Digital Commons Network^™

Establishment Stand Thresholds For Switchgrass Grown As A Bioenergy Crop, Marty R. Schmer, Kenneth P. Vogel, Robert B. Mitchell, Lowell E. Moser, Kent M. Eskridge, Richard K. Perrin

Department of Agronomy and Horticulture: Faculty Publications

Switchgrass (Panicum virgatum L.) is a warm-season (C4) perennial grass and a potential bioenergy crop. On-farm switchgrass field scale trials, which were initiated to obtain economic production information for switchgrass grown as a bioenergy crop in the northern Plains, provided information on establishment year stands and post-establishment year yields and stands both within and across fields and were used to determine if a stand threshold exists for switchgrass grown as a biomass energy crop. Switchgrass was seeded in 10 cropland fields, ranging in size from 3 to 9.5 ha, in Nebraska, South Dakota, and North Dakota in 2000 and …

Life History Traits Of The Threatened Purple Amole (Chlorogalum Purpureum Var. Purpureum), John A. Guretzky, Elizabeth Clark, Darlene Woodbury

Department of Agronomy and Horticulture: Faculty Publications

Researchers monitored the threatened plant, purple amole (Chlorogalum purpureum var. purpureum) at Fort Hunter Liggett, California, from 1998 to 2004. The objectives of this research were to complete a statistical analysis of these data to evaluate: (1) demographics; (2) trends in population density; and (3) the relationship of purple amole to associated species, biological soil crusts, and disturbance. Overall, purple amole was most likely to flower and have greater seed production when it attained about 8 leaves or widths of 7 to 8 mm for its widest leaf, revealing a clear relationship between plant size and successful reproduction and seed …

Cattle Grazing And Tracked Vehicle Training On Central And Southwest U.S. Army Lands, John A. Guretzky, Jeffrey Fehmi, Alan Anderson

Department of Agronomy and Horticulture: Faculty Publications

Sustainability of training lands continues to be a primary concern for natural resource managers on Army installations. Tracked vehicle training, the main disturbance of grasslands, does not occur in isolation from other land uses including cattle grazing. Yet, no documented studies exist examining the interactive effects of these activities on soils and vegetation. The objective of this research was to begin filling this knowledge gap. This report reviews the lit-erature documenting the impacts of tracked vehicle training and cattle grazing on soils and grassland plant communities and discusses potential interactive effects. Responses to tracked vehicle training generally included increased soil …

Effects Of Summer Grazing Strategies On Organic Reserves And Root Characteristics Of Big Bluestem, E. M. Mousel, Walter H. Schacht, C. W. Zanner, Lowell E. Moser

Department of Agronomy and Horticulture: Faculty Publications

Quantifying root structure response to multiple defoliation events in a grazing situation is critical in developing management plans for warm-season tall grasses. A pasture experiment was conducted in 1999, 2000, and 2001 near Mead, NE. The objective of the experiment was to determine the effect of timing and frequency of grazing on big blue- stem (Andropogon gerardii Vitman) etiolated tiller growth and root and rhizome structure. Paddocks were grazed at a stocking rate of 9.9 Animal Unit Month (AUM) ha^-1 in two to four cycles from mid-May to early-September. In April 2002, five 6.6- 132-cm soil cores were …

Quality Effect Of Wheat-Rye (1r) Translocation In ‘Pavon 76’, W. Kim, J. W. Johnson, P. Stephen Baenziger, A. J. Lukaszewski, C. S. Gaines

Department of Agronomy and Horticulture: Faculty Publications

A growing interest exists in using wheat for producing both hard and soft wheat products. It would be desirable if 1RS translocations in hard wheat could produce flour suitable for soft wheat products. The objective of this study was to test the effects of centric translocations of chromosome 1 from different rye sources for end-use quality. The quality influences of the 1RS and 1RL translocations and 1R substitutions from different rye sources were studied in a set of hard spring wheat ‘Pavon 76’ (CIMMYT) lines in three environments in Georgia. The protein concentration of the 1RL translocations was the highest …

Annual Carbon Dioxide Exchange In Irrigated And Rainfed Maize-Based Agroecosystems, Shashi Verma, Achim Dobermann, Kenneth G. Cassman, Daniel T. Walters, Johannes M. H. Knops, Timothy J. Arkebauer, Andrew E. Suyker, George Burba, Brigid Amos, Haishun Yang, Daniel Ginting, Kenneth Hubbard, Anatoly A. Gitelson, Elizabeth A. Walter-Shea

