Life Sciences Commons^™

Advances In Nutrient Management Of Grass Seed Crops, René Gislum, Birte Boelt

IGC Proceedings (1997-2023)

Nutrient management of herbage grass seed crops is just as complex as for other agricultural crops when the aim is to optimise economic net return and minimise environmental impact. The use of economic optimum nitrogen (N) application rate (ECO-N) defined as the N application rate that maximise net return for the seed grower is an easy and applicable method for seed growers. Besides the economic advantages of implementing ECO-N there is an additional positive environmental effect as ECO-N is lower than the N rate that maximises seed yield and a lower N application rate will concomitantly lower the potential risk …

Alternate Trait‐Based Leaf Respiration Schemes Evaluated At Ecosystem‐Scale Through Carbon Optimization Modeling And Canopy Property Data, R. Q. Thomas, M. Williams, M. A. Cavaleri, J.‐F. Exbrayat, T. L. Smallman, L. E. Street

Michigan Tech Publications

Leaf maintenance respiration (R_leaf,m) is a major but poorly understood component of the terrestrial carbon cycle (C). Earth systems models (ESMs) use simple sub‐models relating R_leaf,m to leaf traits, applied at canopy scale. R_leaf,m models vary depending on which leaf N traits they incorporate (e.g., mass or area based) and the form of relationship (linear or nonlinear). To simulate vegetation responses to global change, some ESMs include ecological optimization to identify canopy structures that maximize net C accumulation. However, the implications for optimization of using alternate leaf‐scale empirical R_leaf,m models are undetermined. Here we combine …

Response Of Cucumber, Yellow Squash, And Zucchini To Six Nitrogen Rates, Ron G. Goldy

Midwest Vegetable Trial Reports

There were few significant differences across the six nitrogen levels for the traits measured for all three crops. No clear trends were observed as nitrogen level was increased from 50 to 175#/acre. Better separation may have been obtained with more replication. Results indicate growers of slicing cucumber, yellow squash, and zucchini should be able to obtain adequate fruit yields using a season total of between 75 and 100#/acre nitrogen.

Impacts Of Eutrophication On Benthic Invertebrates & Fish Prey Of Birds In Farmington And Bear River Bays Of Great Salt Lake, Trip Armstrong, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

Farmington Bay’s watershed is primarily in the heavily populated metropolitan Salt Lake City, and consequently, it receives approximately 50% of its inflow from nutrient‐ rich wastewater releases. The high nutrient loads make it eutrophic and reducing the loading has been suggested to reduce blooms of toxic cyanobacteria. However, the bay also supports thousands of wading birds and waterfowl, and there is concern that reducing nutrient inflows might reduce the production of bottom‐dwelling insects and other invertebrates that the birds rely upon.

Viability Of Wetland Crops For Use In Treatment Wetlands: Nitrogen Removal From Water And Production Of Food, Andrew Denson Corder

Theses and Dissertations

Treatment wetlands are used to treat wastewater from a variety of sources, but their functionality depends on the macrophytes present therein. To better understand the viability of wetland macrophytes both as sources of food and as agents of nitrogen removal from wastewater, this study quantified plant growth, food production, and nitrogen removal capacity of three common wetland crops as well as three locally dominant graminoid species in a variety of relevant ecological contexts. All six plant species and a control were grown over a ten-week period in three related experiments: (1) under three moisture regimes, (2) with or without competition …

Strategies To Improve Forage Utilization By Sheep Offered Forage Mixtures, Valens Niyigena

