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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. 108(5)



  • AGRONOMY, SOILS & ENVIRONMENTAL QUALITY

    • Jiyul Chang, David E. Clay, Sharon A. Clay, Rajesh Chintala, Janet M. Miller and Thomas Schumacher
      Biochar Reduced Nitrous Oxide and Carbon Dioxide Emissions from Soil with Different Water and Temperature Cycles

      Interactions among biochar, respiration, nitrification, and soils can result in biochar increasing, decreasing, or not impacting greenhouse gas (GHG) emissions. This experiment determined the impact of water-filled porosity (WFP) and corn (Zea mays L.) stover biochar on CO2 and N2O emissions in May (spring) and August (summer). The May experiment contained two N rates [0 and 224 kg Ca(NO3)2–N ha–1], whereas the August had three N rates [0, 224 kg Ca(NO3)2–N ha–1, and 224 kg (NH4)2SO4–N ha–1]. The average temperatures in the May and Augusts 2014 experiments were 14 and 24°C, respectively. (continued)

      Core Ideas:
      • Biochar reduces CO2 gas emission from soil in high soil temperature.
      • Biochar reduces N2O gas emission from soil in high soil temperature.
      • Biochar reduces N2O gas emission from high water-filled porosity condition.

      doi:10.2134/agronj2016.02.0100
      Published: September 29, 2016



    • Filip Mercl, Václav Tejnecký, Jiřina Száková and Pavel Tlustoš
      Nutrient Dynamics in Soil Solution and Wheat Response after Biomass Ash Amendments

      Among the possible methods for biomass ash (BA) utilization, land application represents an important nutrient-saving approach of BA management. The land application of BA results in an increase of soil pH, but in contrast to conventional liming, ash application on agricultural land can supply additional nutrients to soil, such as K, Mg, or P. However, due to the complex mineral phase composition of ashes, release of nutrients from the ash matrix into soil solution is not well understood. In the presented pot experiment, two agricultural soils were amended using two common types of BA (wood and straw ash) at rate 1% (w/w). (continued)

      Core Ideas:
      • Nutrient leaching from straw and wood ash matrix in soil-plant conditions is investigated.
      • The influence of ashes on yield and nutrient uptake differed substantially depending on types of ash and soil.
      • Highly soluble K-compounds in straw ash revealed by X-ray powder diffraction.
      • Straw ash is a much more efficient P source than wood ash.

      doi:10.2134/agronj2016.03.0176
      Published: September 29, 2016



    • Guillermo Alvarez, Elena Sevostianova, Matteo Serena, Rossana Sallenave and Bernhard Leinauer
      Surfactant and Polymer-Coated Sand Effects on Deficit Irrigated Bermudagrass Turf

      Sand topdressing and soil surfactants are commonly applied to turfgrass areas but it is unclear whether these practices improve visual appearance or reduce hydrophobicity under deficit irrigation. A study was conducted from 2011 to 2013 at New Mexico State University in Las Cruces, NM, to evaluate two topdressing materials and a soil surfactant on deficit irrigated Princess 77 bermudagrass (Cynodon dactylon L.) grown on a loamy sand (mixed, thermic Typic Torripsamment). Treatments consisted of monthly applications of a polymer-coated hydrophilic sand (ACA 3114) or straight sand with or without the soil surfactant and an untreated control. Plots were mowed at 2.0 cm and irrigated at either 70 or 50% of reference evapotranspiration for short grass (ETos). (continued)

      Core Ideas:
      • We describe the use of a novel, polymer coated, hydrophilic sand for topdressing bermudagrass turf in an arid climate.
      • We examined if the coated sand affects bermudagrass quality differently than a commercially available surfactant or topdressing with sand only.
      • We also investigated if the polymer coated sand is useful in preventing drought stress when irrigation is applied at reduced evapotranspiration replacement.

