@article{durand_fonteno_michel_2024, title={A review and analysis of particle size parameters and their relationships to physical properties of growing media}, ISSN={["1435-0661"]}, DOI={10.1002/saj2.20661}, abstractNote={AbstractAn expanded description of particle morphology and the analysis of its relationships with physical properties may help to optimize the selection of raw materials and particle size fractions used as growing media constituents. Previous works have described the outlines of these relations based mostly on sieving procedures to characterize particle size distribution. They have shown limited and sometimes contradictory results due to the different methods used, size fractions selected, and physical properties measured. Also, sieve analysis, which separates particles based on their width, is less accurate for non‐spherical particles, which is the case for most growing media constituents. Recent works have promoted the use of dynamic image analysis (DIA) to precisely analyze both particle length and width. Five raw materials were chosen (white and black peats, coir, pine bark, and wood fiber) and sieved to obtain various particle size fractions. For each particle size fraction and the raw materials, the mean weight diameter (MWD), derived from sieving, was calculated, whereas mean particle length and width were determined using a DIA tool, the QicPic device. Also, physical properties were assessed from water retention curves established using Hyprop systems. The statement that the larger the particle size, the higher the air‐filled porosity (AFP), the lower the water holding capacity (WHC) was more precisely redefined. Large variations in WHC and AFP mainly occurred for finest particle size fractions, whereas changes were conversely very small or non‐existent for larger particle sizes. From data obtained for each particle size fractions, regression models were established to relate mean particle length and width (both determined using DIA) and MWD (determined from sieving) with WHC and AFP. Mean particle length was identified as the most relevant parameter for predicting WHC and AFP of the raw materials tested.}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Durand, Stan and Fonteno, William Carl and Michel, Jean-Charles}, year={2024}, month={Mar} }
 @article{durand_jackson_fonteno_michel_2023, title={Advances in substrate particle characterization using dynamic image analysis compared to sieving procedure for predicting water retention properties}, volume={1377}, ISSN={["2406-6168"]}, DOI={10.17660/ActaHortic.2023.1377.66}, journal={XXXI INTERNATIONAL HORTICULTURAL CONGRESS, IHC2022: INTERNATIONAL SYMPOSIUM ON INNOVATIVE TECHNOLOGIES AND PRODUCTION STRATEGIES FOR SUSTAINABLE CONTROLLED ENVIRONMENT HORTICULTURE}, author={Durand, S. and Jackson, B. E. and Fonteno, W. C. and Michel, J. C.}, year={2023}, pages={537–543} }
 @article{durand_jackson_fonteno_michel_2023, title={Particle size distribution of growing media constituents using dynamic image analysis: Parametrization and comparison to sieving}, volume={4}, ISSN={["1435-0661"]}, DOI={10.1002/saj2.20518}, abstractNote={AbstractGrowing media constituents have heterogeneous particle size and shape, and their physical properties are partly related to them. Particle size distribution is usually analyzed through sieving process, segregating the particles by their width. However, sieving techniques are best describing more granular shapes and are not as reliable for materials exhibiting large varieties of shapes, like growing media constituents. A dynamic image analysis has been conducted for a multidimensional characterization of particle size distribution of several growing media constituents (white and black peats, pine bark, coir, wood fiber, and perlite), from particles that were segregated and dispersed in water. Diameters describing individual particle width and length were analyzed, then compared to particle size distribution obtained by dry and wet sieving methods. This work suggests the relevance of two parameters, FeretMAXand ChordMINdiameters for assessing particle length and width, respectively. They largely varied among the growing media constituents, confirming their non‐spherical (i.e., elongated) shapes, demonstrating the advantages of using dynamic image analysis tools over traditional sieving methods. Furthermore, large differences in particle size distribution were also observed between dynamic image analysis and sieving procedures, with a finer distribution for dynamic image analysis. The discrepancies observed between methodologies were discussed (particle segregation, distribution weighing, etc.), while describing in details methodological limitations of dynamic image analysis.}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Durand, Stan and Jackson, Brian E. and Fonteno, William C. and Michel, Jean-Charles}, year={2023}, month={Apr} }
