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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(6)



  • AGRONOMIC APPLICATION OF GENETIC RESOURCES

    • José Juvencio Castañeda-Nava, Fernando Santacruz-Ruvalcaba, José de Jesús Sánchez González, José Ron Parra, Lino De la Cruz Larios and Rodrigo Barba-González
      Shading and Container Effects on the Weight of the Dioscorea sparsiflora Tuber

      Dioscorea sparsiflora Hemsley (camote de cerro) is a wild species with agricultural potential that is not exploited as a crop but is collected for consumption and sale in western Mexico. The objective of the present research was to evaluate the effect of different light intensities (26,000, 18,000, and 14,000 lux), three shading periods (60, 90, and 180 d), and five types of containers two cylindrical (7 and 9 L), one rectangular (60 L), and two hydroponic channels: one 30 cm wide (45 L), and the other, 40 cm wide (60 L) on two D. sparsiflora accessions. The performances of two accessions (751 and 112) in previous treatments were also evaluated. (continued)

      Core Ideas:
      • Effect of the light intensity in the weight of the tuber in D. sparsiflora.
      • Influence of the container in the development of the tuber in D. sparsiflora.
      • Response to shade-house period on the tuber weight of D. sparsiflora.
      • Crop managing in D. sparsiflora.

      doi:10.2134/agronj2015.0452
      Published: November 14, 2016



  • AGRONOMY, SOILS & ENVIRONMENTAL QUALITY

    • Aristotelis C. Tagarakis, Quirine M. Ketterings, Sarah Lyons and Greg Godwin
      Proximal Sensing to Estimate Yield of Brown Midrib Forage Sorghum

      Increasing home-grown forage production is important for the dairy industry. Double cropping of forage crops like corn (Zea mays L.) silage with cereal rye (Secale cereale L.) or triticale (× Triticosecale spp.) can increase full-season yield but could impact the length of the growing season for corn silage. Brown midrib (BMR) brachytic dwarf forage sorghum (Sorghum bicolor L.) has great potential as an alternative to corn silage in double crop rotations. Both winter cereals and forage sorghum require N management. (continued)

      Core Ideas:
      • Forage sorghum has potential as alternative to corn silage in rotation with winter cereals.
      • Crop sensing is a promising approach for predicting end-of-season yields. Yield prediction is the first step in development of algorithms for sensor-based N management.
      • To develop reliable algorithms for fertility management of forage sorghum in double crop rotations that account for timing, height of scanning and sensor orientation.
      • To evaluate which method of reporting of sensor measurements (NDVI, INSEYGDD, or INSEYDAP) gives the better prediction of yield.

      doi:10.2134/agronj2016.07.0414
      Published: January 5, 2017



    • Luis Villalobos and Joe E. Brummer
      Yield and Nutritive Value of Cool-Season Annual Forages and Mixtures Seeded into Pearl Millet Stubble

      Cool-season annual forages can provide grazing for beef cattle during fall and early winter. The objective of this study was to evaluate yield and nutritive value of nine forage combinations seeded in early August into pearl millet (Pennisetum glaucum L.) hay stubble that was either sprayed or allowed to regrow. Grass species included spring triticale (×Triticosecale Wittmack), winter wheat (Triticum aestivum L.), and winter barley (Hordeum vulgare L.). Each grass was then combined with a brassica mixture {turnip [Brassicas rapa L. (continued)

      Core Ideas:
      • Annual cool-season forages with high biomass yields may be stockpiled for fall grazing.
      • Species composition was affected by the seeding rates of individual species used within the bulk seeding rate.
      • Controlling millet regrowth with herbicide prior to seeding resulted in greater establishment, yield, and nutritive value of the seeded cool-season forages.
      • Annual forages can meet the requirements of beef cattle grazing during the fall and early winter.

      doi:10.2134/agronj2016.06.0324
      Published: January 5, 2017



    • Gurpreet Kaur, Brendan A. Zurweller, Kelly A. Nelson, Peter P. Motavalli and Christopher J. Dudenhoeffer
      Soil Waterlogging and Nitrogen Fertilizer Management Effects on Corn and Soybean Yields

      In the midwestern United States, excessive soil moisture resulting from extreme precipitation events during early spring can often cause decreases in corn (Zea mays L.) grain yields and escalate N loss. A field trial was conducted from 2013 to 2015 in Northeast Missouri to determine the effects of soil waterlogging duration, pre-plant N and rescue N fertilizer applications on corn and succeeding soybean [Glycine max (L.) Merr] production. Plots were either non-flooded or flooded for durations of 1, 3, or 7 d when corn was at V6 growth stage. Pre-plant N fertilizer treatments included non-treated control (CO), urea (NCU), urea plus nitrapyrin (NCU+NI), and polymer coated urea (PCU) applied at 168 kg N ha–1. (continued)

      Core Ideas:
      • Excessive soil moisture resulting from extreme precipitation events during early spring can often cause decreases in corn grain yields in the midwestern United States.
      • Each day of waterlogging resulted in an average corn grain yield loss of 0.42 Mg ha–1 and 0.72 Mg ha–1 in 2013 and 2014, respectively.
      • Pre-plant N fertilizer applications of non-coated urea; polymer coated urea, and non-coated urea+nitrification inhibitor resulted in 19% higher yields compared to the non-treated control in 2014.
      • Effects of rescue N fertilizer were seen on soybean yields in the succeeding year after corn, while rescue N affected corn yields only in 2014.
      • Climatic conditions including rainfall and air temperature had a significant role in crop response to waterlogging and N fertilizer treatments.

      doi:10.2134/agronj2016.07.0411
      Published: January 3, 2017



    • Yi-Min Chen, Yue-Yu Sui, Xiao-Guang Jiao and Xiao-Bing Liu
      Eight-Year Cattle Manure Amendment Alters Chemical and Biochemical Properties of Eroded Mollisols

      Soil chemical and biochemical properties are important indicators in assessing soil quality. To investigate the effect of manure application on eroded Mollisols, soil organic carbon (SOC), total nitrogen (TN), C/N ratio, and potentially mineralizable nitrogen (PMN), microbial biomass carbon (MBC), urease activity, and sucrase activity were determined after 8-yr application of cattle manure in combination with chemical fertilizers in a soil erosion simulation facility by removing the topsoil by 0, 5, 10, 20, and 30 cm in a typical Mollisols region in China. All parameters except C/N ratio showed a declining trend with the increasing of erosion depth. Soil organic C, TN, PMN, MBC, urease activity, and sucrase activity were 11 to 23, 5 to 9, 5 to 16, 11 to 19, 18 to 32 and 13 to 37% higher under the chemical fertilizer + manure treatment than the chemical fertilizer alone plots, respectively. (continued)

