an essential agricultural variable constraining food security. Large-scale soil moisture monitoring has advanced in recent years, creating opportunities to transform scientific understanding of soil...
Remote sensing techniques have been applied extensively in geospatial investigations, but their use in measuring soil physical attributes has been far less explored. Soil particle size distributions (PSD) are indispensable in modeling pedological and hydrological processes as well as biodiversity. However, estimation of PSD via gravimetric measurement methods, the standard...
Engineered capillary barriers typically consist of two layers of granular materials designed so that the contrast in material hydraulic properties and sloping interface retain infiltrating water in the upper layer. We conducted two benchtop capillary barrier experiments, followed by interpretation and numerical modeling. The hydraulic parameters for two coarse materials...
The heat pulse probe method can be implemented with actively heated fiber optics (AHFO) to obtain distributed measurements of soil water content (θ) by using reported soil thermal responses measured by Distributed Temperature Sensing (DTS) and with a soil-specific calibration relationship. However, most reported applications have been calibrated to homogeneous...
Accurate methods are needed to measure changing soil water content from meter to kilometer scales. Laboratory results demonstrate the feasibility of the heat pulse method implemented with fiber optic temperature sensing to obtain accurate distributed measurements of soil water content. A fiber optic cable with an electrically conductive armoring was...
Temperate coniferous forests, such as those that cover vast areas of the western US and Canada, have evolved to depend on cycles of disturbance for succession of species and overall ecosystem maintenance. Many of these forest systems are managed, often for timber production, where disturbances are of anthropogenic origin and...
Measurement of soil hydraulic retention and conduction parameters using tension infiltrometers has been found to be useful but has suffered from unreliable instrument membranes at the soil interface and the need for manual control, which limits the range of boundary conditions that can feasibly be established. An automated design is...
Abstract: In semi-arid climates, seed is often sown into soil with inadequate water for rapid germination. Distinguishing between adequate and marginal water can be difficult. Planting decisions become increasingly complicated when one considers possible differences between cultivars. This study was designed to measure the soil water potential limits for rapid,...
Understanding the processes controlling organic matter (OM) stocks in upland soils, and the ability to management them, is crucial for maintaining soil fertility and carbon (C) storage as well as projecting change with time. OM inputs are balanced by the mineralization (oxidation) rate, with the difference determining whether the system...
The Pacific Northwest region of the United States is known for quality production of blueberries, blackberries, and red raspberries. However, as the climate shifts to warmer, drier, and more extreme summers, growing these water intensive berry crops is becoming increasingly difficult. Furthermore, water regulations within agriculture are becoming more prevalent...
“Active carbon” is a rapidly cycling soil organic carbon (SOC) fraction that acts as an energy and nutrient source for the microbial community. Dilute permanganate oxidation has been used to measure an “active carbon” fraction with the assumption that permanganate oxidation mimics enzymatic decomposition. Permanganate oxidizable carbon (PoxC) has become...
Coastal Temperate Rainforests of western North America are carbon dense ecological regions of great importance due to their high biological productivity and climatic conditions leading to the natural accumulation of soil organic carbon (SOC). Yet, the distribution of SOC remains understudied in the CTR environments, particularly in upland mineral soils,...
Soil organic matter (SOM) processes in dynamic landscapes are strongly influenced by soil erosion and sedimentation. We determined the contribution of physical isolation of organic matter (OM) inside aggregates, chemical interaction of OM with soil minerals, and molecular structure of SOM in controlling storage and persistence of SOM in different...
Amendments and fertilizers applied to optimize crop production and improve soil health also supply inputs of soil organic matter (SOM) and nutrients that affect soil microorganisms. In the dairy-intensive Pacific Northwest, dairy manure is stored as slurry mixtures until conditions are appropriate for soil application. During storage, the manure begins...
Vadose zone fractures and soil cracks exposed to the atmosphere have an impact on gas exchange processes at the Earth-atmosphere interface. In this study we explored and quantified the role of ground-surface winds on fracture ventilation. While the governing physical mechanisms that cause ventilation are relatively well understood, this is...
In Oregon perennial and annual grass seed cropping systems conservation management practices and their impacts on soil health and soil microbial community is not well understood. There is strong motivation to employ conservation tillage and other conservation practices to curb atmospheric carbon levels and improve soil health. However, the few...
Nitrate is a toxic surface and ground water contaminant that poses human-health and ecological hazards. Contamination is anthropogenically sourced to over-amendment of ammonia-based fertilizers, in turn generated by the most carbon intensive chemical process in use today. Electrochemical approaches offer a green alternative to transform harmful waste nitrate into value-added...
The rapid pace of climate change is increasing tree mortality and highlighting the need to improve the mechanistic understanding of plant function under increased water stress. However, the processes that control soil moisture availability in steep mountainous terrain are poorly understood, as are the relative effects of atmospheric and soil...
Soils, with their potential to store and stabilize carbon (C), are an essential resource for sustaining forest productivity, as well as for efforts to reduce atmospheric C concentrations. Protecting existing soil C and harnessing the sequestration potential of our soils require an improved understanding of the processes through which soil...
It is known that soil biota affects water dynamics through various complex mechanisms. The impact on retention by soil biota are due to a combination of changes to pore geometry, pore clogging by biofilms, biofilms that serve to connect thin water films across many pores as the soil dries, and...
