Digital Commons Network^™

Soil Surface Fluxes Of Greenhouse Gases In An Irrigated Maize-Based Agroecosystem, Brigid Amos, Timothy J. Arkebauer, John W. Doran

Department of Agronomy and Horticulture: Faculty Publications

An understanding of the effect of fertility management on soil surface fluxes of CO₂, N₂O, and CH₄ is essential in evaluating C sequestration measures that attempt to increase the amount of crop residue returned to the soil through increased fertilizer inputs. In this, soil surface CO₂ flux was measured over a 27-mo sampling period in continuous maize (Zea mays L.) plots managed under either an intensive fertility regime (M2) or recommended best management (M1). Flux was significantly higher in the M2 treatment on only 2 d during the first growing season. Annual estimates …

Processing Of Yield Map Data, J. L. Ping, Achim R. Dobermann

Department of Agronomy and Horticulture: Faculty Publications

Yield maps reflect systematic and random sources of yield variation as well as numerous errors caused by the harvest and mapping procedures used. A general framework for processing of multi-year yield map data was developed. Steps included (1) raw data screening, (2) standardization, (3) interpolation, (4) classification of multi-year yield maps, (5) post-classification spatial filtering to create spatially contiguous yield classes, and (6) statistical evaluation of classification results. The techniques developed allow more objective mapping of yield zones, which are an important data layer in algorithms for prescribing variable rates of production inputs.

Environmental Factors Affecting Seed Persistence Of Annual Weeds Across The U.S. Corn Belt, Adam S. Davis, John Cardina, Frank Forcella, Gregg A. Johnson, George Kegode, John L. Lindquist, Edward C. Luschei, Karen A. Renner, Christy L. Sprague, Martin M. Williams Ii

Department of Agronomy and Horticulture: Faculty Publications

Weed seedbanks have been studied intensively at local scales, but to date, there have been no regional-scale studies of weed seedbank persistence. Empirical and modeling studies indicate that reducing weed seedbank persistence can play an important role in integrated weed management. Annual seedbank persistence of 13 summer annual weed species was studied from 2001 through 2003 at eight locations in the north central United States and one location in the northwestern United States. Effects of seed depth placement, tillage, and abiotic environmental factors on seedbank persistence were examined through regression and multivariate ordinations. All species examined showed a negative relationship …

Influence Of Soybean Row Width And Velvetleaf Emergence Time On Velvetleaf (Abutilon Theophrasti), Shawn M. Hock, Stevan Z. Knezevic, Alex R. Martin, John L. Lindquist

Department of Agronomy and Horticulture: Faculty Publications

Row spacing and the relative time of velvetleaf emergence affects the time of soybean canopy closure relative to velvetleaf, influencing the growth and development of velvetleaf. Field studies were conducted in northeastern Nebraska in 2002 and 2003 to describe velvetleaf growth as influenced by soybean presence or absence (velvetleaf grown with soybean or in monoculture), soybean row spacing (19 and 76 cm), and relative time of velvetleaf emergence. Velvetleaf seed production, leaf area (LA), and total dry matter (TDM) were greater in 76-cm- than in 19-cm-wide soybean rows. LA, TDM, and seed production of velvetleaf were reduced with later emergence …

Nitrogen Supply Affects Root:Shoot Ratio In Corn And Velvetleaf (Abutilon Theophrasti), Kimberly D. Bonifas, Daniel T. Walters, Kenneth G. Cassman, John L. Lindquist

Department of Agronomy and Horticulture: Faculty Publications

Competitive outcome between crops and weeds is affected by partitioning of new biomass to above- and below-ground plant organs in response to nutrient supply. This study determined the fraction of biomass partitioned to roots vs. shoots in corn and velvetleaf in response to nitrogen (N) supply. Pots measuring 28 cm in diam and 60 cm deep were embedded in the ground and each contained one plant of either corn or velvetleaf. Each plant received one of three N treatments: 0, 1, or 3 g N applied as ammonium nitrate in 2001, and 0, 2, or 6 g N in 2002. …