      Core Ideas:
      • Chemical and biochemical properties of eroded Mollisols were determined to assess the amending of the effect of organic manure on eroded Mollisols.
      • Organic manure in combination with NPK increased soil organic carbon and total nitrogen, but C/N ratios changed irregularly.
      • Organic manure in combination with NPK increased all biochemical indicators selected in eroded Mollisols.
      • Combination of organic manure and chemical fertilizers is recommended to amend eroded Mollisols.

      doi:10.2134/agronj2016.06.0378
      Published: December 16, 2016



    • Rakesh Awale and Amitava Chatterjee
      Enhanced Efficiency Nitrogen Products Influence Ammonia Volatilization and Nitrous Oxide Emission from Two Contrasting Soils

      Potentials of enhanced efficiency nitrogen (EEN) products to control N losses can vary with soil pH, cation exchange capacity, organic matter, water, temperature, and management. A laboratory experiment was conducted to quantify and compare ammonia (NH3) volatilization and nitrous oxide (N2O) losses with (i) control, (ii) urea, urea treated with (iii) urease inhibitor, NBPT [N-(n-butyl) thiophosphoric triamide], (iv) nitrification inhibitor, nitrapyrin (NP) [2-chloro-6-trichloro methyl pyridine], (v) urea stabilized with NBPT and nitrification inhibitor dicyandiamide (SuperU), and (vi) slow release N fertilizer polymer coated urea (PCU) amendments from Ulen sandy loam and Fargo silty clay soils. Across N amendments, cumulative NH3–N losses from sandy loam soil ranged from 0.7 to 4.3% of applied N, and were higher than those from silty clay soil (0.1–0.4% of applied N). In sandy loam, compared to urea, NBPT and PCU reduced NH3–N volatilization by 32.3 and 84.2%, respectively, whereas NP and SuperU increased NH3–N losses by 98.7 and 20.3%, respectively. (continued)

      Core Ideas:
      • Ammonia volatilization and N2O emissions from N-sources were assessed in two soils.
      • The N-(n-butyl) thiophosphoric triamide reduced NH3 volatilization losses from both sandy loam and silty clay soils.
      • Nitrapyrin and SuperU reduced N2O emissions from sandy loam soil only.
      • Polymer coated urea was effective in reducing both NH3 and N2O emissions from sandy loam soil.
      • Right N-source could mitigate gaseous N losses from agroecosystems.

      doi:10.2134/agronj2016.04.0219
      Published: November 17, 2016



    • Xingming Zhang, Hao Guo, Ran Wang, Degen Lin, Yuan Gao, Fang Lian and Jing’ai Wang
      Identification of the Most Sensitive Parameters of Winter Wheat on a Global Scale for Use in the EPIC Model

      The purpose of this study was to identify the most sensitive parameters (MSPs) of the Environmental Policy Integrated Climate (EPIC) model for winter wheat (Triticum aestivum L.) simulations across the globe. First, 48 crop parameters related to the growth process of winter wheat were selected from the EPIC model. The range and distribution were assigned to each crop parameter. Second, a number of samples of parameter combinations (SPCs) were generated, containing 48 random values of model parameters for each grid. (continued)

      Core Ideas:
      • Using computer technology, crop models are widely used in agricultural research and applications.
      • Sensitivity analysis can screen sensitive parameters to calibrate the EPIC model for different regions.
      • WA, HI, and TBS had a greater influence on simulated wheat yield than other parameters.
      • Elevation had a higher impact on the sensitivity of crop parameters, especially on TBS (0.53) and HI (–0.47).
      • These results can increase the efficiency of regional calibration of the EPIC model on a large scale.

      doi:10.2134/agronj2016.06.0347
      Published: November 14, 2016



    • Mostafa Ibrahim, Chang Oh. Hong, Shikha Singh, Sandeep Kumar, Shannon Osborne and Vance Owens
      Switchgrass Biomass Quality as Affected by Nitrogen Rate, Harvest Time, and Storage

      The purpose of this study was to assess the changes in switchgrass (Panicum virgatum L.) biomass quality as affected by N rate, harvest time, and storage. This research was conducted near Bristol, SD, in 2010 and 2011. Treatments included three N rates (0, 56, and 112 kg N ha–1) applied annually and each N rate replicated four times. After a killing frost, all of the plots were harvested and baled in large round bales in October 2010 and November 2011. (continued)

      Core Ideas:
      • Switchgrass, being an efficient perennial biofuel crop, can be used as an alternative to fossil fuels and help in the sustainability of energy. Thus, it is important that we understand the effect of storing switchgrass for extended periods of time.
      • Storing switchgrass for an extended period may have an impact on quality and yield.
      • Storing switchgrass in bales or as a standing crop in the field are two storage methods assessed in this study.

      doi:10.2134/agronj2016.07.0380
      Published: November 14, 2016



    • Mary A. Harty, Patrick J. Forrestal, Rachael Carolan, Catherine J. Watson, Deirdre Hennessy, Gary J. Lanigan, David P. Wall and Karl G. Richards
      Temperate Grassland Yields and Nitrogen Uptake Are Influenced by Fertilizer Nitrogen Source

      In temperate grasslands, N source influences greenhouse gas emissions. Nitrification and urea hydrolysis inhibitors can reduce these losses. The objective of this study was to evaluate the impact of N source, urease inhibitors, and nitrification inhibitors on temperate grassland yields and N uptake. Experiments were conducted at three locations over 2 years (6 site-years) on the island of Ireland, covering a range of soils and climatic conditions. (continued)

      Core Ideas:
      • CAN is a widely used form of straight N in Western Europe.
      • Urea+NBPT consistently delivered equal yields and N uptake compared with CAN.
      • CAN had higher N uptake than urea in 2 of 6 site-years, but yields were not different.
      • NBPT increased the N uptake of urea in 2 of 6 site-years but had no effect on yield.
      • Urea+DCD had lower yield and N uptake than CAN in 3 and 4 of 6 site-years, respectively.

      doi:10.2134/agronj2016.06.0362
      Published: November 14, 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.

      doi:10.2134/agronj2016.01.0030
      Published: October 20, 2016



  • BIOFUELS

    • José Alberto Oliveira, C. P. West, Elias Afif and Pedro Palencia
      Comparison of Miscanthus and Switchgrass Cultivars for Biomass Yield, Soil Nutrients, and Nutrient Removal in Northwest Spain

