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- Critical time for weed removal (2)
- Functional equilibrium (2)
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- Anaerobic; Lignin; Nitrogen; NMR; Soil organic matter; Phenols; Rice (1)
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Articles 1 - 28 of 28
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Nitrate Accumulation And Movement Under Deficit Irrigation In Soil Receiving Cattle Manure And Commercial Fertilizer, D. D. Tarkalson, J. O. Payero, S. M. Ensley, Charles A. Shapiro
Nitrate Accumulation And Movement Under Deficit Irrigation In Soil Receiving Cattle Manure And Commercial Fertilizer, D. D. Tarkalson, J. O. Payero, S. M. Ensley, Charles A. Shapiro
Department of Agronomy and Horticulture: Faculty Publications
Nitrate leaching from agricultural soils can increase groundwater nitrate concentrations. The objectives of the study were to assess the accumulation and movement of nitrate in the soil profile over a 2-year period under def¬icit irrigation conditions following a one time application of N in cattle feedlot manure and commercial fertilizer to corn at rates to achieve yield goals expected under conditions of full irrigation. Cattle manure and ammonium nitrate were applied in 2002 at the University of Nebraska recommended rate (1M and 1F, respectively) and cat¬tle manure was applied at twice the recommended rate (2M) for N for the 2002 …
Effect Of Cultivation And Within-Field Differences In Soil Conditions On Feral Helianthus Annuus Growth In Ridge-Tillage Maize, Michael G. Burton, David A. Mortensen, John L. Lindquist
Effect Of Cultivation And Within-Field Differences In Soil Conditions On Feral Helianthus Annuus Growth In Ridge-Tillage Maize, Michael G. Burton, David A. Mortensen, John L. Lindquist
Department of Agronomy and Horticulture: Faculty Publications
Differences in weed population dynamics with respect to within-field heterogeneity are not well documented despite increasing interest in site-specific management of agro-ecosystems. The focus of this study was to determine if mechanical weed management (cultivation) and/or soil factors help to explain observed within-field distributions of feral common sunflower ( Helianthus annuus L.). The ridges and furrows created by the ridge–tillage system adds additional microsites to existing spatial heterogeneity for soil characteristics such as soil organic carbon (SOC) concentration. Experimental areas were selected on the basis of naturally high or low SOC concentration. Cultivation resulted in 100% mortality of H. annuus …
Seasonal Changes In Dry Matter Partitioning, Yield, And Crude Protein Of Intermediate Wheatgrass And Smooth Bromegrass, Alexander J. Smart, Walter H. Schacht, Jerry D. Volesky, Lowell E. Moser
Seasonal Changes In Dry Matter Partitioning, Yield, And Crude Protein Of Intermediate Wheatgrass And Smooth Bromegrass, Alexander J. Smart, Walter H. Schacht, Jerry D. Volesky, Lowell E. Moser
Department of Agronomy and Horticulture: Faculty Publications
Seasonal patterns of dry matter partitioning and nutritive value of leaf and stem components of grass species is important for selecting species for planting, planning grazing strategies, and making management decisions. Our objective was to compare dry matter yield and crude protein (CP) yield of blade, sheath, and stem fractions of intermediate wheatgrass [Elytrigia intermedia (Host) Nevski] and smooth bromegrass (Bromus inermis Leyss.) during the growing season. Intermediate wheatgrass and smooth bromegrass were sampled on a weekly basis from 14 May to 25 June in 1997 and from 5 May to 23 June in 1998 at Lincoln, NE. …
Features, Applications, And Limitations Of The Hybrid-Maize Simulation Model, Haishun Yang, Achim Dobermann, Kenneth G. Cassman, Daniel T. Walters
Features, Applications, And Limitations Of The Hybrid-Maize Simulation Model, Haishun Yang, Achim Dobermann, Kenneth G. Cassman, Daniel T. Walters
Department of Agronomy and Horticulture: Faculty Publications
The objective of this paper is to provide an overview of the Hybrid- Maize software (www.hybridmaize.unl.edu, verified 28 Feb. 2006), with emphasis on its practical applications based on our own experience and feedback from users. The Hybrid-Maize model is a computer program that simulates the growth and yield of a corn crop (Zea mays L.) under non-limiting or water-limited (rainfed or irrigated) conditions. The scientific formulations of the model and its test and validation was published elsewhere. The model can be used to (i) assess the overall site yield potential and its variability based on historical weather data, (ii) …
