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Agronomy Journal : Just Published

 

Accepted, edited articles are published here after author proofing to provide rapid publication and better access to the newest research. Articles are compiled into issues at dl.sciencesocieties.org/publications/aj, which includes the complete archive.

Citation | Articles posted here are considered published and may be cited by the doi.

Zhu, Q., M.J. Schlossberg, R.B. Bryant, and J.P. Schmidt. 2012. Creeping bentgrass putting green response to foliar nitrogen fertilization. Agron. J. doi:10.2134/agronj2012.0157

Current issue: Agron. J. 109(2)



  • AGRONOMIC APPLICATION OF GENETIC RESOURCES

    • Krishna P. Woli, John E. Sawyer, Matthew J. Boyer, Lori J. Abendroth and Roger W. Elmore
      Corn Era Hybrid Dry Matter and Macronutrient Accumulation across Development Stages

      Evaluating corn (Zea mays L.) aboveground dry matter (DM) and macronutrient accumulation patterns across era hybrids is necessary to understand changes in plant nutrient requirements and effects on accumulation timing and fertilization management. Two popular hybrids for each of five era-decades from 1960 to 2000 were grown in 2007 and 2008. Whole plant samples were collected at 10 development stages, with dry matter (DM), N, P, and K determined. Era hybrids differed in DM and nutrient accumulation, with differences in nutrient content mainly related to DM production. (continued)

      Core Ideas:
      • Evaluating corn dry matter and macronutrient accumulation patterns across era hybrids is necessary to understand changes in plant nutrient requirements and effects on accumulation timing and fertilization management.
      • Era hybrids differed in dry matter and nutrient accumulation, with differences in nutrient content mainly related to dry matter production.
      • Dry matter and P accumulation was linear, however, N and K accumulation slowed during the reproductive stages.
      • Although the absolute dry matter production and nutrient content was greater with the most recent hybrids, relative to the maximum dry matter and N, P, and K content and the accumulation rate (cumulative growing degree unit-based) remained the same across era hybrids.
      • Results indicate that overall dry matter production and yield potential has been mainly responsible for changes in corn macronutrient requirements with development of new hybrids.

      doi:10.2134/agronj2016.08.0474
      Published: March 23, 2017



    • Rachel Soares Ramos, Bruno Portela Brasileiro, Luis Claudio Inácio da Silveira, Volmir Kist, Luiz Alexandre Peternelli and Márcio Henrique Pereira Barbosa
      Selecting Parents, Families, and Clones to Obtain Energy Cane

      Sugarcane (Saccharum spp.) is a crop with a high potential for biomass production. Sugarcane residue and bagasse can be used in the production of ethanol and electricity. The genetic breeding program of the Inter-University Network for the Development of the Sugarcane Industry (RIDESA) initiated a hybridization program that includes species of the Saccharum complex. The objective of this study was to evaluate the genetic diversity in selected segregating populations, select the best families and clones, and identify potential parents for inclusion in the next phase of the energy cane breeding program to develop energy cane cultivars. (continued)

      Core Ideas:
      • The results presented the possibility of selection of energy cane clones.
      • Develop energy cane clones with high fiber contents, involving Saccharum spontaneum accesses.
      • We found clones with high fiber content and high sucrose levels.

      doi:10.2134/agronj2016.09.0489
      Published: March 9, 2017



  • AGRONOMY, SOILS & ENVIRONMENTAL QUALITY

    • Sarah E. Lyons, Quirine M. Ketterings, Greg Godwin, Jerome H. Cherney, Karl J. Czymmek and Tom Kilcer
      Early Fall Planting Increases Growth and Nitrogen Uptake of Winter Cereals

      Winter cereals such as triticale (× Triticosecale) have shown to be excellent cover and double crops in the northeastern United States due to beneficial environmental and economic qualities, including the potential to scavenge residual N and take up N from fall-applied manure. Total fall N uptake is impacted by fall seeding date and available N supply. Here we determined the impact of fall planting date and available N on pre-frost biomass accumulation and N uptake of triticale. Two planting dates, ranging from late August to early October, were evaluated at four locations in upstate New York. (continued)

      Core Ideas:
      • Double cropping of forages can increase yield per ha and reduce nutrient loss.
      • Timely planted winter cereals can take up N leftover from the summer crop.
      • Timely planted winter cereals also provide a safe window for fall-applied manure.
      • Late planting of winter cereals in corn silage rotations will limit fall N uptake.

      doi:10.2134/agronj2016.10.0620
      Published: March 23, 2017



    • John E. Sawyer, Krishna P. Woli, Daniel W. Barker and Jose L. Pantoja
      Stover Removal Impact on Corn Plant Biomass, Nitrogen, and Use Efficiency

      Corn (Zea mays L.) stover has become an important commodity for many uses, including cellulosic ethanol production. However, there are concerns about the impacts of aggressive stover removal at the industrial scale. The objective of this study was to evaluate the effect of continuous stover removal (SR) on plant component productivity, N uptake, and nitrogen use efficiency (NUE). Treatments were none, partial, and complete SR, no-till (NT) and chisel plow (CP), and 0, 168, and 280 kg N ha–1 rates. (continued)

      Core Ideas:
      • Corn stover has many uses, including recent interest for cellulosic bioenergy production.
      • For corn stover use in ethanol production, an increased understanding is needed of plant component biomass and N content within a stover harvest system, and the impact on N cycling and corn N use.
      • Improving N use efficiency in corn is important for optimizing yield and reducing environmental impacts.

