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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)


    • Susan P. Latshaw, Merle F. Vigil and Scott D. Haley
      Genotypic Differences for Nitrogen Use Efficiency and Grain Protein Deviation in Hard Winter Wheat

      Breeding superior bread wheat (Triticum aestivum L.) genotypes requires sufficient genetic variation to obtain high grain yield and adequate grain protein concentration. This study was conducted to determine variation for nitrogen use efficiency (NUE) and grain protein deviation among 20 hard winter wheat genotypes in one season and for two recently released cultivars (Snowmass and Byrd) in a second season, under five N application rates (0, 28, 56, 84, 112 kg ha–1). Among these genotypes, the proportionate contributions of component traits to total variance for NUE ranged widely: N uptake efficiency (57–89 kg kg–1) and N utilization efficiency (11–43 kg kg–1). Across all genotypes, N utilization efficiency contributed the most to variance for NUE under moderate to high N supply while N uptake efficiency contributed more under N limiting conditions. (continued)

      Core Ideas:
      • We assessed variation available to improve N use efficiency and grain protein deviation through breeding.
      • We determined variation for N use efficiency component traits in 20 breeding lines and cultivars.
      • Nitrogen utilization efficiency contributed the most to variance for N use efficiency under moderate to high N.
      • Nitrogen uptake efficiency contributed the most to variance for N use efficiency under N limiting conditions.
      • Grain protein deviation varies among these genotypes; the highest was 6.7 g kg–1 above the mean.

      Published: October 6, 2016


    • Huan Wang, Zongze Yang, Yanan Yu, Siyu Chen, Zhang He, Yong Wang, Li Jiang, Guan Wang, Chunwu Yang, Bao Liu and Zhian Zhang
      Drought Enhances Nitrogen Uptake and Assimilation in Maize Roots

      Nitrogen metabolism has important roles in plant drought tolerance, and higher N uptake can enhance plant drought tolerance. The aim of this study was to investigate the role of N metabolism regulation in maize drought tolerance. We measured the expression of genes known to be involved in N uptake and assimilation, together with various photosynthetic parameters, and nutrient content, in different tissues from maize plants exposed to water deficit conditions. Different tissues displayed significant differences in their regulation of N metabolism during the adaptation of maize plants to drought stress. (continued)

      Core Ideas:
      • Different tissues displayed different N-metabolic responses to drought condition.
      • Drought stress enhanced N uptake and assimilation in maize roots.
      • AMT1;1b, AMT1;3, NRT1;2 and NRT2;5 play important roles in maize drought tolerance.

      Published: October 20, 2016

    • Xue-Lian Tan, Tian-Wen Guo, Shang-You Song, Ping-Liang Zhang, Xu-Cheng Zhang and Cai Zhao
      Balanced Fertilizer Management Strategy Enhances Potato Yield and Marketing Quality

      Optimizing nutrient supply can promote plant growth, minimize production input, and enhance economic returns in crops. Here, we determined the effect of different fertilizer strategies on the tuber yield and economic outcomes in potato (Solanum tuberosum L.). Six fertilizer treatments were arranged in a randomized, complete block design at Dingxi Research Station (104°35′ E, 35°36′ N), Gansu Academy of Agricultural Sciences, from 2008 to 2010. Balanced fertilizer strategy (i.e., N, P, and K nutrients were combined in an appropriate ratio) was compared with imbalanced treatments where N, P, or K nutrient was omitted in decrement in the fertilizer strategy. (continued)

      Core Ideas:
      • One of the primary objectives in this study was to determine the relative contribution of individual nutrient elements (N, P, or K) to the tuber yield and to quantify whether the combination of the three key nutrients in a package would increase potato tuber yield further.
      • The fertilizer management treatments had a significant effect on the economic outcome each year. Averaged across the study sites, the NPK balanced fertilizer strategy had the highest production cost due to the highest input of fertilizers, but this strategy also led to a 11% greater net return (gross income mines input cost excluding laboring) than the other fertilizer treatments and 29% greater than the zero-fertilizer control.
      • The mechanism responsible for the additional 18% of the increased tuber yield with the balanced fertilizer strategy was not determined in the present study. However, our data suggest that the combination of all the nutrients together in a package promoted the coordination between aboveground DM accumulation and tuber yield, expressed by the ratios of the two variables at the various growth stages.