Graduate Theses and Dissertations

In the first experiment, alfalfa and novel endophyte-infected tall fescue (NE+) forages were harvested after a killing frost, then mixed to formulate 4 different treatments; alfalfa alone, 67% alfalfa +33% fescue, 33% alfalfa + 67% fescue, or 100% fescue. After 3 months of storage as silage, Dorper ewe lambs (n = 20; mean BW = 34.7 ± 6.65 kg) were fed silage for ad libitum consumption, using 5 animals per treatment. Increasing the proportion of NE+ tall fescue improved (P < 0.05) silage total acids and lactic acid concentrations and decreased silage ammonia concentration. Digestible dry matter and organic matter intake and nitrogen utilization parameters decreased with increasing inclusion of NE+ in diet. In the second experiment, 16 Dorper ewe lambs (41.8 ± 4.61 kg BW) were assigned to 4 different treatments; alfalfa silage alone (0 g/kg; CONT) or alfalfa silage mixed with chopped sericea lespedeza (SL) hay to provide 90 (LOW), 180 (MED), or 270 g/kg SL (HIGH) on a dry matter basis in a randomized complete block design experiment with 2 period to provide 4 observations per treatment for each experimental period. Increasing the proportion of sericea lespedeza in the diet decreased dry matter and organic matter digestibility but did not affect feed intake. Fecal nitrogen (g/kg N intake) increased linearly (P < 0.01) while urinary N (g/ day and g/ kg of N intake) tended to decreased linearly and quadratically (P ≤ 0.1) with increasing the proportion of SL in diet. In the third experiments, 16 gestating Dorper ewe lambs (49.1 ± 4.61 kg BW) were allocated to 4 treatments; alfalfa silage alone (0% g/kg; CONT) or alfalfa silage mixed with lablab purpureus(LP) hay to provide 90 (LOW), 180 (MED), or 270 g/kg LP (HIGH) on a dry matter (DM) basis, in a randomized complete block design experiment with a total 8 replication per treatment. Supplementation of LP in diet increased quadratically (P ≤ 0.04) forage dry matter, organic matter intake, digestible dry matter and digestible organic matter intake (P < 0.05). Nitrogen apparently absorbed and urinary N both decreased linearly (P < 0.01) with adding more LP hay in diet. Harvesting and mixing alfalfa and fescue after a killing frost improved silage fermentation characteristics and supplementation of tannins from SL and polyphenol from LP altered N excretion.

Key words: lablab, sericea lespedeza, alfalfa silage, nitrogen, sheep.

Understanding Nitrogen Limitation In Soybean, Nicolas Cafaro La Menza

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

Meeting soybean demand on existing cropland area for a global population of 9.7 billion people by the year 2050 requires narrowing the existing gap between average producer yield and yield potential. Soybean relies on two sources on nitrogen (N): biological N2 fixation and indigenous soil N supply. As soybean yield continues to increase, it seems critical to know if there is a yield level at which potential contribution of indigenous nitrogen sources and fixation becomes insufficient to meet crop N requirements for high yields, while still maintaining or increasing protein and oil concentration. This study evaluated N limitation across 29 …

Effects Of Different Water And Nitrogen Regimens On Yield Of Winter Wheat Produced In Nebraska, Joseph Emory Davis

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

Wheat is the 3rd most prominent crop in the USA and approximately 50% is exported annually. Nebraska wheat production is 11^th in the country, and it plays a major role in the state's agricultural economy, especially in western NE. Generally, wheat is grown under dryland conditions and the region grows much more wheat on unirrigated land than it does on irrigated. However, deficit irrigation has shown great value in producing high yielding wheat with much less water than needed for other crops. Finding new ways to leverage irrigation in wheat production may help address the need to produce food …

Benchmarking On-Farm Maize Nitrogen Balance In The Western U.S. Corn Belt, Fatima Amor Tenorio

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

A nitrogen (N) balance, calculated as the difference between N inputs and grain-N removal, provides an estimate of the potential N losses. We used N balance with other N-related metrics (partial factor productivity for N inputs, and yield-scaled N balance), to benchmark maize yields in relation with N input use in the US Corn Belt. We first used experimental data on grain-N concentration (GNC) to assess variation in this parameter due to biophysical and management factors. Subsequently, we used N balance and N-related metrics to benchmark yields in relation with N inputs in irrigated and rainfed fields in Nebraska using …

Does Intensification Of Grassland And Forage Use Lead To Efficient, Profitable And Sustainable Ecosystems?, Oene Oenema, Cecile De Klein, Marta Alfaro

IGC Proceedings (1997-2023)

The increasing demand for safe and nutritional dairy and beef products in our globalizing world, together with the needs to increase resource use efficiency and to protect biodiversity, provide strong incentives for intensification of grassland and forage use. This paper addresses the question in the title. Firstly, we present some notions about ‘intensification of agricultural production’. Secondly, we discuss the intensification of grassland-based dairy production in The Netherlands (NL), Chile and New Zealand (NZ). Finally, we arrive at some conclusions. External driving forces and ‘the law of the optimum’ provide strong incentives for intensification, i.e., for increasing the output per …