Marketing Locally Produced Foods: Consumer And Farmer Opinions In Washington County, Nebraska, Mindi L. Schneider, Charles A. Francis

Department of Agronomy and Horticulture: Faculty Publications

Local food system potentials were studied in Washington County, Nebraska, United States. As a departure from most studies of locally based systems, farmers were surveyed in addition to consumers for potential participation. Data about the current food system and opinions and preferences for local production, marketing, and purchasing of food were collected using self-administered mail questionnaires. The response rate was 35% for the farmer survey and 37% for the consumer survey. Results indicated that, on the farming side of the food system, conventional corn and soybean production and marketing predominated in Washington County, and farmer interest in producing for local …

Use Of The Hybrid-Maize Model To Improve Management Decisions, Achim R. Dobermann, Haishun Yang, Daniel T. Walters, Kenneth G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

Yield potential and yield gaps

Basic structure of Hybrid-Maize

Model inputs

Model applications

Validation, uncertainties & future improvements

Farmer Research: Conventional Experiences And Guidelines For Alternative Agriculture And Multi-Functional Agro-Ecosystems, Charles S. Wortmann, A. P. Christensen, Keith L. Glewen, Terence A. Hejny, J. Mulliken, J. M. Peterson, D. L. Varner, S. Wortmann, Gary L. Zoubek

Department of Agronomy and Horticulture: Faculty Publications

Crop producers are challenged to operate profitably, use resources efficiently, meet high standards of quality and protect the environment, while sustaining rural economies and societies. Cropping systems are generally fine-tuned and improved through changes that have small effects which can often be verified only through research. The processes and successes of two farmer research projects were studied. Results of these studies, information from other sources and the authors’ reflections on their own experiences were integrated to develop guidelines for the implementation of farmer research projects for alternative agriculture and multi-functional agro-ecosystems with diverse stakeholders. Surveys were mailed to 118 farmers …

Species Diversity And Functional Composition Of Pastures That Vary In Landscape Position And Grazing Management, John A. Guretzky, Kenneth J. Moore, E. Charles Brummer, C. Lee Burras

Department of Agronomy and Horticulture: Faculty Publications

The productivity of grasslands depends in part on their diversity of species and functional composition. Our objective was to examine the effects of three landscape positions (summit, backslope, and toe-slope) and three stocking systems (continuous, rotational, and non-grazed) on species diversity and percentage of cover of grass, legume, and weed species functional types in southeastern Iowa pastures.Data were collected in 0.2-m² plots randomly distributed throughout each of four replicate pastures in spring and summer 2000 and 2001. Backslope landscape positions within pastures managed with either continuous or rotational stocking contained the greatest overall diversity of species. Across years, overall …

Registration Of ‘Antelope’ Hard White Winter Wheat, Robert A. Graybosch, C.J. Peterson, P. Stephen Baenziger, Lenis Alton Nelson, B.B. Beecher, D. D. Baltensperger, J.M. Krall

Department of Agronomy and Horticulture: Faculty Publications

‘Antelope’ (Reg. no. CV-968, PI 633910) is a hard white winter wheat (Triticum aestivum L.) cultivar developed cooperatively by USDA-ARS, the Nebraska Agricultural Experiment Station, and the Wyoming Agricultural Experiment Station. Antelope has shown exceptional productivity under irrigated trials in western Nebraska, eastern Wyoming, and eastern Colorado. It combines high grain yield under irrigation with excellent lodging resistance.