      Comparative performance tests of perennial grasses for biomass yield, quality, and soil nutrient removal are needed to guide decisions toward meeting European Union targets for renewable energy production. We compared hybrid miscanthus (Miscanthus × giganteus Greef and Deuter ex Hodkinson and Renvoize) and switchgrass (Panicum virgatum L.) cultivars Cave-in-Rock, (upland type), Alamo, and Kanlow (lowland types) for biomass yield and changes in soil macronutrient levels and removal rates in a humid Spanish environment. Soil and plant nutrient and C levels were measured after each annual biomass harvest for 4 yr. Plant nutrient concentrations were multiplied by biomass yield to express nutrient removal. (continued)

      Core Ideas:
      • Miscanthus and switchgrass are often touted as biomass crop choices, but have rarely been compared side-by-side.
      • Miscanthus was slower to establish than switchgrass cultivars, but out-yielded switchgrass in the latter 3 yr of the trial.
      • Phosphorus was the soil nutrient most likely to be drawn down to levels requiring fertilization, after N.

      doi:10.2134/agronj2016.07.0440
      Published: January 5, 2017



    • Michael J. W. Maw, James H. Houx and Felix B. Fritschi
      Nitrogen Use Efficiency and Yield Response of High Biomass Sorghum in the Lower Midwest

      High biomass sorghum [Sorghum bicolor (L.) Moench] could potentially produce high yields in the midwestern United States with minimal fertilizer inputs. However, little is known about the yield response, N uptake, nitrogen use efficiency (NUE), and nitrogen recovery efficiency (NRE) of high biomass sorghum (HBS) at varying N fertilization rates when grown for lignocellulosic ethanol. The objectives of this 2-yr study were to determine the effect of five N rates (0, 56, 112, 168, 224 kg N ha–1) on the dry matter (DM) yield and lignocellulosic ethanol yield (LEY), and the NRE and NUE of two HBS varieties in the midwestern United States. The two varieties responded similarly for most measured parameters. (continued)

      Core Ideas:
      • Two-year study evaluating high biomass sorghum yield response to a broad range of N treatments.
      • A minimal N fertilizer rate of 56 kg ha–1 is needed to increase average ethanol yield to 5519 L ha–1, with no additional yield benefit at greater N rates.
      • Yields were limited by varying environmental conditions and delayed planting.
      • Nitrogen recovery efficiency were greatest at low N rates, but N use efficiency more stable across N rates, but greatly impacted by environment.

      doi:10.2134/agronj2016.01.0044
      Published: December 1, 2016



  • BIOMETRY, MODELING & STATISTICS

    • Qi Jing, Budong Qian, Jiali Shang, Ted Huffman, Jiangui Liu, Elizabeth Pattey, Taifeng Dong, Nicolas Tremblay, Craig F. Drury, Bao-Luo Ma, Guillaume Jégo, Xianfeng Jiao, John Kovacs, Dan Walters and Jinfei Wang
      Assessing the Options to Improve Regional Wheat Yield in Eastern Canada Using the CSM–CERES–Wheat Model

      Wheat (Triticum aestivum L.) yield is relatively low in eastern Canada. This study aimed to assess fertilizer N management options to improve the regional yield of wheat using the CSM–CERES–Wheat model. The model was adapted to simulate winter wheat by replacing air temperatures with estimated temperatures under snow cover, and then the model was evaluated for simulating winter wheat using experimental data collected at two sites and spring wheat at three sites in eastern Canada. Across all the experimental years and sites, the normalized root mean squared error (nRMSE) between simulated and measured yields was 14%. (continued)

      Core Ideas:
      • Wheat yield at both field and regional scales was successfully simulated using CSM–CERES–Wheat.
      • There is a considerable room to improve spring wheat yield in eastern Ontario.
      • Average yield in eastern Ontario can reach 3600 kg ha–1 with fertilization at 100 kg N ha–1.
      • Crop models may need to include lodging—often related to high N rates in eastern Canada.

      doi:10.2134/agronj2016.06.0364
      Published: January 12, 2017



    • Tiago Olivoto, Velci Q. de Souza, Maicon Nardino, Ivan R. Carvalho, Maurício Ferrari, Alan J. de Pelegrin, Vinícius J. Szareski and Denise Schmidt
      Multicollinearity in Path Analysis: A Simple Method to Reduce Its Effects

      Some data arrangement methods often used may mask correlation coefficients among explanatory traits, increasing multicollinearity in multiple regression analysis. This study was performed to determine if the harmful effects of multicollinearity might be reduced in the estimation of the XX correlation matrix among explanatory traits. For this, data on 45 treatments (15 maize [Zea mays L.] hybrids sown in three places) were used. Three path analysis methods (traditional, with k inclusion, and traditional with trait exclusion) were tested in two scenarios: with XX matrix estimated with all sampled observations (ASO, n = 900) and with the XX matrix estimated with the average values of each plot (AVP, n = 180). (continued)

      Core Ideas:
      • The multicollinearity in path analysis was investigated in different scenarios.
      • A biometrical approach identified the multicollinearity-generating traits.
      • Data derived from averages overestimated the correlation coefficients.
      • The use of all sampled observations increased the accuracy in path analysis.
      • A simple sample tracking method that reduces multicollinearity is proposed.

      doi:10.2134/agronj2016.04.0196
      Published: January 5, 2017



    • K. T. Zeleke and D. J. Luckett
      A Canola Cultivar-Testing Dataset Used to Calculate Stress Tolerance Indices and Crossover Interactions

      Canola (Brassica napus L.) is a major temperate crop in Australia, and there is a dynamic commercial breeding industry producing new cultivars for growers. Improved stress tolerance in canola cultivars is of increasing importance, but it is difficult to detect and to breed for. Public-sector researchers need reliable information on which existing cultivars possess good stress tolerance and can be used as germplasm sources for traits worthy of pre-breeding research. We utilized the Australian National Variety Trial (NVT) data for released canola cultivars to examine two aspects of canola performance. (continued)

      Core Ideas:
      • Canola yield data were analyzed for 144 cultivars over 7 yr and 100 sites.
      • Cultivars showed large differences for the stress tolerance index.
      • Cultivars worthy of further stress-tolerance studies were identified.
      • G×E crossover analysis showed that adaptation was more often specific than general.

      doi:10.2134/agronj2016.05.0278
      Published: December 16, 2016



  • CLIMATOLOGY & WATER MANAGEMENT

    • 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.

      doi:10.2134/agronj2016.03.0166
      Published: October 27, 2016



  • CROP ECOLOGY & PHYSIOLOGY

    • Lucas A. Haag, Jonathan D. Holman, Joel Ransom, Tom Roberts, Scott Maxwell, Mark E. Zarnstorff and Leigh Murray
      Compensation of Corn Yield Components to Late-Season Stand Reductions in the Central and Northern Great Plains