 @article{durand_jackson_fonteno_michel_2023, title={Quantitative Description and Classification of Growing Media Particle Morphology through Dynamic Image Analysis}, volume={13}, ISSN={["2077-0472"]}, DOI={10.3390/agriculture13020396}, abstractNote={The physical properties of growing media are dependent on the morphological characteristics of the particles composing them. Thus, their characteristics can be more precisely altered for specific purposes by a better morphological design of materials to optimize the use of raw materials and increase water efficiency. There are many references on the relationship between basic particle size and physical properties, but the arrangement of the particles and the resulting physical properties are also affected by the shape of the particles. Growing media have seldom been characterized by shape criteria and, therefore, their influence remains unknown. A dynamic image analyzer, the QicPic device, was used to assess particle shape and size for a wide diversity of growing media constituents. As well as FeretMAX and ChordMIN diameters describing individual particle length and width, respectively, individual particle shape was analyzed in terms of several descriptors (aspect ratio, circularity, roundness, and convexity). A classification was established to discern different particle shapes and all materials were described accordingly. Correlations between particle morphology descriptors were reported, showing that the greater the particle length, the smaller the width/length ratio, circularity, roundness, and convexity. Circularity, roundness, particle length, and its associated relative span were identified as the most relevant parameters describing materials’ morphology. This work shows a large diversity in particle morphology of growing media constituents, which were categorized into four classes of materials. Three classes were mainly described according to their particle shapes, with a decreasing elongation and an increasing circularity, roundness, and convexity: (1) fine and coarse wood and coir fibers; (2) all Sphagnum white peats, milled or sod; and (3) black peats, sedge peat, coir pith, fresh and composted pine bark, green waste compost, and perlite. A fourth class was represented by coir medium (mixing pith and fibers) and was above all characterized by high diversity in particle length. These findings extend the characterization of the materials for a more thorough evaluation of the links between particle morphology and physical properties.}, number={2}, journal={AGRICULTURE-BASEL}, author={Durand, Stan and Jackson, Brian E. and Fonteno, William C. and Michel, Jean-Charles}, year={2023}, month={Feb} }
 @misc{bartley_fonteno_jackson_2022, title={A Review and Analysis of Horticultural Substrate Characterization by Sieve Analysis}, volume={57}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI16583-22}, abstractNote={The physical, hydrological, and physico-chemical properties of horticultural substrates are influenced by particle shape and size. Sieve analysis has been the predominate method used to characterize the particle size distribution of horticultural substrates. However, the literature shows a diversity of techniques and procedures. The effects of agitation time and sample size on particle size distributions of soilless substrates were evaluated for several measures of sieve analysis, including sieve rate (a calculation of the percentage of material passed for each unit time of agitation), distribution median, sd, mass relative span, skewness, and kurtosis. To obtain the standard sieve rate (0.1%/min), pine bark, peat, perlite, and coir required agitation times of 4 minutes and 47 seconds, 7 minutes and 18 seconds, 10 minutes, and 11 minutes, respectively. However, there was concern that unwanted particle breakdown may occur during the particle size analysis of some materials. Therefore, a sieve rate (0.15%/min) for more friable materials was also determined. As a result, the endpoint of sieving was reached sooner for pine bark, peat, perlite, and coir, at 3 minutes and 10 seconds, 4 minutes and 42 seconds, 5 minutes and 14 seconds, and 6 minutes and 24 seconds, respectively. Increasing agitation time resulted in decreased distribution median, sd, and skewness for all materials. Sample sizes half and twice the volume of the recommended initial volume sieved did not change particle size distributions. For more precise characterization of particle size distributions when characterizing substrate components, agitation times and sample sizes should be specified for each material or collectively for all materials to ensure consistency and allow comparisons between results.}, number={6}, journal={HORTSCIENCE}, author={Bartley, Paul C., III and Fonteno, William C. and Jackson, Brian E.}, year={2022}, month={Jun}, pages={715–725} }
 @article{bartley_amoozegar_fonteno_jackson_2022, title={Particle Densities of Horticultural Substrates}, volume={57}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI16319-21}, abstractNote={The heterogeneity of horticultural substrates makes basic physical characteristics, such as total porosity and particle density, difficult to estimate. Due to the material source, inclusion of occluded pores, and hydrophobicity, particle density values reported from using liquid pyknometry, vary widely. Gas pycnometry was used to determine the particle density of coir, peat, perlite, pine bark, and wood substrates. Further precision was examined by gas species and separation by particle size. The calculated particle densities for each material determined by He, N2, and air were relatively constant and varied little despite the species of gas used. Particle size affected the measured particle density of perlite and pine bark but was minimal with coir, peat, and wood. Reducing the particle size removed more occluded pores and the measured particle density increased. Given the small variability, the use of particle density values obtained by gas pycnometry provides repeatable, precise measurements of substrate material total porosity.}, number={3}, journal={HORTSCIENCE}, author={Bartley, Paul C., III and Amoozegar, Aziz and Fonteno, William C. and Jackson, Brian E.}, year={2022}, month={Mar}, pages={379–383} }
