@article{morales_gatiboni_osmond_vann_kulesza_crozier_hardy_2023, title={Critical soil test values of phosphorus and potassium for soybean and corn in three long-term trials in North Carolina}, volume={1}, ISSN={["1435-0661"]}, url={https://doi.org/10.1002/saj2.20491}, DOI={10.1002/saj2.20491}, abstractNote={Abstract Soil test correlation is continuously necessary to affirm critical soil test values (CSTV) for specific nutrients, as changes in crop management and development of new plant varieties may change CSTVs. The objective of this study was to determine the CSTVs of phosphorus (P) and potassium (K) for soybean [ Glycine max (L.) Merr.] and corn ( Zea mays L.) using three long‐term trials in North Carolina. Soybean was cultivated in 2020 and corn in 2021 in three long‐term trials established on research stations located in the Tidewater, Coastal Plain, and Piedmont regions of NC. In each trial, up to five rates of P (0–88.2 kg P ha −1 ) and K (0–186.8 kg K ha −1 ) were applied annually at planting. Soil and tissue samples were analyzed and yield measured. There was yield response to P in all site‐years. The average CSTVs of P for corn and soybean were 51, 66, and 14 mg kg −1 for the sites at Tidewater, Coastal Plain, and Piedmont regions. The CSTV of P for Piedmont (14 mg kg −1 ) differs greatly from the current recommendation for NC (52 mg kg −1 ). The response to K fertilization was observed only in three site‐years and the CSTVs varied from 49 to 93 mg kg −1 , while the current recommendation is setting the CSTV of K at 85 mg kg −1 . These results indicate it is necessary to develop further studies of soil test correlation for P and K in North Carolina to better estimate the CSTVs for the state.}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Morales, Nelida Agramont and Gatiboni, Luke and Osmond, Deanna and Vann, Rachel and Kulesza, Stephanie and Crozier, Carl and Hardy, David}, year={2023}, month={Jan} }
 @article{tilley_jordan_vann_gatiboni_heiniger_stevens_ambrose_2023, title={Influence of planting pattern on corn response to sub-surface drip irrigation}, volume={9}, ISSN={["2374-3832"]}, DOI={10.1002/cft2.20247}, abstractNote={NoneThis article is protected by copyright. All rights reserved}, number={2}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Tilley, M. Scott and Jordan, David L. and Vann, Rachel A. and Gatiboni, Luke and Heiniger, Ronnie W. and Stevens, Brian and Ambrose, Derek}, year={2023}, month={Dec} }
 @article{almeida_correndo_ross_licht_casteel_singh_naeve_vann_bais_kandel_et al._2023, title={Soybean yield response to nitrogen and sulfur fertilization in the United States: contribution of soil N and N fixation processes}, volume={145}, ISSN={["1873-7331"]}, DOI={10.1016/j.eja.2023.126791}, abstractNote={Soybean [Glycine max (L.) Merr.] is the most important legume grown worldwide. The effect of nitrogen (N) and sulfur (S) fertilization on seed yield is commonly studied in the United States (US). However, soybean yield response to fertilization remains inconsistent, partly due to the lack of standardized field designs and a better understanding of the plant nutrition processes underpinning yield formation. The aims of this study were to assess the i) seed yield, (ii) plant N status (as N nutrition index, NNI), (iii) the contribution of N fixation, and (iv) the uncertainties on i), ii), and iii) in response to N-S fertilization using a uniform protocol across environments. Twenty-six trials in twelve US states tested five fertilization strategies that combined N and S at varying rates and timings. Using Bayesian statistics, seed yield response to fertilizer, NNI, and contribution of N fixation were analyzed at site and treatment levels providing both magnitude of responses and estimation of their uncertainties. From the significance of responses on seed yield, sites were split into two groups: non-responsive (18 sites) and responsive (8 sites). The NNI, ratio of the actual to the critical plant N concentration, was calculated to diagnose soybean N deficiency, and the N derived from the atmosphere (Ndfa, %) as N fixation contribution were investigated to better understand the source of plant N across all sites. Roughly for three-fourths of the sites, fertilization resulted in an unlikely (non-responsive) yield effect, with uncertainties ranging from 0.09 to 2.62 Mg ha−1. The other one-third of the sites were mainly responsive to S or both N + S, with the yield responses ranging from − 0.42–1.1 Mg ha−1 and uncertainties varying from 0.47 to 1.36 Mg ha−1. For the yield responsive sites, NNI presented a high proportion of deficiency (NNI<1) for most of the treatments, except for the “Full” signaling to a potential for yield response. Likewise, only 6% of the changes in Ndfa were not related to the treatment “Full”, and regardless of the seed yield response to fertilization, within the same site, soil and N fixation showed similar contributions to plant N demand. Due to the high uncertainty in treatment response and contribution of N fixation, N fertilization is unlikely to increase yields, leading to non-profitable recommendations. Sulfur deficiency, on the other hand, should be explored under site-specific conditions. A decision support system should include appropriate diagnosis methods for identifying N and S deficiencies, such as NNI in soybean. Attainable maximum Ndfa did not appear to be affected by fertilization but largely varying depending on the site. Future research should assess the role of soil and meteorological variables underpinning N fixation and soil N, along with the impact on seed quality composition, as a critical trait for this crop.}, journal={EUROPEAN JOURNAL OF AGRONOMY}, author={Almeida, Luiz Felipe A. and Correndo, Adrian and Ross, Jeremy and Licht, Mark and Casteel, Shaun and Singh, Maninder and Naeve, Seth and Vann, Rachel and Bais, Jose and Kandel, Hans and et al.}, year={2023}, month={Apr} }