Chemical Stabilization Of Soil Organic Nitrogen By Phenolic Lignin Residues In Anaerobic Agroecosystems, D.C. Olk, Kenneth G. Cassman, K. Schmidt-Rohr, M.M. Anders, J.-D. Mao, J.L. Deenik
Chemical Stabilization Of Soil Organic Nitrogen By Phenolic Lignin Residues In Anaerobic Agroecosystems, D.C. Olk, Kenneth G. Cassman, K. Schmidt-Rohr, M.M. Anders, J.-D. Mao, J.L. Deenik
Department of Agronomy and Horticulture: Faculty Publications
This review summarizes independent reports of yield decreases in several agricultural systems that are associated with repeated cropping under wet or submerged soil conditions. Crop and soil data from most of these agroecosystems have led researchers to attribute yield decreases to a reduction in crop uptake of N mineralized from soil organic matter (SOM). These trends are most evident in several long-term field experiments on continuous lowland rice systems in the Philippines, but similar trends are evident in a continuous rice rotation in Arkansas, USA and with no-till cropping systems in North American regions with cool, wet climatic conditions in …
Comparison Of An Antitranspirant Spray, A Polyacrylamide Gel, And Wind Protection On Early Growth Of Muskmelon, Laurie Hodges, Entin Daningsih, James R. Brandle
Comparison Of An Antitranspirant Spray, A Polyacrylamide Gel, And Wind Protection On Early Growth Of Muskmelon, Laurie Hodges, Entin Daningsih, James R. Brandle
Department of Agronomy and Horticulture: Faculty Publications
Field experiments were conducted over 4 years to evaluate the effects of antitranspirant (Folicote, Aquatrol Inc., Paulsboro, N.J.) and polyacrylamide gel (SuperSorb, Aquatrol Inc., Paulsboro, N.J.) on early growth of transplanted muskmelon grown either protected by tree windbreaks or exposed to seasonal winds. A randomized complete block design (RCBD) with split plot arrangement was used with wind protection (sheltered and exposed) areas as the main treatment and use of an antitranspirant spray or gel dip as subtreatments. Based on destructive harvests in the field, treatments and subtreatments did not affect dry weight or leaf area index in the first 2 …
Comment On “Carbon Budget Of Mature No-Till Ecosystem In North Central Region Of The United States”, Achim R. Dobermann, Daniel T. Walters, John M. Baker
Comment On “Carbon Budget Of Mature No-Till Ecosystem In North Central Region Of The United States”, Achim R. Dobermann, Daniel T. Walters, John M. Baker
Department of Agronomy and Horticulture: Faculty Publications
Following a 6-year study of net ecosystem exchange of carbon (NEE) in a maize–soybean system, Hollinger et al. (2005) concluded that the system was a net sink of 90 g C m-2 year-1. This estimate was erroneous because a wrong equation for computing grain carbon removal (Eq. 1) was used and because the authors computed average annual values for each of the two crops (average C gain under maize: 184 g C m-2; average C loss under soybean: -94 g C m-2), then added them together, as if both crops were present each …
Acidification Of Soil In A Dry Land Winter Wheat-Sorghum/Corn-Fallow Rotation In The Semiarid U.S. Great Plains, David D. Tarkalson, Jose O. Payero, Gary W. Hergert, Kenneth G. Cassman
Acidification Of Soil In A Dry Land Winter Wheat-Sorghum/Corn-Fallow Rotation In The Semiarid U.S. Great Plains, David D. Tarkalson, Jose O. Payero, Gary W. Hergert, Kenneth G. Cassman
Department of Agronomy and Horticulture: Faculty Publications
Soil pH is decreasing in many soils in the semiarid Great Plains of the United States under dry land no-till (NT) cropping systems. This study was conducted to determine the rate of acidification and the causes of the acidification of a soil cropped to a winter wheat (Triticum aestivum L.)-grain sorghum [Sorghum bicolor (L.) Moench]/corn (Zea mays L.)-fallow rotation (W-S/C-F) under NT. The study was conducted from 1989 to 2003 on soil with a long-term history of either continuous NT management [NT(LT)] (1962–2003) or conventional tillage (CT) (1962–1988) then converted to NT [NT(C)] (1989–2003). Nitrogen was applied …
Long-Term Effects Of Tillage On Soil Chemical Properties And Grain Yields Of A Dryland Winter Wheat–Sorghum/Corn–Fallow Rotation In The Great Plains, David D. Tarkalson, Gary W. Hergert, Kenneth G. Cassman
Long-Term Effects Of Tillage On Soil Chemical Properties And Grain Yields Of A Dryland Winter Wheat–Sorghum/Corn–Fallow Rotation In The Great Plains, David D. Tarkalson, Gary W. Hergert, Kenneth G. Cassman
Department of Agronomy and Horticulture: Faculty Publications