Antelope was derived from the cross ‘Pronghorn’/‘Arlin’. Pronghorn (PI 593047, Baenziger et al., 1997) is a strong gluten hard red winter wheat developed by the University of Nebraska. Arlin (PI 564246, Sears et al., 1997) is a hard white winter wheat …

Leaf Radiative Properties And The Leaf Energy Budget, Timothy J. Arkebauer

Department of Agronomy and Horticulture: Faculty Publications

Leaf radiative properties are the physical properties of leaves that characterize radiant energy exchange with their surroundings. Radiant energy exchange is an important consideration in studies of plant function since, for example, absorption of photosynthetically active radiation (PAR) leads to the transformation of this energy into chemical energy via photosynthesis. Thus, plant productivity, and hence, agricultural production, ultimately depend on leaf radiative properties.

Leaf temperature is an additional, very important, parameter in intimate association with leaf radiant energy exchange. This association occurs since energy gained via radiation must be in balance with energy lost through various processes and energy loss …

Standard Meteorological Measurements, Kenneth Hubbard, Steven E. Hollinger

Department of Agronomy and Horticulture: Faculty Publications

Instruments that measure weather variables have been invented and tested since the time of Leonardo de Vinci. The earliest instruments were crude by today’s standards and required manual observation and notation of the weather variable of interest. In recent years, the miniaturization of circuits–sensors and the use of electronic processors have made it possible to collect ever-increasing numbers of observations on scales not previously considered.

In many agricultural applications, the primary portion of the atmosphere that is of interest is the lower planetary boundary layer, or that layer affected by the earth’s surface. Accurate measurement of weather variables in the …

Estimating Surface Wetness On Plants, R.D. Magarey, R.C. Seem, A. Weiss, T. Gillespie, L. Huber

Department of Agronomy and Horticulture: Faculty Publications

Plant surface (leaf, stem, petiole, etc) wetness or leaf wetness is an important agricultural weather variable for the prediction of plant diseases (Yarwood, 1978). The estimation of surface wetness has received considerable attention from a diverse group of scientists but unfortunately, no standard for measuring surface wetness has been widely accepted. Since surface wetness is not a true meteorological variable, as is temperature or precipitation, its measurement has not been routinely made as part of a general observation program by most national meteorological agencies. The main problem of not observing surface wetness on a routine basis has been the lack …

Nematode-Induced Changes Of Transporter Gene Expression In Arabidopsis Roots, Ulrich Z. Hammes, Daniel P. Schachtman, R. Howard Berg, Erik Nielsen, Wolfgang Koch, Lauren M. Mcintyre, Christopher G. Taylor

Department of Agronomy and Horticulture: Faculty Publications

Root-knot plant-parasitic nematodes (Meloidogyne spp.) account for much of the damage inflicted to plants by nematodes. The feeding sites of these nematodes consist of “giant” cells, which have characteristics of transfer cells found in other parts of plants. Increased transport activity across the plasma membrane is a hallmark of transfer cells, and giant cells provide nutrition for nematodes; therefore, we initiated a study to identify the transport processes that contribute to the development and function of nematode- induced feeding sites. The study was conducted over a 4-week period, during which time the large changes in the development of giant …

Self-Assembly Of Nanoparticles On Live Bacterium: An Avenue To Fabricate Electronic Devices, Ravi F. Saraf, Vikas Berry

Papers in Nanotechnology

Recently, hybrid structures of microorganisms with inorganic nanoscale moieties have received great interest owing to their potential in fabricating electronic systems. The electronic properties of metal nanoparticles, as a result of the singleelectron transport of current,[1] make them ideal materials for nanodevices. Concomitantly, the nanostructure of microorganisms such as bacteria,[2] viruses,[3, 4] and yeast[5] are attractive scaffolds for the templating of metal nanoparticles through the interactions of the former with surface charges and the affinity of certain metals for specific biological molecules.[2–7] However, the key challenges in building hybrid devices are 1) to pattern nanostructures without destroying the biological construct …

Crystallization And Preliminary X-Ray Analysis Of Na-Asp-1, A Multi-Domain Pathogenesis-Related-1 Protein From The Human Hookworm Parasite Necator Americanus, Oluwatoyin A. Asojo, Alex Loukas, Mehmet Inan, Rick Barent, Jicai Huang, Brad Plantz, Amber Swanson, Mark Gouthro, Michael M. Meagher, Peter J. Hotez