      doi:10.2134/agronj2016.11.0672
      Published: March 23, 2017



    • Zaid Bello, Leon Van Rensburg and Phesheya Dlamini
      Response of Glasshouse Grown Malt Barley Yield to Water Stress

      The study was performed to investigate the effect of water stress and duration of water stress at different growth stages on yield and yield components of glasshouse grown malt barley (Hordeum vulgare L.). The crop was grown for two seasons on lysimeters, and was subjected to water stress at different growth stages (Late tillering, Flag leaf, Anthesis, and Milk/Dough) from the beginning until the end of each growth stage. Yield and yield components focused on were number of plants per pot (NP), tillers without ear (TWE), full ears (FE), empty ears (EE), mass of grains of 10 ears, total biomass per pot (TBPP) and total grain per pot (TGPP). Irrespective of season, results show that water stress during different growth stages did not significantly affect NP and EE but had a significant effect on TWE and FE. (continued)

      Core Ideas:
      • Malt barley was subjected to water stress at different growth stages.
      • The yield and yield components were used to evaluate the effect of water stress on barley.
      • Effect of water stress at anthesis growth stage is more pronounced than in other growth stages.

      doi:10.2134/agronj2016.05.0280
      Published: March 9, 2017



    • Lance S. Conway, Matt A. Yost, Newell R. Kitchen, Kenneth A. Sudduth, Allen L. Thompson and Raymond E. Massey
      Topsoil Thickness Effects on Corn, Soybean, and Switchgrass Production on Claypan Soils

      Diminished topsoil thickness, or depth to claypan (DTC), is a major cause of yield and profit depression in corn (Zea mays L.) and to a lesser extent in soybean [Glycine max (L.) Merr.] production on claypan soils in the U.S. Midwest. Perennial grasses, such as switchgrass (Panicum virgatum L.), may be more resilient to reduced DTC than grain crops. Therefore, a study was conducted on a Missouri claypan soil to compare production and profitability of switchgrass grown for bioenergy to corn and soybean grain over varying DTC. (continued)

      Core Ideas:
      • Grain relative yield increased with depth to claypan, while switchgrass relative yield was unaffected.
      • Grain yield was twice as temporally variable as switchgrass yield.
      • Grain crops generally were more profitable than switchgrass across depth to claypan.
      • Switchgrass has the capacity to reduce yield variability caused by depth to claypan.

      doi:10.2134/agronj2016.06.0365
      Published: March 9, 2017



  • BIOFUELS

    • Ben W. Thomas, Xiaomei Li, Virginia Nelson and Xiying Hao
      Anaerobically Digested Cattle Manure Supplied More Nitrogen with Less Phosphorus Accumulation than Undigested Manure

      Solid beef cattle manure is a good anaerobic digestion feedstock for methane production, but more research is needed to determine how co-products of the anaerobically digested manure may be used in crop production, while limiting the risk of nutrient loss to the environment. Over four growing seasons, we measured the N and P supplied to barley (Hordeum vulgare L.) forage test crops from (i) anaerobically digested solid beef cattle manure (digestate), (ii) separated solids from the digestate (separated solids), (iii) pelletized separated solids (pellets), and (iv) undigested solid beef cattle manure (manure) that were applied to target 1× (260 kg N ha–1) and 2× (520 kg N ha–1) the recommended N rates. Non-amended soil was the control. Digestate led to 31 to 50% greater barley forage yield than the other amendments. (continued)

      Core Ideas:
      • Barley recovered 19% of N applied by anaerobically digested cattle manure over 4 yr.
      • Barley recovered 10% of N applied by undigested cattle manure over 4 yr.
      • Separated solids and cattle manure supplied similar amounts of N and P to barley.
      • Pelletized separated solids released N too slowly for a barley yield benefit.
      • Separated solids posed a greater risk of P accumulation than cattle manure.

      doi:10.2134/agronj2016.12.0719
      Published: March 23, 2017



    • J. Xu, M. Gauder, S. Gruber and W. Claupein
      Yields of Annual and Perennial Energy Crops in a 12-year Field Trial

      To find an energy cropping system with low input and high productivity, a 12-yr field trial was conducted in Southwest Germany with perennial crops, and monocropping or rotation of annual crops. The perennials were willow (Salix schwerinii E. Wolf × viminalis L.) short rotation coppice, miscanthus (Miscanthus × giganteus Greef et Deu.), and switchgrass (Panicum virgatum L.). The monocropped annual was maize (Zea mays L.), and the rotation was oilseed rape (Brassica napus L. (continued)

      Core Ideas:
      • A long-term field trial of important perennial and annual energy crops was conducted.
      • Maize is most high yielding of biomass with high N inputs.
      • Miscanthus is most high yielding of biomass without or with moderate N inputs.
      • In crop rotations, no-till practice with less input does not reduce the productivity.
      • Nitrogen input is more important in annuals than perennials to maintain the yield level.

      doi:10.2134/agronj2015.0501
      Published: March 9, 2017



  • BIOMETRY, MODELING & STATISTICS

    • Raghuveer Sripathi, Patrick Conaghan, Dermot Grogan and Michael D. Casler
      Field Design Factors Affecting the Precision of Ryegrass Forage Yield Estimation

      Field-based agronomic and genetic research relies heavily on data generated from field trials. Therefore, it is imperative to optimize the precision of yield estimates in cultivar evaluation trials. Experimental error in yield trials is sensitive to several factors, some of which are classified as experimental design factors (i.e., plot size, block size, and number of replicates). The objective of this study was to conduct a retrospective case-study analysis of long-term perennial ryegrass (Lolium perenne L.), Italian ryegrass [Lolium perenne L. (continued)