      doi:10.2134/agronj2016.06.0329
      Published: September 22, 2016



  • CLIMATOLOGY & WATER MANAGEMENT

    • Seyed Reza Amiri, Reza Deihimfard and Afshin Soltani
      A Single Supplementary Irrigation Can Boost Chickpea Grain Yield and Water Use Efficiency in Arid and Semiarid Conditions: A Modeling Study

      Chickpea (Cicer arietinum L.) is an agronomically important legume in Iran that is grown predominantly as a rainfed crop due to severely limited supplies of water suitable for irrigation. Long-term daily weather data for the period of 1982 to 2012, were collected for 12 locations in Khorasan-Razavi province in northeastern Iran with a cold semiarid and arid climate. A crop simulation model was used to investigate the effect of a single irrigation (at flowering or pod-filling stage) under a range of sowing dates on the yield and water use efficiency (WUE) of chickpea. The results showed that supplementary irrigation substantially increased grain yield at all the locations. (continued)

      Core Ideas:
      • SSM-legume model can be used for evaluation of production limitation efficiently.
      • Early sowing enabled chickpea to better exploit rainfall during crop season.
      • One single supplementary irrigation substantially increased grain yield.
      • Early sowing with one-time irrigation applied at flowering hugely improve water use efficiency.

      doi:10.2134/agronj2016.02.0087
      Published: September 29, 2016



  • CROP ECOLOGY & PHYSIOLOGY

    • Jing Wang, Yonggan Zhao, Huancheng Pang, Li Zhang and Yuyi Li
      Grain Shape as a Predictor of Salt Tolerance in Sunflower

      To determine whether sunflower (Helianthus annuus L.) grain shape should be considered as a predictor of salt tolerance, seeds of three grain shapes, namely long seeds (DC6009 and RH3146 with a width-length ratio [WLR] of 0.39), long ovate seeds (SH909 and 135 with a WLR of 0.49) and broadly ovoid seeds (RH118 with a WLR of 0.61) were exposed to 0, 1000, and 2000 mg L–1 NaCl for 30 d. Increases in the WLR increased the 100-seed weight and kernel/hull rate (KHR) but decreased the water absorption rate (WAR). A level of 2000 mg L–1 NaCl delayed the seed mean germination time (MGT), reduced the germination percentage (GP) and germination index (GI) and caused shorter root length (RL). A level of 1000 mg L–1 NaCl improved the GP and GI compared with the no NaCl-stressed control with the exception of the long ovate seeds. (continued)

      Core Ideas:
      • Low dose of NaCl generally improved the germination of most cultivars.
      • Broadly ovoid seeds exhibited the greatest enzyme activities at both NaCl levels and grain shapes.
      • Sunflowers with long-ovate seeds perform better when subjected to slightly salinized land.

      doi:10.2134/agronj2016.04.0191
      Published: September 29, 2016



    • Yang Yu, David Makowski, Tjeerd-Jan Stomph and Wopke van der Werf
      Robust Increases of Land Equivalent Ratio with Temporal Niche Differentiation: A Meta-Quantile Regression

      Intercropping has been shown to be land use efficient, but there is a large variation in the land equivalent ratio (LER) among studies. We used quantile regression to estimate the effect of temporal niche differentiation and its interaction with other key characteristics of intercropping, i.e., crop type combination, N fertilizer, relative density, and intercropping pattern, using data from the intercropping literature. Quantile regression characterizes the entire distribution of the response metric by estimating quantiles of this distribution. This method gives a comprehensive characterization of the diversity of the response in the population. (continued)

      Core Ideas:
      • Land equivalent ratio (LER) of intercrops increases with temporal niche differentiation (TND).
      • The positive effect of TND on LER is robust across a wide range of LER.
      • At lower LER, the effect of TND is stronger in C3–C4 than C3–C3 intercrops.
      • N fertilizer amount interacted negatively with TND but only at lower LER.
      • Quantile regression complemented insights obtained with ordinary regression.