      Hail insurance adjustment procedures for corn (Zea mays L.) in the United States prior to 2014 assumed that yield reductions from V9 through milk stage were linear with stand reduction on a percentage basis. Other research suggests that corn plants retain some level of yield plasticity past the V9 growth stage. Some methods of estimating yield reductions may not be appropriate for modern hybrids and management practices. Field trials were conducted in the central Great Plains near Garden City, KS, in 2008, 2009, and 2011 and the northern Great Plains near Prosper, ND, in 2008 to 2010. (continued)

      Core Ideas:
      • Plasticity of remaining yield components can reduce the impact of late season stand losses.
      • Stand reductions as late as V14 did not result in 1:1 yield losses.
      • The relative importance of yield component compensation varied by timing and location/hybrid.

      doi:10.2134/agronj2015.0523
      Published: January 12, 2017



    • Tohru Kobata, Hibiki Ishi and Hiroyuki Iwasaki
      A Reduction in Spikelet Number and Fertility Causes Yield Vulnerability in High-Yielding Rice

      In Japan, the indica × japonica rice (Oryza sativa L.) cultivars released since 1990 are high-yielding under favorable weather conditions. However, climate change may delay the end of the rainy season to midsummer and decrease irradiance in the dominant rice-growing season. The objectives of this study were to identify the critical yield component factor causing yield instability in these high-yielding cultivars under fluctuations of solar radiation. One standard-yield japonica, three high-yielding japonica-dominant, and two indica-dominant cultivars were grown in western Japan over 3 yr under contrasting radiation levels. (continued)

      Core Ideas:
      • Low irradiance caused by a later end to the rainy season as a result of climate change is of concern in Japan. The objectives of this study were to identify the critical factors causing yield instability in high-yielding indica- and japonica-dominant rice cultivars released from 1990 to 2010 in Japan over 3 yr with contrasting levels of radiation. In most of these new cultivars, the yield response to the decline in radiant conditions is not well known.
      • The spikelet number decreased with a decrease in solar radiation during the panicle formation stage, such that under low radiation conditions, the benefit of a high spikelet number in the high-yielding cultivars disappeared.
      • The significant effect of spikelet fertility on grain-filling under fluctuating radiation levels is specific to the high-yielding cultivars, whereas in the common cultivars, inadequate grain-filling in fertilized spikelets is the dominant effect of low irradiance after the middle of the reproductive stage.

      doi:10.2134/agronj2016.05.0274
      Published: January 5, 2017



    • Alexander J. Lindsey, Peter R. Thomison, David J. Barker and James D. Metzger
      Evaluating Water Exclusion using Plastic Ground Cover in Maize at Two Population Densities

      Evaluating maize (Zea mays L.) hybrids under drought conditions in rain-fed environments can be difficult using deficit irrigation practices, and installation of permanent rain-exclusion structures can be cost prohibitive. Covering the soil surface to reduce infiltration has been successful in other crops, but limited evaluation has been conducted in maize systems of the U.S. Corn Belt. The objective of this study was to determine if black plastic ground cover could exclude water from maize under varying agronomic conditions to generate dry soil conditions. (continued)

      Core Ideas:
      • Evaluating drought-tolerant maize hybrids is a challenge in the eastern U.S. Corn Belt.
      • Treatments with black plastic had lower soil moisture with minor increases in soil temperature.
      • Water exclusion using plastic ground cover reduced soil moisture and grain yield compared to the rain-fed plus irrigation control.

      doi:10.2134/agronj2016.09.0508
      Published: January 5, 2017



    • Gabriel Santachiara, Lucas Borrás and José L. Rotundo
      Physiological Processes Leading to Similar Yield in Contrasting Soybean Maturity Groups

      Soybean [Glycine max (L.) Merr.] maturity groups (MGs) exhibit large variation in time to maturity, and are adapted to different latitudes. There is a range of MGs that have similar yield potential at most production regions, especially at temperate and tropical environments. We tested whether similar yields in contrasting MGs are achieved through different physiological processes. Our objectives were: (i) to characterize biomass accumulation, reproductive partitioning and seed set efficiency, and (ii) to analyze the role of N and radiation in biomass accumulation during the seed set period in contrasting MGs. (continued)

      Core Ideas:
      • Different soybean maturity groups with similar yields are farmed in many temperate regions.
      • Reproductive biology and biomass accumulation during seed set was similar for MGs III and IV.
      • Groups differed in radiation interception, N uptake, and the length of the seed set period.
      • Yield limiting traits tailored for earlier and later soybean were identified.

      doi:10.2134/agronj2016.04.0198
      Published: December 1, 2016



    • Eltayib Abidallha, Leila I. M. Tambel, Li Heng, Xiang Zhang and De-Hua Chen
      Changed Growth Characteristics with Bacillus thuringiensis Gene Introduction and Nitrogen Regulation in Bt Cotton

      Changes in vegetative and reproductive growth have been widely observed in Bacillus thuringiensis (Bt) transgenic cotton (Gossypium hirsutum L.). The objectives of this study were to determine the characteristics of vegetative and reproductive growth after the Bt gene was introduced into cotton and to study the effect of N on vegetative and reproductive growth to determine if N nourishment could provide a potential mechanism for changed growth characteristics in Bt cotton. Three Bt cultivars (Sikang1, Ccsi41, and Ccsi45), with their current parents (Simian3, Ccsi23, and Jimian7, respectively), were chosen to compare the characteristics of vegetative and reproductive growth and N distribution, in 2011 to 2012; the same six cultivars with two N fertilizer application rate treatments (0 and 450 kg/ha) were further designed to investigate the N regulation impact on growth in 2013. The results indicated that the Bt cotton cultivars had higher growth rates of main stem leaf area, sympodium leaf number, and plant height and a lower growth rate of sympodium leaf area than their parents. (continued)

      Core Ideas:
      • Bt cotton cultivars had higher sympodium leaf number and plant height.
      • Bt cotton cultivars had higher growth rates of main stem leaf and lower growth rate of sympodium leaf area.
      • Bt cotton cultivars had higher numbers of fruiting branches, fruiting nodes, bolls, and retained boll rates.
      • N-deficit and N-rich treatments affected number and rates of vegetative and reproductive organs.

      doi:10.2134/agronj2016.04.0209
      Published: December 1, 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.

      doi:10.2134/agronj2016.06.0353
      Published: October 20, 2016



  • CROP ECONOMICS, PRODUCTION & MANAGEMENT

    • Christopher A. Seifert, Michael J. Roberts and David B. Lobell
      Continuous Corn and Soybean Yield Penalties across Hundreds of Thousands of Fields