 @article{burns_kulesza_vann_woodley_2022, title={Effects of Nitrogen Source and Rate on Soybean Yield and Quality}, volume={9}, ISSN={["1532-2416"]}, url={https://doi.org/10.1080/00103624.2022.2118299}, DOI={10.1080/00103624.2022.2118299}, abstractNote={ABSTRACT The poultry industry in North Carolina (NC) has increased substantially over the past few decades, which has led to widespread availability of poultry litter. While many grain producers in NC utilize litter in their fertilization programs, it is typically applied to the corn or wheat crops that are in the rotation with soybean, instead of directly prior to soybeans. However, there is interest in application to soybean. Therefore, three field sites were established across NC in both 2019 and 2020, with four replicates of 11 treatments: four litter rates (22.4, 44.8, 89.7 and 134.5 Mg/hectare), six inorganic nitrogen (N) fertilizer rates (16.8, 33.6, 67.3, 134.5, 201.8, and 269.0 kg N/hectare), and a control. The impact of these treatments on biomass production, tissue N, plant population, yield, and grain quality were investigated. There was no significant effect on yield in 2019; however, there was a significant effect on yield in 2020, showing a negative correlation with inorganic N fertilizer in Plymouth and a 22% reduction in yield over the range of inorganic N treatments. It is possible there was an increased salt effect in these plots, as there was a negative response in plant population at five of six site years. While there was a positive correlation between grain protein and increasing inorganic N rate, growers are not paid based on grain quality. The results of this study suggest N application at planting is not beneficial for growers, but litter could be applied to meet soybean phosphorus or potassium demands.}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, author={Burns, Joseph and Kulesza, Stephanie and Vann, Rachel and Woodley, Alex}, year={2022}, month={Sep} }
 @article{schug_reisig_huseth_thrash_vann_2022, title={Helicoverpa zea (Lepidoptera: Noctuidae) Thresholds and Yield Compensation Between Soybeans with Determinate and Indeterminate Growth Habits}, volume={8}, ISSN={["1938-291X"]}, url={https://doi.org/10.1093/jee/toac119}, DOI={10.1093/jee/toac119}, abstractNote={Abstract Soybean (Glycine max L.) is an important row crop in the United States and Helicoverpa zea (Boddie) is one of the most serious insect pests in this system. Economic thresholds for H. zea were developed from soybean varieties with determinate growth habits. However, southern USA farmers have recently planted more soybeans varieties with indeterminate growth habits. Trials were conducted with two determinate and two indeterminate varieties within the same relative maturity group. Levels were compared among groups with differing H. zea pressure (low, medium, high, naturally infested) and manipulated using insecticides. Our objectives were to evaluate yield compensation differences among determinate and indeterminate varieties at these different H. zea pressures and to see if the existing economic threshold should be adjusted between growth habits. Since H. zea larval populations varied across trials, we compared trials with low populations, high populations, and no population. Generally, larval counts did not differ among varieties. We found no yield differences among varieties or between growth habits, regardless of H. zea pressure. In the high population tests, yield was highest in the low population plots, but there was no compensation by the plant in yield components except in number of pods with one seed. In contrast, yield components varied widely across varieties, but these differences were independent of H. zea pressure. These results suggest the economic threshold can be used for determinate and indeterminate growth habits, but more research is needed to confirm this with a larger selection of varieties, planting dates, and maturity groups.}, journal={JOURNAL OF ECONOMIC ENTOMOLOGY}, author={Schug, Hayden and Reisig, Dominic and Huseth, Anders and Thrash, Ben and Vann, Rachel}, editor={Jabbour, RandaEditor}, year={2022}, month={Aug} }
 @article{brooks_mourtzinis_conley_reiter_gaska_holshouser_irby_kleinjan_knott_lee_et al._2022, title={Soybean yield response to sulfur and nitrogen additions across diverse US environments}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.21216}, abstractNote={Abstract As soybean [ Glycine max (L.) Merr.] yields reach record highs, more nutrients are required to maintain these production levels. This study was conducted to evaluate the effect of S and N on soybean yield in diverse environments across the United States. Data were collected from a total of 52 sites in 10 states over 2 yr (2019 and 2020) for this study. A factorial arrangement of three S rates (11, 22, and 33 kg S ha −1 ) using two sources (ammonium sulfate [AMS] and calcium sulfate [CaSO 4 ]) were broadcasted by hand at planting. Additionally, to examine the impact of N on soybean yield, urea was applied at 10, 20, and 29 kg N ha −1 to equal that supplied by AMS. A zero‐fertilizer control treatment was also included. Soil samples prior to fertilization as well as grain yield at R8 were collected and analyzed to understand what environmental conditions favor soybean response to S additions. Results indicated that soil and environmental factors are poor indicators of yield response to S and N additions. Yield responses to S and N additions were observed in yield environments averaging >3,643 kg ha −1 , but S did not limit yield in most environments ( n = 49). Partial profit analysis was conducted at two soybean grain prices (US$0.32 and $0.55 kg ha −1 ). Yield increases were only profitable at 2 site‐years at the tested soybean grain prices. Overall results suggest that use of N and S fertilizers are rarely justified across diverse growing environments.}, journal={AGRONOMY JOURNAL}, author={Brooks, Keren and Mourtzinis, Spyridon and Conley, Shawn P. and Reiter, Mark S. and Gaska, John and Holshouser, David Lee and Irby, Trent and Kleinjan, Jonathan and Knott, Carrie and Lee, Chad and et al.}, year={2022}, month={Dec} }