      Core Ideas:
      • The row-column designs were 36% more efficient than the randomized complete block designs.
      • The impact of block size and number of replicates on trial precision was dependent on block shape.
      • Increasing number of replicates decreased LSD only in wider blocks compared to narrow blocks.

      doi:10.2134/agronj2016.07.0397
      Published: March 23, 2017



    • Paul D. Colaizzi, Steven R. Evett, David K. Brauer, Terry A. Howell, Judy A. Tolk and Karen S. Copeland
      Allometric Method to Estimate Leaf Area Index for Row Crops

      Leaf area index (LAI) is critical for predicting plant metabolism, biomass production, evapotranspiration, and greenhouse gas sequestration, but direct LAI measurements are difficult and labor intensive. Several methods are available to measure LAI indirectly or calculate LAI using allometric methods (i.e., exploiting relationships between LAI and more easily measured plant variables), but these depend on other measurements not widely available, and have limited transferability to different seasons. A new allometric method using a log normal function was developed to calculate LAI. Input variables were normalized cumulative growing degree days (CGDD), canopy height (CH), and plant population (PP), which were usually more widely available in crop production datasets. (continued)

      Core Ideas:
      • A new allometric method was developed to estimate LAI for row crops.
      • Good agreement resulted for four crops over multiple seasons.
      • Best agreement resulted using GDD, plant population, and canopy height.

      doi:10.2134/agronj2016.11.0665
      Published: March 23, 2017



    • Timothy Schwinghamer, Rachel Backer, Donald Smith and Pierre Dutilleul
      Block-Recursive Path Models for Rooting-Medium and Plant-Growth Variables Measured in Greenhouse Experiments

      Searching for statistically significant and biologically relevant relationships in complex datasets is generally a difficult task, in many fields including agronomy. Path analysis is an accessible, graphical, and inferential method for multivariate data exploration, which allows for more than unidirectional causal relationships between the measured variables. Here, data from experimental rooting media, and from corn plants grown in a greenhouse experiment, are used to introduce the theory and methodology of path analysis. Block-recursive path diagrams are hypothesized for each set of variables measured from the rooting media and the plants. (continued)

      Core Ideas:
      • Path analysis reveals multidirectional causal relationships in systems of variables.
      • Variable selection and model modification result in plausible path diagrams.
      • Softwood biochar water-extractable components enhance corn P uptake and root length.
      • Biochar water and nutrient holding capacities positively affect corn N and Ca uptake.
      • WEBC and WNHC directly affect corn dry weight and K content, in opposite ways.

      doi:10.2134/agronj2016.08.0473
      Published: March 23, 2017



  • CROP ECOLOGY & PHYSIOLOGY

    • Wellison Filgueiras Dutra, Alberto Soares de Melo, Janivan Fernandes Suassuna, Alexson Filgueiras Dutra, Duval Chagas da Silva and Josemir Moura Maia
      Antioxidative Responses of Cowpea Cultivars to Water Deficit and Salicylic Acid Treatment

      Drought stress is one of the greatest problems facing agriculture and a critical factor affecting the success or failure of agricultural activity. Application of an elicitor substance to plants, such as salicylic acid (SA), might be a strategy to induce tolerance to water deficit by acting especially on the regulation of stress-responsive mechanisms. This study aimed to evaluate the antioxidant activity of cowpea [Vigna unguiculata (L.) Walp.] seedlings as a function of water deficit and exogenous application of SA. Six cowpea cultivars were subjected to three seed treatments before sowing (WS = without soaking; SPW = soaking seeds in purified water, and SSA = soaking seeds in SA) and five water potentials induced by polyethylene glycol 6000 solution (–1.0, –0.8, –0.6, –0.4, and 0.0 MPa) during germination and early growth. (continued)

      Core Ideas:
      • Performance of salicylic acid to reduce the effects of water deficit in cowpea seedlings.
      • Oxidative protection in cowpea seedlings under water deficit.
      • Salicylic acid improve the biochemical metabolism in cowpea seedlings.
      • The cowpea cultivar BRS Itaim is suitable for semiarid regions by its tolerance to water deficit.

      doi:10.2134/agronj2015.0519
      Published: March 23, 2017



    • Duli Zhao, Mike Irey, Chris LaBorde and Chen-Jian Hu
      Identifying Physiological and Yield-Related Traits in Sugarcane and Energy Cane

      A growing interest of producing sugarcane (a complex hybrid of Saccharum spp.) for both sugar and bioenergy and saturation of using organic soils provide an opportunity to expand production on mineral (sand) soils. However, sugarcane yields and profits on sand soils are generally low. Energy cane may be an alternative on sand soils in the future to improve profits. The objective of this study was to identify physiological and biomass traits of sugarcane and energy cane growing on sand soils. (continued)

      Core Ideas:
      • Energy cane may be an alternative crop on sand soils in the future to improve profits.
      • It is unclear if energy cane differs from sugarcane in physiology and yield on sand soils.
      • Energy cane had 26 to 35% greater normalized difference vegetation index and 21% higher yield than sugarcane.
      • Increased yield of energy cane was associated with great normalized difference vegetation index and high stalk population rather than leaf net photosynthetic rate.

      doi:10.2134/agronj2016.10.0585
      Published: March 23, 2017



  • CROP ECONOMICS, PRODUCTION & MANAGEMENT

    • Elwin G. Smith, Robert P. Zentner, Con A. Campbell, Reynald Lemke and Kelsey Brandt
      Long-Term Crop Rotation Effects on Production, Grain Quality, Profitability, and Risk in the Northern Great Plains