Tillage systems and nutrient management influence soil chemical properties that can impact the long-term sustainability of dryland production systems. This study was conducted to compare the effects of no-till (NT) and conventional till (CT) on the soil chemical properties and grain yield of a dryland winter wheat (Triticum aestivum L.)– grain sorghum [Sorghum bicolor (L.) Moench]/corn (Zea mays L.)– fallow rotation. The effects of tillage practice over a 27-yr period (1962– 1989) and the effect of the conversion of CT to NT over a 14-yr period (1989–2003) on selected soil chemical properties [pH, cation exchange capacity (CEC), …
Anthropogenic Drivers Of Ecosystem Change: An Overview, Gerald C. Nelson, Elena Bennett, Asmeret A. Berhe, Kenneth G. Cassman, Ruth Defries, Thomas Dietz, Achim R. Dobermann, Andrew Dobson, Anthony Janetos, Marc Levy, Diana Marco, Nebojsa Nakicenovic, Brian O'Neill, Richard Norgaard, Gerhard Petschel-Held, Dennis Ojima, Prabhu Pingali, Robert Watson, Monika Zurek
Anthropogenic Drivers Of Ecosystem Change: An Overview, Gerald C. Nelson, Elena Bennett, Asmeret A. Berhe, Kenneth G. Cassman, Ruth Defries, Thomas Dietz, Achim R. Dobermann, Andrew Dobson, Anthony Janetos, Marc Levy, Diana Marco, Nebojsa Nakicenovic, Brian O'Neill, Richard Norgaard, Gerhard Petschel-Held, Dennis Ojima, Prabhu Pingali, Robert Watson, Monika Zurek
Department of Agronomy and Horticulture: Faculty Publications
This paper provides an overview of what the Millennium Ecosystem Assessment (MA) calls “indirect and direct drivers” of change in ecosystem services at a global level. The MA definition of a driver is any natural or human-induced factor that directly or indirectly causes a change in an ecosystem. A direct driver unequivocally influences ecosystem processes. An indirect driver operates more diffusely by altering one or more direct drivers. Global driving forces are categorized as demographic, economic, sociopolitical, cultural and religious, scientific and technological, and physical and biological. Drivers in all categories other than physical and biological are considered indirect. Important …
Evaluation Of The Single Kernel Characterization System (Skcs) For Measurement Of Sorghum Grain Attributes, S. R. Bean, O. K. Chung, M. R. Tuinstra, Jeffrey F. Pedersen, J. Erpelding
Evaluation Of The Single Kernel Characterization System (Skcs) For Measurement Of Sorghum Grain Attributes, S. R. Bean, O. K. Chung, M. R. Tuinstra, Jeffrey F. Pedersen, J. Erpelding
Department of Agronomy and Horticulture: Faculty Publications
The single kernel characterization system (SKCS) has been widely used in the wheat industry, and SKCS parameters have been linked to end-use quality in wheat. The SKCS has promise as a tool for evaluating sorghum grain quality. However, the SKCS was designed to analyze wheat, which has a different kernel structure from sorghum. To gain a better understanding of the meaning of SKCS predictions for grain sorghum, individual sorghum grains were measured for length, width, thickness (diameter), and weight by laboratory methods and by the SKCS. SKCS predictions for kernel weight and thickness were highly correlated to laboratory measurements. However, …
Plant Breeding Training In The U.S., P. Stephen Baenziger
Plant Breeding Training In The U.S., P. Stephen Baenziger
Department of Agronomy and Horticulture: Faculty Publications
The plant breeding enterprise is large and highly interdisciplinary. In considering how to approach this topic, it is necessary to define who is a plant breeder for that defines the scope of this paper. For the purpose of this paper, a plant breeder will be defined as a person who is actively involved in creating new plant germplasm that may lead to new cultivars or be used as parents to create new cultivars of food, feed, fiber, and ornamental plants. This definition is deliberately narrow. For example it does not include those who are developing molecular markers for marker assisted …
Guide For Weed Management In Nebraska, Mark L. Bernards, Stevan Z. Knezevic, Roch E. Gaussoin, Drew J. Lyon, Brady F. Kappler, Alex Martin, Robert N. Klein, Fred Roeth, Robert G. Wilson, Robert A. Masters, Patrick J. Shea, Larry D. Schulze
Guide For Weed Management In Nebraska, Mark L. Bernards, Stevan Z. Knezevic, Roch E. Gaussoin, Drew J. Lyon, Brady F. Kappler, Alex Martin, Robert N. Klein, Fred Roeth, Robert G. Wilson, Robert A. Masters, Patrick J. Shea, Larry D. Schulze
Department of Agronomy and Horticulture: Faculty Publications
Each year we strive to provide a publication that is updated, informative, and easy to use. Last year’s edition has been revised to include the latest research-based information and several new sections outlined below. We hope you find these revisions useful and that they make this guide an even better resource than the previous edition.