 @article{bartley iii_yap_jackson_fonteno_boyette_chaves-cordoba_2023, title={Quantifying the Sorptive Behavior of Traditional Horticultural Substrate Components Based on Initial Hydraulic Conditioning}, volume={58}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI16698-22}, abstractNote={The ability of a substrate component (organic or inorganic) to capture and retain water (hydration and wettability) is important to investigate and promote water-use–efficient practices. Many factors may play a role in the wettability of the material, including the processing of the material and its initial handling. The goal of this experiment was to determine the effect of moisture content (MC) on the sorptive behavior of substrates after an initial and secondary hydration cycle. Coir, peat, and aged pine bark were evaluated at a 33%, 50%, and 66% MC by weight. At all moisture levels, coir and bark were minimally affected by MC or the initial hydration cycle. Peat was the most vulnerable to changes in sorptive behavior as a result of wetting and drying cycles. After a wetting and drying cycle, the maximum volumetric water content of peat from surface irrigation was reduced 21.5% (volumetrically), more than three times any other treatment. The hydration efficiency of peat was improved when blended with as little as 15% coir. These experiments provide evidence that MC and initial handling of the substrate can lead to differences in initial water use efficiency.}, number={1}, journal={HORTSCIENCE}, author={Bartley III, Paul C. and Yap, Ted C. and Jackson, Brian E. and Fonteno, William C. and Boyette, Michael D. and Chaves-Cordoba, Bernardo}, year={2023}, month={Jan}, pages={79–83} }
 @article{schulker_jackson_fonteno_heitman_albano_2021, title={Exploring Substrate Water Capture in Common Greenhouse Substrates through Preconditioning and Irrigation Pulsing Techniques}, volume={11}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy11071355}, abstractNote={Particles in a substrate create a network of pore pathways for water to move through, with size and shape determining the efficacy of these channels. Reduced particle size diversity can lead to increased leachate, poor substrate hydration, and an inefficient irrigation practice. This research examined the hydration characteristics of three greenhouse substrate components at three preconditioned initial moisture contents using subirrigation under five different irrigation durations and three water depths (2 mm, 20 mm, and 35 mm). Sphagnum peatmoss, coconut coir, and aged pine bark were tested at 67%, 50%, and 33% initial moisture (by weight). The objectives were to determine the impact of varying irrigation event durations (5, 10, 20, 30, 60 min) over a 60-min period, and the further influence of water depth and initial moisture, on the water capture abilities of peat, coir, and pine bark. The number of irrigation events depended on the irrigation event time of that experimental unit divided by the total time of 60 min, varying from 12, 6, 3, 2, and 1 event. Hydration efficiency was influenced by initial moisture content (IMC), water depth, pulsing duration, and inherent substrate characteristics (hydrophobicity/hydrophilicity). Initial MC had the largest impact on peat, regardless of water level or irrigation duration. Lower IMCs increased the hydrophobic response of peat, further reducing the amount of water the substrate was able to absorb. Pine bark had a 5–10% decrease in initial hydration between 67%, 50%, and 33% IMC, while coir’s hydrophilic nature reduced any IMC affects. At 50% IMC or less, coir had the highest volumetric water content (VWC) across all substrates, pulsing durations, and water depths. Water depth was found to increase initial hydration and final hydration 6–8% across all substrates. These three materials had altered and varied water capture responses depending on the combination of treatments employed. This work demonstrated the effects of intensity and exposure on substrates and the need for more integrated research for improving water use efficiency on container crops.}, number={7}, journal={AGRONOMY-BASEL}, author={Schulker, Brian A. and Jackson, Brian E. and Fonteno, William C. and Heitman, Joshua L. and Albano, Joseph P.}, year={2021}, month={Jul} }
 @article{smith_jackson_whipker_fonteno_2021, title={Industrial hemp vegetative growth affected by substrate composition}, volume={1305}, ISSN={["2406-6168"]}, DOI={10.17660/ActaHortic.2021.1305.12}, journal={III INTERNATIONAL SYMPOSIUM ON GROWING MEDIA, COMPOSTING AND SUBSTRATE ANALYSIS}, author={Smith, J. T. and Jackson, B. E. and Whipker, B. E. and Fonteno, W. C.}, year={2021}, pages={83–89} }
 @article{durand_jackson_fonteno_michel_2021, title={The Use of Wood Fiber for Reducing Risks of Hydrophobicity in Peat-Based Substrates}, volume={11}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy11050907}, abstractNote={Peat substrates are well known to become hydrophobic during desiccation, thus degrading their water retention properties. Synthetic wetting agents are commonly incorporated to limit the risk of hydrophobicity, but substrates companies are searching for more sustainable alternatives. To that end, the effect of wood fiber addition in peat-based mixes was measured using contact angles and hydration curves. The study was carried out on two raw materials (white milled peat and wood fiber) and binary mixes. The results showed a shift from hydrophilic to more hydrophobic character with a decrease in the ability to rewet of peat-based substrates in relation to the intensity of drying, whereas wood fiber remained hydrophilic. Increasing wood fiber content in peat-based mixes improved the rehydration efficiency, but with a lower intensity of that measured with synthetic wetting agent addition. Our results highlighted the hydrophilic nature of wood fiber and demonstrated an additional benefit of wood fiber use in peat-based growing media.}, number={5}, journal={AGRONOMY-BASEL}, author={Durand, Stan and Jackson, Brian E. and Fonteno, William C. and Michel, Jean-Charles}, year={2021}, month={May} }