Department of Chemical and Biomolecular Engineering: Faculty Publications

Human hookworm infection is a major cause of anemia and malnutrition in the developing world. In an effort to control hookworm infection, the Human Hookworm Vaccine Initiative has identified candidate vaccine antigens from the infective larval stage (L3) of the parasite, including a family of pathogenesis-related-1 (PR-1) proteins known as the ancylostoma-secreted proteins (ASPs). The functions of the ASPs are unknown. In addition, it is unclear why some ASPs have one while others have multiple PR-1 domains. There are no known structures of a multi-domain ASP and in an effort to remedy this situation, recombinant Na-ASP-1 has been expressed, …

Polar Ordering Of Reactive Chromophores In Layer-By-Layer Nonlinear Optical Materials, Kevin Van Cott, James R. Heflin Jr., Harry Gibson, Richey M. Davis

Department of Chemical and Biomolecular Engineering: Faculty Publications

Thin films exhibiting second-order nonlinear optical (NLO) properties, as well as materials and methods for producing Such films, are provided. The films are formed by depositing, on a Substrate, alternate layers of a polyelectrolyte and a low molecular weight chromophore. The chromophore contains an electrophilic group that reacts with a previously deposited polyelectrolyte, and ionizable groups which present absorption sites for the next polyelectrolyte layer. The films find application in, for example, electro-optic modulators and frequency doubling devices.

Evaluating Livestock System Environmental Performance With Whole-Farm Nutrient Balance, Richard K. Koelsch

Department of Agricultural and Biological Systems Engineering: Faculty Publications

As a part of the USEPA’s concentrated animal feeding operation (CAFO) final rule, all CAFOs are required to develop and implement a nutrient management plan (NMP). The USEPA’s emphasis on better management of nutrients appropriately targets a critical environmental issue associated with animal production. The concentration of animals in livestock feeding operations, often separate from feed grain production, requires importing of substantial quantities of feed nutrients. Due to the inefficiencies of nutrient utilization in livestock production, quantities of nitrogen (N) and phosphorus (P) in manure greater than can be utilized in local crop production often result. With the focus of …

Improvement Of Tractor Performance, K. U. Kim, Leonard L. Bashford, Brent T. Sampson

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Improvement of agricultural tractor performance was analyzed using the data from 926 diesel tractors tested at the Nebraska Tractor Test Laboratory from 1959 through 2002. The performance analysis included the specific volumetric fuel consumption, power per unit weight, traction coefficient, maximum torque rise, and sound level. They were evaluated based on the PTO power level and chassis type of tractor. Some of the results are: (1) The average specific volumetric fuel consumptions for the maximum PTO and drawbar powers increased by 20.5% and 23.4% to 3.47 kW•h/L and 3.01 kW•h/L, respectively, from 1959 through 2002. (2) The average maximum PTO …

Takagi–Sugeno Fuzzy Modeling Of Skin Permeability, Deepak R. Keshwani, David D. Jones, Rhonda M. Brand

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The skin is a major exposure route for many potentially toxic chemicals. It is, therefore, important to be able to predict the permeability of compounds through skin under a variety of conditions. Available skin permeability databases are often limited in scope and not conducive to developing effective models. This sparseness and ambiguity of available data prompted the use of fuzzy set theory to model and predict skin permeability. Using a previously published database containing 140 compounds, a rule-based Takagi–Sugeno fuzzy model is shown to predict skin permeability of compounds using octanol-water partition coefficient, molecular weight, and temperature as inputs. Model …

Extraction Of Lipids From Grain Sorghum Ddg, L. Wang, Curtis L. Weller, K. T. Hwang