Differential Responses And Controls Of Soil Co2 And N2o Fluxes To Experimental Warming And Nitrogen Fertilization In A Subalpine Coniferous Spruce (Picea Asperata Mast.) Plantation Forest, Dandan Li, Qing Liu, Huajun Yin, Yiqi Luo, Dafeng Hui

Biology Faculty Research

Emissions of greenhouse gases (GHG) such as CO2 and N2O from soils are affected by many factors such as climate change, soil carbon content, and soil nutrient conditions. However, the response patterns and controls of soil CO2 and N2O fluxes to global warming and nitrogen (N) fertilization are still not clear in subalpine forests. To address this issue, we conducted an eight-year field experiment with warming and N fertilization treatments in a subalpine coniferous spruce (Picea asperata Mast.) plantation forest in China. Soil CO2 and N2O fluxes were measured using a static chamber method, and soils were sampled to analyze …

Spatial And Temporal Variation In The Diet Composition Of Zooplankton In Mission Bay, Bryanna Paulson

Theses

Analyses of quantitative data on zooplankton diets are vital for understanding the drivers of zooplankton abundance within an ecosystem. Such analyses also provide insight into trophic pathways within the lower planktonic food web, which support populations of higher trophic level species. This study used carbon and nitrogen stable isotope ratios of size-fractionated plankton in Mission Bay, San Diego, CA to examine the spatial and temporal variation in zooplankton trophic ecology and determine potential environmental drivers of zooplankton community structure. Carbon stable isotopes reflect primary production sources in an organism’s diet, and nitrogen stable isotope ratios can be used to estimate …

Influence Of Varying Inorganic Nutrients Supply On Ergosterol And Glucosamine Concentrations And Biomass Nutrient Stoichiometry In Ectomycorrhizal Fungi, Stephanie S. Koury

Master's Theses

Ectomycorrhizal (ECM) fungi are critical for the health of forest ecosystems where they can sequester large amounts of carbon in the form of soil organic matter, a matter of growing interest due to anthropogenic climate change. A clear understanding of their growth dynamics and responses to environmental changes is imperative for future work in forest management and the possible mitigation of increased atmospheric CO₂. Six ECM fungal species were grown in liquid culture under varying nitrogen and phosphorus concentrations and ratios to assess how exogenous nutrient supplies affect fungal biomass stoichiometry and the degree of elemental homeostasis. Additional …

Experimental Nitrogen Addition Alters Structure And Function Of A Boreal Bog: Critical Load And Thresholds Revealed, R. Kelman Wieder, Dale H. Vitt, Melanie A. Vile, Jeremy A. Graham, Jeremy A. Hartsock, Hope Fillingim, Et Al.

Michigan Tech Publications

Bogs and fens cover 6% and 21%, respectively, of the 140,329 km² Oil Sands Administrative Area in northern Alberta. Development of the oil sands has led to increasing atmospheric N deposition, with values as high as 17 kg N^.ha^-1yr^-1; regional background deposition is N^.ha^-1yr^-1. Bogs, being ombrotrophic, may be especially susceptible to increasing N deposition. To examine responses to N deposition, over five years, we experimentally applied N (as NH₄NO₃) to a bog near Mariana Lake, Alberta, unaffected by oil sands activities, at …

Linking Water Quality To Aedes Aegypti And Zika In Flood-Prone Neighborhoods, Susan Harrell Yee, Donald A. Yee, Rebeca De Jesus Crespo, Autumn Oczkowski, Fengwei Bai, Stephanie Friedman

Faculty Publications

The ability of ecosystems to regulate water quality and flood events has been linked to health outcomes, including mosquito-borne illnesses. In the San Juan Bay Estuary watershed of Puerto Rico, habitat alterations and land-use development have disrupted watershed hydrology, exacerbating wastewater discharges and subjecting some neighborhoods to frequent flooding events. In 2016, the mosquito-borne illness Zika became a new cause for concern. We hypothesized that nutrient-enriched flood water could provide pulses of supplemental nutrients to local mosquito populations. We conducted a field study in six neighborhoods adjacent to the estuary to assess whether environmental variability of nutrient inputs could be …

