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An Integrated Crop- And Soil-Based Strategy For Variable-Rate Nitrogen Management In Corn, Darrin F. Roberts

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Nitrogen (N) management in cereal crops has been the subject of considerable research and debate for several decades. Historic N management practices have contributed to low nitrogen use efficiency (NUE). Low NUE can be caused by such things as poor synchronization between soil N supply and crop demand, uniform application rates of fertilizer N to spatially variable landscapes, and failure to account for temporally variable influences on soil N supply and crop N need. Active canopy reflectance sensors and management zones (MZ) have been studied separately as possible plant- and soil-based N management tools to increase NUE. Recently, some have …

Nutrient Allocations And Metabolism In Two Collembolans With Contrasting Reproduction And Growth Strategies, Thomas Larsen, Marc Ventura, Christian Damgaard, Erik A. Hobbie, Paul Henning Krogh

Faculty Publications

Physiological mechanisms such as allocation and release of nutrients are keys to understanding an animal's adaptation to a particular habitat. This study investigated how two detrivores with contrasting life‐history traits allocated carbon (C) and nitrogen (N) to growth, reproduction and metabolism. As model organisms we used the collembolans, Proisotoma minuta (Tullberg 1871) and Protaphorura fimata (Gisin 1952).

To estimate allocations of C and N in tissue, we changed the isotopic composition of the animal's yeast diets when they became sexually mature and followed isotope turnover in tissue, growth and reproduction for 28 days. In addition, we measured the composition of …

Effect Of Nitrogen Application Timing On Corn Production Using Subsurface Drip Irrigation, David D. Tarkalson, Simon J. Van Donk, James L. Petersen

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The use of subsurface drip irrigation (SDI) in row-crop agriculture is increasing because of potential increases in water and nutrient use efficiency. Research-based information is needed to manage N applications through SDI systems in field corn (Zea-mays L.) production. This study was conducted to assess the effect of different in-season SDI system N application timings on corn production and residual soil N0₃-N at the University of Nebraska-Lincoln West Central Research and Extension Center in North Platte, Neb, on a Cozad silt loam (fine-silty, mixed, mesic Fluventic Haplustoll). We evaluated the effect of three N application timing methods …

Crop Updates 2009 - Cereals, Jeff Baldock, Doug Edmeades, Mark Seymour, Paul Carmody, Ian Pritchard, Alan Meldrum, Michael Robertson, Roger Lawes, Rob Sands, Peter White, Felicity Byrne, Andrew Bathgate, Kedar Adhikari, Tanveer Khan, Stuart Morgan, Alan Harris, P. Gaur, K. M. H. Siddique, H. Clarke, N. C. Turner, W. Macleod, S. Morgan, Chris Veitch, Tony Leonforte, Kith Jayasena, Geoff Thomas, Rob Loughman, Kazue Tanaka, Ravjit Khangura, M. Amjad, Richard Oliver, Dusty Severtson, Peter Mangano, John Botha, Brenda Coutts, Manisha Shankar, Kasia Rybak, Michael Baker, Andrea Hills, Shahajahan Miyan, Peter Portmann, Nicole Rice, Robert Henry, Jeff J. Russell, B. H. Paynter, Linda Price, Brenda Shackley, Vicki Scanlan, Darshan Sharma, Christine Zaicou-Kunesch

Crop Updates

This session covers twenty seven papers from different authors:

PLENARY

1. Building soil carbon for productivity and implications for carbon accounting, Jeff Baldock, CSIRO Land and Water, Adelaide, SA

2. Fact or Fiction: Who is telling the truth and how to tell the difference, Doug Edmeades, agKnowledge Ltd, Hamilton

3. Four decades of crop sequence trials in Western Australia, Mark Seymour,Department of Agriculture and Food

BREAK CROPS

4. 2008 Break Crops survey Report, Paul Carmody,Development Officer, Department of Agriculture and Food

5. Attitudes of Western Australian wheatbelt growers to ‘Break Crops’, Paul Carmody and Ian …

Quantifying Turfgrass-Available N From Returned Clippings Using Anion-Exchange Membranes, Kelly L. K.Opp, Karl Guillard

