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<p> Increased nitrogen (N) fertilizer additions to modern agricultural cropping systems will be necessary to feed a growing world population. However, greater nitrogen use efficiency (NUE) is required if agroecosystems are to continue to provide certain ecosystem services (e.g., greenhouse gas emission reductions and water quality goals). The aim of this research was to investigate the role of variable rate N and seeding of winter wheat (<i>Triticum aestivum</i>) for optimizing yield-water-NUE relationships across heterogeneous landscapes. Field plot studies were conducted at the Cook Agronomy Farm (CAF) near Pullman, WA during the 2010, 2011 and 2012 winter wheat harvest years. A randomized complete block split plot N rate x seeding rate experiment with N fertilizer rate as main plot and seeding rate as subplot was employed across three landscape positions. Assessed were evidence of &ldquo;haying-off&rdquo;, depletion of available water resources, and the link between yield, protein, and NUE response to landscape by N fertilization rate by seeding rate treatment combinations. A performance classification was developed to evaluate wheat performance with regard to N utilization efficiency (Gw/Nt) and N uptake efficiency (Nt/Ns) components of the NUE. </p><p> Evidence of haying-off in winter wheat was medium to high for drier landscape positions, particularly during low precipitation years and likely occurs in these landscapes most years. Treatment impacts on NUE varied by year and landscape but overall NUE decreased by 14 to 22 kg grain yield per kg N supply as N rate increased from 0 to 160 kg N ha^-1 across three landscape positions and two site years (2011 and 2012). Target NUE and maximum anthesis biomass could be achieved with a 34 to 68% reduction in typical seeding rates. The NUE-based performance classification was helpful in identifying environmental or management conditions contributing to low or high NUE indicating potential to be used as an evaluation tool. This research also included a policy fellowship focused on N₂O emission reductions and greenhouse gas offset credits that could be generated from adoption of variable rate N for wheat and concluded that offset credits alone would not provide enough incentive for adoption of variable rate N.</p>

<p>Nutrient concentrations in plant tissues are directly correlated with the nutritional status and productivity of fruit trees. Plant tissue testing is one of the most effective and accurate methods to determine nutritional status of perennial plants. Tissue test analyses were performed on tart cherry (Prunus cerasus) and peach (Prunus persica) leaves to validate tissue sufficiency levels used in Utah and to determine optimal timing of tissue sampling for prediction of harvest nutrient status, focusing on phosphorus (P), potassium (K), calcium (Ca), iron (Fe), and zinc (Zn). Sufficiency limits that were adopted in Utah were developed in the 1960s from research data accumulated from the primary fruit growing regions in the United States. Limited research has been conducted under Utah growing conditions. Tissue nutrient concentrations over time correlated well with current sufficiency limits and observed nutrient deficiencies in the field. Tissue concentrations of P, K, Fe, and Zn were found to be chronically low in Utah orchards. Plant tissue data demonstrates that mid-season sampling can predict nutrient status at harvest. Mid-season sampling also allows time for corrective adjustments to maintain sufficiency levels and reach optimal fruit production. Nutrient management practices are commonly applied annually to increase yield, fruit quality, and overall health of an orchard. Yield was measured on previously treated tart cherry orchards to determine residual effect on tree nutrient status. Orchards were treated 2 to 3 years prior with rate-response formulations of P and K; one has since adopted recommended fertilizer rates for optimizing tart cherry production in Utah and the other continued with their less aggressive management practices. The less aggressively managed orchard showed trends across treatments, but differences were not significant. Annual fertilizer applications may not immediately show effect during year of application, but long term management is essential for overall productivity of orchards.