 @article{gross_vann_woodley_jordan_2022, title={Winter crop effect on soybean production in the Southeast United States}, volume={114}, ISSN={["1435-0645"]}, url={https://doi.org/10.1002/agj2.20950}, DOI={10.1002/agj2.20950}, abstractNote={Abstract Various winter crops can be produced before soybean [ Glycine max (L.) Merr] in the Southeast United States, however the effect of these winter crops on soybean productivity and the optimum maturity group to use following various winter crops remains unknown. This experiment was conducted in five environments across North Carolina in 2019 and 2020 to understand the effect of winter crop and soybean maturity group (MG) on soybean productivity. Winter crops investigated included cereal rye ( Secale cereale L.) as cover crop, cereal rye–crimson clover ( Trifolium incarnatum L.) as cover crop mixture, May fallow, wheat ( Triticum aestivum L.) for grain, rapeseed ( Brassica napus L.) for grain, and June fallow. Three soybean cultivars (MGs III, V, and VII) were evaluated following each winter crop. Data collected were cover crop/residue biomass, winter crop grain yields, soybean stand, soil moisture, soil temperature, soybean chlorophyll content, and soybean yield. Across environments, winter crop did not affect soybean yield despite differences in soybean stand, soil moisture, soil temperature, and soybean chlorophyll content following various winter crops. The results indicate that across the environments evaluated in this experiment, factors such as soybean stand, soil moisture, or N availability were not limiting factors for soybean productivity and that soybean yield response is relatively insensitive to previous crops. Across winter crops, greater yields typically were achieved with a MGs V and VII cultivar than with a MG III cultivar. Results from this experiment demonstrate that the insensitivity of soybean yield to the previous crop allows for flexibility incorporating soybean into rotations and that regardless of the previous winter crop, yield is typically optimized with a MG V cultivar or later when standard management practices are employed.}, number={1}, journal={AGRONOMY JOURNAL}, publisher={Wiley}, author={Gross, MaKayla R. and Vann, Rachel Atwell and Woodley, Alex L. and Jordan, David}, year={2022}, month={Jan} }
 @article{tilley_jordan_heiniger_vann_crozier_gatiboni_2021, title={A survey of twin-row cropping systems in North Carolina}, volume={7}, ISSN={["2374-3832"]}, DOI={10.1002/cft2.20099}, abstractNote={Abstract Twin‐row (TR) cropping systems have maintained a presence in North Carolina (NC) for more than 30 years. Introduced as an alternative to the single‐row (SR) configuration, it is hypothesized individual plants arranged 7‐ to 9‐inches apart see a decrease in plant‐to‐plant competition. However, the success of TR remains elusive. Only a handful of farmers across NC have been able to increase yield through the implementation of TR. As higher yields are achieved in research using SR, the use of TR is becoming less attractive to growers looking to modernize. In order to understand future trends, two surveys were administered across the state of NC with the following objectives: (a) identify standard production practices used such as row spacing, TR spacing, starter fertilizer placement, and layby application methods, (b) evaluate grower testimonies concerning observed plant stress under diverse environmental conditions, and (c) identify the successes and limitations observed with TR production. Of the 461 farmers surveyed in the general survey, 42% stated they are planting on narrow (30 inch or less) SR with 58% still planting on 36‐inch or greater row spacing. Within the 58%, 148 farmers stated they are considering a transition from wide (>30 inches) to narrow row systems. One hundred and twenty farmers said they would remain on wide SR. In time, 74% of growers will potentially be planting on narrow rows. Twenty‐eight TR farmers (6%) were identified. Two of the 28 twin‐row growers stated they would be reverting back to single‐row production.}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Tilley, M. Scott and Jordan, David L. and Heiniger, Ronnie W. and Vann, Rachel and Crozier, Carl R. and Gatiboni, Luke}, year={2021} }
 @article{gross_vann_brown_formella_gibbs_gurganus_heiniger_hurry_jordan_leary_et al._2021, title={Agronomic management of early maturing soybeans in North Carolina}, volume={9}, ISSN={["2374-3832"]}, DOI={10.1002/cft2.20122}, abstractNote={Abstract Interest in producing indeterminate, early maturing soybean [ Glycine max (L.) Merr.] varieties [maturity group (MG) ≤IV] has increased in the southeastern United States as producers seek ways to increase soybean yields. The objective of this experiment was to generate agronomic management recommendations for early maturing soybean varieties across the southeastern United States and compare these management recommendations to historical recommendations for later‐maturing varieties through identification of the optimal seeding rates, row spacing, planting dates, and fertility management. Experiments were conducted across North Carolina at seven environments in 2018 and at four environments in 2019. Two MGs were used in this study: MG III and MG IV. Data on soybean yield and soybean seed quality were collected. Row spacing recommendations were similar to recommendations for later‐maturing varieties with narrow rows providing a 7.3 bu acre –1 yield advantage across environments on average, with more pronounced yield advantages in high‐yield environments. Seeding rate impacted soybean yield but not seed quality. An economic analysis was conducted for seeding rate, suggesting that 80,000 to 120,000 seeds per acre will optimize both profit and yield across environments with May planting. Planting date sometimes impacted yield and seed quality, suggesting that earlier planting with these varieties could be critical to optimizing soybean yield and seed quality. Fertility applications at R1 (beginning of flowering) did not have an impact on soybean yield or seed quality.}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Gross, MaKayla Raquel and Vann, Rachel and Brown, Austin and Formella, Adam and Gibbs, Andrea and Gurganus, Rod and Heiniger, Ryan and Hurry, Jarette and Jordan, David and Leary, Matthew and et al.}, year={2021}, month={Sep} }
