@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={AbstractAgronomic 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{parvej_holshouser_kratochvil_whaley_dunphy_roth_fae_2020, title={Early high-moisture wheat harvest improves double-crop system: I. Wheat yield and quality}, volume={60}, ISSN={["1435-0653"]}, DOI={10.1002/csc2.20172}, abstractNote={AbstractDouble cropping winter wheat (Triticum aestivum L.) and soybean [Glycine max (L.) Merr.] increases total food production without additional land. However, yield and/or quality of both crops often suffer if wheat harvest is delayed beyond maturity. We evaluated the impact of high‐moisture wheat harvest on wheat yield and quality and soybean planting time across eighteen site‐years in five Mid‐Atlantic states during 2015 to 2017. Wheat was harvested three to five times beginning at 150 to 200 g kg−1 moisture at 4 to 14 d intervals. High‐moisture wheat harvest facilitated 4 to 21 d earlier soybean planting. Grain moisture generally decreased with harvest date, but temperature and rainfall varied moisture content. Wheat test weight declined linearly 2.91 to 4.87 kg m−3 d−1 delay in harvest. Wheat relative yield was not affected by delayed harvest in Pennsylvania but declined linearly 2.6% per day delay in harvest after 4 July in Maryland, 0.55% after 30 June in Delaware, 3.1% after 19 June in Virginia, and 0.42% after 4 June in North Carolina. Test weight was positively associated with relative yield and explained 37 to 82% of relative yield variability. Critical days for desirable test weight were similar to the critical harvesting days for maximum yield, indicating that test weight is an excellent predictor of optimum harvesting day. Delayed harvest decreased grain falling number but increased softness equivalent. Overall, high‐moisture wheat harvest improved wheat yield and quality by reducing test weight loss and would allow earlier soybean planting to maximize growth and yield.}, number={5}, journal={CROP SCIENCE}, author={Parvej, Md Rasel and Holshouser, David L. and Kratochvil, Robert J. and Whaley, Cory M. and Dunphy, E. James and Roth, Gregory W. and Fae, Giovani S.}, year={2020}, pages={2633–2649} }
 @article{parvej_holshouser_kratochvil_whaley_dunphy_roth_fae_2020, title={Early high-moisture wheat harvest improves double-crop system: II. Soybean growth and yield}, volume={60}, ISSN={["1435-0653"]}, DOI={10.1002/csc2.20174}, abstractNote={AbstractDouble cropping soybean [Glycine max (L.) Merr.] after winter wheat (Triticum aestivum L.) increases total food production without additional land. However, double‐crop soybean usually yields less than full‐season soybean, mainly due to late planting. We evaluated double‐crop soybean growth and yield as affected by early planting immediately after high‐moisture wheat harvest across 20 site‐years in five Mid‐Atlantic states during 2015–2017. At each site, six soybean cultivars from relative maturity group (rMG) 3.1–5.9 were planted at three to five dates in a 4‐ to 14‐d interval. Soybean growth, measured by normalized difference vegetation index (NDVI) across the growing season, was affected only by planting date. Although NDVI peaked near the R5 stage, it took 9–27 more days to reach the peak NDVI (0.84–0.98) for early‐planted soybean than for late‐planted soybean. Relative yield declined with planting dates, which explained 41–81% of the relative yield variability. The yield loss from delayed planting was greater in the north (33–80%; Pennsylvania, Maryland, and Delaware) than in the south (20–27%; Virginia, North Carolina) due to longer delay in planting and shorter growing season in the north. Soybean NDVI from the R1–R6 stages was associated with yield, with the strongest association (R2 = .55–.57) at the R2 and R3 stages. The area under the NDVI curve (AUNDVIC) was also strongly associated (R2 = .77) with relative yield, indicating an excellent tool for explaining double‐crop soybean yield loss due to poor growth. High‐moisture wheat harvest facilitated soybean planting 4–21 d earlier, which increased growth and yield.}, number={5}, journal={CROP SCIENCE}, author={Parvej, Md Rasel and Holshouser, David L. and Kratochvil, Robert J. and Whaley, Cory M. and Dunphy, E. James and Roth, Gregory W. and Fae, Giovani S.}, year={2020}, pages={2650–2666} }
 @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={AbstractPlanting 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{andrade_edreira_mourtzinis_conley_ciampitti_dunphy_gaska_glewen_holshouser_kandel_et al._2019, title={Assessing the influence of row spacing on soybean yield using experimental and producer survey data}, volume={230}, ISSN={["1872-6852"]}, DOI={10.1016/j.fcr.2018.10.014}, abstractNote={Narrowing row width in soybean fields leads to earlier canopy closure, which may increase capture of incoming solar radiation during critical crop stages for yield determination. Theoretically, this should enhance seed yield. However, in prior studies, the impact of narrowing row spacing on soybean yield has been inconsistent. To explore on a broader scale the potential factors underlying this inconsistency, we evaluated the yield difference between narrow (NR; ≈38 cm) and wide (WR; ≈76 cm) row spacing using two sources of yield and management information: (i) data collected from 4879 soybean production fields via a multi-year, multi-state survey of soybean producers in the North Central US region; and (ii) data extracted from 129 site-year experiments that quantified NR-WR yield difference. The producer fields were allocated to their respective climate-soil domains to enable analysis of the NR-WR yield difference within each domain. The experimental trial data originated from three US geographic regions: south, central, and north. Key crop developmental stages in each trial were estimated using a soybean crop simulation model to discern if changes in crop phenology or any weather variable occurring before versus after a specific crop stage modulated the magnitude of the NR-WR yield difference. Analysis of experimental trial data indicated that, while NR yields were overall higher than WR yields, the NR-WR yield difference varied by region: 540 (south), 104 (central), and 240 kg ha−1 (north); the respective NR yields were greater than WR yields in 92%, 68%, and 84% of the cases. In the north and south regions, the NR-WR yield difference increased when the crop cycle length decreased as a consequence of later sowing date, earlier cultivar maturity group, and/or higher temperature. The relatively smaller (and occasionally negative) NR-WR yield difference detected in the central region was likely the result of environmental conditions that favored canopy closure irrespective of row spacing. In contrast to the analysis of the experimental database, no consistent NR-WR yield differences were detected in the producer field database. We hypothesize that the apparent absence of a significant NR-WR effect in the producer dataset is likely associated with the background management used with narrow spacing, together with yield losses due to wheel damage and greater disease pressure. This complementary approach using both producer and experimental data can help evaluate if practices documented in experimental trials to enhance yield realize equivalent yield increases in producer fields and, if not, explore underlying causes for the discrepancy.}, journal={FIELD CROPS RESEARCH}, author={Andrade, Jose F. and Edreira, Juan I. Rattalino and Mourtzinis, Spyridon and Conley, Shawn P. and Ciampitti, Ignacio A. and Dunphy, James E. and Gaska, John M. and Glewen, Keith and Holshouser, David L. and Kandel, Herman J. and et al.}, year={2019}, month={Jan}, pages={98–106} }