<p> Root Zone Soil Moisture (RZSM) data have both drought monitoring and seasonal forecasting applications. It is the lifeblood of vegetation, an integral component of the hydrologic system, a determining factor in irrigation requirements, and works to govern the means by which energy imbalances are settled between land and atmosphere. The National Integrated Drought Information System (NIDIS) has worked in conjunction with the Colorado Climate Center to improve regional drought early warning through enhanced monitoring and understanding of RZSM. The chief goals of this research have been as follows: 1. Examine regional drought monitoring in the Upper Colorado River Basin and eastern Colorado with specific inquiry as to soil moisture&rsquo;s role in the process. 2. Develop operational products that can be used to improve the weekly drought monitoring process in the Upper Colorado River Basin and eastern Colorado with an emphasis on utilization of soil moisture data. 3. Review in-situ soil moisture data from high elevation Snow Telemetry measurement sites in Colorado in order to understand the descriptive climatology of soil moisture over the Colorado Rockies. 4. Compare output from soil sensors installed by the Snow Telemetry and Colorado Agricultural Meteorological Network using current calibration methods in order to better understand application of direct comparison between output from the two different sensor types. Engineer a soil moisture core measurement protocol that is reliable within ten percent of the true volumetric water content value. This protocol, if successful on a local plot, will be expanded to alpha testers around the United States and used by the USDA for drought monitoring as well as NASA for ground validation of the Soil Moisture Active Passive (SMAP) Satellite. 5. Expose the seasonality and spatial variability of positive feedbacks that occur between RZSM and the atmosphere across the Upper Colorado River Basin and western High Plains using reanalysis data from the North American Land Data Assimilation System Phase-2 (NLDAS). </p><p> Regional drought monitoring was found to involve assimilation of data from a bevy of sources. The decision-making process includes assessment of precipitation, soil moisture, snowpack, vegetative health, streamflow, reservoir levels, reference evapotranspiration, surface air temperature, and ground reports from the regional agricultural sector. Drought monitoring was expanded upon in this research through the development of several products intended for future Colorado Climate Center use. In-situ soil moisture timeseries are now being created from select SNOTEL and SCAN measurement sites. Reservoir monitoring graphics are being produced to accompany spatial analyses downloaded from the bureau of reclamation. More soil moisture data is being used, and now come from an ensemble of models rather than just the VIC model. </p><p> While only ten years of data were collected in analyzing the descriptive soil moisture climatology of the Colorado Rockies, these data were telling in terms of the expected seasonal cycle of soil moisture at high elevations. SNOTEL measurements reveal that soil moisture levels peak prior to snowmelt, large decreases in soil moisture are expected in June and early July, a slight recovery is anticipated in association with the North American Monsoon, and the sign of near-surface water balance flips back to positive in the first two weeks of September before soils freeze. Seasonal variance and distribution of volumetric water content varies in ways that are useful to understand from a drought monitoring standpoint. The data show that measurements are affected when soil freezes. </p><p> Comparing output from soil sensor relays using sensor types and calibration methods consistent with current SNOTEL and CoAgMet specifications revealed large differences in output regardless of being subject to the same meteorologic conditions. </p><p> Soil moisture measurement protocol development proved to be a trial and error process. The data collected at Christman Field was not sufficient proof that soil coring results did come within ten percent of ground truth perhaps due to microscale variations in infiltration. It was possible to develop a protocol of an acceptable standard that could be followed by citizen scientist for an estimated cost of $50. </p><p> Results from statistical modeling of post-processed NLDAS data from the last 30 years point primarily to a time frame between May and July in which soil moisture anomalies become significantly correlated with seasonal temperature and precipitation anomalies. This time of year is partially characterized by a climatologic maximization of downwelling solar radiation and a northward recession of the polar jet, but also precedes the anticipated arrival of the North American Monsoon. (Abstract shortened by ProQuest.)</p>

<p> Measurement of bioturbation reflects physical and biological processes operating over time and can be used to reveal information about paleo-environments. The purpose of this study was to determine the intensity of bioturbation in Triassic Moenkopi Formation at Hurricane Mesa in Southwestern Utah. This formation is interpreted as having been deposited mostly in large ancient river channels, tidal flats, delta and shallow marine environments. Five stratigraphic sections measured in the Virgin Limestone Member provided the basis for this study. Detailed descriptions and quantification of bioturbation were recorded in each of the sections. Similar treatment was given to additional study sites in the rest of the formation, above the Virgin Limestone. Treatments on selected samples were implemented to better reveal evidence of bioturbation. In these treatments samples were coated with water or oil, etched with HCL and viewed under blacklight. Integrating the results of the treatments with x-ray diffraction and petrographic analysis suggest that there was minimal bioturbation. These findings are consistent with more rapid deposition than previously reported by other researchers.</p>