      Crop production in the semiarid Northern Great Plains has historically been limited to wheat (Triticum aestivum L.), with fallow every second or third year. In response to current prices and new production technologies, these cropping systems have been replaced with reduced frequency of fallowing and inclusion of oilseed and pulse crops in the rotation. This study examined the long-term changes that producers can expect in their production levels and economic returns for five wheat-based rotations with different fallow frequencies, use of an annual legume green manure to partially replace fallow, and a continuous diversified rotation of cereal–oilseed–cereal–pulse crops. The findings were based on the last 11 yr of a 28-yr (1987–2014) crop rotation experiment performed at Swift Current, SK, Canada. (continued)

      Core Ideas:
      • Diversified rotations are more productive and profitable than cereal only rotations.
      • Fallow rotations are less profitable than continuous cropping in the Northern Plains.
      • Continuous cropping is riskier; however, it is preferred when averse to risk.

      doi:10.2134/agronj2016.07.0420
      Published: March 23, 2017



    • Alyssa S. DuVal, Thomas G. Chastain, Carol J. Garbacik and Donald J. Wysocki
      Nitrogen Affects Seed Production Characteristics in Yellow Mustard

      The response of applied N in yellow mustard (Sinapis alba L.) seed production is unknown in the high rainfall environments of the Pacific Northwest. The objective of this study was to determine the effect of applied N on growth, seed yield, and oil production in yellow mustard in this unique environment. Trials were conducted over 3 yr near Corvallis, OR, on cultivar IdaGold yellow mustard with five N rates: 0, 56, 112, 168, and 224 kg N ha–1. Growth and dry matter partitioning were measured at stem elongation (Biologische Bundesanstalt, Bundessortenamt und CHemische In [BBCH] 30), inflorescence emergence (BBCH 50), and harvest (BBCH 87). (continued)

      Core Ideas:
      • Applied N increased seed and oil yield in yellow mustard in a high rainfall environment.
      • Seeds m–2 was the most influential factor in determining seed yield in yellow mustard.
      • Applied N increased height, biomass, tissue N content, leaf area index, and crop growth rate.

      doi:10.2134/agronj2016.10.0587
      Published: March 23, 2017



    • Augustine K. Obour, Eric Obeng, Yesuf A. Mohammed, Ignacio A. Ciampitti, Timothy P. Durrett, Jose A. Aznar-Moreno and Chengci Chen
      Camelina Seed Yield and Fatty Acids as Influenced by Genotype and Environment

      Camelina (Camelina sativa L. Crantz) is an alternative oilseed crop with potential for fallow replacement in dryland cereal-based crop production systems in the semiarid Great Plains. The interaction between genotype and environment was investigated on camelina seed yield, oil content, and fatty acid composition across two locations in the U.S. Great Plains. (continued)

      Core Ideas:
      • Genotype × environment affected camelina seed yield, oil and constituent fatty acids.
      • Blaine Creek produced the greatest seed among the camelina genotypes studied.
      • Camelina grown at Hays, KS, had less yields and oil content compared to Moccasin, MT.
      • Camelina at Moccasin, MT had greater linolenic acid content compared to Hays, KS.

      doi:10.2134/agronj2016.05.0256
      Published: March 23, 2017



    • Amanda J. Ashworth, Fred L. Allen, Arnold M. Saxton and Donald D. Tyler
      Impact of Crop Rotations and Soil Amendments on Long-Term No-Tilled Soybean Yield

      Continuous cropping systems without cover crops are perceived as unsustainable for long-term yield and soil health. To test this, cropping sequence and cover crop effects on soybean (Glycine max L.) yield were assessed. Main effects were 10 sequences of soybean, corn (Zea mays L.), and cotton (Gossypium hirsutum L.) grown on a Loring silt loam at the Research and Education Center at Milan (RECM), TN, and six cropping sequences of corn and soybean on a Maury silt loam at the Middle Tennessee Research and Education Center (MTREC), Spring Hill, TN. Sequences were repeated in 4-yr Phases (i.e., I, II, and III) from 2002 to 2013. (continued)

      Core Ideas:
      • Poultry litter increased yields by 11% across locations and years when compared to wheat cover crops.
      • Yields in soybean–soybean–corn–cotton rotations during Phase II and corn–corn–soybean–corn during Phase I were greatest.
      • Incorporating corn once within a 4-yr cropping cycle resulted in 8% greater yields than continuous soybean.
      • Continuous cropping systems without cover crops are often perceived as unsustainable for long-term yields and soil health.

      doi:10.2134/agronj2016.04.0224
      Published: March 9, 2017



    • Matt A. Yost, Newell R. Kitchen, Kenneth A. Sudduth, Allen L. Thompson and Eric Allphin
      Topsoil Thickness and Harvest Management Influence Switchgrass Production and Profitability

      Switchgrass (Panicum virgatum L.) is an attractive dual use forage and/or biomass crop option for eroded soils where corn (Zea mays L.) grain production is often not profitable. Topsoil thickness, especially on soils with a claypan, relates directly to crop productivity and nutrient removal, but knowledge is lacking on how it impacts switchgrass grown for summer forage and advanced biofuels. Therefore, a study was conducted near Columbia, MO, to determine how topsoil thickness, or depth to claypan (DTC) affects the production and profitability of integrated (forage and biomass) and biomass only switchgrass. Switchgrass was planted in 2009 on a range of DTC classified as exposed (<8 cm), shallow (8–15 cm), moderate (16–30 cm), or deep (>30 cm), and was annually harvested twice (pre-anthesis and postdormancy) in the integrated system or once (postdormancy) in the biomass only system during 2011 to 2015. (continued)