Plant Science Articles

Returning clippings can provide N to turf, but the amount of plant-available N derived from clippings is not easy to quantify. An accurate estimate of N released by clippings would be useful in guiding turf N fertilizer recommendations. The objective of this study was to determine if anion-exchange membranes (AEMs) could be used to quantify plant-available soil N when clippings are returned. A greenhouse and two field experiments were set out in randomized block designs using a factorial arrangement of 2 clipping practices [removed (CRM) and returned (CRT)] and 4 rates of N fertilization (0 to 392 kg N ha-1 …

Nutrient Uptake And Mineralization During Leaf Decay In Streams – A Model Simulation, J. R. Webster, J. D. Newbold, Steven A. Thomas, P. J. Mulholland

School of Natural Resources: Faculty Publications

We developed a stoichiometrically explicit computer model to examine how heterotrophic uptake of nutrients and microbial mineralization occurring during the decay of leaves in streams may be important in modifying nutrient concentrations. The simulations showed that microbial uptake can substantially decrease stream nutrient concentrations during the initial phases of decomposition, while mineralization may produce increases in concentrations during later stages of decomposition. The simulations also showed that initial nutrient content of the leaves can affect the stream nutrient concentration dynamics and determine whether nitrogen or phosphorus is the limiting nutrient. Finally, the simulations suggest a net retention (uptake > mineralization) of …

Development And Application Of A System For The Analysis Of Atmospheric, Water And Sediment Nitrogen And Carbon, Ann Stavert, Stephen R. Wilson, Dianne F. Jolley

Faculty of Science - Papers (Archive)

Eutrophication and climate change, key environmental concerns, are both linked to the carbon and nitrogen cycles hence the improved understanding of these cycles is essential. Currently, there is no system that simultaneously measures the fluxes of the three key gas phase products of nitrogen and carbon cycling (CO2, CH4 and N2O) in submerged ecosystems with hourly time resolution. A “Lake-in-a-box” (mesocosm) was developed in the laboratory which allowed the monitoring of key components of the carbon and nitrogen cycles within the air, water and sediments. The approach is automated, simple and time efficient and novel in its ability to examine …

Nutrient Limitation Of Phytoplankton By Nitrogen And Phosphorus: Erosion Of The Phosphorus Paradigm, Wayne A. Wurtsbaugh, William M. Lewis Iii

Watershed Sciences Faculty Publications

No abstract provided.

Freshwater Responses To Nitrogen And Phosphorus Pollution And A Case Study Of Cutler And Dingle Marsh Wetlands, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

No abstract provided.

Is The Growth Of Temperate Forest Trees Enhanced Along An Ambient Nitrogen Deposition Gradient?, James E. Bedison, Brenden E. Mcneil

Faculty & Staff Scholarship

The extent to which atmospheric N deposition is enhancing primary production and CO2sequestration along the ambient N deposition gradients found within many regional temperate forest ecosystems remains unknown. We used tree diameter measurements from 1984 and 2004, allometric equations, and estimates of wet N deposition from 32 permanent plots located along an ambient N deposition gradient in the Adirondack Park, New York, USA, to determine the effects of N deposition on the basal area and woody biomass increments (BAI and WBI, respectively) of individual stems from all the major tree species. Nitrogen deposition had either a neutral or positive effect …

Container And Installation Time Effects On Soil Moisture, Temperature, And Inorganic Nitrogen Retention For An In Situ Nitrogen Mineralization Method, Brian J. Wienhold, Gary E. Varvel, Wallace W. Wilhelm

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Mineralization contributes significantly to agronomic nitrogen (N) budgets and is difficult to accurately predict. Models for predicting Nmineralization contributions are needed, and development of these models will require field-based data. In situ mineralization methods are intended to quantify N mineralization under ambient environmental conditions. This study was conducted to compare soil moisture and temperature in intact soil cores contained in cylinders to those in adjacent bulk soil, compare the effect of two resin-bag techniques on water content of soil within cylinders, and assess the effect of installation duration on inorganic N retention by resins. The study was conducted at a …

Successional Change In Phosphorus Stoichiometry Explains The Inverse Relationship Between Herbivory And Lupin Density On Mount St. Helens, Jennifer L. Apple, Michael Wink, Shannon E. Wills, John G. Bishop