Plant Community Responses To Stand‐Level Nutrient Fertilization In A Secondary Tropical Dry Forest, Bonnie G. Waring, Daniel Pérez-Aviles, Jessica G. Murray, Jennifer S. Powers

Ecology Center Publications

The size of the terrestrial carbon (C) sink is mediated by the availability of nutrients that limit plant growth. However, nutrient controls on primary productivity are poorly understood in the geographically extensive yet understudied tropical dry forest biome. To examine how nutrients influence above‐ and belowground biomass production in a secondary, seasonally dry tropical forest, we conducted a replicated, fully factorial nitrogen (N) and phosphorus (P) fertilization experiment at the stand scale in Guanacaste, Costa Rica. The production of leaves, wood, and fine roots was monitored through time; root colonization by mycorrhizal fungi and the abundance of N‐fixing root nodules …

Ecophysiology Of Ponderosa Pine Seedlings After Severe Fire: The Effect Of Tree Canopy, Lauren M. Bansbach

Biology ETDs

Ponderosa pine forests evolved with low-severity surface fires to maintain forest structure and process. However, increasingly common high-severity fires often result in complete overstory canopy loss and a shift from forest to shrub- and grass-dominated vegetation that may persist as an alternate stable state due to limited rates of ponderosa seedling regeneration in severely burned areas. Though overstory tree canopy is an important driver of understory plant response, little is known about how the absence of tree canopy following severe fires interacts with changes in year-to-year climate to affect the physiological function of ponderosa pine seedlings. This field study tested …

Algal-Mediated Priming Effects On The Ecological Stoichiometry Of Leaf Litter Decomposition: A Meta-Analysis, Halvor M. Halvorson, Steven N. Francoeur, Robert H. Findlay, Kevin A. Kuehn

Faculty Publications

In aquatic settings, periphytic algae exude labile carbon (C) that can significantly suppress or stimulate heterotrophic decomposition of recalcitrant C via priming effects. The magnitude and direction of priming effects may depend on the availability and stoichiometry of nutrients like nitrogen (N) and phosphorus (P), which can constrain algal and heterotrophic activity; in turn, priming may affect heterotrophic acquisition not only of recalcitrant C, but also N and P. In this study, we conducted a meta-analysis of algal-mediated priming across leaf litter decomposition experiments to investigate (1) bottom-up controls on priming intensity by dissolved N and P concentrations, and (2) …

Nutrient Limitation Of Phytoplankton In Lake Wateree, South Carolina: Implications For Future Water Quality Management, Kara M. Clyburn

Theses and Dissertations

Cultural eutrophication is a primary contributor to phytoplankton production in freshwater lakes from excess anthropogenic nutrient inputs, and resulting impacts on water quality, aquatic ecosystems, human and animal health are increasing worldwide. Understanding the factors that limit phytoplankton growth is an important strategy for identifying and managing nutrient sources and successfully controlling the over- enrichment of nitrogen (N) and/or phosphorus (P) in freshwater lakes. The Redfield molecular ratio of carbon (C), N and P maintains that the C:N:P molar ratio is 106:16:1 when nutrients are not limiting, and the ecosystem is balanced. A N:P molar ratio > 20:1 tends to be …

Metabolomics Of Sorghum Roots During Nitrogen Stress Reveals Compromised Metabolic Capacity For Salicylic Acid Biosynthesis, Amy M. Sheflin, Dawn Chiniquy, Chaohui Yuan, Emily Goren, Indrajit Kumar, Max Braud, Thomas Brutnell, Andrea L. Eveland, Susannah Tringe, Peng Liu, Stephen Kresovich, Ellen Marsh, Daniel P. Schachtman, Jessica E. Prenni

Nebraska Center for Biotechnology: Faculty and Staff Publications

Sorghum (Sorghum bicolor [L.] Moench) is the fifth most productive cereal crop worldwide with some hybrids having high biomass yield traits making it promising for sustainable, economical biofuel production. To maximize biofuel feedstock yields, a more complete understanding of metabolic responses to low nitrogen (N) will be useful for incorporation in crop improvement efforts. In this study, 10 diverse sorghum entries (including inbreds and hybrids) were field-grown under low and full N conditions and roots were sampled at two time points for metabolomics and 16S amplicon sequencing. Roots of plants grown under low N showed altered metabolic profiles at …