Chemical Composition And Response To Dilute-Acid Pretreatment And Enzymatic Saccharification Of Alfalfa, Reed Canarygrass, And Switchgrass, Bruce S. Dien, Hans-Joachim G. Jung, Kenneth P. Vogel, Michael D. Casler, Joann F. S. Lamb, Loren Iten, Robert C. Mitchell, Gautum Sarath
Chemical Composition And Response To Dilute-Acid Pretreatment And Enzymatic Saccharification Of Alfalfa, Reed Canarygrass, And Switchgrass, Bruce S. Dien, Hans-Joachim G. Jung, Kenneth P. Vogel, Michael D. Casler, Joann F. S. Lamb, Loren Iten, Robert C. Mitchell, Gautum Sarath
Department of Agronomy and Horticulture: Faculty Publications
Alfalfa stems, reed canarygrass, and switchgrass; perennial herbaceous species that have potential as biomass energy crops in temperate regions; were evaluated for their bioconversion potential as energy crops. Each forage species was harvested at two or three maturity stages and analyzed for carbohydrates, lignin, protein, lipid, organic acids, and mineral composition. The biomass samples were also evaluated for sugar yields following pretreatment with dilute sulfuric followed by enzymatic saccharification using a commercial cellulase preparation. Total carbohydrate content of the plants varied from 518 to 655 g kg-1 dry matter (DM) and cellulose concentration from 209 to 322 g kg …
Mutations In Arabidopsis Yellow Stripe-Like1 And Yellow Stripe-Like3 Reveal Their Roles In Metal Ion Homeostasis And Loading Of Metal Ions In Seeds, Brian M. Waters, Heng-Hsuan Chu, Raymond J. Didonato, Louis A. Roberts, Robynn B. Eisley, Brett Lahner, David E. Salt, Elsbeth L. Walker
Mutations In Arabidopsis Yellow Stripe-Like1 And Yellow Stripe-Like3 Reveal Their Roles In Metal Ion Homeostasis And Loading Of Metal Ions In Seeds, Brian M. Waters, Heng-Hsuan Chu, Raymond J. Didonato, Louis A. Roberts, Robynn B. Eisley, Brett Lahner, David E. Salt, Elsbeth L. Walker
Department of Agronomy and Horticulture: Faculty Publications
Here, we describe two members of the Arabidopsis (Arabidopsis thaliana) Yellow Stripe-Like (YSL) family, AtYSL1 and AtYSL3. The YSL1 and YSL3 proteins are members of the oligopeptide transporter family and are predicted to be integral membrane proteins. YSL1 and YSL3 are similar to the maize (Zea mays) YS1 phytosiderophore transporter (ZmYS1) and the AtYSL2 iron (Fe)-nicotianamine transporter, and are predicted to transport metal-nicotianamine complexes into cells. YSL1 and YSL3 mRNAs are expressed in both root and shoot tissues, and both are regulated in response to the Fe status of the plant. β-Glucuronidase reporter expression, driven by …
Application Of Machine Learning In Snp Discovery, Lakshmi K. Matukumalli, John J. Grefenstette, David L. Hyten, Ik-Young Choi, Perry B. Cregan, Curtis P. Van Tassell
Application Of Machine Learning In Snp Discovery, Lakshmi K. Matukumalli, John J. Grefenstette, David L. Hyten, Ik-Young Choi, Perry B. Cregan, Curtis P. Van Tassell
Department of Agronomy and Horticulture: Faculty Publications
Background: Single nucleotide polymorphisms (SNP) constitute more than 90% of the genetic variation, and hence can account for most trait differences among individuals in a given species. Polymorphism detection software PolyBayes and PolyPhred give high false positive SNP predictions even with stringent parameter values. We developed a machine learning (ML) method to augment PolyBayes to improve its prediction accuracy. ML methods have also been successfully applied to other bioinformatics problems in predicting genes, promoters, transcription factor binding sites and protein structures. Results: The ML program C4.5 was applied to a set of features in order to build a SNP classifier …
Snp-Phage – High Throughput Snp Discovery Pipeline, Lakshmi K. Matukumalli, John J. Grefenstette, David L. Hyten, Ik-Young Choi, Perry B. Cregan, Curt P. Van Tassell
Snp-Phage – High Throughput Snp Discovery Pipeline, Lakshmi K. Matukumalli, John J. Grefenstette, David L. Hyten, Ik-Young Choi, Perry B. Cregan, Curt P. Van Tassell