      Published: October 6, 2016

    • 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.

      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.

      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.

      Published: September 22, 2016


    • Hans-Peter Piepho and Emlyn R. Williams
      Augmented Row–Column Designs for a Small Number of Checks

      Augmented designs allow the testing of a large number of unreplicated entries. Replication of interspersed check cultivars according to a blocked design allows estimation of an error variance as well as local control for unreplicated entries. The most commonly used augmented designs use one-way blocking, but extensions have been suggested using blocking in rows and columns. We propose a flexible strategy to generate such designs, which is particularly suitable when the number of check cultivars is small. (continued)

      Core Ideas:
      • For augmented designs, the number of unreplicated entries and blocking unit dimensions needs flexibility.
      • Blocking in rows and columns is desirable for local error control.
      • Super-blocks can be defined based on groups of adjacent rows and columns.
      • Units formed by the intersection of row and column groups can be a further blocking unit.
      • These blocking units provide a convenient mechanism to distribute replications of check cultivars.

      Published: October 6, 2016


    • Lucas Eduardo de Oliveira Aparecido, Glauco de Souza Rolim, Rubens Augusto Camargo Lamparelli, Paulo Sergio de Souza and Eder Ribeiro dos Santos
      Agrometeorological Models for Forecasting Coffee Yield

      Some forecasting techniques have been tested with crop models using various statistical analyses for generating future scenarios of yield (Y). Forecasting, however, can be achieved by simply using regression analysis and carefully selecting independent variables (IVs) with time displacement relative to the dependent variable. The early forecasting of Y is the vanguard of agronomic modeling, promoting improvements in planning, allowing more rational strategic decisions, and increasing food and economic security. Climatic variables are the most important factors controlling the yield and quality of coffee (Coffea arabica L.). (continued)

      Core Ideas:
      • Multiple linear regression can efficiently forecast crop yields related to climatic conditions.
      • We can forecast coffee yield at least 5 mo prior to harvesting.
      • An increase in T during vegetative growth was inversely proportional to coffee yield.
      • Coffee yield in southern Minas Gerais is controlled by all meteorological elements.
      • Coffee yield in Cerrado Mineiro is controlled by hydric conditions.

      Published: October 27, 2016

    • 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.

      Published: September 29, 2016


    • Baizhao Ren, Jiwang Zhang, Shuting Dong, Peng Liu, Bin Zhao and Hui Li
      Nitrapyrin Improves Grain Yield and Nitrogen Use Efficiency of Summer Maize Waterlogged in the Field

      Effects of nitrapyrin [2-chloro-6-(trichloromethyl) pyridine] on grain yield and nitrogen use efficiency (NUE) of summer maize (Zea mays L.) hybrids Denghai 605 (DH605) and Zhengdan 958 (ZD958) waterlogged in the field were investigated. Results showed that waterlogging significantly decreased NUE, nitrogen partial factor productivity (NPFP), and nitrogen harvest index (NHI) of summer maize, resulting in the inhibition of N transport and assimilation, and ultimately resulted in a significant grain yield reduction. Grain yields of DH605 and ZD958 were reduced by 38 and 42%, respectively, compared to no waterlogging treatment. However, nitrapyrin application increased N efficiency of waterlogged summer maize. (continued)

      Core Ideas:
      • Waerlogging decreases N efficiency.
      • Nitrapyrin application increased N efficiency of waterlogged summer maize.
      • Nitrapyrin application increased grain yield of waterlogged maize.