      doi:10.2134/agronj2016.03.0170
      Published: September 1, 2016



  • CROP ECONOMICS, PRODUCTION & MANAGEMENT

    • J. D. Copeland, D. M. Dodds, A. L. Catchot, J. Gore and D. G. Wilson
      Evaluation of PRE Herbicides and Seed Treatment on Thrips Infestation and Cotton Growth, Development, and Yield

      The use of preemergence (PRE) herbicides may result in decreased early season cotton (Gossypium hirsutum L.) growth, which may exacerbate injury from thrips. Studies were conducted in 2013 and 2014 at the Black Belt Branch Experiment Station near Brooksville, MS; at the R.R. Foil Plant Science Research Center near Starkville, MS; and at the Delta Research and Extension Center in Stoneville, MS, to evaluate the impact of PRE herbicides and insecticide seed treatments on thrips infestations in cotton. DP 0912 B2RF was treated with thiamethoxam + fungicide, imidacloprid + fungicide, and fungicide only. (continued)

      Core Ideas:
      • Cotton seed treated with imidacloprid resulted in greater cotton yields compared with cotton grown from seed treated with thiamethoxam.
      • Preemergence herbicide application had no impact on cotton yield.
      • Based on these data, growers are encouraged to utilize a preemerence herbicide of their choice to manage Palmer amaranth, and imidacloprid-based seed treatments are recommended.

      doi:10.2134/agronj2016.03.0151
      Published: September 29, 2016



    • George W. Mueller-Warrant, Gerald W. Whittaker and Kristin M. Trippe
      Remote Sensing of Perennial Crop Stand Duration and Pre-Crop Identification

      Crop sequence history both describes results of on-farm decision-making processes and signals potential environmental impacts across landscapes. Remote sensing classifications for 11 yr in western Oregon identified multi-year production of established perennial crops and successive plantings of annual crops, quantified durations, and defined frequencies of pre- and post-crops for multi-year production periods. Measuring duration of continuous production of specific crops and characterizing crop sequence patterns required: (i) optimizing year-to-year landuse consistency and within-year landuse classification accuracy, (ii) sufficiently detailed landuse classes to capture 99% of all crops grown in the diverse agriculture of this region, and (iii) enough years of data that majorities of fields experienced at least one full cycle of planting new stands of perennial grass seed crops (or successive plantings of specific annual crops), maintaining those fields in production until their eventual termination, and subsequent planting of new crops. Averaged over all possible starting and ending years between 2004 and 2014, continuous production of the same crop on the same field ranged from highs of 2.9, 4.6, 3.7, and 5.9 yr for perennial ryegrass (Lolium perenne L.), orchardgrass (Dactylis glomerata L.), tall fescue [Schedonorus arundinaceus (Schreb.)], and Italian ryegrass [L. (continued)

      Core Ideas:
      • Crop rotation history can be derived from landuse classifications over multiple years.
      • Perennial grass seed crop stand duration variability localized to individual fields.
      • Frequency at which specific crops followed each other was mostly stable over time.

      doi:10.2134/agronj2016.03.0145
      Published: September 22, 2016



    • Marcos J. Perdoná and Rogério P. Soratto
      Arabica Coffee–Macadamia Intercropping: A Suitable Macadamia Cultivar to Allow Mechanization Practices and Maximize Profitability

      Intercropping Arabica coffee (Coffea arabica L.) with trees species that generate an economic return, such as macadamia (Macadamia integrifolia Maiden & Betche), has been suggested as an alternative for diversifying and maximizing income. However, there is no information on how macadamia cultivars affect the performance of coffee plants, system mechanization, and profitability. An 8-yr experiment was conducted in southeastern Brazil, to evaluate the growth, yield, and profitability of Arabica coffee intercropped with six macadamia cultivars (Hawaiian cultivars: HAES 344, HAES 660, and HAES 816; Brazilian cultivars: IAC 9-20, IAC 4-12B, and IAC 4-20) or monocropped coffee (continuously cropped coffee monoculture) under drip irrigation and a mechanized system. Relative to the Brazilian cultivars, the smaller canopy diameters of the Hawaiian macadamia cultivars resulted in less competition with the intercropped coffee plants and required less pruning, enabling mechanized management of the crop. (continued)