 @article{michel_jackson_fonteno_2021, title={The use of coir for reducing risks of peat-based substrate hydrophobicity}, volume={1305}, ISSN={["2406-6168"]}, DOI={10.17660/ActaHortic.2021.1305.59}, abstractNote={The wettability of peat, coir and peat:coir mixes (90:10, 80:20 and 70:30 v v-1) were analyzed from contact angle measurements and hydration efficiency tests, and also compared to the effects of wetting agents. Results showed a change from a hydrophilic to an increasing hydrophobic character of peat in relation to the intensity of drying, whereas coir remained hydrophilic. Although its influence is lower than those measured with wetting agent, coir addition in peat-based substrates improved the ability to rewet (i.e. to reduce the risks of hydrophobicity occurring during drying).}, journal={III INTERNATIONAL SYMPOSIUM ON GROWING MEDIA, COMPOSTING AND SUBSTRATE ANALYSIS}, author={Michel, J. C. and Jackson, B. E. and Fonteno, W. C.}, year={2021}, pages={449–454} }
 @article{schulker_jackson_fonteno_heitman_albano_2020, title={Comparison of Water Capture Efficiency through Two Irrigation Techniques of Three Common Greenhouse Soilless Substrate Components}, volume={10}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy10091389}, abstractNote={Substrate wettability is an important factor in determining effective and efficient irrigation techniques for container-grown crops. Reduced substrate wettability can lead to lower substrate water capture, excessive leaching and poor plant growth. This research examined substrate water capture using surface and subirrigation under three initial moisture contents (IMC). Sphagnum peat moss, coconut coir, and pine bark were tested at IMCs of 67% 50%, and 33%. Substrate water capture was influenced by both IMC and irrigation technique. Surface irrigation increased the water capture of coir and peat, regardless of IMC, whereas IMC influenced pine bark water capture more than irrigation method. Surface-irrigated coir at or above 50% IMC provided the greatest water capture across all treatments. The first irrigation had the highest capture rate compared to all other events combined. Container capacities of pine bark and coir were unaffected by IMC and irrigation type, but the CC of peat was less by ~ 40% volumetrically under low IMC conditions. Coir, had the greatest ability to capture water, followed by pine bark and peat, respectively. Moisture content, irrigation type and component selection all influence the water capture efficiency of a container substrate.}, number={9}, journal={AGRONOMY-BASEL}, author={Schulker, Brian A. and Jackson, Brian E. and Fonteno, William C. and Heitman, Joshua L. and Albano, Joseph P.}, year={2020}, month={Sep} }
 @article{owen_jackson_fonteno_whipker_2020, title={Liming Requirements of Greenhouse Peat-based Substrates Amended with Pine Wood Chips as a Perlite Alternative}, volume={30}, ISSN={["1943-7714"]}, DOI={10.21273/HORTTECH04506-19}, abstractNote={Processed loblolly pine (Pinus taeda) wood has been investigated as a component in greenhouse and nursery substrates for many years. Specifically, pine wood chips (PWCs) have been uniquely engineered/processed into a nonfibrous blockular particle size suitable for use as a substrate aggregate. The objective of this research was to compare the dolomitic limestone requirements of plants grown in peat-based substrates amended with perlite or PWC. In a growth trial with ‘Mildred Yellow’ chrysanthemum (Chrysanthemum ×morifolium), peat-based substrates were amended to contain 0%, 10%, 20%, 30%, 40%, or 50% (by volume) perlite or PWC for a total of 11 substrates. Substrates were amended with dolomitic limestone at rates of 0, 3, 6, 9, or 12 lb/yard3, for a total of 55 substrate treatments. Results indicate that pH of substrates amended with ≥30% perlite or PWC need to be adjusted to similar rates of 9 to 12 lb/yard3 dolomitic limestone to produce similar-quality chrysanthemum plants. In a repeated study, ‘Moonsong Deep Orange’ african marigold (Tagetes erecta) plants were grown in the same substrates previously formulated (with the exclusion of the 50% ratio) and amended with dolomitic limestone at rates of 0, 3, 6, 9, 12, or 15 lb/yard3, for a total of 54 substrate treatments. Results indicate a similar dolomitic limestone rate of 15 lb/yard3 is required to adjust substrate pH of 100% peatmoss and peat-based substrates amended with 10% to 40% perlite or PWC aggregates to the recommended pH range for african marigold and to produce visually similar plants. The specific particle shape and surface characteristics of the engineered PWC may not be similar to other wood products (fiber) currently commercialized in the greenhouse industry, therefore the lime requirements and resulting substrate pH may not be similar for those materials.}, number={2}, journal={HORTTECHNOLOGY}, author={Owen, W. Garrett and Jackson, Brian E. and Fonteno, William C. and Whipker, Brian E.}, year={2020}, month={Apr}, pages={219–230} }