 @article{vann_reberg-horton_castillo_murphy_martins_mirsky_saha_mcgee_2021, title={Differences among eighteen winter pea genotypes for forage and cover crop use in the southeastern United States}, volume={61}, ISSN={["1435-0653"]}, DOI={10.1002/csc2.20355}, abstractNote={Abstract Winter pea ( Pisum sativum L.) can be used as a forage and cover crop in the southeast and mid‐Atlantic United states; however, minimal effort has been devoted to optimize winter pea genetics for forage and cover crop production in these regions. Studies were conducted from 2015–2017 in Maryland and North Carolina screening 18 winter pea genotypes for forage and cover crop use. Winter pea genotypes were compared with widely grown crimson clover ( Trifolium incarnatum L.) and hairy vetch ( Vicia villosa Roth]. All legume genotypes were harvested across four timings. Legume winter hardiness, disease incidence, biomass production, quality, and N release were estimated. Winter hardiness was severe with many winter pea genotypes at the Maryland environments, which restricted winter pea biomass production. There was considerable variation for disease incidence among the winter pea genotypes depending on biotic stressors at each environment. At the North Carolina environments, several winter pea genotypes produced similar biomass to crimson clover and hairy vetch across harvest timings. At the Maryland environments, crimson clover and hairy vetch biomass exceeded winter pea biomass. The winter pea genotypes varied considerably for quality traits including protein, lignin, and cellulose. Relative forage value declined as biomass harvest was delayed and was generally higher with all winter pea genotypes than crimson clover or hairy vetch. These results show wide genetic variation in the winter pea genotypes screened for biomass and quality; this variation could be utilized in breeding efforts to enhance winter pea production in the region.}, number={2}, journal={CROP SCIENCE}, author={Vann, Rachel A. and Reberg-Horton, S. Chris and Castillo, Miguel S. and Murphy, J. Paul and Martins, Lais B. and Mirsky, Steven B. and Saha, Uttam and McGee, Rebecca J.}, year={2021}, month={Mar}, pages={947–965} }
 @article{matcham_vann_lindsey_gaska_lilley_ross_wright_knott_lee_moseley_et al._2021, title={Foliar fertilizers rarely increase yield in United States soybean}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.20889}, abstractNote={There is interest among farmers and agronomists to test different fertilizer products to improve soybean yield. With increasing soybean yields across the U.S., there are concerns that fields with higher yields may need supplemental fertilizer. Soybean farmers are interested in foliar products that apply a mixture of micronutrients and macronutrients and can be tank-mixed with insecticides and fungicides and applied during early reproductive growth (R1-R4). This timeline corresponds with a period of high nutrient uptake for soybean (Gaspar et al., 2017).}, journal={AGRONOMY JOURNAL}, author={Matcham, Emma G. and Vann, R. Atwell and Lindsey, Laura E. and Gaska, John M. and Lilley, Dylan T. and Ross, W. Jeremy and Wright, David L. and Knott, Carrie and Lee, Chad D. and Moseley, David and et al.}, year={2021}, month={Oct} }
 @article{morris_vann_heitman_collins_heiniger_2021, title={Maximizing soybean yield by understanding planting date, maturity group, and seeding rate interactions in North Carolina}, volume={9}, ISSN={["1435-0653"]}, DOI={10.1002/csc2.20603}, abstractNote={Abstract Growers across theU.S. Southeast use a diversity of soybean [ Glycine max (L.) Merr.] planting dates, maturity groups, and seeding rates for soybean production depending on their rotational complexity. Studies were conducted across seven North Carolina environments in 2019 and 2020 to determine the effect of planting date (mid‐March through mid‐July), maturity group (MG 2–8), and seeding rate (185,329–432,434 seeds ha –1 ) on soybean emergence, stand, and yield. Across environments, soybean typically emerged more quickly with later planting dates; however, there were location‐specific variations in soybean emergence due to weather conditions around the time of planting. The longest and shortest emergence periods were 26 d for soybean planted in mid‐March and 4 d for soybean planted in June and July, respectively. In the higher yielding environments, yield was maximized with MG 3–4 cultivars planted at early April planting dates and yield declined as planting was delayed. In the low yield environments, yield was maximized with late April to mid‐May planting dates, typically with MG 5–7 cultivars. There was a penalty in both yield environments to planting past mid‐May and in the low yield environments for planting before mid‐April. Across environments, yields tended to be more similar among cultivars higher than MG 3 at planting dates in June and July. The effect of seeding rate on soybean yield was variable across planting dates, maturity groups, and yield environments. Future research is needed in North Carolina to validate the planting date and maturity group interactions on yield observed in this experiment to capture more variation in weather conditions.}, journal={CROP SCIENCE}, author={Morris, Tristan C. and Vann, Rachel A. and Heitman, Josh and Collins, Guy D. and Heiniger, Ryan W.}, year={2021}, month={Sep} }
 @article{morris_vann_collins_heitman_kulesza_2021, title={Planting date and maturity group impact on soybean seed quality in the southeastern United States}, volume={11}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.20913}, abstractNote={Abstract The impacts on soybean seed quality from shifting to using earlier soybean planting dates (PDs) and earlier‐maturing varieties in the southeastern United States are not well understood. The objective of this study was to determine the impact of diverse PDs and maturity groups (MGs) on soybean protein content, oil content, seed damage, and purple seed stain. Studies were installed across seven North Carolina locations in 2019 and 2020 to determine the impact of PD (mid‐March through mid‐July) and MG (2–7) on seed quality. Protein content declined as planting was delayed for the early MGs (2–5) but was stable across PD for the later MGs (6–7). It was observed that early‐maturing varieties (MG ≤5) had a lower protein content than the later‐maturing varieties (MGs 6–7). The oil content was greater in the early MGs (MGs 2–4) compared with the later MGs (MGs 5–7), with oil content and protein content having an inverse relationship. Seed damage was greatest when planting before late April with early MGs (MGs 2–4). Less purple seed stain was found in MGs 5–7 compared with the earlier MGs across all PDs. Further research is needed to understand how to minimize seed damage and purple seed stain as producers consider shifting to an earlier production system for the associated yield benefits in North Carolina and across the southeastern United States.}, journal={AGRONOMY JOURNAL}, author={Morris, Tristan C. and Vann, Rachel A. and Collins, Guy D. and Heitman, Joshua and Kulesza, Stephanie B.}, year={2021}, month={Nov} }