      Core Ideas:
      • Coffee–macadamia intercropping resulted in higher profitability than monocropped coffee.
      • It should define which macadamia cultivar is suitable to intercrop with coffee.
      • Hawaiian macadamia cultivars resulted in less competition with intercropped coffee plants.
      • The cultivar HAES 816 was the most successful intercrop with coffee in a mechanized system.

      doi:10.2134/agronj2016.01.0024
      Published: August 25, 2016



    • C. Z. Ogles, E. A. Guertal and D. B. Weaver
      Edamame Cultivar Evaluation in Central Alabama

      Edamame [Glycine max (L.) Merr.] is vegetable soybean harvested and consumed at the R6 development stage. The growing popularity of edamame as a healthy snack food has led to increased interest in edamame production from soybean producers across the Southeast. The objective of this study was to evaluate selected edamame cultivars for adaptation and production in central Alabama. Selected cultivars were represented by four maturity groups (MGs): MG III (Midori Giant, Chiba Green, Butterbean, Sayamusume, and BeSweet 2001), MG IV (Gardensoy 42, Mojo Green), MG V (Mooncake, Lanco, and Gardensoy 51), and MG VI (Owens).Cultivars were planted in replicated plots at the Plant Breeding Unit in Tallassee, AL, in May 2014 and June 2015. (continued)

      Core Ideas:
      • This study evaluated selected edamame cultivars for production in Alabama.
      • Cultivar characteristics such as bean weight, bean per pod, and plant height were documented.
      • Many of the cultivars in this study have never been evaluated for production in the southeastern United States.
      • This study will provide growers detailed production information that was previously unavailable.

      doi:10.2134/agronj2016.04.0218
      Published: September 1, 2016



    • Bhupinder S. Farmaha, Kent M. Eskridge, Kenneth G. Cassman, James E. Specht, Haishun Yang and Patricio Grassini
      Rotation Impact on On-Farm Yield and Input-Use Efficiency in High-Yield Irrigated Maize–Soybean Systems

      Cereal yields tend to be higher in cereal–legume rotations relative to cereal monoculture yields. We investigated the influence of crop rotation on yield and input-use efficiency in high-yield irrigated maize (Zea mays L.)-based cropping systems using producer-reported data from western U.S. Corn Belt (about 11,000 observations). Across regions, average yield of maize grown after soybean [Glycine max (L.) Merr.] (S–M) was 0.2 to 0.6 Mg ha–1 (2–5%) higher, relative to yield of maize grown after maize (M–M). (continued)

      Core Ideas:
      • We assessed rotation effect on on-farm yield and input-use efficiency.
      • Analysis was based on a large producer-reported database collected from high-yield irrigated maize–soybean systems.
      • There was a consistent positive rotation effect on yield and partial factor productivity for N fertilizer.
      • Number of previous maize crops did not affect maize yield in monoculture but soybean yields were higher following multiple maize crops.
      • Increasing maize area in rotation relative to monoculture accounts for 8% of the maize yield gain in the U.S. Corn Belt since 1970.

      doi:10.2134/agronj2016.01.0046
      Published: September 1, 2016



    • Z. Zhang, X. B. Zhou and Y. H. Chen
      Effects of Irrigation and Precision Planting Patterns on Photosynthetic Product of Wheat

      Winter wheat (Triticum aestivum L.) is characterized by a high tillering capacity and disadvantageous spatial structures, which may result in intraspecific competition. This study aimed to determine whether tiller productivity, radiation use efficiency (RUE), and grain yield of winter wheat could be manipulated through irrigation and precision planting patterns in North China. The experiment was conducted during winter seasons of 2011/2012, 2012/2013, and 2013/2014 at Tai’an, Shandong Province, China. The field experiment was based on a two-factor split-plot design with three replications under the same plant density (200 × 104 ha–1). (continued)