 @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{bartley_jackson_fonteno_2019, title={Effect of particle length to width ratio on sieving accuracy and precision}, volume={355}, ISSN={["1873-328X"]}, DOI={10.1016/j.powtec.2019.07.016}, abstractNote={The physical, hydrological, and physico-chemical properties of horticultural substrates are influenced by particle shape and size. Sieve analysis is the predominate method utilized to characterize the particle size distribution of horticultural substrates. However, the effect of particle length on sieve analysis results have only been speculated. Laser cut particles with eight different length to width (L:W) ratios were sorted by sieves for agitation times ranging from 1 min to 5 min. To quantify the effect of L:W ratio and agitation time, the means (mid-point) and standard deviations of particle distributions were compared. Particles with a 1:1 L:W ratio were the most accurately sorted particles, containing midpoints most similar to true sieve size. As particle length increased, distribution midpoints and standard deviation increased. Elongated particles, 2:1 L:W ratio and greater, may cause the particle size distribution to skew positively. Increasing agitation time influences the probability of a particle and open sieve aperture converging in an orientation which allows it passage and can improve sieve accuracy and precision. By improving the consistency of sieving protocols, the accuracy of sieve analysis could potentially be improved. However, alternative instruments should be evaluated to improve the characterization of horticultural substrates. If, in the future, the characteristics of elongated or complex-shaped particles are desired, it may prove more beneficial to refine engineering practices than rely on sieving to precisely sort and isolate them.}, journal={POWDER TECHNOLOGY}, author={Bartley, Paul C., III and Jackson, Brian E. and Fonteno, William C.}, year={2019}, month={Oct}, pages={349–354} }
 @article{judd_jackson_fonteno_domec_2016, title={Measuring root hydraulic parameters of container-grown herbaceous and woody plants using the hydraulic conductance flow meter}, volume={51}, number={2}, journal={HortScience}, author={Judd, L. A. and Jackson, B. E. and Fonteno, W. C. and Domec, J. C.}, year={2016}, pages={192–196} }
 @article{owen_jackson_whipker_fonteno_2016, title={Paclobutrazol drench activity not affected in sphagnum peat-based substrates amended with pine wood chip aggregates}, volume={26}, number={2}, journal={HortTechnology}, author={Owen, W. G. and Jackson, B. E. and Whipker, B. E. and Fonteno, W. C.}, year={2016}, pages={156–163} }
 @article{owen_jackson_whipker_fonteno_2016, title={Pine wood chips as an alternative to perlite in greenhouse substrates: Nitrogen requirements}, volume={26}, number={2}, journal={HortTechnology}, author={Owen, W. G. and Jackson, B. E. and Whipker, B. E. and Fonteno, W. C.}, year={2016}, pages={199–205} }
 @article{fields_owen_zhang_fonteno_2016, title={Use of the evaporative method for determination of soilless substrate moisture characteristic curves}, volume={211}, ISSN={["1879-1018"]}, DOI={10.1016/j.scienta.2016.08.009}, abstractNote={Historically, substrate science has utilized the pressure extraction method to measure soilless substrate moisture characteristic curves, albeit with published discrepancies. Recently, a device utilizing the evaporative method to generate moisture characteristic curves by measuring water potential as volumetric water content decreases via evaporation, known as a Hyprop, has become available. This research compares and contrasts moisture characteristic curves developed over a 2-week period using both the pressure extraction and the evaporative methods for two-component greenhouse (Sphagnum peat and perlite) and nursery (aged pine bark and sand) soilless substrates. The pressure extraction method was conducted between water potentials of 0 and −300 hPa (10 data points used in conventional methodology for allotted time), while the evaporative method measurements continued until the tensiometers cavitated (≈ −500 to −700 hPa) and provided higher data density (100 data points) within the two week period. The evaporative method was found to produce repeatable results, with subsequent measurements of each substrate providing analogous measurements (P > 0.9000 and P > 0.3700 for the peat and bark substrate, respectively). There was little variation between the two methodologies for the peat substrate (0.004% difference in the area under the curves from 0 to −300 hPa). However, differences were observed between the methodologies for the bark substrate, with the percentage difference increasing with increasing water potential (9.6% at −100 hPa; 23.7% at −300 hPa). Additionally, the evaporative method measured a continued decrease in volumetric water content of the aged pine bark and sand substrate with increasing water potentials throughout the range of measurements, unlike the pressure extraction method, which has documented issues with loss of hydraulic connectivity between the sample and the plate in coarse highly porous organic substrates. Therefore, the pressure extraction method ceases to decrease in volumetric water content (≤ −65 hPa) resulting in a divergence in curves generated by the two methods. Both methods were found to have limitations while measuring substrate water content near saturation, with the pressure plate resistance to free drainage of water influencing measurements and the evaporative method continually underestimating the saturation point. As a result, both methods provided decreased volumetric water content measurements near saturation than when static physical properties were directly measured; therefore, moisture characteristic curves should be used collectively with static properties to correct for underestimation of total porosity and to better yield an understanding of the hydrophysical properties of a soilless substrate.}, journal={SCIENTIA HORTICULTURAE}, author={Fields, Jeb S. and Owen, James S., Jr. and Zhang, Lin and Fonteno, William C.}, year={2016}, month={Nov}, pages={102–109} }