Biogeochemical Recuperation Of Lowland Tropical Forest During Succession, Benjamin W. Sullivan, Rachel L. Nifong, Megan K. Nasto, Silvia Alvarez-Clare, Camie M. Dencker, Fiona M. Soper, Kevin T. Shoemaker, F. Yoko Ishida, Joana Zaragoza-Castells, Eric A. Davidson, Cory C. Cleveland

Biology Faculty Publications

High rates of land conversion and land use change have vastly increased the proportion of secondary forest in the lowland tropics relative to mature forest. As secondary forests recover following abandonment, nitrogen (N) and phosphorus (P) must be present in sufficient quantities to sustain high rates of net primary production and to replenish the nutrients lost during land use prior to secondary forest establishment. Biogeochemical theory and results from individual studies suggest that N can recuperate during secondary forest recovery, especially relative to P. Here, we synthesized 23 metrics of N and P in soil and plants from 45 secondary …

Ammonium Recycling Supports Toxic Planktothrix Blooms In Sandusky Bay, Lake Erie: Evidence From Stable Isotope And Metatranscriptome Data, Justyna J. Hampel, Mark J. Mccarthy, Michelle Neudeck, George S. Bullerjahn, Robert Michael L. Mckay, Silvia E. Newell

Great Lakes Institute for Environmental Research Publications

Sandusky Bay, Lake Erie, receives high nutrient loadings (nitrogen and phosphorus) from the Sandusky River, which drains an agricultural watershed. Eutrophication and cyanobacterial harmful algal blooms (cyanoHABs) persist throughout summer. Planktothrix agardhii is the dominant bloom-forming species and the main producer of microcystins in Sandusky Bay. Non-N2 fixing cyanobacteria, such as Planktothrix and Microcystis, thrive on chemically reduced forms of nitrogen, such as ammonium (NH4+) and urea. Ammonium regeneration and potential uptake rates and total microbial community demand for NH4+ were quantified in Sandusky Bay. Potential NH4+ uptake rates in the light increased from June to August at all stations. …

Individual Tree And Stand-Level Carbon And Nutrient Contents Across One Rotation Of Loblolly Pine Plantations On A Reclaimed Surface Mine, Hannah Z. Angel, Jeremy S. Priest, Jeremy P. Stovall, Brian P. Oswald, Hans M. Williams

Faculty Publications

While reclaimed loblolly pine (Pinus taeda L.) plantations in east Texas, USA have demonstrated similar aboveground productivity levels relative to unmined forests, there is interest in assessing carbon (C) and nutrients in aboveground components of reclaimed trees. Numerous studies have previously documented aboveground biomass, C, and nutrient contents in loblolly pine plantations; however, similar data have not been collected on mined lands. We investigated C, N, P, K, Ca, and Mg aboveground contents for first-rotation loblolly pine growing on reclaimed mined lands in the Gulf Coastal Plain over a 32-year chronosequence and correlated elemental rates to stand age, stem …

Approaches To Evaluating Grower Irrigation And Fertilizer Nitrogen Amount And Timing, Tsz Him Lo, Daran Rudnick, Charles Burr, Matt Stockton, Rodrigo Werle

West Central Research and Extension Center, North Platte

Diversity in the knowledge, mindset, strategies, and tools that growers use to manage irrigation and fertilizer nitrogen culminates in diversity in profitability and environmental impact among farms. As growers, academia, and industry strive together to tackle the technological and non-technological challenges impeding better irrigation and fertilizer nitrogen management, a science-based evaluation of grower input amount and timing becomes an important initial step in the process. Providing such valuable feedback to growers is a high-priority objective for the University of Nebraska-Lincoln Testing Ag Performance Solutions (UNL-TAPS) farm management competition. In this competition, each team of mostly growers made management decisions for …

Agronomic And Quality Response Of Hard Red Spring Wheat Genotypes To Management Systems In South Dakota, Jonathan Kleinjan