      Published: October 20, 2016

    • Sudhir Singla, Kulbhushan Grover, Sangamesh V. Angadi, Brian Schutte and Dawn VanLeeuwen
      Guar Stand Establishment, Physiology, and Yield Responses to Planting Date in Southern New Mexico

      Guar (Cyamopsis tetragonoloba L.) is a drought-tolerant summer annual legume that can be grown for forage, green pods, or seeds. Galactomannans use in various industries such as food, cosmetic, paper, and oil etc. has attracted the guar production for seed. Currently, most of the United States’ demand for guar is met through imports. (continued)

      Core Ideas:
      • Planting date had a significant effect on guar seed yield.
      • Significant genotypic variation for seed yield was observed across planting dates.
      • Planting dates and genotypes showed a significant interaction for guar seed yield.
      • Mid-June planting increased guar seed yield over other tested planting dates.

      Published: October 17, 2016

    • C. Harbach, S. Chawla, C. R. Bowen, C. B. Hill, E. D. Nafziger and G. L. Hartman
      Association of Green Stem Disorder with Agronomic Traits in Soybean

      Green stem disorder (GSD) of soybean [Glycine max (L.) Merr.] is the occurrence of non-senescent, fleshy green stems of plants with normal, fully mature pods and seeds. The main focus of this study was to determine the relationship between GSD incidence and agronomic traits and to determine if GSD incidence was associated with soybean cultivars, years, location of trials, and rainfall. Data on GSD incidence based on a percentage of plants in plots showing symptoms were collected for soybean cultivars in 86 trials from 2009 to 2012 at seven locations in Illinois. The incidence of GSD ranged from 0% (three trials) to 88% with a mean incidence of 12% averaged over the 83 trials. (continued)

      Core Ideas:
      • Out of the 83 field trials, 12 had positive and 8 had negative associations of green stem disorder with yield.
      • Green stem disorder was more often positively correlated with protein content and negatively correlated with oil content.
      • Ratings of cultivars for green stem disorder were positively associated in 132 out of 332 pairs of trials with 10 or more cultivars in common with no negative associations.

      Published: October 17, 2016

    • 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.

      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.

      Published: September 1, 2016


    • Andrew Trlica, Maninder K. Walia, Ron Krausz, Silvia Secchi and Rachel L. Cook
      Continuous Corn and Corn–Soybean Profits over a 45-Year Tillage and Fertilizer Experiment

      Studies comparing profitability of tillage systems often examine narrow historic windows or exclude annual price fluctuations. This study uses a continuous corn (Zea mays L.) (CC; 1970–1990) and corn–soybean [Glycine max (L.) Merr.] (CS; 1991–2014) Tillage × Fertilizer study in somewhat poorly drained soils in southern Illinois to reconstruct partial annual budgets with historical prices for crops, fertilizers, lime, herbicides, fuel, labor, and machinery. Combinations of tillage (moldboard plow [MP], chisel tillage [ChT], alternate tillage [AT], and no-till [NT]) and fertilizer (Control, N-only, N+NPK starter, NPK+NPK starter, and NPK broadcast) treatments were evaluated. The CC profits were highest in NPK-applied treatments followed by N-only and Control. (continued)

      Core Ideas:
      • Cumulative profit (1970–2014) in no-till was similar to other tillage types with NPK.
      • Relative profits were more sensitive to changes in machinery than herbicide cost.
      • Return on fertilizer ranged from 56 to 251% for P and K and 69 to 434% for N.

