Urszula Norton - Academia.edu (original) (raw)

Papers by Urszula Norton

Frontiers in Remote Sensing

Leafy spurge (Euphorbia esula L.) has been introduced to the Yampa River in Northwestern Colorado... more Leafy spurge (Euphorbia esula L.) has been introduced to the Yampa River in Northwestern Colorado for over 40 years and flood and runoff events transport leafy spurge propagules onto adjacent landscapes. The spread of leafy spurge beyond the river channels has yet to be mapped and recorded, and this research was conducted to map leafy spurge occurrence in the Yampa River Valley. Significant stakeholder mapping efforts took place in the summer of 2019–2021, leading to excellent spatial data on leafy spurge presence and absence along the main channel. In summer 2019, multispectral SPOT seven satellite imagery, stakeholder ground mapping efforts, and bright yellow-green leafy spurge bracts were used to interpret imagery, identify dense, unobscured patches of leafy spurge, and digitize them. Spectral signatures from training samples for leafy spurge and other land cover classes (generalized as “not leafy spurge”) were then used to train a Random Forest machine learning classification. I...

In dryland organic winter wheat-fallow rotation systems of U.S. Central High Plains, the usual pr... more In dryland organic winter wheat-fallow rotation systems of U.S. Central High Plains, the usual practice of 10–15 Mg/ha compost application every 3–4 years, has not yielded desired soil organic matter (SOM) improvements. One-time high rate compost application and annual cover crop planting (instead of repetitive tillage) to control weeds have been proposed for carry-over SOM improvement in these systems. In this study, 15, 30 and 45 Mg/ha compost rates and controls (‘no amendment’ and inorganic fertilizer) were considered. One-half of fallow blocks were planted to cover crop mixtures. SOM indices: soil nitrate (NO3−), ammonium (NH4+), dissolved organic C/N (DOC/N), potential mineralizable N (PMN), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions, and soil moisture were measured bi-weekly across three winter wheat growing seasons. The 45 Mg/ha compost affected 25–35% more NO3− in the first growing season; 27–70%; 8–49%; 12–44% more DON, PMN, DOC and 25–57% less CO...

Biogeochemistry

Wildlands of the United States’ Intermountain West contain recurring interspersed plant-community... more Wildlands of the United States’ Intermountain West contain recurring interspersed plant-community types; namely native sagebrush (Artemisia tridentata spp. wyomingensis Nutt.), non-native invasive cheatgrass (Bromus tectorum L.), and crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.]. Soil nitrogen (N) cycling in these water and N co-limited ecosystems shows very strong spatial and temporal variability, but the mechanism(s) by which these semi-arid plant communities control soil N transformations are not well understood. Over two growing seasons, we conducted field and laboratory incubations of intact soil cores (0–10 cm) with and without water added, and created a mass balance model to predict N mineralization. We found that soils under cheatgrass had the highest net N mineralization, net nitrification and soil moisture compared to soils from under the other two plant communities. Moreover, water additions to field-incubated soil cores under cheatgrass more than doubled net N mineralization (0.18 ± 0.02 vs 0.07 ± 0.01 mg N kg−1 d−1). Temperature had a small effect on net N mineralization and net nitrification, with both rates increasing by < 0.005 mg N kg−1 d−1 per °C. The model’s ability to predict N mineralization was relatively low (R2 = 0.33). However, both our model and the data themselves strongly support plant community regulation of soil N cycling through modification of soil moisture.

Dataset summarizes physicochemical properties of lead-contaminated calcareous soil treated with: ... more Dataset summarizes physicochemical properties of lead-contaminated calcareous soil treated with: (1) hardwood biochar (BIOC), (2) composted manure (COMP), and commercial water-soluble inorganic fertilizer (INF), along with an unamended control soil (UNAM). It further provides data on plant growth indicators for Raphanus sativus L. and Lactuca sativa L. grown in the four treatments. Lead tissue concentrations for Raphanus sativus L. are described, along with key plant Pb uptake indicators.

Despite the fact that there is high usage of agrochemicals and use of urban waste water for irrig... more Despite the fact that there is high usage of agrochemicals and use of urban waste water for irrigation, the concentration of potentially toxic metals in urban and peri-urban agriculture (UPA) farms has not been widely investigated in Botswana. The study focused on quantitative assessment of potentially toxic metals in horticultural production under UPA. Crops which are cultivated at the selected study sites include spinach (Spinacia oleracea L.), rape (Brassica rapa var. rapa.), cabbage (Brassica oleracea var. capitata), green pepper (Capsicum annum) and tomato (Solanum lycopersicum). Two farms from areas surrounding Gaborone namely Glenn Valley and Mmankgodi, were sampled for the determination of total heavy metals concentration in soils. In Glenn Valley secondary treated waste water is used for irrigation while in Mmankgodi underground water is used. Four soil profile pits were dug at each farm and soil samples of 20 cm increment were collected from the surface to a depth of 100 c...