Biology

Background: The average nitrogen-to-phosphorus ratio (N:P) of insect herbivores is less than that of leaves, suggesting that P may mediate plant-insect interactions more often than appreciated. We investigated whether succession-related heterogeneity in N and P stoichiometry influences herbivore performance on N-fixing lupin (Lupinus lepidus) colonizing primary successional volcanic surfaces, where the abundances of several specialist lepidopteran herbivores are inversely related to lupin density and are known to alter lupin colonization dynamics. We examined larval performance in response to leaf nutritional characteristics using gelechiid and pyralid leaf-tiers, and a noctuid leaf-cutter. Methodology/Principal Findings: We conducted four studies. First, growth of larvae …

Reactive Oxygen And Nitrogen Species Induce Protein And Dna Modifications Driving Arthrofibrosis Following Total Knee Arthroplasty., Theresa A Freeman, Javad Parvizi, Craig J Della Valle, Marla J Steinbeck

Department of Orthopaedic Surgery Faculty Papers

BACKGROUND: Arthrofibrosis, occurring in 3%-4% of patients following total knee arthroplasty (TKA), is a challenging condition for which there is no defined cause. The hypothesis for this study was that disregulated production of reactive oxygen species (ROS) and nitrogen species (RNS) mediates matrix protein and DNA modifications, which result in excessive fibroblastic proliferation. RESULTS: We found increased numbers of macrophages and lymphocytes, along with elevated amounts of myeloperoxidase (MPO) in arthrofibrotic tissues when compared to control tissues. MPO expression, an enzyme that generates ROS/RNS, is usually limited to neutrophils and some macrophages, but was found by immunohistochemistry to be expressed …

Hydrologic Control Of Nitrogenremoval, Storage And Export In A Mountain Stream, R. O. Hall Jr., Michelle A. Baker, C. D. Arp, B. J. Koch

Biology Faculty Publications

Nutrient cycling and export in streams and rivers should vary with flow regime, yet most studies of stream nutrient transformation do not include hydrologic variability. We used a stable isotope tracer of nitrogen (¹⁵N) to measure nitrate (NO₃^-) uptake, storage, and export in a mountain stream, Spring Creek, Idaho, U.S.A. We conducted two tracer tests of 2-week duration during snowmelt and baseflow. Dissolved and particulate forms of ¹⁵N were monitored over three seasons to test the hypothesis that stream N cycling would be dominated by export during floods, and storage during low flow. Floods …

Aspen Succession And Nitrogen Loading: A Case For Epiphytic Lichens As Bioindicators In The Rocky Mountains, Usa, Paul C. Rogers, Kori D. Moore, Ronald J. Ryel

Wildland Resources Faculty Publications

Question: Can lichen communities be used to assess shortand long-term factors affecting seral quaking aspen (Populus tremuloides) communities at the landscape scale? Location: Bear River Range, within the Rocky Mountains, in northern Utah and southern Idaho, USA. Method: Forty-seven randomly selected mid-elevation aspen stands were sampled for lichens and stand conditions. Plots were characterized according to tree species cover, basal area, stand age, bole scarring, tree damage, and presence of lichen species. We also recorded ammonia emissions with passive sensors at 25 urban and agricultural sites throughout an adjacent populated valley upwind of the forest stands. Nonmetric multidimensional scaling (NMS) …

Friends Of Casco Bay (Focb) Water Quality (2010 State Of The Bay Report), Friends Of Casco Bay

Publications

No abstract provided.

Soil Carbon And Nitrogen Accumulation In A Forested Debris Flow Chronosequence, California, Judith K. Turk, Robert C. Graham

Conservation and Survey Division

The role of forest soils in the biogeochemical cycling of C and N is most dynamic during the early stages of soil development. To define C and N trends that occur with soil development in a mixed coniferous forest, a chronosequence formed by debris flows was studied. The accumulation rates of total organic C (TOC) and total N (TN) were evaluated in soils on 10 debris flow deposits, ranging from depth, since this was the depth of the shallowest debris flows. Carbon was found to accumulate in the organic horizons at a rate of 26.5 g m⁻² yr^{−1 …}