Department of Agronomy and Horticulture: Faculty Publications

Carbon dioxide exchange was quantified in maize–soybean agroecosystems employing year-round tower eddy covariance flux systems and measurements of soil C stocks, CO₂ fluxes from the soil surface, plant biomass, and litter decomposition. Measurements were made in three cropping systems: (a) irrigated continuous maize, (b) irrigated maize–soybean rotation, and (c) rainfed maize–soybean rotation during 2001–2004. Because of a variable cropping history, all three sites were uniformly tilled by disking prior to initiation of the study. Since then, all sites are under no-till, and crop and soil management follow best management practices prescribed for production-scale systems. Cumulative daily gain of C …

Registration Of N30-N56, N741, N743, N745, N747, U362, U363, U367, U369-U374, U389-U394, U396-U398, And U500 Sweetclover Genetic Stocks, Kenneth P. Vogel, H. J. Gorz, F. A. Haskins

Department of Agronomy and Horticulture: Faculty Publications

Forty-nine white-flowered sweetclover (Melilotus alba Medik.) genetic stocks [N30-N45 (Reg. GS-1–16, PI 549120–549135); N46-N53 (Reg. GS-17–24, PI 557503–PI 557510); N54-N55 (Reg. GS-25–Reg. GS-26, PI 629289–PI 629290); N741, N743, N745, N747 (Reg. GS-27–GS-30, PI 557511–PI 557514); U362, U363, U367 (Reg. GS-31, Reg. GS-32, Reg. GS-33, PI 557515–PI 557517); U369-U374 (Reg. GS-34–GS 39, PI 557518–PI 557523); U389-U394 (Reg. GS-40–GS 45, PI 557524–PI 557529); U396- U398 (Reg. GS-46–GS 48, PI 557530–PI 557532); U500 (Reg. GS-49, PI 557533)] (Table 1); and N56 (Reg. no. GS-50, PI 634019), a yellow-flowered sweetclover [Melilotus officinalis (L.) Lam.] genetic stock, were developed jointly by USDA- ARS …

Nitrogen Use Efficiency – State Of The Art, Achim R. Dobermann

Department of Agronomy and Horticulture: Faculty Publications

Nitrogenous fertilizers have contributed much to the remarkable increase in food production that has occurred during the past 50 years (Smil, 2001). Globally, however, N fertilizers also account for 33% of the total annual creation of Nr or 63% of all anthropogenic sources of reactive nitrogen (Nr) (Table 1). Reactive nitrogen is defined as all biologically, photochemically, and/or radiatively active forms of N -- a diverse pool of nitrogenous compounds that includes organic compounds (e.g. urea, amines, proteins, amides), mineral N forms, such as NO₃^- and NH₄⁺ as well as gases that are chemically active in …

Backcross Breeding For Improved Resistance To Common Bacterial Blight In Pinto Bean (Phaseolus Vulgaris L. ), Nedim Mutlu, P. Miklas, J. Reiser, D. Coyne

Department of Agronomy and Horticulture: Faculty Publications

Common bacterial blight (CBB) caused by Xanthomonas campestris pv. phaseoli reduces common bean (Phaseolus vulgaris L. ) yield and quality worldwide. Genetic resistance provides effective disease control; however, a high level of resistance is difficult to attain and does not exist in pinto bean, the most important dry bean market class in North America. Our objective was to determine if a backcross breeding approach with the aid of molecular markers linked to quantitative trait loci (QTL) for resistance to CBB in a donor parent could be used to attain higher levels of resistance to CBB in pinto bean. QTL …

Temporal Origin Of Nitrogen In The Grain Of Tropical Wet-Season Rice, J. E. Sheehy, M. Mnzava, Kenneth G. Cassman, P. L. Mitchell, A. B. Ferrer, R. P. Robles, P. Pablico

Department of Agronomy and Horticulture: Faculty Publications

The total N in the grain is the integral of the product of the total N absorbed at any instant and the fraction of that N eventually allocated to the grain. We investigated the temporal origin of N in the grain of a wet season rice crop and tested the suitability of ¹⁵N nitrate (NH₄ ¹⁵NO₃) as a label for that purpose. The total N content of rice (Oryza sativa L.) plants was measured by growth analysis throughout the duration of the crop and the measurements were used to calculate the rate of total …

Remotely Measuring Chlorophyll Content In Corn Leaves With Differing Nitrogen Levels And Relative Water Content, Michael R. Schlemmer, Dennis D. Francis, J.F. Shanahan, James S. Schepers

Department of Agronomy and Horticulture: Faculty Publications

Measuring a crop’s physiological parameters provides information for interpreting its response to the environment. Remote sensing is quickly becoming recognized as a valuable tool that has the potential to assess a wide variety of physiological properties over a large area in a short amount of time. This study examined the relationship of corn (Zea mays L.) leaf spectral response to its chlorophyll contentand relative water content. The effects of N stress and water stress were examined on each of these physiological parameters. Over the years, several spectral indices have been introduced for a wide variety of applications. A number …