 @article{judd_jackson_fonteno_evans_boyette_2015, title={Changes in Root Growth and Physical Properties in Substrates Containing Charred or Uncharred Wood Aggregates (c)}, volume={1085}, ISSN={["2406-6168"]}, DOI={10.17660/actahortic.2015.1085.86}, journal={PROCEEDINGS OF THE 2014 ANNUAL MEETING OF THE INTERNATIONAL PLANT PROPAGATORS SOCIETY}, author={Judd, Lesley A. and Jackson, Brian E. and Fonteno, William C. and Evans, Michael R. and Boyette, Michael D.}, year={2015}, pages={421–425} }
 @article{judd_jackson_fonteno_2015, title={Rhizometer: An apparatus to observe and measure root growth and its effect on container substrate physical properties over time}, volume={50}, number={2}, journal={HortScience}, author={Judd, L. A. and Jackson, B. E. and Fonteno, W. C.}, year={2015}, pages={288–294} }
 @inproceedings{yap_jackson_fonteno_2015, title={Water retention of processed pine wood and pine bark and their particle size fractions ?}, volume={1085}, DOI={10.17660/actahortic.2015.1085.95}, booktitle={Proceedings of the 2014 annual meeting of the international plant propagators society}, author={Yap, T. C. and Jackson, Brian and Fonteno, W. C.}, year={2015}, pages={467–471} }
 @inproceedings{kraus_pledger_riley_fonteno_jackson_bilderback_arboretum_2014, title={Defining rain garden filter bed substrates based on saturated hydraulic conductivity}, volume={1034}, booktitle={International symposium on growing media and soilless cultivation}, author={Kraus, H. and Pledger, R. and Riley, E. and Fonteno, W. C. and Jackson, B. E. and Bilderback, T. and Arboretum, J. C. R.}, year={2014}, pages={57–64} }
 @article{lindsay_byrns_king_andhvarapou_fields_knappe_fonteno_shannon_2014, title={Fertilization of Radishes, Tomatoes, and Marigolds Using a Large-Volume Atmospheric Glow Discharge}, volume={34}, ISSN={0272-4324 1572-8986}, url={http://dx.doi.org/10.1007/s11090-014-9573-x}, DOI={10.1007/s11090-014-9573-x}, number={6}, journal={Plasma Chemistry and Plasma Processing}, publisher={Springer Science and Business Media LLC}, author={Lindsay, Alex and Byrns, Brandon and King, Wesley and Andhvarapou, Asish and Fields, Jeb and Knappe, Detlef and Fonteno, William and Shannon, Steven}, year={2014}, month={Aug}, pages={1271–1290} }
 @article{fields_fonteno_jackson_2014, title={Hydration efficiency of traditional and alternative greenhouse substrate components}, volume={49}, number={3}, journal={HortScience}, author={Fields, J. S. and Fonteno, W. C. and Jackson, B. E.}, year={2014}, pages={336–342} }
 @article{fields_fonteno_jackson_heitman_owen_2014, title={Hydrophysical properties, moisture retention, and drainage profiles of wood and traditional components for greenhouse substrates}, volume={49}, number={6}, journal={HortScience}, author={Fields, J. S. and Fonteno, W. C. and Jackson, B. E. and Heitman, J. L. and Owen, J. S.}, year={2014}, pages={827–832} }
 @article{judd_jackson_yap_fonteno_2014, title={Mini-horhizotron: An apparatus for observing and measuring root growth of container-grown plant material in situ}, volume={49}, number={11}, journal={HortScience}, author={Judd, L. A. and Jackson, B. E. and Yap, T. C. and Fonteno, W. C.}, year={2014}, pages={1424–1431} }
 @inproceedings{fields_fonteno_jackson_2014, title={Plant available and unavailable water in greenhouse substrates: Assessment and considerations}, volume={1034}, DOI={10.17660/actahortic.2014.1034.42}, abstractNote={Accurate assessment of available water in substrates usually includes a measurement of water unavailable to plants. Plant roots have an ability to pull suctions up to 1.0 to 2.0 MPa, depending on species, with the classic value for unavailability measured at 1.5 MPa. Five samples each of peat moss, pine bark and perlite and a clay soil were placed in a 1.5 MPa porous plate system for 48 hours. The samples were then removed and run in a dewpoint potentiometer then dried for 24 hours at 105°C. The mineral soil potentials averaged 1.39 MPa, but the others were much smaller: peat = 0.38, bark = 0.21 and perlite = 0.28 MPa. Peat and bark were re-tested at 0.3 MPa on the porous plate system then placed in the potentiometer. The peat water potential was 0.33 MPa while the bark was 0.34 MPa, showing good agreement with the porous plate pressures. The samples of highly porous materials of peat, bark and perlite possibly seemed to lose hydraulic continuity between the samples and porous plate above 0.3 MPa of pressure which stopped the flow of water from the samples. This resulted in artificially high values. In a second study, substrate samples (3 peat: 1 perlite: 1 vermiculite, v/v/v) were taken from mature marigold plants in three stages of wilt: Stage 1: light wilt (initial leaf flagging), Stage 2: moderate wilt (leaves wilted to ~ 45°of vertical) and Stage 3: heavy wilt (leaves wilted and curled to main stem). Water potentials were measured at each stage using the potentiometer. After substrate sampling, each plant was re-watered and level of recovery was noted. Plants at Stage 1 wilt had soil potentials of ~ 0.6 MPa. Stage 2 wilt was at ~ 1.55 MPa and Stage 3 wilt was ~ 2.2 MPa. All plants visually recovered from wilt at all stages. The potentiometer may be useful in determining actual soil water potentials under dry conditions, not normally measurable using the traditional porous plate system. Unavailable water content for horticultural substrates may be overly high using the porous plate system as confirmed with the dew point potentiometer. Measuring water potentials