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Soxhlet and recirculated solvent extraction methods were used to extract lipid materials from grain sorghum DDG. The lipid content in DDG with a moisture content of 6.7% (dry basis) was as high as 9.32% of the dried DDG as determined by Soxhlet extraction with n-hexane. There was a slight increase in the lipid yield from 9.21% to 9.68% when the moisture contents increased from 2.1% to 17.4% (d.b.). Thin-layer chromatography (TLC) analysis showed that the sorghum lipids were composed of triacylglycerols, fatty acids, fatty alcohols, fatty aldehydes, free sterols, wax esters, and steryl esters. A bench-scale recirculated extraction system was …

Finite Element Modeling And Experimental Validation Of Cooling Rates Of Large Ready-To-Eat Meat Products In Small Meat-Processing Facilities, A. Amézquita, L. Wang, Curtis L. Weller

Department of Agricultural and Biological Systems Engineering: Faculty Publications

A two−dimensional axisymmetric transient heat conduction model was developed to simulate air chilling of large ready−to−eat meat products of ellipsoidal shape. A finite element scheme, using 1,600 linear triangular elements with 861 nodes, was implemented in Matlab 6.5 to solve the model. The model considered a variable initial temperature distribution and combined convective, radiative, and evaporative boundary conditions. Predicted values agreed well with experimental data collected in actual processing conditions. Validation of model performance resulted in maximum deviations of 2.54°C and 0.29% for temperature and weight loss histories, respectively. The maximum temperature deviation (2.54°C) occurred at the surface; however, for …

Policosanol Contents And Compositions In Wax-Like Materials Extracted From Selected Cereals Of Korean Origin, Keum Taek Hwang, Ji Eun Kim, Curtis L. Weller

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Policosanols. long-chained alcohols. have been reported to have beneficial physiological activities. Content and composition of policosanols in wax-like materials extracted from selected cereals of Korean origin were determined. Wax-like materials were extracted using hot hexane. Yields of wax-like materials from unpolished grain sorghum, polished grain sorghum. brown rice. purple rice, wheat, and maize were 223, 37, 33, 61, 10, and 10 mg/100 g of dry kernels, respectively. Policosanol contents, as determined using HPLC, in the wax-like materials from the cereals were 33, 29, 6.0, and 2% (w/w, db), respectively. Major alcohols in the policosanols from grain sorghum were octacosanol and …

Modeling Of Bubble Growth Dynamics And Nonisothermal Expansion In Starch-Based Foams During Extrusion, Lijun Wang, Girish M. Ganjyal, David D. Jones, Curtis L. Weller, Milford Hanna

Department of Agricultural and Biological Systems Engineering: Faculty Publications

A mathematical model was developed to describe expansion phenomena in starch-based foams during extrusion. The model was divided into three parts to describe the microbubble growth dynamics, to couple bubble growth with extrudate expansion, and to describe the macrotransport phenomena in the extrudate, respectively. The differential equations involved in the model were solved by finite element schemes. For validating the model, the predicted radius, density, and residual moisture of final extrudate were compared with experimental data. Standard deviations between the predicted and experimental radius, density, and residual moisture of final extrudates were 16.7%, 11.2%, and 39.3%, respectively. The model was …

Root Zone Temperatures Of Viburnum Odoratissimum Grown In The Multipot Box System And Conventional Systems: Measurement And Analyses Of Temperature Profiles And Predicting Root Zone Temperatures, Suat Irmak, D. Z. Haman, Ayse Kilic, J. W. Jones, B. Tonkinson, D. Burch, T. H. Yeager, C. Larsen

Department of Agricultural and Biological Systems Engineering: Faculty Publications

This research study evaluates the effectiveness of a recently introduced irrigation- plant production system, multipot box system (MPBS), for moderating root zone temperature (RZT) compared with the conventional nursery containers. The study also deals with the development, calibration, and validation of a series of models that can be used to predict maximum (max) and minimum (min) RZTs using commonly available input variables. The Viburnum odoratissimum (Ker.-gawl.) was used as the test plant. Models were calibrated in the fall growing season and validated during the summer. The RZT was used as the dependent variable while the max and min air temperatures …