Irrigated agricultural production in sandy soils presents several unique challenges to growers, including naturally high permeability, low native water retention, as well as high rates of water drainage losses and leaching of chemicals to the shallow aquifers. This study is an initial investigation into water motion in the sandy agricultural...
Wildland urban interface (WUI) communities in the Western United States have recently dealt with historic and devastating wildfires year after year. The fires have cost tens of billions in damage, burned tens of thousands of structures, displaced thousands of residents, and killed over one hundred people. The 2017 Tubbs fire...
Forests and forest soils are some of the largest biologically active carbon reservoirs in the world. Therefore, understanding how disturbances, such as forest harvest, influence biogeochemical cycling is particularly important for managing forests sustainably. Timber harvest can have large impacts on forest soils, which may affect the long-term productivity and...
Andic soils (aka Andisols) have unique properties that are important to society. For soil scientists, the genesis and taxonomy of Andisols is often confused because they can form in both volcanic and non-volcanic material. This dissertation seeks to address such confusion by looking at andic soil development in the Cascade...
This work advances a unified approach to process-based hydrologic modeling, which we term the ‘‘Structure for Unifying Multiple Modeling Alternatives (SUMMA).’’ The modeling framework, introduced in the companion paper, uses a general set of conservation equations with flexibility in the choice of process parameterizations (closure relationships) and spatial architecture. This...
In the Columbia Basin, pre-plant soil fumigation is commonly used in potato production for pest control, but fumigation can kill non-target organisms within the soil, result in unintended shifts in the microbial community, and disrupt long-term soil health. Cover crops have been shown to strongly influence the numbers and communities...
Climate change impacts everyone’s food and water security. Increasing global temperatures accelerate the hydrologic cycle and consequently impact the water resources for billions of people worldwide. Countless models have been developed to represent various components of the hydrologic cycle at various spatial and temporal scales. These are often validated against...
Easier access to X-ray microtomography (lCT) facilities has provided much new insight from high-resolution imaging for various problems in porous media research. Pore space analysis with respect to functional properties usually requires segmentation of the intensity data into different classes. Image segmentation
is a nontrivial problem that may have a...
Accurate estimates of water losses by evaporation from shallow water tables are important for hydrological, agricultural, and climatic purposes. An experiment was conducted in a weighing lysimeter to characterize the diurnal dynamics of evaporation under natural conditions. Sampling revealed a completely dry surface sand layer after 5 days of evaporation....
As the western United States continues to experience prolonged drought that is extending water deficits and threatening ecosystem resilience and socioeconomic systems, it will be vital to understand the relationship between water use and transport for proper water resource management. This is especially important to the agricultural areas of the...
Urban agriculture (UA) is defined as the production of food crops or livestock within urban areas. Despite its popularity in the United States, research into UA systems suffers from a general underrepresentation of commercial urban systems. As a result, urban growers often have unique technological needs that are unmet by...
Tropical peatlands play an important role in global climate system by storing an immense of carbon that had been accumulated over thousands of years. Peatlands provide another important ecosystem service by regulating the hydrology. It is believed that peatlands act like a giant sponge by absorbing substantial amounts of water...
Forest soils of the Pacific Northwest contain immense amounts of carbon (C). Increasing acreage burned by severe wildfire in the western Oregon Cascades threatens belowground carbon stocks and future site viability. This study investigates forest soil carbon changes after the 2020 Holiday Farm wildfire in a young, intensively managed Douglas-fir...
Biochar has shown promise as a soil amendment for improvement of agricultural and forest productivity, remediation of heavy metals, and sequestration of carbon, but has not yet been adopted for widespread use in any of these applications. By assessing the production potential as a carbon sequestration tool, and the stability...
Understanding the mechanisms controlling colloid transport and deposition in the vadose zone is an important step in protecting our water resources. Colloid transport in unsaturated porous media was studied using X-Ray Microtomography (XMT), which is a non-destructive imaging technique that provides three-dimensional images at a resolution on the order of...
Fuel accumulation and climate shifts are predicted to increase the frequency of high-severity fires in ponderosa pine (Pinus ponderosa Dougl. ex Laws) forests of central Oregon. The combustion of fuels containing large downed wood can result in intense soil heating, alteration of soil properties, and mortality of microbes. Previous studies...
Using X-ray computed tomography (CT) scanning to characterize the physical characteristics of soil and sediment cores allows scientists to observe and analyze stratigraphy without destroying the integrity of different layers. Microbiologists often work with geologists to characterize the microbial communities in such cores; however, X-rays are known to be destructive...
Pumping water from coal seams decreases the pressure in the seam and in turn releases trapped methane; this is the most common and economic method of methane extraction. The water that is pumped out is known as "coal-bed methane water" (CBMW), which is high in sodium and other salts. In...
Accurate measurement of the amount and timing of surface runoff at multiple scales is needed to understand fundamental hydrological processes. At the plot scale (i.e., length scales on the order of 1–10 m) current methods for direct measurement of runoff either store the water in a collection vessel, which is...
Accurate measurement of the amount and timing of surface runoff at multiple scales is needed to understand fundamental hydrological processes. At the plot-scale (i.e., length scales on the order of 1 to 10 m) current methods for direct measurement of runoff either store the water in a collection vessel, which...