@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{tiecher_pace_gatiboni_vann_hardy_fisher_2023, title={Flue-cured tobacco and Cl rates: Implications on yield, quality, and nutrient concentration}, volume={2}, ISSN={["1435-0645"]}, url={https://doi.org/10.1002/agj2.21272}, DOI={10.1002/agj2.21272}, abstractNote={The increase in flue-cured tobacco (Nicotiana tabacum L.) yields in recent decades due to genetic improvements of new cultivars and management technologies may increase the plant demand for Cl, and the increased dry mass may dilute Cl concentration, thereby reducing negative effects. This study evaluated the effect of increasing doses of Cl on tobacco production, quality, and chemical composition of leaves, in four growing environments located at research stations where flue-cured tobacco is produced in North Carolina. The treatments consisted of 11 rates of Cl (0, 11, 22, 34, 45, 56, 67, 78, 90, 101, and 112 kg ha−1) in each growing environment, with four replications in a randomized complete block design. The yield and visual quality, total alkaloids, and reducing sugars concentrations of cured leaf were determined. In addition, the concentration of selected nutrients (N, P, K, Ca, Mg, S, and Cl) and nitrate (NO3−) in tobacco leaves was measured in five different periods. Rates of Cl up to 112 kg ha−1 did not reduce the productivity or quality of flue-cured tobacco in any environment. The Cl rate required to reach the threshold of 1.0% Cl content in cured leaf was site-specific, being surpassed even in the control treatment at one location, or with Cl rates higher than 34 and 90 kg ha−1 in two environments. In one environment, the Cl rates increased tobacco yield, probably due the direct effect of Cl as a nutrient. Although the increasing Cl rates increased the reducing sugars concentration, visual quality was not attenuated.}, journal={AGRONOMY JOURNAL}, author={Tiecher, Tales and Pace, Cara Ruth and Gatiboni, Luke and Vann, Matthew and Hardy, David and Fisher, Loren}, year={2023}, month={Feb} }
 @article{havlin_austin_hardy_howard_heitman_2022, title={Nutrient Management Effects on Wine Grape Tissue Nutrient Content}, volume={11}, ISSN={["2223-7747"]}, url={https://doi.org/10.3390/plants11020158}, DOI={10.3390/plants11020158}, abstractNote={With limited research supporting local nutrient management decisions in North Carolina grape (Vitis vinifera) production, field studies (2015-17) were conducted to evaluate late season foliar nitrogen (N) application on leaf and petiole N concentration and yeast assimilable N (YAN) in the fruit. Foliar urea (1% v/v) was applied at different rates and application times beginning pre-and post-veraison. Compared to soil applied N, late season foliar N substantially enhanced petiole N and grape YAN. Smaller split N applications were generally more effective in increasing YAN than single larger N rates. These data demonstrate the value of assessing plant N content at full bloom with petiole N analysis or remote sensing to guide foliar N management decisions. Additional field studies (2008-11) were conducted to evaluate pre-bud soil applied phosphorus (P) and potassium (K) effects on petiole P and K nutrient status. Fertilizer P and K were initially broadcast applied (0-896 kg P2O5 ha-1; 0-672 kg K2O ha-1) prior to bud-break in 2008-09 and petiole P and K at full bloom soil test P and K were monitored for three to four years after application. Soil test and petiole P and K were significantly increased with increasing P and K rates, which subsequently declined to near unfertilized levels over the sampling time depending on site and P and K rate applied. These data demonstrate the value of annually monitoring petiole P and K levels to accurately assess plant P and K status to better inform nutrient management decisions.}, number={2}, journal={PLANTS-BASEL}, author={Havlin, John L. and Austin, Robert and Hardy, David and Howard, Adam and Heitman, Josh L.}, year={2022}, month={Jan} }