      The effects of crop rotations on yields have historically been assessed with field trials, but new datasets offer an opportunity to evaluate these effects using data from commercial farmers’ fields. Here we develop a unique dataset of 748,374 joint observations of field-level yields, crop histories, and soil and weather conditions across the U.S. Midwest to empirically evaluate crop rotations. For rainfed fields, we found an average continuous corn (Zea mays L.) yield penalty (CCYP) of 4.3% and continuous soybean [Glycine max (L.) Merr.] yield penalty (CSYP) of 10.3% during the 2007 to 2012 growing seasons. (continued)

      Core Ideas:
      • Analysis of 748,374 yield records showed a 4.3% yield penalty for continuous corn.
      • Corn yield penalties were more severe in areas with low moisture and low yields.
      • Continuous soybean showed a 10.3% yield penalty, worse in low-yielding years.
      • Corn yield penalties grew with up to 3 yr of continuous cropping, but not more.
      • Soybean penalties increased monotonically with number of years continuously cropped.

      doi:10.2134/agronj2016.03.0134
      Published: January 12, 2017



    • L. Nalley, J. Tack, A. Durand, G. Thoma, F. Tsiboe, A. Shew and A. Barkley
      The Production, Consumption, and Environmental Impacts of Rice Hybridization in the United States

      The introduction of hybrid rice in the United States gives producers an alternative to traditionally cultivated, conventional lines. The objective of our study is to estimate the economic (consumer and producer welfare) and environmental impacts of the commercial adoption of hybrid rice in the Mid-South of the United States. In our study, the revenue gains associated with hybrid adoption were estimated at an average of $76.24 million annually from 2003 to 2013, using existing research findings in combination with original modeling. Disease packages, specifically the blast resistance found in all publically released hybrids, led to both cost and fungicide reductions, which in turn result in higher profits and increased levels of environmental sustainability. (continued)

      Core Ideas:
      • This study estimated the economic and environmental impact of hybrid rice adoption.
      • The blast resistance in hybrid rice is estimated to be worth $14.35 million annually.
      • Hybrid adoption in the Mid-South feeds an additional 5.89 million people annually.
      • The LCA indicated that hybrid rice had lower environmental impact, mainly due to increase d yields.

      doi:10.2134/agronj2016.05.0281
      Published: January 5, 2017



    • Ti Zhang, Eric N. Johnson, Thomas C. Mueller and Christian J. Willenborg
      Early Application of Harvest Aid Herbicides Adversely Impacts Lentil

      Applying harvest aid herbicides can dry down lentil (Lens culinaris Medik.) crops evenly and quickly, and can help control late-emerging weeds. However, improper application timing may reduce yield and quality, and leave unacceptable herbicide residues in seed, which can cause commercial issues when marketing lentil. The objective of this research was to determine the response of lentil to various application timings of glyphosate, saflufenacil, and the combination of these two herbicides. A field experiment consisting of a randomized complete block design was run at Saskatoon and Scott, SK, Canada in 2012, 2013, and 2014 to address the objective. (continued)

      Core Ideas:
      • Improper application timing of harvest aids may reduce lentil seed yield and quality, and leave unacceptable herbicide residues in seed.
      • Application of harvest aids before 30% seed moisture content reduced lentil seed yield and thousand seed weight.
      • These application timings resulted in lentil seed samples exceeding residue levels of 2 and 0.03 mg kg–1 for glyphosate and saflufenacil, respectively.

      doi:10.2134/agronj2016.07.0419
      Published: December 8, 2016



    • Alan J. Schlegel, Yared Assefa, Lucas A. Haag, Curtis R. Thompson, Johnathon D. Holman and Loyd R. Stone
      Yield and Soil Water in Three Dryland Wheat and Grain Sorghum Rotations

      Diverse crop rotations sustain crop productivity by increasing crop water productivity and improving soil structure. The objective of this study was to compare two 4-yr winter wheat (Triticum aestivum L.) and grain sorghum (Sorghum bicolor L.) rotations in terms of grain yield, available soil water, and water productivity along with continuous winter wheat. A field study was conducted from 1996 through 2015 on a deep silt loam soil near Tribune, KS. The study consisted of three crop rotations: continuous annual wheat (WW), wheat–wheat–sorghum–fallow (WWSF), and wheat–sorghum–sorghum–fallow (WSSF). (continued)

      Core Ideas:
      • Grain yield of the second wheat crop was 80% of first wheat crop in WWSF.
      • Grain yield of the second sorghum crop was 63% of first sorghum crop in WSSF.
      • Four-year rotations were similar in productivity to 3-yr WSF.
      • Water productivity was greater with 4-yr rotations than continuous wheat.
      • Continuous no-till did not increase second year wheat and sorghum yields.

      doi:10.2134/agronj2016.07.0387
      Published: November 17, 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.

      doi:10.2134/agronj2016.06.0377
      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.

      doi:10.2134/agronj2016.05.0289
      Published: October 27, 2016



  • EUROPEAN TURFGRASS SOCIETY CONFERENCE

    • 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.

      doi:10.2134/agronj2016.05.0257
      Published: October 20, 2016



  • FORUM

    • C. A. Francis, E. S. Jensen, G. Lieblein and T. A. Breland
      Agroecologist Education for Sustainable Development of Farming and Food Systems

      Twelve educational strategies for future agroecologists are based on experiences in Nordic universities, with priorities informed by six propositions about future resource challenges. The principal objective is student learning for future challenges and contributions to sustainable development of farming and food systems, including practice in acquiring capacities needed for responsible future action. The heart of the program is learning to apply ecological principles in design of farming and food systems, using multi-criteria evaluation for prioritizing sustainability challenges, and measuring ex-ante success of transition. Working closely with farming and food system stakeholders in design and implementation of learning environment is essential, plus recognizing contributions of farmers and food system professionals as vital to education for design of future systems. (continued)

      Core Ideas:
      • Ecological principles are applied in design of future farming systems.
      • Close working relationships with farmers and other stakeholders are essential to education.
      • Educational programs will develop autonomous and social learners.
      • Local food systems provide an alternative to growing globalization of food.
      • Graduate study in agroecology prepares students for responsible action in the future.

      doi:10.2134/agronj2016.05.0267
      Published: January 5, 2017



    • Alyssa Cho, Debolina Chakraborty and Diane Rowland
      Gender Representation in Faculty and Leadership at Land Grant and Research Institutions

      Representation of women in agricultural science was 5% in 1979, increasing to 12% by 2005. The near equal numbers of women and men receiving Ph.D. degrees in agricultural science in 2012 (44 to 56%, respectively) would suggest an upward trend of women scientists above 12% should be occurring over time. To monitor possible trends in the representation of women in agricultural science, we quantified the numbers of women at land grant institutions at the faculty and higher administration level and in leadership positions within scientific societies, industry boards, and government research positions. (continued)