 @article{vann_drake-stowe_buol_dunphy_2021, title={Production practices that maximize soybean yield: What we have learned from the North Carolina soybean yield contest}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.20728}, abstractNote={Abstract Agronomic production practices associated with high‐yielding soybean [ Glycine max (L.) Merr.] in North Carolina can be used to inform production recommendations across the southeastern United States. The 877 individual entries submitted from 2002 to 2019 into the North Carolina Soybean Yield Contest (SYC) were analyzed with the objectives to describe the production practices associated with high‐yielding soybean in North Carolina and to identify management strategies for increasing soybean yield in the southeastern U.S. region. From 2002 to 2019, SYC entries averaged 4,379 kg ha –1 . The three most important management practices influencing soybean yield were maturity group (MG), foliar fungicide use, and planting date. Using a MG IV or earlier variety provided a 1,199 kg ha –1 yield advantage across all entries. When MG ≤ IV was used, foliar fungicide use provided a 754 kg ha –1 yield protection and when MG > IV was used fungicide use provided a 640 kg ha –1 yield protection. Planting dates earlier than 12 May generally provided more yield benefit when earlier maturing varieties were used. Herbicide and insecticide use, irrigation, fungicidal and inoculant seed treatments, tillage, and row spacing were less important predictors of soybean yield. Soybean producers can implement several of these identified management strategies without additional economic investment in an effort to increase soybean yield and profitability in the southeastern U.S. region.}, journal={AGRONOMY JOURNAL}, author={Vann, Rachel A. and Drake-Stowe, Katherine and Buol, Greg S. and Dunphy, E. Jim}, year={2021}, month={Jun} }
 @article{hare_jordan_edmisten_leon_post_vann_dunphy_heiniger_collins_washburn_2020, title={Response of agronomic crops to planting date and double-cropping with wheat}, volume={112}, ISSN={["1435-0645"]}, url={https://doi.org/10.1002/agj2.20164}, DOI={10.1002/agj2.20164}, abstractNote={Abstract Planting date can affect crop yield and is an important management decision for practitioners. Although wheat ( Triticum aestivum L.) and soybean [ Glycine max (L.) Merr.] can be effectively double‐cropped in North Carolina, if commodity prices and projected economic returns are higher for crops other than soybean, growers might consider a nontraditional, double‐crop system. Direct comparisons of major agronomic crops with different planting dates or in a double‐crop system with wheat are limited in North Carolina. Therefore, research was conducted in North Carolina from 2013 through 2017 to determine yield potential of corn ( Zea mays L.), cotton ( Gossypium hirsutum L.), grain sorghum [ Sorghum bicolor (L.) Moench], peanut ( Arachis hypogaea L.), and soybean planted at two dates within the recommended planting window for full‐season production versus planting these crops after wheat harvest. The experimental design was a split plot, with summer crop serving as the whole plot unit and planting date within a crop serving as the subplot unit. Yield of corn, cotton, grain sorghum, peanut, and soybean in full‐season production exceeded that of double‐cropping with wheat in 5, 5, 2, 4, and 5 yr out of 5 yr of the study, respectively. Estimated economic returns were generated using the 10‐yr average (2008–2017) summer crop prices with the 10‐yr average wheat price. When considering all possible combinations of years and crops (n = 25), in only 20% of the possible combinations was the economic return of the double‐cropping system greater than economic return of full‐season crop production when compared with at least one of the planting dates within the traditional planting window.}, number={3}, journal={AGRONOMY JOURNAL}, publisher={Wiley}, author={Hare, Andrew T. and Jordan, David L. and Edmisten, Keith L. and Leon, Ramon G. and Post, Angela R. and Vann, Rachel and Dunphy, E. James and Heiniger, Ronnie and Collins, Guy and Washburn, Derek}, year={2020}, pages={1972–1980} }
 @article{vann_reberg-horton_castillo_mcgee_mirsky_2019, title={Winter Pea, Crimson Clover, and Hairy Vetch Planted in Mixture with Small Grains in the Southeast United States}, volume={111}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2018.03.0202}, abstractNote={Legume and small grain cover crop mixtures may simultaneously fix N and suppress weeds. Studies were conducted from 2015 to 2017 in Maryland and North Carolina to compare winter pea (Pisum sativum L.) to crimson clover (Trifolium incarnatum) and hairy vetch (Vicia villosa Roth) for cover crop use in mixture with small grains. Five winter pea genotypes, one crimson clover cultivar, and one hairy vetch cultivar were screened in mixture with barley (Hordeum vulgare), oats (Avena sativa), and wheat (Triticum aestivum). Cold injury of the pea genotypes in Maryland severely impacted pea biomass. Peas were able to recover from cold injury in North Carolina. A robustly growing small grain aided in legume cold tolerance in some environments. In the Coastal Plain environments, all legume genotypes generally contributed to at least 50% of mixture biomass production. In the Maryland and Piedmont environments, the small grain dominated the cover crop mixture. Oats were generally more competitive with the legume species than barley or wheat. In the North Carolina Coastal Plain and Piedmont, several winter pea genotypes produced as much biomass in mixture as crimson clover and hairy vetch. Hairy vetch was the most competitive legume with the small grains across environments. The variability in total biomass composition across environments in this study demonstrates the importance of site specific cover crop species selection and mixture seeding rate recommendations.}, number={2}, journal={AGRONOMY JOURNAL}, author={Vann, R. A. and Reberg-Horton, S. C. and Castillo, M. S. and McGee, R. J. and Mirsky, S. B.}, year={2019}, pages={805–815} }