      Published: October 27, 2016

    • Zhen Zheng, Huanjie Cai, Lianyu Yu and Gerrit Hoogenboom
      Application of the CSM–CERES–Wheat Model for Yield Prediction and Planting Date Evaluation at Guanzhong Plain in Northwest China

      Water is the most important limiting factor for winter wheat (Triticum aestivum L.) production on the Guanzhong Plain in Northwest China. It is important to develop water management practices by knowing when to irrigate and how much water should be applied. The impact of different irrigation conditions on crop production can be analyzed with crop simulation models. The objectives of this study were (i) to evaluate the performance of the Cropping System Model (CSM)–CERES–Wheat model for simulating the impact of different irrigation regimes on winter wheat growth, development, and grain yield, and (ii) to determine the optimum sowing dates for irrigated and rainfed winter wheat grown under semiarid conditions using the CSM–CERES–Wheat model. (continued)

      Core Ideas:
      • CSM-CERES-Wheat model simulated different irrigation regimes under shield and field conditions.
      • Simulated and measured phenology, LAI, total biomass, and grain yield agreed well.
      • The model was not suitable as a tool to determine the optimum sowing date.
      • High density and medium irrigation was the best management practice for wheat.

      Published: October 27, 2016

    • David C. Nielsen, Merle F. Vigil and Neil C. Hansen
      Evaluating Potential Dryland Cropping Systems Adapted to Climate Change in the Central Great Plains

      Climate in the semiarid central Great Plains is expected to become warmer and drier in coming decades, with potentially greater variability in precipitation and temperature. Cropping systems that include forages and allow flexibility for determining if a crop should be planted and which crop to plant (based on available soil water at planting) may provide the opportunity to maintain economic viability in a changing climate environment. The objective of this study was to compare cropping system productivity and profitability of flexible rotations that incorporate forages against grain-based cropping systems that are set rotational sequences. Yield and net returns for five set rotations and three flexible rotations were compared at Akron, CO, over 5 yr. (continued)

      Core Ideas:
      • Including forages in semi-arid dryland cropping systems increases profitability.
      • Using flexible rotations based on soil water at planting can reduce fallow frequency.
      • Continuously cropping with an all-forage rotation maximizes net returns.
      • Flexible rotations with forages may mitigate negative effects of climate variability.

      Published: October 17, 2016

    • Curtis D. Dick, Nathanael M. Thompson, Francis M. Epplin and Daryl B. Arnall
      Managing Late-Season Foliar Nitrogen Fertilization to Increase Grain Protein for Winter Wheat

      Late-season applications of foliar N have the potential to increase protein content in hard red winter (HRW) wheat (Triticum aestivum L.), but the optimal N management strategy and economics of this decision have yet to be determined for the U.S. southern Great Plains. This study was conducted to determine the expected net return from HRW wheat managed for enhanced protein and marketed to receive a protein premium. Field experiments were conducted during the 2011 to 2013 harvest years at two Oklahoma locations to estimate the grain yield and protein content response of HRW wheat to N source (urea ammonium nitrate [UAN] or a low salt, controlled release [LSCR] specialty N), N timing (flag leaf or post-flowering), and N rate (0, 7, 13, or 27 kg N ha–1). (continued)

      Core Ideas:
      • Late-season foliar N applications may increase wheat grain protein percentage.
      • Late-season foliar N applications are costly.
      • Southern Plains producers do not routinely receive a premium for high protein wheat.
      • Additional returns were insufficient to offset the additional cost.

      Published: October 17, 2016

    • Nídia Raquel Costa, Marcelo Andreotti, Carlos Alexandre Costa Crusciol, Cristiano Magalhães Pariz, Keny Samejima Mascarenhas Lopes, Kazuo Leonardo de Almeida Yokobatake, João Paulo Ferreira, César Gustavo da Rocha Lima and Daniel Martins de Souza
      Effect of Intercropped Tropical Perennial Grasses on the Production of Sorghum-Based Silage

      Sorghum [Sorghum bicolor (L.) Moench] intercropped with tropical grasses can be used in silage production systems to increase the dry matter yield per area, provide pasture after sorghum harvesting and improve land-use efficiency (LUE). Our objective was to compare the production and quality of sorghum silage intercropped with palisade grass [Urochloa brizantha (A. Rich.) Stapf ‘Marandu’] or guinea grass [Megathyrsus maximus (Jacq.) B.K. Simon & S.W.L. (continued)

      Core Ideas:
      • Intercropping crops in a no-till system increase the diversification of agricultural production.
      • Intercropping systems provide better uses of agricultural areas throughout the year.
      • The intercropping systems productivity is as high as that of monocropped crops.
      • Intercropping sorghum with grasses is a viable option for feed production.
      • One of the intercropping systems benefits is established grazing during the off-season.