Department of Agronomy and Horticulture: Faculty Publications
Background: Single nucleotide polymorphisms (SNPs) as defined here are single base sequence changes or short insertion/deletions between or within individuals of a given species. As a result of their abundance and the availability of high throughput analysis technologies SNP markers have begun to replace other traditional markers such as restriction fragment length polymorphisms (RFLPs), amplified fragment length polymorphisms (AFLPs) and simple sequence repeats (SSRs or microsatellite) markers for fine mapping and association studies in several species. For SNP discovery from chromatogram data, several bioinformatics programs have to be combined to generate an analysis pipeline. Results have to be stored in …
Impacts Of Genetic Bottlenecks On Soybean Genome Diversity, D. L. Hyten, Qijian Song, Youlin Zhu, Ik-Young Choi, Randall L. Nelson, Jose M. Costa, James E. Specht, Randy C. Shoemaker, Perry B. Cregan
Impacts Of Genetic Bottlenecks On Soybean Genome Diversity, D. L. Hyten, Qijian Song, Youlin Zhu, Ik-Young Choi, Randall L. Nelson, Jose M. Costa, James E. Specht, Randy C. Shoemaker, Perry B. Cregan
Department of Agronomy and Horticulture: Faculty Publications
Soybean has undergone several genetic bottlenecks. These include domestication in Asia to produce numerous Asian landraces, introduction of relatively few landraces to North America, and then selective breeding over the past 75 years. It is presumed that these three human-mediated events have reduced genetic diversity. We sequenced 111 fragments from 102 genes in four soybean populations representing the populations before and after genetic bottlenecks. We show that soybean has lost many rare sequence variants and has undergone numerous allele frequency changes throughout its history. Although soybean genetic diversity has been eroded by human selection after domestication, it is notable that …
Soybean Cultivars Resulted From More Recombination Events Than Unselected Lines In The Same Population, T. R. Stefaniak, D. L. Hyten Jr., V. R. Pantalone, A. Klarer, T. W. Pfeiffer
Soybean Cultivars Resulted From More Recombination Events Than Unselected Lines In The Same Population, T. R. Stefaniak, D. L. Hyten Jr., V. R. Pantalone, A. Klarer, T. W. Pfeiffer
Department of Agronomy and Horticulture: Faculty Publications
The selection of superior adapted cultivars has contributed to the doubling of soybean [Glycine max (L.) Merr.] yields in the USA since 1930. Genetic variation was required for this selection to be effective. The objective of this study was to evaluate the importance of homologous chromosome meiotic recombination in the creation of soybean cultivars. A set of 10 adapted high-yielding cultivars selected from the cross ‘Williams’ × ‘Essex’ was com-pared with a set of 156 random recombinant inbred lines (RILs) from the same population. Crossover events were identified using 143 simple sequence repeat (SSR) markers span-ning all 20 soybean …
Ethylene Could Influence Ferric Reductase, Iron Transporter, And H+-Atpase Gene Expression By Affecting Fer (Or Fer-Like) Gene Activity, Carlos Lucera, Brian M. Waters, Francisco Javier Romera, María José García, María Morales, Esteban Alcántara, Rafael Pérez-Vicente
Ethylene Could Influence Ferric Reductase, Iron Transporter, And H+-Atpase Gene Expression By Affecting Fer (Or Fer-Like) Gene Activity, Carlos Lucera, Brian M. Waters, Francisco Javier Romera, María José García, María Morales, Esteban Alcántara, Rafael Pérez-Vicente
Department of Agronomy and Horticulture: Faculty Publications
In previous works, it has been shown, by using ethylene inhibitors and precursors, that ethylene could participate in the regulation of the enhanced ferric reductase activity of Fe-deficient Strategy I plants. However, it was not known whether ethylene regulates the ferric reductase gene expression or other aspects related to this activity. This paper is a study of the effects of ethylene inhibitors and precursors on the expression of the genes encoding the ferric reductases and iron transporters of Arabidopsis thaliana (FRO2 and IRT1) and Lycopersicon esculentum (= Solanum lycopersicum) (FRO1 and IRT1) plants. The effects …
