@article{fulcher_rihn_warner_lebude_schexnayder_altland_bumgarner_marble_nackley_palma_et al._2023, title={Overcoming the Nursery Industry Labor Shortage: A Survey of Strategies to Adapt to a Reduced Workforce and Automation and Mechanization Technology Adoption Levels}, volume={58}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI17230-23}, abstractNote={US nurseries are experiencing a workforce shortage that is expected to intensify. A mixed-mode survey of decision-makers representing the US nursery industry was conducted in 2021. The survey assessed practices used in 2020 to elicit a better understanding of nursery approaches to the challenges presented by persistent labor scarcity. We compare our results with survey data collected ∼15 years earlier at container nurseries. Survey responses revealed that nurseries were undertaking strategies that aimed to improve production efficiency, better recruit and retain employees, and secure other sources of labor to overcome this shortage. Specifically, more than 65% of surveyed US nurseries increased worker wages, and more than 55% of respondents adopted automation to address the labor shortage. Strategies in use by ≥23% of respondents may limit future growth or jeopardize long-term nursery survival. These include diversifying tasks of current employees, reducing production of labor-intensive plants, or delaying expansion plans. Survey results suggested that production tasks excluding irrigation were on average 31% automated or mechanized at container nurseries, an increase from 16% during the prior survey. Field nurseries were 35% automated or mechanized in 2020. Newly developed or yet-to-be developed automated and mechanized technology (AMT) that decision-makers perceive as being helpful were reported. This article explores linkages between nursery characteristics and AMT adoption and highlights research and extension programming initiatives that are needed to help growers make informed decisions regarding adopting automation.}, number={12}, journal={HORTSCIENCE}, author={Fulcher, Amy and Rihn, Alicia L. and Warner, Laura A. and LeBude, Anthony V and Schexnayder, Susan and Altland, James E. and Bumgarner, Natalie and Marble, S. Chris and Nackley, Lloyd and Palma, Marco and et al.}, year={2023}, month={Dec}, pages={1513–1525} }
 @article{shreckhise_owen_eick_niemiera_altland_jackson_2020, title={Dolomite and Micronutrient Fertilizer Affect Phosphorus Fate When Growing Crape Myrtle in Pine Bark}, volume={55}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI14558-20}, abstractNote={Soilless substrates are routinely amended with dolomite and sulfate-based micronutrients to improve fertility, but the effect of these amendments on phosphorous (P) in substrate pore-water during containerized crop production is poorly understood. The objectives of this research were as follows: compare the effects of dolomite and sulfate-based micronutrient amendments on total P (TP), total dissolved P (TDP), orthophosphate P (OP), and particulate P (PP; TP − TDP) concentrations in pour-through extracts; to model saturated solid phases in substrate pore-water using Visual MINTEQ; and to assess the effects of dolomite and micronutrient amendments on growth and subsequent P uptake efficiency (PUE) of Lagerstroemia L. ‘Natchez’ (crape myrtle) potted in pine bark. Containerized crape myrtle were grown in a greenhouse for 93 days in a 100% pine bark substrate containing a polymer-coated 19N–2.6P–10.8K controlled-release fertilizer (CRF) and one of four substrate amendment treatments: no dolomite or micronutrients (control), 2.97 kg·m−3 dolomite (FL); 0.89 kg·m−3 micronutrients (FM); or both dolomite and micronutrients (FLM). Pour-through extracts were collected approximately weekly and fractioned to measure pore-water TP, TDP, and OP and to calculate PP. Particulate P concentrations in pour-through extracts were generally unaffected by amendments. Relative to the control, amending pine bark with FLM reduced water-extractable OP, TDP, and TP concentrations by ≈56%, had no effect on P uptake efficiency, and resulted in 34% higher total dry weight (TDW) of crape myrtle. The FM substrate had effects similar to those of FLM on plant TDW and PUE, and FM reduced pore-water OP, TDP, and TP concentrations by 32% to 36% compared with the control. Crape myrtle grown in FL had 28% lower TDW but pour-through OP, TDP, and TP concentrations were similar to those of the control. Chemical conditions in FLM were favorable for precipitation of manganese hydrogen phosphate (MnHPO4), which may have contributed to lower water-extractable P concentrations in this treatment. This research suggests that amending pine bark substrate with dolomite and a sulfate-based micronutrient fertilizer should be considered a best management practice for nursery crop production.}, number={6}, journal={HORTSCIENCE}, author={Shreckhise, Jacob H. and Owen, James S., Jr. and Eick, Matthew J. and Niemiera, Alexander X. and Altland, James E. and Jackson, Brian E.}, year={2020}, month={Jun}, pages={832–840} }