      Core Ideas:
      • Topsoil thickness, or depth to claypan, mainly affected the biomass harvest of the integrated system.
      • The integrated system had greater weed cover, less yield, more N, P, and K removal, and less profit than the biomass only system.
      • The only advantage of the integrated system was enhanced yield resiliency in an extreme drought year.

      doi:10.2134/agronj2016.09.0561
      Published: March 9, 2017



    • Jesse C. Cameron, R. Michael Lehman, Peter Sexton, Shannon L. Osborne and Wendy I. Taheri
      Fungicidal Seed Coatings Exert Minor Effects on Arbuscular Mycorrhizal Fungi and Plant Nutrient Content

      Seed-applied fungicides have become standard on commodity crop seed to control pathogenic fungi prior to germination. However, fungicidal seed coatings containing multiple systemic ingredients targeting multiple metabolic processes may inhibit non-target soil fungi such as obligate plant symbiotic arbuscular mycorrhizal (AM) fungi. Our experimental objectives were to: (i) determine if seed-applied fungicidal formulations containing one or more systemic fungicides inhibit colonization of plant roots by AM fungi, plant development, or plant nutrient content during early vegetative stages of several commodity crops; (ii) identify interactions between fungicide and plant genotype. We evaluated seed-applied fungicides labeled for use with corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and oat (Avena sativa L.). (continued)

      Core Ideas:
      • Seed-applied fungicides may inhibit arbuscular mycorrhizal fungi and plant nutrient content.
      • Non-target effects of seed applied fungicides may vary with crop and genotype.
      • No negative effects of seed applied fungicides on arbuscular mycorrhizal fungi were found.
      • Plant genotype affected arbuscular mycorrhizal fungal colonization and plant nutrient content more than fungicide.

      doi:10.2134/agronj2016.10.0597
      Published: March 9, 2017



    • Seth R. Appelgate, Andrew W. Lenssen, Mary H. Wiedenhoeft and Thomas C. Kaspar
      Cover Crop Options and Mixes for Upper Midwest Corn–Soybean Systems

      The use of cover crops can decrease soil erosion, weed density, and nitrate leaching while improving soil quality. We investigated nine cover crops, winter rye (Secale cereale L.), winter triticale (× Triticosecale Wittm. ex A. Camus), two winter canola (Brassica napus L.), winter camelina [Camelina sativa (L.) Crantz], spring barley (Hordeum vulgare L.), spring oat (Avena sativa L.), turnip (B. (continued)

      Core Ideas:
      • Cover crop mixtures did not provide benefits beyond cover crop monocultures.
      • Cover crops did not influence soil temperature, soil P or K concentrations, or corn yield.
      • Cover crops did not influence weed density or weed community in subsequent corn.

      doi:10.2134/agronj2016.08.0453
      Published: March 2, 2017



  • INTERNATIONAL TURFGRASS SOCIETY CONFERENCE

    • Joseph Young, Mike Richardson and Douglas Karcher
      Golf Ball Mark Severity and Recovery as Affected by Mowing Height, Rolling Frequency, Foot Traffic, and Moisture

      Putting greens experience stress from golf balls striking the surface, maintenance equipment, and foot traffic. Improved creeping bentgrass (Agrostis stolonifera L.) cultivars, sand-based root zones, and skilled superintendents maintain plant health while providing firmer conditions. Many researchers have studied effects of compaction and wear on putting greens, but few have determined the effect of these stresses on ball marks. The objective of this research was to evaluate ball mark severity and recovery of creeping bentgrass under different mowing heights (2.5, 3.2, and 4.0 mm), rolling frequencies (0, 3, or 6 d wk–1), and foot traffic using digital image analysis. (continued)

      Core Ideas:
      • Digital image analysis methods to evaluate putting green ball mark severity and recovery.
      • Firmer surfaces from dry conditions or lightweight rolling increased maximum ball mark injury area.
      • Rate of recovery was similar for all treatments, but increased wear increased time to 50% recovery.
      • Demonstrates positive attributes of dispersing foot and equipment traffic throughout the green.

      doi:10.2134/agronj2016.04.0240
      Published: January 5, 2017



    • John R. Brewer, John Willis, Sandeep S. Rana and Shawn D. Askew
      Response of Six Turfgrass Species and Four Weeds to Three HPPD-Inhibiting Herbicides

      Mesotrione (2-[4-(methylsulfonyl)-2-nitrobenzoyl]-1,3-cyclohexanedione), tembotrione (2-[2-chloro-4-(methylsulfonyl)-3-[(2,2,2-trifluoroethoxy)methyl]benzoyl]-1,3-cyclohexanedione), and topramezone ([3-(4,5-dihydro-3-isoxazolyl)-2-methyl-4-(methylsulfonyl)phenyl](5-hydroxy-1-methyl-1H-pyrazol-4-yl)methanone) are new herbicides that control many troublesome weeds, but little is known about the response of several turfgrass species to these herbicides. A multiyear study was conducted to determine the response of six turfgrass species and four weeds to these three herbicides. Study results generally agreed with previous reports of turfgrass and weed response to mesotrione, and suggest that tembotrione could be safely used, depending on rate, to control weeds such as smooth crabgrass [Digitaria ischemum (Schreb.) Schreb. ex Muhl.], broadleaf plantain (Plantago major L.), and white clover (Trifolium repens L.) selectively in tall fescue [Schedonorus arundinaceus (Schreb.) Dumort., nom. (continued)