      Core Ideas:
      • Double-double row improved distribution of radiation, leaf area index, and stem number.
      • Precision planting patterns increased radiation use efficiency and yield of wheat.
      • The optimal precision planting pattern under abundant and scarce water in China.

      doi:10.2134/agronj2016.01.0051
      Published: September 1, 2016



  • INTERNATIONAL TURFGRASS SOCIETY CONFERENCE

    • 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



  • ORGANIC AGRICULTURE & AGROECOLOGY

    • R. A. Vann, S. C. Reberg-Horton and C. M. Brinton
      Row Spacing and Seeding Rate Effects on Canola Population, Weed Competition, and Yield in Winter Organic Canola Production

      Increasing seeding rate and widening row spacing to allow for between row cultivation may reduce weed competition in organic canola (Brassica napus L.) production. Research was conducted to evaluate the effects of row spacing and seeding rate on canola population, weed competition, and yield in organic canola production. Canola variety Hornet was planted at five seeding rates (3.4, 6.7, 10.1, 13.4, and 16.8 kg ha–1) at three row spacings (17, 34, 68 cm) in Goldsboro, Kinston, and Salisbury, NC, in 2011 and 2012. Between row cultivation was performed in the 68-cm row spacing as weather permitted. (continued)

      Core Ideas:
      • Increasing canola seeding rate and widening row spacing to allow for between row cultivation may serve as mechanisms to reduce weed competition in canola production, but have rarely been evaluated in organic production. This study was conducted to evaluate seeding rate and row spacing effects on weed competition and yield in organic canola production.
      • Despite different canola populations across canola row spacings, yield tended to be similar at low seeding rates across the row spacings indicating canola has the ability to compensate for low population.
      • Depending on the weed species at your environment, widening row spacing to allow for between row cultivation may prove critical for reducing weed competition and increasing canola yield.
      • Yield tended to increase with increases in seeding rate at the 17-cm row spacing, however yield declines were observed with higher seeding rates in the 68-cm row spacing, which is likely attributed to intraspecific competition.
      • Organic canola producers have flexibility when selecting row spacing and seeding rates due to the great plasticity of canola.

      doi:10.2134/agronj2016.02.0097
      Published: September 22, 2016



  • REVIEW & INTERPRETATION

    • Ronaldo E. Vibart, Iris Vogeler, Mike Dodd and John Koolaard
      Simple versus Diverse Temperate Pastures: Aspects of Soil–Plant–Animal Interrelationships Central to Nitrogen Leaching Losses

      Decoupling productivity and environmental pollution growth is a key objective of modern agricultural systems. The use of diverse (multispecies) pastures may contribute to this objective. Increasing the species diversity of intensively managed pastures can potentially increase annual herbage growth and N use efficiency. Here, we review the literature on simple (predominantly perennial ryegrass and white clover mixes) and diverse temperate pastures (those with three or more sown species) that address the soil–plant–animal interrelationships relevant to N leaching losses from intensive grazing systems. (continued)

      Core Ideas:
      • Decoupling productivity and environmental pollution growth is critical to modern agriculture.
      • The use of diverse (multispecies) pasture swards may contribute to this objective.
      • Annual herbage yields from diverse mixtures are greater than those from simple mixtures.
      • Greater species diversity in pastures can increase plant N uptake.
      • The inclusion of forbs aid in reducing the N load of urine patches, which reduces the risk of N leaching.

      doi:10.2134/agronj2016.04.0193
      Published: August 25, 2016



  • SOIL FERTILITY & CROP NUTRITION

    • William L. Pan, Isaac J. Madsen, Ronald P. Bolton, Lisa Graves and Tara Sistrunk
      Ammonia/Ammonium Toxicity Root Symptoms Induced by Inorganic and Organic Fertilizers and Placement