Overseeding Buffalograss Turf With Fine-Leaved Fescues, Songul Severmutlu, Terrance P. Riordan, Robert C. Shearman, Roch E. Gaussoin, Lowell E. Moser

Department of Agronomy and Horticulture: Faculty Publications

Buffalo grass [Buchloe dactyloides (Nutt.) Engelm.] use as a turf in the northern USA is limited to a certain extent by its extended winter dormancy. A mixture of buffalo grass with cool-season turf- grasses might extend the turf’s green appearance and enhance quality. Research was conducted to determine the effects of over-seeding fine-leaved fescue (Festuca spp.) in buffalo grass turf on turf grass color and quality and the effects of species, seeding rate and date, and core cultivation on fine-leaved fescue establishment in buffalo grass turf. Hard fescue (F. longifolia Thuill.), blue fescue (F. ovina L. …

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 …

Plant Resins---Chemistry, Evolution Ecology And Ethnobotany, Ellen T. Paparozzi

Department of Agronomy and Horticulture: Faculty Publications

Plant resins are often something ornamental horticulturists either ignore or endure-particularly when they clog up pruners. This book gives a different view-a rhyme and reason as to why plants produce resins and how generations of people have used resins for economic or personal benefit. When reading this book, I was struck with the pervasiveness of resins in terms of representation across plant communities and civilizations.

The book is divided into three parts. Part I, chapters 1 through 3, cover resin production by plants. This section starts out by defining and identifying the different types of resins based on chemical similarities …

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 …

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. …

Genetic Improvement Trends In Agronomic Performances And End-Use Quality Characteristics Among Hard Red Winter Wheat Cultivars In Nebraska, H. Fufa, P. Stephen Baenziger, B. S. Beecher, Robert A. Graybosch, Kent M. Eskridge, Lenis Alton Nelson

Department of Agronomy and Horticulture: Faculty Publications

Evaluation of wheat cultivars from different eras allows breeders to determine changes in agronomic and end-use quality characteristics associated with grain yield and end-use quality improvement over time. The objective of this research was to examine the trends in agronomic and end-use quality characteristics of hard red winter wheat cultivars grown in Nebraska. Thirty historically important and popular hard red winter wheat cultivars introduced or released between 1874 and 2000 were evaluated at Lincoln, Mead, and North Platte, Nebraska in 2002 and 2003. An alpha lattice design with 15 incomplete blocks of two plots and three replications was used at …

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 …

Maize Radiation Use Efficiency Under Optimal Growth Conditions, John L. Lindquist, Timothy J. Arkebauer, Daniel T. Walters, Kenneth G. Cassman, Achim Dobermann

Department of Agronomy and Horticulture: Faculty Publications

Accurate measurement of crop growth and radiation use efficiency (RUE) under optimal growth conditions is required to predict plant dry matter accumulation and grain yield near the genetic growth potential. Research was conducted to quantify the biomass and leaf area index (LAI) accumulation, extinction coefficient, and RUE of maize (Zea mays L.) under conditions of optimal growth. Maize was grown in two environments over five growing seasons (1998–2002). Total aboveground biomass at maturity ranged from 2257 g m^-2 in 1998 to 2916 g m^-2 in 2001; values that are considerably greater than the biomass achieved in most …

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 …

Curiosities, Nonsense, Non-Science And Sri, J. E. Sheehy, T. R. Sinclair, Kenneth G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

The advocates of the system of rice intensification (SRI) have claimed both the world record for rice yield and the highest yields (by a substantial margin!) for any grain crop (Rafaralahy, 2002). This is curious because none of the usual information expected in support of these ‘fantastic yields’ was presented to support the claim. Absent were data concerning cultivar, experimental design, statistical errors, dates of planting and harvesting, soil types, fertilizer inputs, weed control, disease control, insect control, water management and the weather. Was the information withheld because they wanted to repeat the experiments and publish their incredible results in …

Effect Of Control Plot Density, Control Plot Arrangement, And Assumption Of Random Or Fixed Effects On Nonreplicated Experiments For Germplasm Screening Using Spatial Models, Boi Sebolai, Jeffrey F. Pedersen, D. B. Marx, D. L. Boykin

Department of Agronomy and Horticulture: Faculty Publications

Early generation selection experiments typically involve several hundred to thousands of lines. Various systematic and statistical techniques have been developed to increase effectiveness and efficiencies in such experiments, including the development and application of spatial statistical models. In this study, mixed model equations were used to provide least squares means (LSMEANs) and best linear unbiased predictors (BLUPs) and compare selection effectiveness and efficiencies to observed (Y) and true values in simulated experiments varying in size (10 X 10, 20 X 20 and 30 X 30 grids), control plots densities (0, 5, 10, 20, and 50%), control plot arrangements (high, medium, …

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 …

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 …

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.