<p> Peatlands act as carbon sinks while representing major sources of biogenic gases such as methane (CH4) and carbon dioxide (CO2), two potent greenhouse gases. Gas production and release in these peats soils are also influenced by overall warm temperatures and water table fluctuations due to the naturally shallow water table in the Florida Everglades. Releases of biogenic gases from Florida Everglades peat soils are not well understood and the temporal distribution and dynamics are uncertain. The general objective of this work was geared towards a methodological approach which aimed to examine the feasibility of capacitance moisture probes to investigate biogenic gas dynamics in various Florida Everglades peat soils at high temporal resolution. This work has implications for establishing capacitance moisture probes as a method to monitor gas dynamics in peat soils at high temporal resolution and better understanding patterns of gas build-up and release from peat soils in the Everglades. </p>

The research investigates random soil movement as suggested by Culling (1963), concentrating on the development of a technique for testing this theory. The technique employed dispenses with the need for continuous monitoring and avoids the inherent problems of soil disturbance arising from the use of soil probes. The theory assumes random and diffusive soil movement leading to a distinctive pattern of soil densities, through time, about obstacles of varying shapes. Solutions for circular and elliptical cylindrical obstacles have been calculated (Culling, 1981). The existence of a soil density pattern has now been investigated for circular obstacles by examining soil from around telegraph poles using photo-microscopy and image analysis to facilitate rapid calculation. Soil samples were removed in brass tubes, dried with acetone, impregnated with resin, made into thin sections, photographed and analysed. From the soil:void ratios of each picture the changing micro-density of soil around an obstacle can be determined. Results indicate significant variations in the density values. Detailed inspection of the two-dimensional information reveals that under sloping site conditions there is a coherent pattern of soil density which reflects that predicted by the theory. Flat sites are also consistent in that there is no identifiable trend in the horizontal plane. The conclusion considers the adequacy of the research undertaken to evaluate the theory.

<p> Anthropogenic trampling affects soil and litter-dwelling invertebrate communities in southern California parks, potentially altering community dynamics and hindering nutrient cycling in coastal oak woodland habitats. I collected meso- and macro-faunal community data from leaf litter and soil in frequently and infrequently trampled areas of six San Diego and three Orange County parks during fall 2011 and spring 2012. I recorded relative compaction, moisture percentage and litter mass then extracted eight soil monoliths at each park (25cm x 25cm x 5cm depth) and the detritus above them. I hypothesized frequently trampled invertebrate communities would show decreased abundance, richness and diversity and altered assemblages compared to infrequently trampled communities. Low impact areas showed higher richness and diversity in the soil layer in fall and leaf litter layer in spring. In the laboratory, I hypothesized Lumbricus terrestris earthworms would be more active, creating more large water-stable soil aggregates in low compaction treatments but found no effect of compaction on soil aggregates.</p>

<p> Northwestern Indiana has land surfaces and soils that are around 15,000 years old, resulting from sediments deposited from the Wisconsinan Glaciation during the late Pleistocene period. These geologically young soils exhibit depletion of base cations and low pH's (near 4.0) which are chemically similar to much older and more intensely weathered soils. We hypothesize that FeS2 (iron pyrite) within the shale fragments of the glacial deposits was oxidized upon exposure of oxygen near the earth's surface and resulted in naturally occurring acid sulfate weathering. To test our hypothesis, we isolated the area with ArcGIS, collected clast samples from gravel pits, utilized historic soils databases, and analyzed samples with X-ray diffraction to determine if associated properties and soil minerals would support acid sulfate weathering as the cause of the current soil chemical properties. Soil samples and glacial outwash cobble-sized clasts were collected and X-ray diffraction was used to determine the presence of pyrite or of pyrite weathering products jarosite and gypsum. Existing soil databases and lab data were examined to obtain further details of the occurrence of the potential acid sulfate weathering. A review of the geologic literature was also conducted to put the acid sulfate weathering processes into a landscape perspective and geologic context. The clast samples and some soil samples indicated the presence of jarosite and gypsum which are commonly associated with acid sulfate weathering. This research also found that ultic soil properties and low pH soils were associated with sandy glacial outwash and this information was displayed spatially. The sandy outwash has a lower CEC and lower buffering capacity when compared to nearby higher clayey glacial till. There was inferential evidence of acid sulfate weathering in calcareous glacial which is illustrated by iron oxide pseudomorphs. The lack of initial pyritic shale combined with the neutralizing potential for the calcareous till prevented these soils from developing ultic properties and low pH's. Additionally, this research assessed the potential for naturally occurring arsenic in the soils. Elevated arsenic levels were found in soils that occurred in the lowest part of the landscape. Understanding the process of naturally occurring acid sulfate weathering and associated elevated arsenic within this landscape will provide more information on use and management of these areas.</p>