during plant wilt may help to refine the nature of permanent wilt and more precisely determine water is truly unavailable to plants. INTRODUCTION The term available water capacity, first defined by Veihmeyer and Hendrickson (1927), describes water held in a soil between field capacity (or container capacity in horticultural substrates) and the permanent wilting point (PWP). Permanent wilt describes the condition where a plant has reached a low enough water potential that there can be no recovery (Taiz and Zeiger, 1996). Richards and Wadleigh (1952) found that the PWP for most agricultural crops is between -1.0 and -2.0 MPa, with the convention of -1.5 MPa to be PWP. Plants do not generally reach permanent wilt at the instant they reach this potential, but instead gradually reduce transpiration until available water is lost. Denmead and Shaw (1962) showed that many plants start to reduce transpiration rate at as low as 0.2 MPa. In order to determine available water content, container capacity and unavailable water must be measured. To measure UW, Bouyoucos (1929) described an apparatus which produces a suction equal to -1.5 MPa which draws upon a soil sample. This idea was refined by Richards and Fireman (1943) who applied 1.5 MPa of pressure, and Proc. IS on Growing Media & Soilless Cultivation Eds.: C. Blok et al. Acta Hort. 1034, ISHS 2014 342 employed the use of porous plates which soil samples are placed upon to allow water to be moved out of the samples until equilibrium is reached with the 1.5 MPa pressure that has been applied. A modified version of Richards and Fireman’s pressure plates is currently the most common method of measuring UW, along with the plant-based method using sunflower (Cassel and Nielsen, 1986). The sunflower method was first proposed by Furr and Reeve (1945) and involves growing sunflower seedlings and allowing them to wilt until PWP is reached, and measuring soil water content. The sunflower method can take long periods of time and due to the noninstantaneous wilt of plants, this method can lack in accuracy. However, inaccuracies have been reported with the use of pressure plates at tensions as high as -1.5 MPa (Stevenson, 1982; Fonteno and Bilderback, 1993; Gee et al., 2002). A possible explanation for the inaccuracies with pressure plates is the loss of hydraulic connectivity, or the lack of an unbroken water column throughout the sample. If the water column between the plate and the length of the sample is broken, pressure will be applied to either end of the sample, and thus result in no net flow of water. Recent research by Curtis and Claassen (2008) has shown the effectiveness of using dewpoint potentiometry to measure the water potential of inorganic amendments with higher precision. The objectives of this research were: 1) to determine the potentials reached when -1.5 MPa are applied to organic greenhouse substrate components, and 2) to determine soil water potentials of plants grown in container substrates during the wilting process. MATERIALS AND METHODS This experiment required the use of pressure plate extractors (PPE; Soilmoisture Equipment Corp.; Santa Barbara, CA) and a WP4C Dewpoint Potentiometer (Decagon; Pullman, WA). Traditional horticultural substrate components including, sphagnum peat moss (Premier Tech, Canada), aged pine bark, and perlite, were tested along with a clay mineral soil classified as Gerogiaville. Five rubber rings were placed on each moistened 1.5 MPa pressure plate, and each ring was filled with one of the materials being tested. In total 20 total samples were tested (4 materials, 5 replications). The samples were saturated for 24 h, and placed in PPEs. Flat circular lead weighs were placed on top of each sample, in order apply a slight downward force to ensure connectivity between the plate and the sample. Nitrogen gas (N2) was then slowly passed into the PPEs until the PPEs were pressurized to 1.5 MPa. The pressure in the PPEs was maintained for 48 h. The samples were then removed, sealed and measured in the WP4C dewpoint potentiometer. The dewpoint potentiometer uses a chilled-mirror dewpoint technique. Relative humidity is measured until equilibrium is attained between the air in the chamber and the sample. Water potentials were determined using repeated measures until successive readings were equal. Testing the samples from the pressure plate allowed the measurement of water potential rendered after pressures of 1.5 MPa. Experiment Two – Plant Wilt Plastic containers of 7.6 cm diameter and 7.6 cm height were filled with a substrate consisting of a mixture of peat: vermiculite: perlite (3:1:1, v/v/v) at a bulk density of 0.13 g/cm3 to ensure uniformity. Marigold (Tagetes erecta L.) seeds were sewn directly into the containers, placed into the greenhouse and irrigated as needed. Fertilization was with 200 ppm N (total) in liquid feed once every 2 to 4 days. Once these plants were mature and flowering the rooting environment (after approximately 8 weeks), each container was saturated, allowed to drain and to begin the wilting process. The plants were observed for wilting until the plant reached one of the three stages of visible wilt (Fig. 1): Stage 1 – initial flagging; Stage 2 – leaves wilted with stems drooping to an angle of 45°; and Stage 3 – all leaves completely wilted. Once at the appropriate wilt stage, plants were photographed and removed from the container. A soil sample approximately 2 cm wide was removed from the top to the bottom of the substrate. Any visible roots were removed and a portion of the sample was placed}, booktitle={International symposium on growing media and soilless cultivation}, author={Fields, J. S. and Fonteno, W. C. and Jackson, Brian}, year={2014}, pages={341–346} }