Early-Season Insect Defoliation Influences The Critical Time For Weed Removal In Soybean, Travis C. Gustafson, Stevan Z. Knezevic, Thomas E. Hunt, John L. Lindquist
Early-Season Insect Defoliation Influences The Critical Time For Weed Removal In Soybean, Travis C. Gustafson, Stevan Z. Knezevic, Thomas E. Hunt, John L. Lindquist
Department of Agronomy and Horticulture: Faculty Publications
To develop more effective pest-management strategies, it is essential to understand how different pests interact with each other and the crop. Field studies were conducted in 2003 and 2004 at two Nebraska locations to determine the effects of early-season crop defoliation on the critical time for weed removal (CTWR) in narrow-row soybean. Three soybean defoliation levels were selected to simulate 0, 30, and 60% leaf tissue removal by the bean leaf beetle. Weeds were allowed to compete with the crop until V2, V4, V6, R3, and R5 growth stages. There were also season-long weedy and weed-free treatments. Results indicated that …
Resistance Gene Analog Polymorphism (Rgap) Markers Co-Localize With Disease Resistance Genes And Qtl In Common Bean, Nedim Mutlu, Phillip Miklas, Dermot Coyne
Resistance Gene Analog Polymorphism (Rgap) Markers Co-Localize With Disease Resistance Genes And Qtl In Common Bean, Nedim Mutlu, Phillip Miklas, Dermot Coyne
Department of Agronomy and Horticulture: Faculty Publications
Resistance (R) genes containing nucleotide-binding site (NBS)-leucine rich repeats (LRR) are the most prevalent types of R gene in plants. The objective of this study was to develop PCR-based R-gene analog polymorphism (RGAP) markers for common bean (Phaseolus vulgaris L). Twenty degenerate primers were designed from the conserved kinase-1a (GVGKTT) and hydrophobic domains (GLPLAL) of known NBSLRR type R-genes and from EST databases. Sixty-six of the 100 primer combinations tested yielded polymorphism. Thirty-two RGAP markers were mapped in the BAT 93/Jalo EEP558 core mapping population for common bean. The markers mapped to 10 of 11 linkage groups with a …
Soil Organic Carbon Changes In Diversified Rotations Of The Western Corn Belt, Gary E. Varvel
Soil Organic Carbon Changes In Diversified Rotations Of The Western Corn Belt, Gary E. Varvel
Department of Agronomy and Horticulture: Faculty Publications
Sequestration and storage of carbon (C) by agricultural soils has been cited as one potential part of the solution to soil degradation and global climate change. However, C sequestration in soils is a slow and dynamic process. The objective of this study was to evaluate the effects of crop rotation and N fertilizer management on soil organic C (SOC) levels at several points in time during 18 yr of a long-term study in the Western Corn Belt. Seven cropping systems (three monoculture, two 2-yr, and two 4-yr rotations) with three levels of N fertilizer were compared. Soil samples were taken …
Performance Of Weedsoft For Predicting Soybean Yield Loss, Shawn M. Hock, Stevan Z. Knezevic, Alex Martin, John L. Lindquist
Performance Of Weedsoft For Predicting Soybean Yield Loss, Shawn M. Hock, Stevan Z. Knezevic, Alex Martin, John L. Lindquist
Department of Agronomy and Horticulture: Faculty Publications
Decision support systems (DSSs) have been developed to assist producers and consultants with weed management decisions. WeedSOFT is a DSS currently used in several states in the northcentral region of the United States. Accurate estimates of crop yield loss due to weed interference are required for cost-effective weed management recommendations. WeedSOFT uses competitive indices (CIs) to predict crop yield loss under multiple weed species, weed densities, and relative times of weed emergence. Performance of several WeedSOFT versions to predict soybean yield loss from weed competition was evaluated using CI values in WeedSOFT version 9.0 compared to new CI values calculated …