Evaluation Of Toxic Agent Effects On Lung Cells By Fiber Evanescent Wave Spectroscopy, Pierre Lucas, David Lee Coq, Christophe Juncker, Jayne Collier, Dianne E. Boesewetter, Catherine Boussard-Pledel, Bruno Bureau, Mark R. Riley

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Biochemical changes in living cells are detected using a fiber probe system composed of a single chalcogenide fiber acting as both the sensor and transmission line for infrared optical signals. The signal is collected via evanescent wave absorption along the tapered sensing zone of the fiber. We spectroscopically monitored the effects of the surfactant Triton X-lOO, which serves as a toxic agent simulant on a transformed human lung carcinoma type II epithelial cell line (A549). We observe spectral changes between 2800-3000 cm-1 in four absorptions bands, which are assigned to hydrocarbon vibrations of methylene and methyl groups in membrane lipids. …

Evaluation Of Methods For Estimating Daily Reference Crop Evapotranspiration At A Site In The Humid Southeast United States, R. E. Yoder, Lameck O. Odhiambo, Wesley C. Wright

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Estimated daily reference crop evapotranspiration (ET_o) is normally used to determine the water requirement of crops using the crop factor method. Many ET_o estimation methods have been developed for different types of climatic data, and the accuracy of these methods varies with climatic conditions. In this study, pair−wise comparisons were made between daily ET_o estimated from eight different ET_o equations and ET_o measured by lysimeter to provide information helpful in selecting an appropriate ET_o equation for the Cumberland Plateau located in the humid Southeast United States. Based on the standard error of the …

Remote Estimation Of Canopy Chlorophyll Content In Crops, Anatoly A. Gitelson, Andrés Viña, Veronica Ciganda, Donald Rundquist, Timothy J. Arkebauer

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Accurate estimation of spatially distributed chlorophyll content (Chl) in crops is of great importance for regional and global studies of carbon balance and responses to fertilizer (e.g., nitrogen) application. In this paper a recently developed conceptual model was applied for remotely estimating Chl in maize and soybean canopies. We tuned the spectral regions to be included in the model, according to the optical characteristics of the crops studied, and showed that the developed technique allowed accurate estimation of total Chl in both crops, explaining more than 92% of Chl variation. This new technique shows great potential for remotely tracking the …

Geographic And Ontogenetic Variation In The Contact Calls Of The Kea, Alan B. Bond, Judy Diamond

Papers in Behavior in Biological Sciences

Regional and ontogenetic variation in the contact calls of the kea (Nestor notabilis), an omnivorous and socially complex New Zealand parrot, were examined throughout the range of the species. We recorded samples of kee-ah contact calls from sixteen resident adults and eleven juveniles and demonstrated significant differences between age classes in the acoustic form of the vocalization. Canonical correlation analysis revealed a gradient in the form of the kee-ah call in both adults and juveniles along and across the escarpment of the Southern Alps, the primary longitudinal mountain range on the South Island of New Zealand. Although the …

An Algorithm For Identification Of Bacterial Selenocysteine Insertion Sequence Elements And Selenoprotein Genes, Yan Zhang, Vadim Gladyshev

Department of Biochemistry: Faculty Publications

Motivation: Incorporation of selenocysteine (Sec) into proteins in response to UGA codons requires a cis-acting RNA structure, Sec insertion sequence (SECIS) element. Whereas SECIS elements in Escherichia coli are well characterized, a bacterial SECIS consensus structure is lacking.

Results: We developed a bacterial SECIS consensus model, the key feature of which is a conserved guanosine in a small apical loop of the properly positioned structure. This consensus was used to build a computational tool, bSECISearch, for detection of bacterial SECIS elements and selenoprotein genes in sequence databases. The program identified 96.5% of known selenoprotein genes in completely sequenced bacterial genomes …