 @article{vann_reberg-horton_crozier_place_2018, title={Effect of Soybean Maturity, Crimson Clover Seeding Method, and Seeding Rate on Clover Biomass and Nitrogen Content}, volume={110}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2018.02.0118}, abstractNote={Core Ideas Crimson clover seeding following the last cultivation of soybeans in July into MG3 to MG5 soybeans did not result in any substantial crimson clover growth in both years. After harvest seeding into MG3 and MG4 soybean and aerial seeding into MG4 and MG5, soybean produced substantial clover N content ranging from 76 to 107 kg ha −1 . After harvest seeding behind MG5 soybeans reduced clover N content because late cover crop establishment restricted biomass production. Seeding rate had no effect on clover biomass, clover N content, or corn yield for both drilled and aerially‐seeded crimson clover. Timely crimson clover ( Trifolium incarnatum L.) establishment is a management challenge for producers in the southeastern United States. Aerial seeding methods and the use of early maturing soybeans may allow for earlier crimson clover establishment and potentially increase nitrogen contributions to the following crop. A soybean ( Glycine max L.)–crimson clover–corn ( Zea mays L.) rotation experiment was conducted in Goldsboro, NC from 2006 to 2008. Three crimson clover seeding methods were evaluated: aerial seeding after last soybean cultivation, aerial application before soybean leaf drop, and after‐harvest drill seeding. Each seeding method was evaluated in three soybean maturity groups (MG; 3, 4, 5) and contained three crimson clover seeding rates (22, 39, 56 kg ha −1 ). Clover biomass accumulation, clover N content, and corn yield were determined. Crimson clover seeding following the last cultivation of soybeans into MG3, MG4, and MG5 did not result in any substantial crimson clover growth. After harvest seeding into MG3 and MG4 soybean residue and aerial seeding prior to soybean leaf drop into MG4 and MG5 soybean produced substantial clover N content ranging from 76 to 107 kg ha −1 . After‐harvest seeding behind MG5 soybeans reduced clover N content likely because late cover crop establishment restricted biomass production. Seeding rate had no effect on clover biomass, clover N content, or corn yield. An independent crimson clover aerial seeding rate experiment conducted from 2006 to 2008 in Goldsboro, NC also confirmed no effect of crimson clover seeding rate on clover biomass or N content.}, number={5}, journal={AGRONOMY JOURNAL}, author={Vann, R. A. and Reberg-Horton, S. C. and Crozier, C. R. and Place, G. T.}, year={2018}, pages={1829–1835} }
 @article{vann_reberg-horton_edmisten_york_2018, title={Implications of cereal rye/crimson clover management for conventional and organic cotton producers}, volume={110}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2017.06.0246}, abstractNote={Core Ideas Cereal rye/crimson clover cover crop mixtures can be used for weed suppression and soil moisture conservation in cotton production. Cover crop management at cotton planting can influence cotton emergence, weed suppression, and soil moisture dynamics. Cotton emergence declined when cotton was planted directly into standing cover crop and without row cleaners engaged, but this reduction did not affect cotton lint yield. Soil temperature was reduced and soil moisture was increased by the presence of a cover crop mulch regardless of cover crop residue management strategy at cotton planting. Cover crop residue management did not affect cotton lint yield when herbicides were used, indicating that conventional producers have flexibility in terminating cover crops and residue management at cotton planting. Cover crop residue management can affect performance of the subsequent crop. This experiment was conducted in five environments in North Carolina from 2014 to 2016 to determine the effect of a cereal rye ( Secale cereale )/crimson clover ( Trifolium incarnatum) mulch on cotton ( Gossypium hirsutum L.) emergence, soil temperature, soil moisture, weed suppression, and cotton yield under a conventional and organic weed control context. The cereal rye and crimson clover mixture was planted in mid‐October and terminated 1 wk prior to cotton planting using a roller‐crimper or herbicide application. Cover crop residue management included fertilized, rolled cover crop with row cleaners engaged at planting (Roll+F+RC), rolled cover crop with row cleaners engaged at planting (Roll+RC), rolled cover crop (Roll), standing cover crop with row cleaners engaged at planting (Stand+RC), and no cover crop (BARE). Weed treatments included with and without herbicides. Cover crop dry biomass ranged from 3820 to 6610 kg ha −1 across environments. Fertilizing the cover crop enhanced cover crop dry biomass production by 250 to 1860 kg ha −1 . Cotton emergence declined when cotton was planted directly into standing cover crop and without row cleaners engaged. Soil temperature was reduced and soil moisture was increased by the presence of a cover crop. Cover crop residue management did not affect late‐season weed biomass at four of the five environments. Cover crop residue management did not affect cotton lint yield when herbicides were used, indicating that conventional producers have flexibility in terminating cover crops and residue management at cotton planting.}, number={2}, journal={Agronomy Journal}, author={Vann, R.A. and Reberg-Horton, S.C. and Edmisten, K.L. and York, A.C.}, year={2018}, pages={621–631} }
 @article{saha_vann_reberg-horton_castillo_mirsky_mcgee_sonon_2018, title={Near-infrared spectroscopic models for analysis of winter pea (Pisum sativum L.) quality constituents}, volume={98}, ISSN={["1097-0010"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85049802740&partnerID=MN8TOARS}, DOI={10.1002/jsfa.8947}, abstractNote={BACKGROUND
Winter pea (Pisum sativum L.) grows well in a wide geographic region, both as a forage and cover crop. Understanding the quality constituents of this crop is important for both end uses; however, analysis of quality constituents by conventional wet chemistry methods is laborious, slow and costly. Near infrared reflectance spectroscopy (NIRS) is a precise, accurate, rapid and cheap alternative to using wet chemistry for estimating quality constituents. We developed and validated NIRS calibration models for constituent analysis of this crop.