Soybean Row Spacing And Weed Emergence Time Influence Weed Competitiveness And Competitive Indices, Shawn M. Hock, Stevan Z. Knezevic, Alex Martin, John L. Lindquist
Soybean Row Spacing And Weed Emergence Time Influence Weed Competitiveness And Competitive Indices, Shawn M. Hock, Stevan Z. Knezevic, Alex Martin, John L. Lindquist
Department of Agronomy and Horticulture: Faculty Publications
Weed competitiveness can be quantified with the concept of competitive index (CI), a relative scale of weed competitiveness. Field studies were conducted in 2002 and 2003 in northeastern and southeastern Nebraska to evaluate the influence of soybean row spacing and relative weed emergence time on the competitiveness of major weed species in soybean. Ten weed species were seeded in soybean spaced 19 and 76 cm apart at the planting, emergence, and first trifoliate leaf stages of soybean. Total weed dry matter (TDM), weed plant volume, and percent soybean yield loss were arbitrarily selected as a base for determining the CI …
Simulated Insect Defoliation And Duration Of Weed Interference Affected Soybean Growth, Travis C. Gustafson, Stevan Z. Knezevic, Thomas E. Hunt, John L. Lindquist
Simulated Insect Defoliation And Duration Of Weed Interference Affected Soybean Growth, Travis C. Gustafson, Stevan Z. Knezevic, Thomas E. Hunt, John L. Lindquist
Department of Agronomy and Horticulture: Faculty Publications
An improved understanding of crop stress from multiple pests is needed for better implementation of integrated pest management (IPM) strategies. Field studies were conducted in 2003 and 2004 at two locations in eastern Nebraska to describe the effects of simulated early-season insect defoliation of soybean and duration of weed interference on soybean growth. Three levels of simulated defoliation (undefoliated, 30, and 60%) and seven durations of weed interference (weedy and weed free; weed removal at V2, V4, V6, R3, and R5) were evaluated in a split-plot design. Defoliation significantly reduced soybean leaf-area index (LAI), total dry matter (TDM), and crop …
Predicting Biomass Partitioning To Root Versus Shoot In Corn And Velvetleaf (Abutilon Theophrasti), Kimberly D. Bonifas, John L. Lindquist
Predicting Biomass Partitioning To Root Versus Shoot In Corn And Velvetleaf (Abutilon Theophrasti), Kimberly D. Bonifas, John L. Lindquist
Department of Agronomy and Horticulture: Faculty Publications
Knowledge of how plants will partition their new biomass will aid in understanding competition between crops and weeds. This study determined if the amount of biomass partitioned to the root versus the shoot can be predicted from tissue carbon [C] and nitrogen [N] concentrations and the daily gain in C (GC) and N (GN) for each unit shoot and root biomass, respectively. Pots measuring 28 cm diameter 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 nitrogen treatments: 0, 1, …
Effect Of Nitrogen Addition On The Comparative Productivity Of Corn And Velvetleaf (Abutilon Theophrasti), Darren C. Barker, Stevan Z. Knezevic, Alex R. Martin, Daniel T. Walters, John L. Lindquist
Effect Of Nitrogen Addition On The Comparative Productivity Of Corn And Velvetleaf (Abutilon Theophrasti), Darren C. Barker, Stevan Z. Knezevic, Alex R. Martin, Daniel T. Walters, John L. Lindquist
Department of Agronomy and Horticulture: Faculty Publications
Weeds that respond more to nitrogen fertilizer than crops may be more competitive under high nitrogen (N) conditions. Therefore, understanding the effects of nitrogen on crop and weed growth and competition is critical. Field experiments were conducted at two locations in 1999 and 2000 to determine the influence of varying levels of N addition on corn and velvetleaf height, leaf area, biomass accumulation, and yield. Nitrogen addition increased corn and velvetleaf height by a maximum of 15 and 68%, respectively. N addition increased corn and velvetleaf maximum leaf area index (LAI) by up to 51 and 90%. Corn and velvetleaf …