Energy Research & Social Science, 2019

Biochar has seen an explosion of research over the past decade as an environmentally sustainable ... more Biochar has seen an explosion of research over the past decade as an environmentally sustainable material for enhancing agricultural yields, treating wastewater, and sequestering atmospheric carbon. In contrast, there is a lack of research into the social and economic sustainability of biochar. To address this gap, we propose environmental justice (EJ) indicators as a proxy for social and economic considerations when siting biochar production facilities. Specifically, we develop a siting index for a biochar pyrolysis facility using low-cost, carbon-neutral solar energy. This siting index provides a framework for analyzing potential facility locations based on both technical and environmental and energy justice considerations. Results indicate that EJ analyses may influence the planning processes for industrial facility siting and that incorporating EJ into siting decisions would represent a commitment to environmental sustainability as well as the social and economic conditions of communities.

Bioresource Technology, 2019

Kinetics, thermodynamics, and physical characterization of corn stover (Zea mays) for solar bioma... more Kinetics, thermodynamics, and physical characterization of corn stover (Zea mays) for solar biomass pyrolysis potential analysis

Grass and Forage Science, 2018

Reduced soil disturbance and increased organic matter inputs in forage production systems may imp... more Reduced soil disturbance and increased organic matter inputs in forage production systems may improve soil quality and crop production through their effects on soil organic matter (SOM) dynamics and nutrient cycling. We evaluated the effects of conventional (CV), organic (OR) and reduced‐tillage (RT) management systems on SOM pools in perennial forage–annual crop rotations established on soils previously under long‐term monocropped corn (Zea mays L.) field. The SOM pools evaluated include potentially mineralizable carbon (PMC) and nitrogen (PMN), dissolved organic carbon (DOC) and nitrogen (DON), microbial biomass carbon (MBC) and nitrogen (MBN), inorganic nitrogen (inorganic‐N), soil organic carbon (SOC) and soil total nitrogen (STN). The crop rotation was 3 years of alfalfa (Medicago sativa L.)–grass mixture (2009‐2011) followed by a fourth year of corn (2012) across all management systems. While soils under the RT system had the highest rate of labile carbon (C) and nitrogen (N) ...

Crops & Soils, 2014

Abbreviations: GHG, greenhouse gas; NTT, first-time tillage of plots in an 11-year no-till field;... more Abbreviations: GHG, greenhouse gas; NTT, first-time tillage of plots in an 11-year no-till field; SOM, soil organic matter.

Journal of Arid Environments, 2017

Recurring drought combined with intensive tillage may accelerate degradation of soils in a soil o... more Recurring drought combined with intensive tillage may accelerate degradation of soils in a soil organic matter (SOM)-loss feedback that undermines agricultural sustainability of semiarid farming systems. Winter wheat (Triticum aestivum, L.) in Wyoming is grown on marginally productive soils and annual precipitation of less than 400 mm. Greenhouse gas (GHG) fluxes, soil nitrogen (N), global warming potential (GWP) and greenhouse gas intensity (GHGI) were monitored in no-till (NT), conventional tillage (CT, four tillage operations), and chemical-free (CF, six tillage operations) for 27 months beginning in May 2011. Severe drought started in April 2012 and lasted 17 months. No-till best mitigated GHG emissions and accumulation of mineral N, emitting 25%e30% less nitrous oxide, 35% less carbon dioxide fluxes and retaining twice as much soil nitrate compared with CT and CF during drought in the summer of 2012. Net GWP and GHGI in NT were 32%e35% and 43% lower than in CT, respectively. NT was the only management system that maintained negative net GWP and GHGI values during the summer of 2013. As drought reduces the amount of residue inputs and SOM restorative processes, reducing tillage frequency and leaving more crop residue after harvest support more effective SOM protection during drought.