      Core Ideas:
      • Female faculty in agricultural sciences has increased from 12 to 23% in the last 10 yr.
      • Higher leadership positions within academia, industry, and government research positions are primarily held by men.
      • The proportion of women with Ph.D. degrees in agricultural sciences is still higher than those with careers and leadership positions.

      doi:10.2134/agronj2015.0566
      Published: December 8, 2016



  • INTERNATIONAL TURFGRASS SOCIETY CONFERENCE

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

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

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

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



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

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

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

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



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

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

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

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



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

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

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

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



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

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

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

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



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

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

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

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



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

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

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

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



  • NOTES & UNIQUE PHENOMENA

    • Stephen C. Mason, Cory G. Walters, Tomie D. Galusha, Roger K. Wilson and Zaher Kmail
      Planting Saved Roundup Ready 1 Soybean Seed Implications on Yield and Profit

      A 3-yr study was conducted to address agronomic considerations and economic feasibility for the legal right for Nebraska farmers to plant saved seed of Roundup Ready (RR1) (Monsanto Company, St. Louis, MO) soybean [GLYCINE MAX (L). Merr.] varieties rather than purchasing commercial Genuity (Monsanto Company, St. Louis, MO) Round Ready 2 Yield (to be referred to as RR2Y throughout the rest of the manuscript) seed. (continued)

      Core Ideas:
      • RR1 Soybean seed produces similar yield to RR2Y seed.
      • Saving RR1 soybean affords large economic advantages with lower risk.
      • Saved RR1 soybean seed had similar yield, bulk densities, and percent lodging as commercial RR2Y seed.

      doi:10.2134/agronj2016.05.0284
      Published: January 5, 2017



  • ORGANIC AGRICULTURE & AGROECOLOGY

    • C. L. Keene, W. S. Curran, J. M. Wallace, M. R. Ryan, S. B. Mirsky, M. J. VanGessel and M. E. Barbercheck
      Cover Crop Termination Timing is Critical in Organic Rotational No-Till Systems

      Cover crop-based rotational no-till enables organic farmers to reduce labor and build soil health. In these systems, cover crops are terminated with a roller-crimper and cash crops are direct-seeded into the resulting mulch. A systems experiment was conducted at three Mid-Atlantic locations to test how cover crop termination timing affects cover crop biomass production, control, and volunteers in subsequent crops during the transition to organic production. The annual crop rotation was hairy vetch (Vicia villosa Roth) plus triticale (x Triticosecale Wittm.)–corn (Zea mays L.)–cereal rye (Secale cereale L.)–soybean [(Glycine max (L.) Merr.]–winter wheat (Triticum aestivum L.) using a full-entry design. (continued)

      Core Ideas:
      • Hairy vetch–triticale biomass peaked at early hairy vetch flowering but mechanical control was highest at late flowering to early pod set.
      • Cereal rye biomass peaked at late dough stage but optimal mechanical control was obtained between 50% anthesis and early milk stages.
      • Volunteer hairy vetch was problematic in Delaware and Maryland whereas volunteer cereal rye was problematic in Pennsylvania.
      • Volunteer cover crops resulting from incomplete termination with mechanical rolling can be problematic in subsequent crops and may impact the benefits of organic rotational no-till.

      doi:10.2134/agronj2016.05.0266
      Published: January 3, 2017



    • 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.

      doi:10.2134/agronj2016.03.0174
      Published: October 20, 2016



  • PEST INTERACTIONS IN AGRONOMIC SYSTEMS

    • José Roberto Brito Freitas, Mara Regina Moitinho, Daniel De Bortoli Teixeira, Elton da Silva Bicalho, João Fernandes da Silva, Diego Silva Siqueira, Bruno Flávio Figueiredo Barbosa, Pedro Luiz Martins Soares and Gener Tadeu Pereira
      Soil Factors Influencing Nematode Spatial Variability in Soybean

      The economic damage to Brazilian soybean [Glycine max (L.) Merr.] production attributed to Pratylenchus brachyurus has increased in recent years. The objective of this study was to determine the influence of soil properties on nematode variability in a soybean crop. Soil and root samples (0–0.20 m) were collected from 142 points in an area that was 180 by 180 m. Root samples were analyzed for nematodes, and soil samples were analyzed for chemical attributes. (continued)

      Core Ideas:
      • Spatial distribution P. brachyurus nematode is influenced by soil chemical properties.
      • In sites with low fertility the plants become more susceptible to nematode attack.
      • In sites concentrating greater amount Mg are favorable to greater number of nematode.

      doi:10.2134/agronj2016.03.0160
      Published: January 5, 2017



    • Guoqi Chen, Qinghu Liu, Yuhua Zhang, Jun Li and Liyao Dong
      Comparison of Weed Seedbanks in Different Rice Planting Systems

      Machine-transplanted rice (Oryza sativa L.) (MTR), water direct-seeded rice (WDSR), and dry direct-seeded rice (DDSR) are three important alternatives to traditional manual transplantation of rice. Weed infestation is a pervasive problem in all rice planting systems. The weed seedbanks under different rice planting systems have seldom been compared. Thus, we sampled weed seeds in fields employing MTR, WDSR, and DDSR consecutively for at least 5 yr in Wujin County, eastern China. (continued)

      Core Ideas:
      • Weed seedbanks were compared in three rice planting systems: machine-transplanted rice, water direct-seeded rice, and dry direct-seeded rice.
      • Weed seedbanks were mainly distributed in soil within a depth of 10 cm.
      • Dry direct-seeded rice tended to maintain larger seedbanks of sedges, grasses, and some upland weeds.
      • Water direct-seeded rice contained the smallest weed seedbank overall.
      • Machine-transplanted rice had larger seedbanks of broadleaf weeds and some traditional rice weeds.

      doi:10.2134/agronj2016.06.0348
      Published: January 5, 2017



  • REVIEW & INTERPRETATION

    • Aijânio G. B. Silva, Cleiton H. Sequeira, Renata A. Sermarini and Rafael Otto
      Urease Inhibitor NBPT on Ammonia Volatilization and Crop Productivity: A Meta-Analysis

      The urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) slows urea hydrolysis, reduces NH3 volatilization loss, and enhances N availability to plants. Even though most studies have proved the potential of NBPT-treated urea to reduce NH3 loss, the benefits to increase crop yield have been less consistent, mainly because N is not always the limiting factor. A meta-analysis was carried out to evaluate the effect of soil properties (e.g., soil pH, soil texture, soil organic C [SOC]), N rate, and NBPT concentration on NH3 volatilization loss and crop yield when comparing urea with NBPT-treated urea. Regression analysis indicated cumulative NH3 loss of 31.0 and 14.8% of applied N for urea and NBPT-treated urea, respectively, a 52% reduction in NH3 loss by using the urease inhibitor. (continued)