RESULTS
Of the 11 constituent models developed, nine constituents including moisture, dry-matter, total-nitrogen, crude protein, acid detergent fiber, neutral detergent fiber, AD-lignin, cellulose and non-fibrous carbohydrate had low standard errors and a high coefficient of determination (R2 = 0.88-0.98; 1 - VR, which is the coefficient of determination during cross-validation = 0.77-0.92) for both calibration and cross-validation, indicating their potential for quantitative predictability. The calibration models for ash (R2 = 0.65; 1 - VR = 0.46) and hemicellulose (R2 = 0.75; 1 - VR = 0.50) also appeared to be adequate for qualitative screening. Predictions of an independent validation set yielded reliable agreement between the NIRS predicted values and the reference values with low standard error of prediction (SEP), low bias, high coefficient of determination (r2 = 0.82-0.95), high ratios of performance to deviation (RPD = SD/SEP; 2.30-3.85) and high ratios of performance to interquartile distance (RPIQ = IQ/SEP; 2.57-7.59) for all 11 constituents.


CONCLUSION
Precise, accurate and rapid analysis of winter pea for major forage and cover crop quality constituents can be performed at a low cost using the NIRS calibration models developed. © 2018 Society of Chemical Industry.}, number={11}, journal={JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE}, author={Saha, Uttam and Vann, Rachel A. and Reberg-Horton, S. Chris and Castillo, Miguel S. and Mirsky, Steven B. and McGee, Rebecca J. and Sonon, Leticia}, year={2018}, month={Aug}, pages={4253–4267} }
 @article{vann_reberg-horton_castillo_mirsky_mcgee_2018, title={Winter pea genotype screening for grain crop production in the southeastern USA}, volume={110}, journal={Agronomy Journal}, author={Vann, R.A. and Reberg-Horton, S.C. and Castillo, M.S. and Mirsky, S.B. and McGee, R.J.}, year={2018}, pages={1–10} }
 @article{wallace_williams_liebert_ackroyd_vann_curran_keene_vangessel_ryan_mirsky_2017, title={Cover crop-based, organic rotational no-till corn and soybean production systems in the mid-Atlantic United States}, DOI={10.3390/agriculture7040034}, abstractNote={Cover crop-based, organic rotational no-till (CCORNT) corn and soybean production is becoming a viable strategy for reducing tillage in organic annual grain systems in the mid-Atlantic, United States. This strategy relies on mechanical termination of cover crops with a roller-crimper and no-till planting corn and soybean into cover crop mulches. Here, we report on recent research that focuses on integrated approaches for crop, nutrient and pest management in CCORNT systems that consider system and regional constraints for adoption in the mid-Atlantic. Our research suggests that no-till planting soybean into roller-crimped cereal rye can produce consistent yields. However, constraints to fertility management have produced less consistent no-till corn yields. Our research shows that grass-legume mixtures can improve N-release synchrony with corn demand and also improve weed suppression. Integration of high-residue inter-row cultivation improves weed control consistency and may reduce reliance on optimizing cover crop biomass accumulation for weed suppression. System-specific strategies are needed to address volunteer cover crops in later rotational phases, which result from incomplete cover crop termination with the roller crimper. The paucity of adequate machinery for optimizing establishment of cash crops into thick residue mulch remains a major constraint on CCORNT adoption. Similarly, breeding efforts are needed to improve cover crop germplasm and develop regionally-adapted varieties.}, journal={Agriculture}, author={Wallace, J.M. and Williams, A. and Liebert, J.A. and Ackroyd, V.J. and Vann, R.A. and Curran, W.S. and Keene, C.L. and VanGessel, M.J. and Ryan, M.R. and Mirsky, S.B.}, year={2017} }
 @article{vann_york_cahoon_buck_askew_seagroves_2017, title={Effect of delayed dicamba plus glufosinate application on Palmer amaranth (Amaranthus palmeri) control and XtendFlexTM cotton yield}, volume={31}, DOI={10.1017/wet.2017.71}, abstractNote={Glufosinate controls glyphosate-resistant Palmer amaranth, but growers struggle to make timely applications. XtendFlexTM cotton, resistant to dicamba, glufosinate, and glyphosate, may provide growers an option to control larger weeds. Palmer amaranth control and cotton growth, yield, and fiber quality were evaluated in a rescue situation created by delaying the first POST herbicide application. Treatments consisted of two POST applications of dicamba plus glufosinate, separated by 14 d, with the first application timely (0-d delay) or delayed 7, 14, 21, or 28 d. All treatments included a layby application of diuron plus MSMA. Palmer amaranth, 14 d after first POST, was controlled 99, 96, 89, 75, and 73% with 0-, 7-, 14-, 21-, or 28-d delays, respectively. Control increased following the second application, and the weed was controlled at least 94% following layby. Cotton yield decreased linearly as first POST application was delayed, with yield reductions ranging from 8 to 42% with 7- to 28-d delays. Delays in first POST application delayed cotton maturity but did not affect fiber quality. Nomenclature: Dicamba; glufosinate; glyphosate; Palmer amaranth, Amaranthus palmeri S. Wats; cotton, Gossypium hirsutum L.}, journal={Weed Technology}, author={Vann, R.A. and York, A.C. and Cahoon, C.W., Jr. and Buck, T.B. and Askew, M.C. and Seagroves, R.W.}, year={2017}, pages={633–640} }