 @article{zhang_antonangelo_grove_osmond_slaton_alford_florence_huluka_hardy_lessl_et al._2021, title={Variation in soil-test-based phosphorus and potassium rate recommendations across the southern USA}, volume={6}, ISSN={["1435-0661"]}, DOI={10.1002/saj2.20280}, abstractNote={Abstract Thirteen states associated with the Southern Extension and Research Activities Information Exchange Group‐6 (SERA‐IEG‐6) agreed to share their soil test based P and K rate recommendations for nine major crops. The objectives were to compare fertilizer P and K rate recommendations, to look for opportunities to rationalize similar recommendations across state lines, and to examine challenges to the development of a cooperative regional approach to P and K recommendations. Mehlich‐3 (eight states), Mehlich‐1 (five states), or Lancaster (one state) extractions were the basis of plant available soil P (STP) and K (STK) assessment. Fertilizer recommendation philosophies (sufficiency, build and maintain, and/or hybrid) variation among the states might be the main reason behind such discrepancies. Although a few similarities in P and K rate recommendations were found, the different philosophies, numerical presentations, and extraction procedures drove important recommendation differences. Widespread adoption of the Mehlich‐3 extraction procedure has not reduced variation in fertilizer P and K rate recommendations among the states. Instead, for states using Mehlich 3, soil test critical concentrations ranged from 30 to 75 mg P kg –1 and 60 to 175 mg K kg –1 for corn ( Zea mays L.) grain and warm‐season grass hay production. The adoption of uniform soil testing terminology, sample collection guidelines, extraction methods, and interpretations across common physiographic regions, soils, and state lines remains a challenge. Differences arise because of the different soil orders and properties, climate conditions, and resulting crop responses to added P and K fertilizers. Such differences in soil‐test‐based fertilizer P and K recommendations are state specific and highlight needs to examine the soil testing and recommendation process, make soil test results end‐user friendly, and, when appropriate, standardize fundamental information used in the soil testing guidelines.}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Zhang, Hailin and Antonangelo, Joao and Grove, John and Osmond, Deanna and Slaton, Nathan A. and Alford, Shannon and Florence, Robert and Huluka, Gobena and Hardy, David Herring and Lessl, Jason and et al.}, year={2021}, month={Jun} }
 @article{jordan_hardy_barnes_corbett_2020, title={Potential economic value for peanut by increasing soil pH in North Carolina}, volume={6}, ISSN={["2374-3832"]}, DOI={10.1002/cft2.20012}, abstractNote={The authors declare no conflict of interest.}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Jordan, David and Hardy, David and Barnes, Steve and Corbett, Tommy}, year={2020} }
 @article{vann_fisher_jordan_smith_hardy_stewart_2013, title={Potassium Rate and Application Effect on Flue-Cured Tobacco}, volume={105}, ISSN={["0002-1962"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84875203584&partnerID=MN8TOARS}, DOI={10.2134/agronj2012.0259}, abstractNote={Research was conducted at two locations in 2009 and 2010 to evaluate the effect of various K rates and application methods on the yield and quality of flue‐cured tobacco ( Nicotiana tabacum L.). Treatments included five rates of K from sulfate of potash magnesia (0–0–22): 0, 84, 140, 196, and 252 kg K 2 O ha −1 that were applied: broadcast 1 mo before transplanting, broadcast 1 wk before transplanting, banded at transplanting, and a split application with one‐half rate banded at transplanting followed by one‐half rate banded at layby. Tissue samples were collected throughout the season at three separate growth stages: layby, topping, and after curing. Tissue samples were analyzed for total alkaloid and reducing sugars, N, P, K, and Mg content. Soil samples were collected the same day as K fertilizer application from plots not receiving supplemental K. Data were subjected to ANOVA using the PROC GLM procedure in SAS. Treatment means were separated using Fisher’s Protected LSD test at p ≤ 0.05. Application method and timing had no effect on any measured parameters; furthermore, crop yield and quality was not affected by K rates >0 kg K 2 O ha −1 at three of four locations. It is likely that early broadcast applications of K 2 O with current rate recommendations would only be of concern with combinations of conditions that included coarse soil textures, low K indices, and/or excessive leaching rainfall.}, number={2}, journal={AGRONOMY JOURNAL}, author={Vann, Matthew C. and Fisher, Loren R. and Jordan, David L. and Smith, W. David and Hardy, David H. and Stewart, Alexander M.}, year={2013}, pages={304–310} }