      Published: October 17, 2016

    • Jennifer L. Corbin, Timothy W. Walker, John M. Orlowski, L. Jason Krutz, Jeffrey Gore, Michael S. Cox and Bobby R. Golden
      Evaluation of Trinexapac-Ethyl and Nitrogen Management to Minimize Lodging in Rice

      Rice (Oryza sativa L.) is an important crop in the midsouthern United States. However, some high-yielding cultivars are highly susceptible to lodging. The plant growth regulator, trinexapac-ethyl (TE), has been shown to decrease lodging in upland cereal crops, but data are scarce that demonstrate rice response to TE. The objective of this study was to determine the effect of TE on rice plant height, lodging, and grain yield. (continued)

      Core Ideas:
      • Trinexapac-ethyl decreased rice plant height and lodging on both clay and silt loam soils.
      • Trinexapac-ethyl at 12 g a.i. ha–1 did not decrease grain yield when applied at panicle differentiation on silt loam soils.
      • Grain yield response to trinexapac-ethyl varied by soil texture and N management strategy.

      Published: October 6, 2016

    • 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.

      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.

      Published: September 22, 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.

      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.

      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.

      Published: September 1, 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.

      Published: August 25, 2016


    • T. Kelly Turkington, Brian L. Beres, H. Randy Kutcher, Byron Irvine, Eric N. Johnson, John T. O’Donovan, K. Neil Harker, Christopher B. Holzapfel, Ramona Mohr, Gary Peng and F. Craig Stevenson
      Winter Wheat Yields Are Increased by Seed Treatment and Fall-Applied Fungicide

      Published: October 17, 2016


    • Alejandra A. Acuña E., Claudio Pastenes V. and Luis Villalobos G.
      Carbon Sequestration and Photosynthesis in Newly Established Turfgrass Cover in Central Chile

      Growth of the urban population in central Chile may have contributed to increased CO2 emissions, thus information regarding the role of turfgrass in public spaces and its ability to sequester CO2 would be valuable. The objectives of this study were to assess and compare the magnitude of C sequestration of seven newly established turfgrass species to bare soil using seasonal organic C stocks measurements aboveground (aboveground organic carbon [AOC]) and belowground (soil organic carbon [SOC]) and to associate these data with turfgrass seasonal photosynthetic behavior. Festuca arundinacea Schreb, Festuca rubra L. ssp. (continued)

      Core Ideas:
      • Soil organic C varied for 3 yr and four seasons for the five cool season turfgrass species (C3) and the two warm season turfgrass species (C4) when compared to bare soil. The effect of turfgrass species was detected in all of the seasons, where turfgrass coverage increased soil organic C over time, primarily at the 0- to 10-cm soil depth.
      • Carbon dioxide fixation rate can be an adequate indicator of carbon sequestration potential in a short-term period for turfgrass species.
      • This study showed that Cynodon dactylon L. and Festuca arundinacea Schreb. were the most promising species to increase C sequestration and to better use the irrigation water in central Chile.

      Published: October 20, 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.

      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.

      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.