 @article{vann_york_cahoon_buck_askew_seagroves_2017, title={Glufosinate plus dicamba for rescue Palmer amaranth control in XtendFlexTM cotton}, volume={31}, DOI={10.1017/wet.2017.68}, abstractNote={Cotton growers commonly use glufosinate-based programs to control glyphosate-resistant Palmer amaranth. Palmer amaranth must be small (≤7.5 cm) for consistent control by glufosinate, and growers often miss the optimum application timing. XtendFlex™ cotton may provide growers a tool to control larger Palmer amaranth. Glufosinate, dicamba, and glufosinate plus dicamba were compared for Palmer amaranth control in a rescue situation. Herbicides were applied to 16- to 23-cm weeds (POST-1) followed by a second application (POST-2) 12 d later. Glufosinateammonium at 590 g ai ha-1 plus dicamba diglycolamine salt at 560 g ae ha-1 POST-1 followed by glufosinate plus dicamba POST-2 was more effective than glufosinate at 880 g ha-1 POST-1 followed by glufosinate at 590 g ha-1 POST-2 or dicamba alone applied twice. Following a directed layby application of glyphosate, diuron, and S-metolachlor 14 d after POST-2, Palmer amaranth was controlled 99% by any system containing dicamba or glufosinate plus dicamba POST-1 followed by dicamba, glufosinate, or glufosinate plus dicamba POST-2 compared with 87% to 91% control by glufosinate alone applied twice. Cotton height and number of main stem nodes at layby were reduced in systems with dicamba only POST-1 followed by dicamba or glufosinate plus dicamba POST-2, presumably due to competition from the slowly dying Palmer amaranth with dicamba only POST-1. These treatments also delayed cotton maturity and reduced lint yield compared with systems containing glufosinate plus dicamba at POST-1. Nomenclature: Dicamba; diuron; glufosinate; glyphosate; S-metolachlor; Palmer amaranth, Amaranthus palmeri S. Watts; cotton, Gossypium hirsutum L.}, journal={Weed Technology}, author={Vann, R.A. and York, A.C. and Cahoon, C.W., Jr. and Buck, T.B. and Askew, M.C. and Seagroves, R.W.}, year={2017}, pages={666–674} }
 @article{vann_reberg-horton_poffenbarger_zinati_moyer_mirsky_2017, title={Starter fertilizer for managing cover crop-based organic corn}, volume={109}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2016.09.0506}, abstractNote={Core Ideas Grass and legume cover crops are combined for weed and fertility management. A cereal rye and hairy vetch mixture provided more than 7500 kg ha −1 biomass. Additional fertility is necessary to maximize cover‐crop based organic corn yield. Subsurface banding feather meal is an option to increase organic corn yield. If cover crop biomass is low, providing adequate N fertility is critical for yield. Grass and legume cover crops are combined in mixtures to provide both weed and N fertility management in organic production; however, additional N fertility may be required to maximize corn yield. The research was conducted in Beltsville, MD; Kinston, NC; and Salisbury, NC; from 2012 to 2014 to evaluate the effect of starter fertilizer source and application method on weed competition and grain yield in cover crop‐based, organic corn production. Fertility treatments included high rate broadcast poultry litter (Plant available nitrogen [PAN] = 160 kg ha −1 ), low rate broadcast poultry litter (PAN = 72 kg ha −1 ), subsurface banded feather meal (PAN = 80 kg ha −1 ), subsurface banded poultry litter (PAN = 12 kg ha −1 ), and no starter fertility. A cereal rye ( Secale cereale L.) and hairy vetch ( Vicia villosa Roth) mixture was established in the fall and was terminated using a roller‐crimper before corn planting. Cover crop biomass more than 7500 kg ha −1 provided excellent weed suppression. In a combined analysis of five environments, corn N content and yield followed the same pattern of high rate broadcast poultry litter > low rate broadcast poultry litter = subsurface banded feather meal > subsurface banded poultry litter = no starter fertility. Results from this study indicate that starter fertilizer is necessary to maximize corn yield in cover crop‐based organic corn production and that decisions regarding additional fertility will need to be dynamic based on site history, cover crop biomass production, and the ability to broadcast poultry litter.}, number={5}, journal={Agronomy Journal}, author={Vann, R.A. and Reberg-Horton, S.C. and Poffenbarger, H.J. and Zinati, G.M. and Moyer, J.B. and Mirsky, S.B.}, year={2017}, pages={2214–2222} }
 @article{vann_reberg-horton_brinton_2016, title={Row spacing and seeding rate effects on canola population, weed competition and yield in winter organic canola production}, volume={108}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2016.02.0097}, abstractNote={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. Canola population increased with increasing seeding rate across all row spacings, and canola populations were highest with the 17-cm row spacing, followed by the 34- then 68-cm row spacings. Yield was similar across row spacings at the lower seeding rates in five of the six environments. At these environments, yield tended to increase in the 17-cm row spacing as seeding rate increased but declined in the 68-cm row spacing with increasing seeding rate. In one environment with a unique weed community, weed suppression and yield were higher with the 68-cm row spacing. It was concluded that the yield plasticity of canola will provide producers flexibility in selecting row spacing, and seeding rate selections should be based on desired row spacing.}, number={6}, journal={Agronomy Journal}, publisher={American Society of Agronomy}, author={Vann, R.A. and Reberg-Horton, S.C. and Brinton, C.M.}, year={2016}, pages={2425–2432} }