 @article{fields_owen_stewart_heitman_caron_2020, title={Modeling water fluxes through containerized soilless substrates using HYDRUS}, volume={19}, ISSN={["1539-1663"]}, DOI={10.1002/vzj2.20031}, abstractNote={Containerized crop production can enhance plant health and ensure environmental sustainability, yet proper management requires improved understanding of water fluxes and storage within soilless substrates. Numerical simulation tools developed to simulate water movement in porous media, such as HYDRUS‐3D, may help to quantify effective hydraulic properties of soilless substrates but have not yet been tested in this capacity. Therefore, this study had three main objectives: (a) to assess the accuracy of HYDRUS‐3D for simulating water flow through peat‐ and bark‐based soilless substrates by comparing measured and modeled drainage and water storage; (b) to determine sensitivity of model outputs to individual hydraulic parameters; and (c) to compare model parameterization using three laboratory characterization methods (instantaneous profile sorption, instantaneous profile desorption, and evaporation) vs. inverse modeling with HYDRUS. The results showed that the modeled water contents and drainage timing and amounts were most sensitive to saturated volumetric water content (θs) and least sensitive to saturated hydraulic conductivity (Ks). With regard to parameterization methods, the inverse modeling approach provided the most accurate water balance simulations for both substrates, followed by the sorption method. These two methods estimated lower peak water contents and greater drainage compared with simulations parameterized using desorption and evaporation measurements. Overall, the study results showed that the Richards equation, as calculated using HYDRUS, can provide accurate simulations of water flux through containers when properly calibrated, though sorption‐derived parameters may suffice when model optimization is impractical.}, number={1}, journal={VADOSE ZONE JOURNAL}, author={Fields, Jeb S. and Owen, James S., Jr. and Stewart, Ryan D. and Heitman, Josh L. and Caron, Jean}, year={2020} }
 @article{fields_fonteno_jackson_heitman_owen_2020, title={The Use of Dewpoint Hygrometry to Measure Low Water Potentials in Soilless Substrate Components and Composites}, volume={10}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy10091393}, abstractNote={Plant water availability in soilless substrates is an important management consideration to maximize water efficiency for containerized crops. Changes in the characteristics (i.e., shrink) of these substrates at low water potential (<−1.0 MPa) when using a conventional pressure plate-base can reduce hydraulic connectivity between the plate and the substrate sample resulting in inaccurate measures of water retention. Soilless substrate components Sphagnum peatmoss, coconut coir, aged pine bark, shredded pine wood, pine wood chips, and two substrate composites were tested to determine the range of volumetric water content (VWC) of surface-bound water at water potentials between −1.0 to −2.0 MPa. Substrate water potentials were measured utilizing dewpoint hygrometry. The VWC for all components or composites was between 5% and 14%. These results were considerably lower compared to previous research (25% to 35% VWC) utilizing conventional pressure plate extraction techniques. This suggests that pressure plate measurements may overestimate this surface-bound water which is generally considered unavailable for plant uptake. This would result in underestimating available water by as much as 50%.}, number={9}, journal={AGRONOMY-BASEL}, author={Fields, Jeb S. and Fonteno, William C. and Jackson, Brian E. and Heitman, Joshua L. and Owen, James S., Jr.}, year={2020}, month={Sep} }
 @article{altland_owen_jackson_fields_2018, title={Physical and Hydraulic Properties of Commercial Pine-bark Substrate Products Used in Production of Containerized Crops}, volume={53}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI13497-18}, abstractNote={Pine bark is the primary constituent of nursery container media (i.e., soilless substrate) in the eastern United States. Pine bark physical and hydraulic properties vary depending on the supplier due to source (e.g., lumber mill type) or methods of additional processing or aging. Pine bark can be processed via hammer milling or grinding before or after being aged from ≤1 month (fresh) to ≥6 month (aged). Additionally, bark is commonly amended with sand to alter physical properties and increase bulk density (Db). Information is limited on physical or hydraulic differences of bark between varying sources or the effect of sand amendments. Pine bark physical and hydraulic properties from six commercial sources were compared as a function of age and amendment with sand. Aging bark, alone, had little effect on total porosity (TP), which remained at ≈80.5% (by volume). However, aging pine bark from ≤1 to ≥6 months shifted particle size from the coarse (>2 mm) to fine fraction (<0.5 mm), which increased container capacity (CC) 21.4% and decreased air space (AS) by 17.2% (by volume) regardless of source. The addition of sand to the substrate had a similar effect on particle size distribution to that of aging, increasing CC and Db while decreasing AS. Total porosity decreased with the addition of sand. The magnitude of change in TP, AS, CC, and Db from a nonamended pine bark substrate was greater with fine vs. coarse sand and varied by bark source. When comparing hydrological properties across three pine bark sources, readily available water content was unaffected; however, moisture characteristic curves (MCC) differed due to particle size distribution affecting the residual water content and subsequent shift from gravitational to either capillary or hygroscopic water. Similarly, hydraulic conductivity (i.e., ability to transfer water within the container) decreased with increasing particle size.}, number={12}, journal={HORTSCIENCE}, author={Altland, James E. and Owen, James S., Jr. and Jackson, Brian E. and Fields, Jeb S.}, year={2018}, month={Dec}, pages={1883–1890} }