      Published: September 22, 2016


    • Ebony G. Murrell, Meagan E. Schipanski, Denise M. Finney, Mitchell C. Hunter, Mac Burgess, James C. LaChance, Barbara Baraibar, Charles M. White, David A. Mortensen and Jason P. Kaye
      Achieving Diverse Cover Crop Mixtures: Effects of Planting Date and Seeding Rate

      Cover crop mixtures may provide greater diversity of benefits than monocultures. To develop management principles to establish diverse cover crop mixtures, we conducted a 3-yr study in which monocultures and mixtures of six cover crop species (cereal rye [Secale cereale L.], oat [Avena sativa L.], common medium red clover [Trifolium pratense L.], Austrian winter pea [Pisum sativum L.], forage radish [Raphanus sativus L.], and winter canola [Brassica napus L.]) were planted in a wheat (Triticum aestivum L.)–maize (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation after wheat (AW) and after maize (AM). Post-emergence stand counts and aboveground biomass in fall and spring were measured by species for all cover crop treatments. All species planted manifested in monocultures and mixtures in fall, though oat dominated and red clover, canola, and radish underperformed in mixtures. (continued)

      Core Ideas:
      • Cover crop mixtures retain higher diversity when allowed sufficient growth in fall.
      • Cereal rye dominates mixtures in spring, particularly when fall planting is delayed.
      • Grasses overperform in cover crop mixtures compared to their growth in monoculture.
      • Brassicas underperform in cover crop mixtures compared to their growth in monoculture.
      • Legumes’ growth in cover crop mixtures varies depending on species and planting time.

      Published: October 20, 2016

    • Alyssa H. Cho, Carlene A. Chase, Rosalie L. Koenig, Danielle D. Treadwell, Jeremy Gaskins, J. Bradley Morris and J. Pablo Morales-Payan
      Phenotypic Characterization of 16 Accessions of Sunn Hemp in Florida

      Adoption of sunn hemp (Crotalaria juncea L.) as a cover crop has been limited primarily due to the availability of seed sources, leading to high seed costs and unreliable supplies. Seed production in Florida with the commercially available sunn hemp cultivar Tropic Sun has been largely unsuccessful. An experiment was designed to evaluate 16 accessions of sunn hemp for potential commercial seed production in Florida at three planting dates (May, June, July). Vegetative and reproductive characteristics were evaluated to provide baseline information for future development of a cultivar of sunn hemp that could produce seed in Florida with desirable cover crop attributes. (continued)

      Core Ideas:
      • Based on vegetative and reproductive characteristics sunn hemp accessions could be divided into two groups.
      • Group 1 accessions produce more shoot biomass and have a short-day flowering response.
      • Flowering occurs in fall when effective pollinators are absent.
      • Group 2 accessions are less sensitive to photoperiod.
      • Group 2 accessions flower in summer when effective pollinators occur and successfully set seed.

      Published: October 17, 2016

    • C. J. Lowry and D. C. Brainard
      Strip-Intercropping of Rye–Vetch Mixtures Affects Biomass, Carbon/Nitrogen Ratio, and Spatial Distribution of Cover Crop Residue

      Altering the spatial arrangement of cover crop mixtures with strip-intercropping is an under-explored strategy that may enhance cover crop performance and provisioning of ecosystem services. We hypothesized that strip-intercropping of a cereal rye (Secale cereale L.; “rye”) and hairy vetch (Vicia villosa Roth; “vetch”) mixture would increase cover crop productivity and concentrate low C/N vetch residue within the future crop zone, thereby increasing the potential for improved N use efficiency. We conducted a field study in southwestern Michigan to examine how strip-intercropping of rye–vetch mixtures influences: (i) total cover crop productivity, and (ii) the spatial distribution and C/N ratio of rye–vetch residues. Spatial arrangements included the standard full-width mixture (MIX) in which rye and vetch were sown together in the same rows; and segregated mixtures with either two rows of rye alternated with two rows of vetch (SEG2) or three rows of rye alternated with one row of vetch (SEG1). (continued)

      Core Ideas:
      • Strip-intercropping of rye and vetch either had no effect or reduced cover crop biomass.
      • Strip-intercropping of rye and vetch concentrated N-rich vetch residue in the future crop row.
      • By reducing the C/N ratio of rye–vetch within the crop row, strip-intercropping may increase crop N.