      Core Ideas:
      • The volatilization losses averaged 31.0% of applied N for urea and 14.8% for NBPT-treated urea.
      • NBPT-treated urea showed a potential yield increase of 5.3% for major crops.
      • The effect of NBPT in reducing volatilization losses were reduced under high N rates.
      • NBPT had a limited effect on increasing yield in coarse-textured soils and for NBPT rates >1060 mg kg–1.

      doi:10.2134/agronj2016.04.0200
      Published: December 16, 2016



  • SOIL FERTILITY & CROP NUTRITION

    • Dan S. Long, John D. McCallum, Catherine L. Reardon and Richard E. Engel
      Nitrogen Requirement to Change Protein Concentration of Spring Wheat in Semiarid Pacific Northwest

      On-combine yield monitors and grain protein analyzers enable mapping of grain N removal at time of harvest. Nitrogen removal maps combined with estimates of the fertilizer nitrogen equivalent (FNE) for each 10 g kg–1 change in grain protein concentration (GPC) are useful for developing site-specific fertilizer prescriptions for fields. This study was conducted to determine the critical protein concentration where yield is maximized and FNE for spring wheat (Triticum aestivum L.) grown under low annual precipitation (<350 mm) in the inland Pacific Northwest. Five hard red spring (HRS) cultivars and one soft white spring (SWS) cultivar were grown under three water levels over an N application range of 0–235 kg ha–1 in eastern Oregon. (continued)

      Core Ideas:
      • Nitrogen removal maps combined with the fertilizer N equivalent are useful for precision N management.
      • More N is needed to change spring wheat protein in Pacific Northwest than in northern Plains.
      • The fertilizer N equivalent is generalizable among spring wheat cultivars.
      • Growers can use yield and protein maps to implement the N replacement approach

      doi:10.2134/agronj2016.09.0518
      Published: January 12, 2017



    • Christopher Graham, Howard Woodard, Anthony Bly, Paul Fixen and Ronald Gelderman
      Chloride Fertilizers Increase Spring Wheat Yields in the Northern Great Plains

      Chloride (Cl) plays an important role in osmoregulatory functions within the plant and aids in disease suppression. Previous research established a soil sufficiency level and fertilizer Cl recommendations based on a 0- to 60-cm soil depth sample. This work found spring wheat (Triticum aestivum L.) yield was responsive to Cl fertilizers on soils with low Cl soil tests. However, the response was often variable and cultivar specific, which suggested that further refinements to the Cl fertilizer recommendations were necessary. (continued)

      Core Ideas:
      • Across all site-years of the study, results show a statistically significant grain yield increase of 0.17 t ha–1.
      • Where pre-plant soil test Cl– levels were lower than 1.87 mg kg–1, fertilizer Cl– applications increased grain yield by 0.26 t ha–1 with an average return of $18.42 ha–1.
      • The potential profitability of Cl– fertilizer application is highly dependent on the choice of cultivar.

      doi:10.2134/agronj2016.04.0205
      Published: January 5, 2017



    • Randy J. Dempsey, Nathan A. Slaton, Richard. J. Norman and Trenton L. Roberts
      Ammonia Volatilization, Rice Yield, and Nitrogen Uptake Responses to Simulated Rainfall and Urease Inhibitor

      The effect of rainfall between urea application and flood establishment on rice (Oryza sativa L.) grain yield has not been studied. We compared the effects of simulated rainfall amount and N-(n-butyl) thiophosphoric triamide (NBPT) urease inhibitor rate on NH3 volatilization and rice growth. Three field experiments were conducted and NH3 volatilization was measured in two trials for 11 d after urea application (DAA). Untreated urea (Urea) or NBPT-treated urea (NBPT-Urea) was subjected to six simulated rainfall amounts (0–25.4 mm) applied 5 to 15 h after fertilizer application and flooded 7 to 12 DAA. (continued)

      Core Ideas:
      • Rainfall between preflood urea-N application and flooding can be detrimental to rice grain yield.
      • Use of the NBPT reduces yield loss from N transformations facilitated by rainfall between the urea application and flooding.
      • Rainfall after urea application appears to reduce NH3 loss but enhance denitrification.

      doi:10.2134/agronj2016.06.0374
      Published: January 3, 2017



    • María Florencia Varela, Mirian Barraco, Adriana Gili, Miguel Angel Taboada and Gerardo Rubio
      Biomass Decomposition and Phosphorus Release from Residues of Cover Crops under No-Tillage

      Under no-tillage field conditions, cover crop (CC) residues remain on the soil surface and decompose at a slow rate. We used three CC species (oat, Avena sativa L.; rye, Secale cereale L.; and ryegrass, Lolium multiflorum L.) to evaluate the residue biomass decomposition and P pools release–total phosphorus (Pt), inorganic phosphorus (Pi), and organic phosphorus (Po)–under no-tillage field conditions. The dynamics of biomass and P in CC residues was evaluated through the litterbag method during two annual periods in a long-term field experiment. Exponential decay models were fitted to each variable. (continued)

      Core Ideas:
      • Residue decomposition and P release was studied under no tillage field conditions.
      • Cover crop residues releases significant quantities of P for the subsequent cash crop.
      • Phosphorus release from residues is affected by precipitation regime and residue quality.
      • A positive tradeoff was observed between crop residue P dynamics and soil coverage.

      doi:10.2134/agronj2016.03.0168
      Published: January 3, 2017



    • Alan J. Schlegel and John L. Havlin
      Corn Yield and Grain Nutrient Uptake from 50 Years of Nitrogen and Phosphorus Fertilization

      Long-term agricultural field experiments provide valuable information regarding the effects of nutrient inputs on crop productivity. The objectives of this study were to quantify the effects of 50 yr of annual N and P application on irrigated continuous corn (Zea mays L.) grain yield, grain nutrient uptake, and economic optimum N rates. Six N (0, 45, 90, 134, 179, and 224 kg N ha–1) and three P rates (0, 20, and 40 kg P ha–1) in a factorial arrangement were applied annually from 1992 to 2010 to a Ulysses silt loam near Tribune, KS. From 1961 to 1991, only two P rates (0 and 20 kg P ha–1) were applied with the six N rates. (continued)

      Core Ideas:
      • Initiated in 1961, a 50-yr field study quantified continuous irrigated corn response to annual N and P rates.
      • Positive N–P interactions on grain yield and grain N/P concentrations were documented.
      • Economic optimum N rate varied greatly over years, but averaged ∼175 kg N ha–1 (1992-2010).
      • Significantly greater apparent fertilizer N recovery in grain (∼45%) occurred with P fertilization compared to no P (∼20%).
      • Long-term field studies can be used to improve nutrient effects on productivity.