      Ammoniacal fertilizers can cause seedling damage. The present aims were to characterize spatial and temporal, root morphological NH3/NH4+ toxicity symptoms, assess the extent of the toxicity zone, and relate species-specific responses to their root architecture. Wheat (Triticum aestivum L.) and canola (Brassica napus L.) were exposed to seed and deep placed urea. Faba (Vicia faba L) seedlings were grown above organic amendments. (continued)

      Core Ideas:
      • NH3/NH4+ toxicity initiates at the root apex and moves basipetally.
      • Symptoms include tissue discoloration, axis shrinkage, root hair disfigurement, and seedling death.
      • Toxicity zones ranged from 1 to 5 cm from the ammonia sources.
      • Putative upward movement of ammonia raised soil pH and NH4+ above chicken manure.
      • Most wheat axes avoided NH3/NH4+ toxicity zones, improving survival over tap-rooted species.

      doi:10.2134/agronj2016.02.0122
      Published: September 29, 2016



    • Charles M. White, Denise M. Finney, Armen R. Kemanian and Jason P. Kaye
      A Model–Data Fusion Approach for Predicting Cover Crop Nitrogen Supply to Corn

      One potential benefit of cover crops (CCs) is that N mineralization from decomposing CC residues may reduce the N fertilizer requirement of a subsequent crop, but predicting this credit remains a significant challenge. This study used a model–data fusion approach to calibrate a model of CC residue N mineralization and pre-emptive competition for soil NO3 that occurs during CC growth to predict the yield response of an unfertilized corn (Zea mays L.) crop. The model was calibrated with a data set of 199 observations from four CC experiments in central Pennsylvania. The most parsimonious model explained 82% of the variation in corn yield response. (continued)

      Core Ideas:
      • A simple model predicts how cover crops affect N availability to the next corn crop.
      • The model highlights the ecological controls on N supply from cover crops.
      • Site-specific cover crop measurements can guide adaptive N management using the model.
      • Regional model calibration could be achieved with easily collected data.

      doi:10.2134/agronj2016.05.0288
      Published: September 29, 2016



    • Valéria Xavier de Oliveira Apolinário, José Carlos Batista Dubeux, Mário de Andrade Lira, Everardo V. S. B. Sampaio, Silvânia Oliveira de Amorim, Nalígia Gomes de Miranda e Silva and James P. Muir
      Arboreal Legume Litter Nutrient Contribution to a Tropical Silvopasture

      Legumes contribute to pasture sustainability through symbiotic N2 fixation, which may increase primary productivity and animal performance in low-input systems. Litterfall is the main way of cycling nutrients from tree legumes. We quantified gliricidia [Gliricidia sepium (Jacq.) Kunth ex Walp.] and sabiá (Mimosa caesalpiniifolia Benth) litter deposition, along two 336-d cycles, in a signalgrass (Brachiaria decumbens Stapf.) pasture. Litterfall was produced throughout the year but concentrated in the dry season. (continued)

      Core Ideas:
      • Litter deposition was an important pathway of N return in warm-climate silvopasture systems.
      • Tree legumes added significant amounts of biological nitrogen fixation to silvopasture systems.
      • Gliricidia litter presented better quality than Mimosa litter.
      • Proportion of litter N derived from atmosphere was significant.

      doi:10.2134/agronj2016.02.0120
      Published: September 22, 2016



    • Md. Rasel Parvej, Nathan A. Slaton, Larry C. Purcell and Trenton L. Roberts
      Critical Trifoliolate Leaf and Petiole Potassium Concentrations during the Reproductive Stages of Soybean