Electronic Theses and Dissertations

Intensive cereals management techniques such as multiple fungicide applications and in-season split N applications have been used to successfully improve wheat yields in Europe and in some winter wheat production areas of the USA. However, research on the effects of these management practices and their interaction with genotypes is limited in the hard red spring wheat (HRSW) production areas of the USA. The objectives of this study were to: (i) compare management treatments and (ii) quantify any interaction effects between management and genotype on the agronomic characteristics and relevant flour and dough properties of locally-adapted HRSW genotypes. A randomized complete …

Global Temporal Patterns In Plant Nutrient Resorption Plasticity, Rebecca E. Drenovsky, Nicole Pietrasiak, Thomas Short

2019 Faculty Bibliography

Aim Leaf nutrient resorption is a key nutrient conservation trait, which also influences nutrient cycling rates and pools. Most global biogeochemical models assume that resorption is non‐varying at a temporal scale. However, this trait can differ substantially within populations among years. We assessed the commonality of attaining proficient resorption, the factors associated with proficient resorption, as well as the variability of this trait and the factors controlling trait variability.

Effect Of Bedding Type And Soil Incorporation On Nitrogen Mineralization Rate Of Broiler Litter Amended Soils, Lydia A. Fitzgerald

Theses and Dissertations--Plant and Soil Sciences

Broiler litter (BL) is a high value manure available to Kentucky crop producers to utilize as a fertilizer. The rate of BL application, timing of application, and method of application are all important factors to take into account when utilizing BL. A laboratory incubation was conducted to observe nitrogen (N) mineralization rates of BL amended soils over time under different conditions. Different application methods, application rates, watering frequencies, and bedding materials were used to determine their influence on N mineralization. Broiler litter applied on the soil surface, at lower rates, at lower watering frequency resulted in lower mineralization rates than …

Nitrogen Fertilizer Timing And Phosphorus And Potassium Fertilization Rates For Established Endophyte-Free Tall Fescue, D. W. Sweeney, J. K. Farney, J. L. Moyer

Kansas Agricultural Experiment Station Research Reports

A tall fescue production study was conducted at two locations, beginning in the fall of 2016 and the fall of 2017. At both sites, phosphorus (P) fertilization rate only affected the spring harvest, with few differences in yield. Applying nitrogen (N) in late fall or late winter resulted in greater spring yields than applying N in spring or not applying N. However, at Site 1 in 2017 fall harvest yields were greater from the spring N applica­tion, but this response was less at Site 2 in 2018. In both years, applying N increased tall fescue yield, but at Site 2 …

Intensive Wheat Management For Yield And Quality: The Role Of Variety, Environment, And Management Practices, R. P. Lollato, B. R. Jaenisch, D. Marburger

Kansas Agricultural Experiment Station Research Reports

Management (M), variety (V), and environment (E) greatly influence wheat yield and quality. With the objective of determining the partial influence of V, E, and M, we conducted a field experiment where we imposed four management intensities to five wheat varieties during six site-years in Kansas and Oklahoma. Management intensities were 1) low-input (N fertility for a yield goal of 60 bu/a); 2) high-input (foliar fungi­cide, sulfur and chloride fertilizers, growth regulator, and nitrogen (N) fertility for a yield goal of 100 bu/a); 3) high-input minus fungicide; and 4) high-input minus addi­tional N. We selected commonly grown wheat varieties with …

Occasional Tillage And Nitrogen Application Effects On Winter Wheat And Grain Sorghum Yield, A. K. Obour, J. D. Holman, A. J. Schlegel

Kansas Agricultural Experiment Station Research Reports

Occasional tillage ahead of winter wheat planting could alleviate herbicide-resistant weeds, redistribute soil acidification, and improve seedbed at wheat planting. The objective of this study is to determine occasional tillage and nitrogen (N) fertilizer application effects on winter wheat, and grain sorghum yields and soil quality in a wheat-sorghum-fallow cropping system. Treatments were three tillage practices: 1) continuous no-tillage (NT); 2) continuous reduced-tillage (RT); and 3) single tillage operation every 3 years (June-July) ahead of winter wheat planting [occasional tillage (OT)]. The sub-plot treatments were assigned to four N fertilizer rates (0, 40, 80 and 120 lb/a of N). Preliminary …