      doi:10.2134/agronj2016.05.0294
      Published: November 17, 2016



    • William Frame
      Ammonia Volatilization from Urea Treated with NBPT and Two Nitrification Inhibitors

      Nitrification inhibitors reduce the rate of transformation of ammonium to nitrate, which may increase ammonia volatilization from urea-based N fertilizers. The objective of this study was to quantify ammonia volatilization from surface-applied granular urea treated with combinations of NBPT and the nitrification inhibitors, DCD and nitrapyrin, under controlled laboratory conditions for three soils. Nine laboratory trials evaluated select combinations of application rates for NBPT, DCD, and nitrapyrin-treated urea. Trials were conducted on three soils selected for differences in pH, organic matter, and cation exchange capacity (CEC). (continued)

      Core Ideas:
      • A comparison of ammonia volatilization from granular urea treated with two commercially available nitrification inhibitors and the interaction with the urease inhibitor, NBPT.
      • Nitrification inhibitors increased ammonia volatilization from surface-applied granular urea compared to untreated urea.
      • When treating urea with nitrification inhibitors, a urease inhibitor should be applied to reduce ammonia volatilization losses.
      • Soil type specific recommendations may be needed when applying nitrification/urease inhibitors to urea in order to maximize N use efficiency.

      doi:10.2134/agronj2016.08.0464
      Published: November 14, 2016



    • Amir Sadeghpour, Quirine M. Ketterings, Gregory S. Godwin and Karl J. Czymmek
      Under- or Over-Application of Nitrogen Impact Corn Yield, Quality, Soil, and Environment

      Under- or over-application of N fertilizer to corn (Zea mays L.) has adverse economic and environmental consequences. A 5-yr study was conducted to determine the impact of N fertilizer on corn silage yield, quality, soil properties, farm economics, and nitrogen-use efficiency (NUE). Corn silage yields were 12.9, 14.2, and 14.7 Mg ha–1 with most economic rate of nitrogen (MERN) of 90, 95, and 114 kg N ha–1 in 2001, 2003, and 2004 (the three responsive years), respectively. In 2002 and 2005 (non-responsive years), yields averaged 9.1 Mg ha–1. (continued)

      Core Ideas:
      • Nitrogen application mid-season cannot overcome drought stress later in the season.
      • Except for crude protein, under-application of N did not impact forage quality.
      • Soil organic matter decreases in a chisel-disked corn silage system regardless of N fertilizer rate.
      • Use of compost, cover crops, and conservation tillage can offset soil organic matter losses.
      • Under-applying N by 30 kg N ha–1 was economically more detrimental than over-applying.

      doi:10.2134/agronj2016.06.0355
      Published: November 14, 2016



    • Juan Orcellet, Nahuel Ignacio Reussi Calvo, Hernán Rene Sainz Rozas, Nicolás Wyngaard and Hernán E. Echeverría
      Anaerobically Incubated Nitrogen Improved Nitrogen Diagnosis in Corn

      Current N diagnostic methods for corn (Zea mays L.) are often based on the nitrate nitrogen (NO3–N) concentration before planting (pre-plant nitrate test, PPNT) and nitrate nitrogen (NO3–N) concentration at V6 stage (PSNT). These tests provide scant information on soil N mineralization during the growing season, which can supply a considerable proportion of corn N requirements. The objective of our study was to evaluate if in-season N recommendations could be improved by inclusion of a N mineralization potential estimator. We conducted field experiments (n = 35) in three different areas and in two planting dates. (continued)

      Core Ideas:
      • Traditional corn N diagnostic methods (pre-plant nitrate N test and pre-sidedress nitrate N test) only account for mineral N.
      • Objective: to improve N diagnostic methods by considering N mineralization.
      • Pre-plant nitrate N test and pre-sidedress nitrate N test were improved by anaerobic-N (Nan) in areas with similar soil/climates.
      • Models combining Nan, texture and temperature improved pre-plant nitrate N test and pre-sidedress nitrate N test in all areas.

      doi:10.2134/agronj2016.02.0115
      Published: November 14, 2016



    • H. Bu, L. K. Sharma, A. Denton and D. W. Franzen
      Comparison of Satellite Imagery and Ground-Based Active Optical Sensors as Yield Predictors in Sugar Beet, Spring Wheat, Corn, and Sunflower

      Algorithms using active-optical (AO) sensors have been developed to direct in-season N application to crops. Many farmers in the United States have a large number of farm fields to manage. Farmers using AO technology must visit each field and operate the sensor across the entire field in order to conduct in-season N application. A field might be driven over with an on-the-go N fertilizer applicator, but the application might not be required. (continued)

      Core Ideas:
      • Satellite imagery could be used to predict yield the study crops.
      • Satellite imagery could be used to screen fields for in-season N application.
      • Obtaining satellite imagery early enough in the season to screen fields for in-season N is a problem.

      doi:10.2134/agronj2016.03.0150
      Published: November 14, 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.

      doi:10.2134/agronj2016.01.0034
      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.

      doi:10.2134/agronj2016.06.0366
      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.

      doi:10.2134/agronj2016.03.0163
      Published: October 20, 2016



  • SOIL TILLAGE, CONSERVATION & MANAGEMENT

    • Upendra M. Sainju, Andrew W. Lenssen, Brett L. Allen, William B. Stevens and Jalal D. Jabro
      Soil Total Carbon and Crop Yield Affected by Crop Rotation and Cultural Practice

      Stacked crop rotations and improved cultural practices have been used to control pests, but their impact on soil total carbon (STC) (soil organic carbon [SOC] + soil inorganic carbon [SIC]) and crop yield are lacking. We evaluated the effects of stacked vs. alternate-year rotations and cultural practices on STC at the 0- to 125-cm depth and annualized crop yields from 2005 to 2011 in the northern Great Plains. Stacked rotations were durum (Triticum turgidum L.)–durum–canola (Brassica napus L.)–pea (Pisum sativum L.) (D–D–C–P) and durum–durum–flax (Linum usitatissimum L.)–pea (D–D–F–P). (continued)

      Core Ideas:
      • Stacked crop rotation and improved cultural practice can control pests.
      • The effects of such management practices on soil total carbon is lacking.
      • Effects of crop rotation and cultural practice on STC and crop yield were evaluated.
      • Crop yield and STC at several depths were lower in stacked than other rotations.
      • Alternate-year rotation may enhance crop yield and STC compared to other rotations.

      doi:10.2134/agronj2016.07.0402
      Published: December 1, 2016



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