      The critical K concentration in soybean [Glycine max (L.) Merr.] has been determined only for leaf tissue at the R2 (full bloom) stage. Our research objective was to develop critical K concentrations in soybean for both leaves and petioles across reproductive stages. Fifteen fully-expanded, uppermost trifoliolate leaves with petioles plot–1 were collected 7 to 12 times from the V5 to R7 stages in five research trials that evaluated multiple fertilizer-K rates and/or cultivars from different maturity groups (MGs). Both leaf- and petiole-K concentrations, regardless of site-year, cultivar, and fertilizer-K rate, peaked around R2 stage and declined linearly with time at average rates of –0.198 g K kg–1 d–1 for leaves and –0.559 g K kg–1 d–1 for petioles. (continued)

      Core Ideas:
      • Critical soybean tissue-K concentrations in the trifoliolate leaf and petiole can be developed for growth stages beyond the R2 stage by modeling the rate of tissue-K decline across time.
      • Petiole-K concentrations are approximately twofold higher and decline at a greater rate than trifoliolate leaf-K concentrations and may be equally as good or a better tissue to sample for the diagnosis of K deficiency.
      • The ability to interpret the K nutritional status in leaves, petioles, or both tissues at numerous reproductive growth stages allows plant K status to be monitored and possibly corrected during the growing season across a range of growth stages.

      doi:10.2134/agronj2016.04.0234
      Published: September 22, 2016



    • Joseph Moyer and Daniel Sweeney
      Growth and Forage Quality Responses of Smooth Bromegrass to Nitrogen Placement and Timing

      Smooth bromegrass [Bromus inermis (L.)] is a cool-season perennial that is widely used in pastures and meadows. More intensive management of N may be required to optimize production. This study was conducted for 4 yr to determine bromegrass dry forage mass (FM) and quality responses to annual rates of 84 or 168 kg ha–1 of N fertilizer solution with three placements at four different fall/late winter (LW) timing combinations. Vegetative forage was harvested in April to represent early grazing, or postanthesis, in May to simulate hay production. (continued)

      Core Ideas:
      • Nitrogen fertility management of smooth bromegrass affects not only yield, but forage quality.
      • Placement of N fertilizer affects bromegrass yield and quality.
      • Responses to N amount and placement are also modified by application timing.

      doi:10.2134/agronj2015.0503
      Published: September 15, 2016



    • Mingwei Yuan, John J. Couture, Philip A. Townsend, Matthew D. Ruark and William L. Bland
      Spectroscopic Determination of Leaf Nitrogen Concentration and Mass Per Area in Sweet Corn and Snap Bean

      Rapid nondestructive measurements at leaf level of nitrogen concentration (%N) and leaf mass per area (LMA) are needed to improve crop simulation model development and calibration, and better understanding of in-season N management. Many contact reflectance-based techniques for %N and LMA estimations require calibration across species, cultivars, growing stages, and cultural practices. Narrowband (hyperspectral) reflectance spectroscopy, in combination with partial least square regression (PLSR) models, offers improved performance over vegetation indices derived from standard linear regression analysis with simple ratios or combined formulas. Little research on the application of contact spectroscopy data and PLSR techniques has been conducted for sweet corn (Zea mays L.) and snap bean (Phaseolus vulgaris L.). (continued)

      Core Ideas:
      • Spectroscopy combined with partial least square regression models is useful for estimates of leaf nitrogen concentration and leaf mass per area.
      • The optimum spectra for nitrogen concentration and leaf mass per area estimations were 1500 to 2400 and 450 to 2400 nm.
      • Spectroscopy appears appropriate for routine agronomic research field experiments.

      doi:10.2134/agronj2016.05.0260
      Published: August 25, 2016



    • Daniel E. Kaiser, Jeffrey A. Coulter and Jeffrey A. Vetsch
      Corn Hybrid Response to In-Furrow Starter Fertilizer as Affected by Planting Date