      Published: October 17, 2016

    • 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.

      Published: September 22, 2016


    • Sulochana Dhital and W. R. Raun
      Variability in Optimum Nitrogen Rates for Maize

      Maize (Zea mays L.) grain yield levels and the response to fertilizer nitrogen (N) are expected to change from year to year and from location to location. Because yield level and N response have been documented to be independent and are known to influence N demand, optimum N rates at the same location vary each year due to unpredictable changes in the environment. The objective of this study was to further analyze maize grain yield levels and optimum fertilizer N rates from published data in maize growing regions of the United States. Optimum N rates were determined by calculating the difference in N uptake between the highest-yielding plot and the check plot (no N applied [0-N]). (continued)

      Core Ideas:
      • Optimum fertilizer nitrogen rates for maize are highly variable.
      • Demand for fertilizer nitrogen changes year to year.
      • Yield level and nitrogen responsiveness are independent.
      • Nitrogen use efficiency can improve by changing N rates every year.
      • In-season sensor based N management can optimize fertilizer nitrogen rates.

      Published: October 17, 2016

    • Kirsten Butcher, Abbey F. Wick, Thomas DeSutter, Amitava Chatterjee and Jason Harmon
      Soil Salinity: A Threat to Global Food Security

      Soil salinity is a global issue threatening land productivity, and estimates predict that 50% of all arable land will become impacted by salinity by 2050. Consequently, it is important to have a fundamental understanding of crop response to salinity to minimize economic loss and improve food security. While an immense amount of research has been performed assessing corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] response to salinity, there are few, if any, comprehensive reviews compiling previously published literature. This review provides a detailed description of our current knowledge on the impacts of salinity on corn and soybean growth and development. (continued)

      Core Ideas:
      • Review of salinity’s effects on corn and soybean growth and development.
      • Impacts of osmotic stress and specific ion toxicities discussed.
      • Potential areas of future research addressed.

      Published: October 6, 2016

    • 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.

      Published: August 25, 2016


    • Mohamed Lazali, Didier Blavet, Catherine Pernot, Dominique Desclaux and Jean Jacques Drevon
      Efficiency of Phosphorus Use for Dinitrogen Fixation Varies between Common Bean Genotypes under Phosphorus Limitation

      Low P availability in the soil is a major constraint to legume production, and efforts are being made to identify legume genotypes with tolerance to low P and greater phosphorus use efficiency (PUE) for N2 fixation. Common bean (Phaseolus vulgaris L.) genotypes vary in their adaptation to low-P soils. To investigate to what extent this variation may be related to PUE for N2 fixation, six recombinant inbred lines (RILs) of common bean contrasting in PUE for symbiotic N2 fixation, namely RILs 147, 115, 104, 83, 34, and 29 were studied in the field conditions during four growing seasons from 2011 to 2015. We collected biomass (aboveground and belowground) at flowering stage, and both samples were analyzed P content. (continued)

      Core Ideas:
      • Phosphorus use efficiency may be classified as trait for P-deficiency tolerance.
      • Low soil P availability is a limiting factor of the rhizobial symbiosis.
      • The increase of P content may be involved in the regulation of nodulation.

      Published: October 27, 2016

    • Francesco Di Gioia, Maria Gonnella, Vito Buono, Osman Ayala, Josefina Cacchiarelli and Pietro Santamaria
      Calcium Cyanamide Effects on Nitrogen Use Efficiency, Yield, Nitrates, and Dry Matter Content of Lettuce

      A 2-yr field study was conducted to evaluate the effects of calcium cyanamide as an alternative nitrogen (N) fertilizer source on N use efficiency (NUE), yield, and quality of two types of lettuce (Lactuca sativa L.), romaine (var. longifolia, cv. Manavert) and red oak-leaf (var. crispa, cv. (continued)

      Core Ideas:
      • Calcium cyanamide may be a good N fertilizer source for lettuce crops.
      • Calcium cyanamide can reduce nitrate accumulation in lettuce crops.
      • Calcium cyanamide did not improve lettuce crop N use efficiency.
      • Lettuce genotypes influence the crop N uptake and N utilization efficiency.