      Core Ideas:
      • Tembotrione controlled weeds selectively in bluegrass, fescue, and zoysiagrass turf.
      • Topramezone controlled key weeds better than mesotrione and tembotrione.
      • Topramezone was among the safest herbicides on four of the six turfgrasses tested.
      • Results will aid herbicidal-risk assessment near potentially sensitive turfgrass species.
      • The study supports considerations for herbicide label expansion or registration in turf.

      doi:10.2134/agronj2016.06.0345
      Published: December 1, 2016



    • Quincy D. Law, Jon M. Trappe, Yiwei Jiang, Ronald F. Turco and Aaron J. Patton
      Turfgrass Selection and Grass Clippings Management Influence Soil Carbon and Nitrogen Dynamics

      Little information is available about how grass species and management practices, such as grass clippings management, influence soil C and N accumulation, especially labile soil C. Thus, the objective of this field experiment was to determine the labile soil C, total soil C, soil organic matter (SOM), and total soil N accumulation of Kentucky bluegrass (Poa pratensis L.) and tall fescue [Schedonorus arundinaceus (Schreb.) Dumort. syn. Festuca arundinacea Schreb. (continued)

      Core Ideas:
      • Less than 3 yr post-establishment, tall fescue accumulated more soil C (i.e., labile soil C, total soil C, and soil organic matter) than Kentucky bluegrass.
      • Returning grass clippings for 2 yr increased both soil C (i.e., labile soil C and total soil C) and N (i.e., total soil N) compared to collecting clippings over the same period.
      • Labile soil C increased linearly over the 5 yr of the experiment.

      doi:10.2134/agronj2016.05.0307
      Published: December 1, 2016



    • Luqi Li, Matthew D. Sousek, Keenan L. Amundsen and Zachary J. Reicher
      Seeding Date and Bur Treatment Affect Establishment Success of Dormant-Seeded Buffalograss

      Dormant seeding is common for establishing cool-season turfgrasses, but minimal information exists on dormant seeding of the native warm-season buffalograss [Buchloë dactyloides (Nutt.) Engelm.] in the Midwest and northern Great Plains of the United States. The objective of these studies was to determine the effect of commercial KNO3 seed treatment on cultivar Cody buffalograss germination when seeded at various dates in winter and spring. Cody buffalograss burs were either commercially treated or untreated and both were seeded in the field the third week of November, January, March, or May. Buffalograss cover was rated monthly until the following August. (continued)

      Core Ideas:
      • Dormant seeding of buffalograss in November can be as effective as traditional May seeding.
      • Commercially potassium nitrate treated burs resulted in consistently higher cumulative germination regardless of seeding date.
      • Commercial treatment of burs may not be necessary when dormant seeding in November, but maximized buffalograss germination following an exceptionally dry winter.

      doi:10.2134/agronj2016.03.0164
      Published: December 1, 2016



    • Joshua Friell, Eric Watkins, Brian P. Horgan and Matthew Cavanaugh
      Sod Strength Characteristics of 51 Cool-Season Turfgrass Mixtures

      Successful establishment of turfgrass on roadsides often necessitates using species mixtures not typically used for sod production. Evaluating mechanical characteristics of sod produced using such mixtures is necessary to determine if they possess sufficient strength for harvest and handling. The objective of this work was to evaluate tensile strength and work required to tear sod of mixtures of nine cool-season turfgrass species previously determined to perform well on Minnesota roadsides. Three replications of 51 mixtures were established in a randomized complete block design at St. (continued)

      Core Ideas:
      • Turfgrass seed mixtures containing fine fescue species can produce sod that achieves equal or greater strength than those containing large amounts of Kentucky bluegrass when harvested 22 mo after establishment.
      • Change in proportion of fine fescues from each initial seed mixture to the resulting final plant community was negatively correlated with sod strength characteristics.
      • Thatch development was only weakly correlated with either maximum tensile load or work required to tear sod.
      • Mixtures with different seed compositions, but resulting in similar or identical final species compositions, often possessed very different mechanical properties.

      doi:10.2134/agronj2016.05.0295
      Published: October 6, 2016



    • Paul Koch
      Optimal Fungicide Timing for Suppression of Typhula Blight under Winter Covers

      Synthetic covers are often used to protect high-value golf course putting greens throughout much of North America and Scandinavia from injury during harsh winter conditions. However, these covers may trap heat and moisture at the turf surface and provide optimal conditions for snow mold development. This study was conducted to determine the most effective fungicide application strategy under both permeable and impermeable synthetic covers. Three different fungicide timings (early, late, and early + late) were tested under no cover, a permeable Evergreen (Hinspergers Poly Industries, Mississauga, ON) cover, and an impermeable GreenJacket cover (GreenJacket, Genoa City, WI) during the winters of 2011–2012 and 2012–2013 in Antigo, WI. (continued)

      Core Ideas:
      • Winter covers increase snow mold severity on golf course turfgrass.
      • Despite increased pressure, effective fungicides are available to limit disease to acceptable levels.
      • Applying fungicides as a single application shortly before snow cover or splitting out into two applications are both effective at reducing snow mold.

      doi:10.2134/agronj2016.04.0241
      Published: September 29, 2016



    • Matthew D. Jeffries, Travis W. Gannon and Fred H. Yelverton
      Tall Fescue Roadside Right-of-Way Mowing Reduction from Imazapic