      Use of in-furrow starter fertilizer (IFSF) is common in the Upper Midwest to enhance early-season corn (Zea mays L.) growth because of cold soils in the early spring which limit P uptake by corn. The objective of this study was to evaluate the agronomic and economic responses of corn to IFSF and how this was affected by planting date (PD) for hybrids of contrasting relative maturity (RM). A 3-yr experiment was conducted in 2010 to 2012 at two locations in southern Minnesota which evaluated IFSF at 0 and 65 kg ha–1 of 100–150–0 (g kg–1 N–P–K) with three corn hybrids (94-, 99-, and 104-d RM) planted on three dates spaced on 10- to 16-d intervals. Delaying PD resulted in greater corn plant density, grain moisture at harvest, and kernel m–2, and decreased early-season plant height, days to silking, kernel mass, and corn grain yield. (continued)

      Core Ideas:
      • A P-based starter fertilizer applied in-furrow increased early corn growth and decreased grain moisture at harvest, but did not increase grain yield on soils testing medium to high in P.
      • Corn hybrids later in relative maturity and earlier planting increased economic net return.
      • Net return per hectare was not increased when in-furrow starter fertilizer was utilized on medium to high P-testing soils.
      • A small reduction in grain moisture at harvest can reduce grain drying expenses to offset the cost of in-furrow starter fertilizer.
      • The likelihood of a profitable economic net return to in-furrow starter fertilizer is not affected by corn planting date or hybrid relative maturity.

      doi:10.2134/agronj2016.02.0124
      Published: September 1, 2016



  • SOIL TILLAGE, CONSERVATION & MANAGEMENT

    • Prakriti Bista, Stephen Machado, Rajan Ghimire, Stephen J. Del Grosso and Melissa Reyes-Fox
      Simulating Soil Organic Carbon in a Wheat–Fallow System Using the Daycent Model

      Crop management practices that contribute to soil organic carbon (SOC) sequestration can improve productivity and long-term sustainability. A simulation study was conducted using the DAYCENT model over an 80-yr period. The objectives of the study were to assess model performance and forecast SOC changes in conventional tillage and no-tillage management in a dryland winter wheat (Triticum aestivum L.)–summer fallow (WW–SF) system. The treatments studied included fall burning of crop residue (FB0), no burning of crop residue with 0 (NB0), 45 (NB45) and 90 (NB90) kg N ha–1, pea vines (PV), and cattle manure (MN) addition. (continued)

      Core Ideas:
      • Management practices that contribute to soil organic C sequestration can improve productivity.
      • DAYCENT model simulated the influence of crop residue and nutrient management on soil organic C.
      • Conventionally tilled winter wheat–summer fallow systems, except manure, lost soil organic C from 1931 to 2080.
      • Conversion to no-tillage had positive effects on soil organic C accumulation in winter wheat–summer fallow systems.

      doi:10.2134/agronj2016.04.0202
      Published: September 29, 2016



    • Cristiano M. Pariz, Ciniro Costa, Carlos A. C. Crusciol, Paulo R. L. Meirelles, André M. Castilhos, Marcelo Andreotti, Nídia R. Costa, Jorge M. Martello, Daniel M. Souza, Jaqueline R. W. Sarto and Alan J. Franzluebbers
      Production and Soil Responses to Intercropping of Forage Grasses with Corn and Soybean Silage

      Agricultural management systems are needed to simultaneously enhance production, and improve soil quality. We investigated the effects of intercropped grass on production of corn (Zea mays L.) harvested for silage at 0.20 and 0.45 m height in the summer, as well as on production of subsequent forage, silage soybean [Glycine max (L.) Merr.], and soil responses on a Typic Haplorthox in Botucatu, SP, Brazil. Palisade grass [Urochloa brizantha (Hochst. ex A. (continued)

      Core Ideas:
      • Agricultural management systems are needed to enhance production and improve soil quality.
      • After corn silage harvest, pasture was grazed by lambs in winter/spring using a semi-feedlot system.
      • Harvesting corn silage crop with palisade grass intercrop at 0.45 m height was the most viable option.

      doi:10.2134/agronj2016.02.0082
      Published: September 1, 2016



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