Nutrient Cycling in Agroecosystems, 2016

Reducing tillage intensity and diversifying crop rotations may improve the sustainability of irri... more Reducing tillage intensity and diversifying crop rotations may improve the sustainability of irrigated cropping systems in semi-arid regions. The objective of this study was to compare the greenhouse gas (GHG) emissions, soil organic matter, and net global warming potential (net GWP) of a sugar beet (Beta vulgaris L.)-corn (Zea mays L,) rotation under conventional (CT) and reduced-tillage (RT) and a corn-dry bean (Phaseolus vulgaris L.) rotation under organic (OR) management during the third and fourth years of 4-year crop rotations. The gas and soil samples were collected during April 2011-March 2013, and were analyzed for carbon dioxide (CO 2), methane (CH 4), and nitrous oxide (N 2 O) emissions, water-filled pore space (WFPS), soil nitrate (NO 3-N) and ammonium (NH 4 ?-N) concentrations, soil organic carbon (SOC) and total nitrogen (TN), and net global warming potential (net GWP). Soils under RT had 26% lower CO 2 emissions compared to 10.2 kg C ha-1 day-1 and 43% lower N 2 O emissions compared to 17.5 g N ha-1 day-1 in CT during cropping season 2011, and no difference in CO 2 and N 2 O emissions during cropping season 2012. The OR emitted 31% less N 2 O, but 74% more CO 2 than CT during crop season 2011. The RT had 34% higher SOC content than CT (17.9 Mg ha-1) while OR was comparable with CT. Net GWP was negative for RT and OR and positive for CT. The RT and OR can increase SOC sequestration, mitigate GWP and thereby support in the development of sustainable cropping systems in semiarid agroecosystems. Keywords Carbon dioxide (CO 2) Á Crop rotation Á Methane (CH 4) Á Net global warming potential (net GWP) Á Nitrous oxide (N 2 O) Á Soil organic carbon (SOC)

Soil Science Society of America Journal, 2016

Core Ideas Dryland organic and no‐till wheat‐fallow systems impact GHG and wheat yields. The orga... more Core Ideas Dryland organic and no‐till wheat‐fallow systems impact GHG and wheat yields. The organic system produced more wheat grain yield than the no‐till system in a dry year. The organic system had greater GHG emissions during the fallow period. Concerted effort toward reducing tillage is needed to reduce overall GHG emission in dryland organic wheat–fallow systems. In the semiarid central Great Plains of the United States, cropping intensification beyond the traditional winter wheat (Triticum aestivum L.)–fallow rotation along with reduced tillage can lead to soil organic matter (SOM) conservation and offset greenhouse gas emission. Here, we quantified (i) soil greenhouse gas (GHG) carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes, and (ii) yield‐scaled GHG emissions from dryland no‐till (NT) and organic production systems in western Nebraska over a 2‐yr period. The systems evaluated were no‐till winter wheat–proso millet (Panicum miliaceum L.)–fallow (NT 3 yr...

Journal of Crop Improvement, 2015

The conventionally tilled winter wheat (Triticum aestivum L.)-fallow system is often water-use in... more The conventionally tilled winter wheat (Triticum aestivum L.)-fallow system is often water-use inefficient as its fallow phase has frequently less storage efficiency than no-till and organic production practices. While such alternatives may increase yield while enhancing the health and the water holding capacity of soils, the major limiting factor for dryland production in the semi-arid regions is water. The objectives of this study were to a) determine the water-use and water productivity of dryland winter wheat under conventional, no-till, and organic production practices, and b) study the impact of improved soil-water storage on no-till winter wheat yield. A field experiment consisting of three tillage practices with three replicates was conducted at the University of Wyoming Sustainable Agricultural Research and Extension Center, near Lingle, Wyoming, USA. The wheat yield was higher in the conventional practice than in the other two production practices, and water-use in the former system was higher than the no-till. Water productivity of dryland winter wheat was not affected by the cropping practices. The CERES-Wheat model in the Decision Support System for Agrotechnology Transfer (DSSAT) was used to simulate long-term effects of no-till and conventional-till cropping practices for yield, water conservation, and water productivity. The simulations showed a good agreement between the observed and simulated crop yield and more efficient water conservation and yield production in the no-till than in the conventional practice.

Lodgepole pine (Pinus contorta var. latifolia) forests in North America have been undergoing a ma... more Lodgepole pine (Pinus contorta var. latifolia) forests in North America have been undergoing a major mortality event caused by mountain pine beetle (Dendroctonus ponderosae) infestation. We studied biotic and abiotic drivers of growing season soil respiration in four mature stands that experienced different levels of mortality between 2008 and 2012 in Wyoming, USA. For five years, beetle infestation significantly altered forest structure. Mortality ranged from near zero to more than 80% in stands with the lowest and highest mortality, respectively. Needle fall increased by more than 50% during the first two years of beetle infestation compared to the pre-disturbance period. Soil respiration rates in midsummer ranged from 1.4 ± 0.1 µmol m-2 s-1 in stands with highest mortality to 3.1 ± 0.2 µmol m-2s-1 in an uninfested stand. Live tree basal area was the dominant factor controlling soil respiration, explaining more than 60% of the interannual and spatial variations in response to the ...