      Tall fescue [Lolium arundinaceum (Schreb.) S.J. Darbyshire] is commonly established along roadside rights-of-way in adapted zones due to its tolerance of drought, heat, and wear; however, its upright growth habit coupled with seedhead production can impair motorist vision. Field research was conducted in 2013 and 2014 to quantify tall fescue mowing requirements following imazapic {( ± )-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid}, an herbicide commonly used for plant growth regulation, application (53 g a.i. ha–1) alone, as well as tank-mixed with clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) + triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid} (158 + 473 g a.i. (continued)

      Core Ideas:
      • Imazapic provided 100% tall fescue seedhead suppression through 56 d after treatment.
      • Imazapic reduced tall fescue mowing requirements by two cycles across 23- and 30-cm intervention heights.
      • Imazapic application to tall fescue mown at 30-cm intervention height required one mowing event through 70 d after treatment.

      doi:10.2134/agronj2016.04.0246
      Published: September 22, 2016



  • NOTES & UNIQUE PHENOMENA

    • Yueyue Wang, Xiao Zhang, Xinhua Xiao, Joshua Heitman, Robert Horton and Tusheng Ren
      An Empirical Calibration for Heat-Balance Sap-Flow Sensors in Maize

      Sap flow measurements with heat-balance sap-flow (HBSF) sensors are subject to errors due to temperature heterogeneity across the plant stem. Here we develop and evaluate an empirical calibration for HBSF sensors to measure transpiration rates (T) of maize (Zea mays L.). A pot experiment was used to establish an empirical calibration equation relating T determined by a mass balance method and sap flow velocity (V) measured with HBSF sensors. The calibration equation was tested in a field weighing lysimeter study, a pot study from the literature, and an additional dataset where V was measured with HBSF sensors, and T was determined from independent measurements of evapotranspiration and evaporation. (continued)

      Core Ideas:
      • Sap flow errors with heat-balance sap-flow sensors are quantified.
      • An empirical equation is established for correcting heat-balance sap-flow measurements in maize.
      • Independent tests proved the usefulness of the calibration equation in maize.

      doi:10.2134/agronj2016.10.0611
      Published: March 2, 2017



  • PEST INTERACTIONS IN AGRONOMIC SYSTEMS

    • Kun Jun Han and Edward K. Twidwell
      Herbage Mass and Nutritive Value of Bermudagrass Influenced by Non-Growing-Season Herbicide Application

      Application of herbicides to dormant bermudagrass [Cynodon dactylon (L.) Pers] in late winter to control cool-season weeds is a possible management practice for more marketable hay harvests. The objective of this study is to determine dormant-season herbicide effects on bermudagrass herbage mass and nutritive value at four harvest dates typical for Louisiana. The experimental design was a randomized complete block of Roundup (glyphosate), Plateau (imazapic), Journey (imazapic + glyphosate), Pastora (nicosulfuron + metsulfuron methyl), and a control (no herbicide treatment). The treatments were applied mid-February of 2013 and 2014. (continued)

      Core Ideas:
      • Dormant-season herbicide applications are effective in controlling cool-season weeds in bermudagrass.
      • Some dormant-season herbicide products can negatively impact bermudagrass forage production.
      • Dormant-season application of glyphosate did not cause significant damage to the bermudagrass stand.
      • Elimination of cool-season weeds in bermudagrass may not always be advantageous.

      doi:10.2134/agronj2016.07.0408
      Published: March 23, 2017



  • SOIL FERTILITY & CROP NUTRITION

    • Mariangela Hungria, Ricardo Silva Araujo, Elson Barbosa Silva Júnior and Jerri Édson Zilli
      Inoculum Rate Effects on the Soybean Symbiosis in New or Old Fields under Tropical Conditions

      Soybean [Glycine max (L.) Merr.] can highly benefit from inoculation with elite strains of Bradyrhizobium, selected for high capacity of N2 fixation. However, to achieve the benefits, the strains must be capable of effectively nodulate the host, and inoculum rate may be critical, especially under stressing tropical environmental conditions. We performed 10 field experiments, in four crop seasons and four Brazilian states, including soils without and with established populations of soybean bradyrhizobia, to investigate the effects of inoculum rates, consisting of zero, 0.6 × 106, 1.2 × 106, and 2.4 × 106 colony forming units (CFU) per seed. Nodule number and dry weight were evaluated at early flowering and grain yield and N content in grains at the physiological maturity. (continued)

      Core Ideas:
      • Inoculum rate with elite strains is critical to achieve the benefits of biological N2 fixation.
      • The minimum rate of 1.2 × 106 cells of Bradyrhizobium seed–1 was determined to benefit biological N2 fixation.
      • Soybean can highly benefit from biological N2 fixation.
      • Some sites required 2.4 × 106 cells seed–1 and could respond to higher rates.

      doi:10.2134/agronj2016.11.0641
      Published: March 23, 2017



    • Yi Zhou, Peter Hooper, David Coventry and Matthew D. Denton
      Strategic Nitrogen Supply Alters Canopy Development and Improves Nitrogen Use Efficiency in Dryland Wheat

      Strategic N application can improve yield in wheat (Triticum aestivum L.) but the reliability of the response in dryland conditions is often low, leading to poor predictability of N responses. The objective of this study was to provide an understanding of how nitrogen use efficiency (NUE) could be improved by strategic N application. Experiments with seven N application timings and two N rates were conducted at two sites over two seasons to evaluate the effects of strategic N supply on N uptake, canopy development, and yield components. Delaying the application of N fertilizer initially produced a thinner, more open crop canopy, compared with application of N at sowing, as indicated by significantly lower light interception (LI) (68 vs. (continued)