      Published: October 20, 2016

    • Yesuf Assen Mohammed, Chengci Chen and Reza Keshavarz Afshar
      Nutrient Requirements of Camelina for Biodiesel Feedstock in Central Montana

      Camelina (Camelina sativa L. Crantz) shows potential to provide an alternative renewable energy source and enhance crop diversification in temperate semiarid regions. Information on the effect of N, P, K, and S on yield and quality of camelina for biodiesel feedstock in the northern Great Plains (NGP) of the United States is limited. The objective of this experiment was to determine the effects of the above nutrients on seed and oil yields, test weight, oil concentration and agronomic nitrogen use efficiency (ANUE) of camelina on a clay loam soil in central Montana. (continued)

      Core Ideas:
      • The responses of camelina seed and oil yields to nutrient applications were substantial compared with the control treatment.
      • Trend analysis showed that camelina requires about 60 kg ha–1 N to achieve agronomic optimum seed and oil yields.
      • This agronomic data will help policy makers, researchers, growers, and end users to make decision in the production and processing of camelina as energy crop.

      Published: October 20, 2016

    • R. J. Yao, J. S. Yang, D. H. Wu, W. P. Xie, P. Gao and X. P. Wang
      Characterizing Spatial–Temporal Changes of Soil and Crop Parameters for Precision Management in a Coastal Rainfed Agroecosystem

      Understanding the intrinsic relationship between highly varied crop productivity and soil characteristics is essential for developing site-specific management practices. Our primary objectives were to quantify the temporal variation of soil attributes and crop productivity, to characterize the spatiotemporal variability and to delineate management zones of crop productivity for precision management. A pool of 12 soil properties (0–15 cm) and crop annual output (CAO) were collected annually from corn (Zea mays L.)–barley (Hordeum vulgare L.) rotation for three consecutive years in a coastal rainfed agroecosystem of East China. Results indicated that varying degrees of sustained temporal increase were observed for percentage of clay particles (CL), soil organic carbon (SOC), available nitrogen (AN), and CAO, whereas electrical conductivity of saturated soil paste extract (ECe), sodium adsorption ration (SAR) and soil available potassium (AK) declined continuously. (continued)

      Core Ideas:
      • Percentage of clay particles, soil organic carbon, and crop annual output increased while soil bulk density and electrical conductivity of saturated soil paste extract decreased over the 3-yr period.
      • Electrical conductivity of saturated soil paste extract showed temporal instability, and soil bulk density and percentage of clay particles exhibited temporal stability.
      • Separating the field into two management zones proved to be a good compromise.
      • The two management zones contributed to reducing sampling efforts.

      Published: October 17, 2016

    • Danilo S. Almeida and Ciro A. Rosolem
      Ruzigrass Grown in Rotation with Soybean Increases Soil Labile Phosphorus

      Crop rotations with species able to solubilize soil P can result in improved P availability for subsequent crops. Ruzigrass [Urochloa ruziziensis (R. Germ. and C.M. (continued)

      Core Ideas:
      • Ruzigrass grown in soybean off-season affects soil fertility.
      • Soil P cycling by ruzigrass may result in benefits to next crops.
      • Agronomic efficiency of phosphate fertilizers may be improved by ruzigrass.

      Published: October 6, 2016

    • 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.

      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.

      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.

      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.

      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.

      Published: September 15, 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.

      Published: September 1, 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.

      Published: August 25, 2016


    • 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.

      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.

      Published: September 1, 2016

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