 @article{vann_fisher_jordan_hardy_smith_stewart_2012, title={THE EFFECT OF POTASSIUM RATE ON THE YIELD AND QUALITY OF FLUE-CURED TOBACCO (NICOTIANA TABACUM L.)}, volume={49}, DOI={10.3381/12-019r.1}, abstractNote={Research was conducted at 2 locations in 2009 and 2010 to determine the effect of potassium rate on the yield and quality of flue-cured tobacco. Treatments included 8 rates of potassium from sulfate of potash magnesia (K-Mag, 0–0–22): 0, 84, 112, 140, 168, 196, 224, and 252 kg K2O ha−1. A complete (N–P–K) fertilizer that supplied 134 kg K2O ha−1 was also included as a control treatment. All fertilizer was applied in a single band application within 10 days after transplanting. Yield was measured and samples were assigned an official U.S. Department of Agriculture (USDA) grade. Crop value was determined based on yield and grade. Tissue samples were collected throughout the season at 3 separate times: at layby, at topping, and after curing. Tissue samples were analyzed for total alkaloid and reducing sugar content as well as N, P, K, and Mg content at North Carolina State University. Soil samples were also collected at transplanting, which corresponded with potassium fertilizer application, and were analyzed by the North Carolina Department of Agriculture and Consumer Services Agronomic Division in Raleigh, North Carolina. Data were subjected to an analysis of variance (ANOVA) with the use of the PROC GLM procedure in SAS. Treatment means were separated with the use of Fisher's protected least significant difference (LSD) test at P ≤ 0.05. A yield or quality response was not observed with potassium rates at and above 84 kg K2O ha−1. Current potassium recommendations are adequate, and in fact may be higher than necessary for fine-textured soils with medium to high potassium indices. In contrast, recommendations appear to be accurate for coarse-textured soils in tobacco-producing areas of North Carolina, where potassium indices are often low.}, journal={Tobacco Science}, publisher={Tobacco Science}, author={Vann, M. C. and Fisher, L. R. and Jordan, D. L. and Hardy, D. H. and Smith, W. D. and Stewart, A. M.}, year={2012}, month={Jan}, pages={14–20} }
 @article{shah_hutchison_hesterberg_grabow_huffman_hardy_parsons_2009, title={Leaching of Nutrients and Trace Elements from Stockpiled Turkey Litter into Soil}, volume={38}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-66649083862&partnerID=MN8TOARS}, DOI={10.2134/jeq2007.0639}, abstractNote={In addition to nutrients, poultry are fed trace elements (e.g., As) for therapeutic purposes. Although a large proportion of the nutrients are assimilated by the birds, nearly all of the As is excreted. Hence, turkey litter constituents can leach into the soil and contaminate shallow ground water when it is stockpiled uncovered on bare soil. This study quantified the leaching of turkey litter constituents from uncovered stockpiles into the underlying soil. Four stockpiles were placed on Orangeburg loamy sand in summer 2004 for 162 d; 14 d after their removal, four stockpiles were created over the same footprints and left over winter for 162 d. Soil samples at depths of 7.6 to 30.5 cm and 30.5 to 61 cm adjacent to and beneath the stockpiles were compared for pH, electrical conductivity, total C, dissolved organic C, N species, P, water-extractable (WE)-P, As, WE-As, Cu, Mn, and Zn. All WE constituents affected the 7.6- to 30.5-cm layer, and some leached deeper; for example, NH(4)(+)-N concentrations were 184 and 62 times higher in the shallow and deep layers, respectively. During winter stockpiling, WE-As concentrations beneath the stockpiles tripled and doubled in the 7.6- to 30.5-cm and 30.5- to 61-cm layers, respectively, with WE-As being primarily as As(V). Heavy dissolved organic C and WE-P leaching likely increased solubilization of soil As, although WE-As concentrations were low due to the Al-rich soil and low-As litter. When used as drinking water, shallow ground water should be monitored on farms with a history of litter stockpiling on bare soil; high litter As; and high soil As, Fe, and Mn concentrations.}, number={3}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Shah, Sanjay B. and Hutchison, Kimberly J. and Hesterberg, Dean L. and Grabow, Garry L. and Huffman, Rodney L. and Hardy, David H. and Parsons, James T.}, year={2009}, pages={1053–1065} }
 @article{crozier_walls_hardy_barnes_2003, title={Tracking phosphorus response of cotton}, volume={87}, ISBN={0006-0089}, number={4}, journal={Better Crops With Plant Food}, author={Crozier, C. R. and Walls, B. and Hardy, D. H. and Barnes, J. S.}, year={2003}, pages={20} }