      Core Ideas:
      • Strategic application of N fertilizer produced a thinner and more open crop canopy.
      • The smaller canopy delayed demand for soil moisture.
      • The smaller canopy reduced shoot mortality and increased harvest index.
      • Higher N uptake from sowing N application did not result in more harvest N.

      doi:10.2134/agronj2016.08.0458
      Published: March 23, 2017



    • Apurba K. Sutradhar, Daniel E. Kaiser and Lisa M. Behnken
      Soybean Response to Broadcast Application of Boron, Chlorine, Manganese, and Zinc

      Efficient use of micronutrients can potentially increase soybean [Glycine max (L.) Merr.] grain yield and economic return. The objectives of this study were to determine the effect of broadcast application of micronutrients on soybean tissue nutrient concentration and grain yield and the relationships between soil and plant tissue tests. Three separate research trials were conducted at 35 sites from 2011 to 2014. Soybean response to Zn application was evaluated in Study 1; B, Mn, and Zn in Study 2; and B, Cl, Mn, and Zn in Study 3. (continued)

      Core Ideas:
      • Application of B, Cl, and Zn increase soybean tissue concentration of each respective nutrient.
      • Addition of B, Cl, Mn, and Zn do not increase soybean grain yield and have a marginal impact on soybean grain quality.
      • Soil tests for B, Cl, and Zn do not predict soybean grain yield response and no relationships exist between trifoliate B, Cl, Mn, and Zn concentration to grain yield or their respective soil tests.
      • It is unlikely that micronutrients are needed to increase soybean grain yield.

      doi:10.2134/agronj2016.07.0389
      Published: March 9, 2017



    • Mary Leggett, Martin Diaz-Zorita, Marja Koivunen, Roger Bowman, Robert Pesek, Craig Stevenson and Todd Leister
      Soybean Response to Inoculation with Bradyrhizobium japonicum in the United States and Argentina

      Although the relevance of biological N nutrition of soybean [Glycine max (L.) Merr.] is recognized worldwide, inoculation with Bradyrhizobium japonicum shows variable results and the benefit needs to be validated under current crop production practices. We conducted statistical analysis of soybean field trial data to provide insight into factors affecting the efficacy of soybean inoculation under contrasting crop production conditions. Most experimental sites, 187 trials in the United States and 152 trials in Argentina, were in soils with soybean history and naturalized B. japonicum strains. (continued)

      Core Ideas:
      • Soybean seed inoculation with Bradyrhizobium japonicum enhances grain production.
      • Greater inoculation response happens in Argentinean sites than in the United States.
      • Several soil properties and crop management practices are related with the responses to inoculation.

      doi:10.2134/agronj2016.04.0214
      Published: March 9, 2017



    • J. K. Yarborough, J. M. B. Vendramini, M. L. Silveira, L. E. Sollenberger, R. G. Leon, J. M. D. Sanchez, F. C. Leite de Oliveira, F. A. Kuhawara, V. Gomes, U. Cecato and C. V. Soares Filho
      Impact of Potassium and Nitrogen Fertilization on Bahiagrass Herbage Accumulation and Nutrient Concentration

      Bahiagrass (Paspalum notatum Flügge) is the most utilized forage for beef cattle (Bos spp.) in Florida, but there is concern that bahiagrass pastures are declining due to insufficient K fertilization. Two studies determined the effects of K and N fertilization on bahiagrass herbage mass (HM) and nutritive value in field plots (Exp. 1), and greenhouse (Exp. 2). (continued)

      Core Ideas:
      • Bahiagrass pastures on soils with low K concentration may not respond to K fertilization.
      • Tissue K concentration in bahiagrass is variable and dependent on fertilization levels.
      • Bahiagrass tissue K concentration of 17 g kg–1 was related to the greatest herbage accumulation in plants receiving greater levels of fertilization.

      doi:10.2134/agronj2016.10.0589
      Published: March 9, 2017



  • SOIL FERTILITY & CROP NUTRITON

    • Paulo Sergio Pavinato, Marcos Rodrigues, Amin Solthangheisi, Laércio Ricardo Sartor and Paul John Anthony Withers
      Effects of Cover Crops and Phosphorus Sources on Maize Yield, Phosphorus Uptake, and Phosphorus Use Efficiency

      This research evaluated the potential benefits of winter cover crops on the utilization and cycling of P in Brazilian tropical cropping systems. The effect of P fertilizer [none, rock phosphate (RP), and soluble phosphate (single superphosphate, SSP)] in combination with cover crop residues (common vetch [Vicia sativa L.], white lupin [Lupinus albus L.], forage radish [Raphanus sativus L.], ryegrass [Lolium multiflorum Lam], black oat [Avena strigosa Schreb.], red clover [Trifolium pratense L.], and fallow) were evaluated on maize (Zea mays L.) yield and P use efficiency over three maize cropping seasons under no-tillage, from 2009 to 2012. Cover crop yields and P uptake were higher under phosphate fertilizers than nil-P across all seasons evaluated. The highest amounts of P recycled in cover crops over the period were under white lupin, followed by radish and ryegrass, but without any significant cover crop effect on maize yield. (continued)

      Core Ideas:
      • Phosphorus recycling by cover crops in a typical Brazilian cropping system.
      • Maize response to phosphate sources under no-till management.
      • Residual effects of phosphate sources in tropical weathered soils.
      • Rock phosphate was more effective than soluble phosphate in supplying P for maize over time.

      doi:10.2134/agronj2016.06.0323
      Published: March 23, 2017



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