 @article{turk_kraus_bilderback_hunt_fonteno_2014, title={Rain garden filter bed substrates affect stormwater nutrient remediation}, volume={49}, number={5}, journal={HortScience}, author={Turk, R. L. and Kraus, H. T. and Bilderback, T. E. and Hunt, W. F. and Fonteno, W. C.}, year={2014}, pages={645–652} }
 @inproceedings{judd_jackson_fonteno_2014, title={Rhizometrics: A review of three in situ techniques for observation and measurement of plant root systems in containers}, volume={1034}, DOI={10.17660/actahortic.2014.1034.48}, abstractNote={Rhizometrics is a term derived from rhizo- (rhizosphere) and -metrics (series of parameters or measures of quantitative assessment used for measuring, comparisons or tracking performance or production), to describe several methods either developed or examined by North Carolina State University to observe and quantify root growth of plants in containers. Three new techniques have been developed and/or investigated as potential new methods of quantifying root growth; 1) Mini-Horhizotron; 2) Rhizometer; and 3) Hydraulic Conductance Flow Meter (HCFM). First, the mini-Horhizotrons have a clear, three-arm configuration suitable for observing root growth of small container plant material. The clear arms allow for visible access and measurements of plant roots. Potential measurements include root length, quantity of root hairs, and root architecture. Second, the Rhizometer is made from a clear cylinder that is 7.6 cm tall x 7.6 cm inside diameter, which allows for visible observations of root systems and they can be fitted in the North Carolina State University Porometer for in situ measurements of the influence of root growth on physical properties in containers during crop production. Thirdly, the HCFM is an apparatus that measures root and shoot conductance based on pressure and water flow through the roots, in the opposite direction of normal transpiration under quasi-steady-state conditions. Conductance values are directly indicative (and correlated) with root mass. These Rhizometric techniques are novel methods of observing and quantifying root growth and potentially identifying ways of improving root growth productivity and efficiency to maximize crop growth. These techniques have also been used to quantify root growth differences between/among various substrates. A summary of the initial experiments testing the usefulness of these three techniques for quantifying undisturbed root growth have yielded promising results.}, booktitle={International symposium on growing media and soilless cultivation}, author={Judd, L. A. and Jackson, Brian and Fonteno, W. C.}, year={2014}, pages={389–397} }
 @inproceedings{fonteno_fields_jackson_2013, title={A pragmatic approach to wettability and hydration of horticultural substrates}, volume={1013}, DOI={10.17660/actahortic.2013.1013.15}, abstractNote={Moisture retention has been a key property in substrate analysis for many years. This work explores the relationship between wettability and hydration using a low cost, practical system. Hydration curves and maximum hydration were used to determine three indexes: HE 1 (initial hydration), HE 3 (a watered-in value) and HE 10 (comparing irrigated vs maximum values). Coir, pine bark and sand at 45% moisture and wetting agent reached maximum values with one hydration. However, both coir and peat captured less than half their max in initial hydration when initial moisture was reduced to 30%. Values obtained with this method numerically described common behaviors of substrates, moisture content and wetting agents. INTRODUCTION Many production practices are being reexamined to insure that they better fit with an overall sustainable process. Irrigation efficiency and water conservation is one such area. Part of this effort should be the examination of substrates for their ability to capture and retain the irrigation water delivered to them. The more efficient these mixes, the less water wasted. Hydration of substrates has been studied for wettability (Michel et al., 2001; Urrestarazu et al., 2007; Levesque and Dinel, 1977; Bilderback and Lorscheider, 1997) and capacity (Handreck and Black, 1984; Puustjarvi, 1974; Milks et al., 1989; Wallach et al., 1992). Both areas are vital to hydration, but neither completely describes the effect of an irrigation event on water capture and retention. The purpose of this work is to expand the description of water capture and retention. This process needs to be described in all substrates, so the procedure should be practical, simple and economical for all levels of investigation. The approach was to perform an irrigation event and determine the water content of the substrate. By performing repeated events, one could develop a hydration curve. This would show how quickly a substrate captured the water applied as well as the quantity. By itself, this information is valuable, but the efficiency of water uptake can only be measured against a capacity or maximum value that the substrate could hold. Therefore this work developed a process to determine the rate of uptake and compared it to maximum uptake values. Since water uptake is greatly affected by water content and degree of hydrophobicity, substrate treatments included these parameters. MATERIALS AND METHODS The equipment for the hydration unit consisted of a transparent cylinder, 5 diameter x 15 cm height, with a mesh screen on the bottom; a 100 ml plastic vial (4 cm dia); a 250 ml separatory funnel; and a 250 ml beaker on the bottom (Fig. 1). The vial was fitted with a large O ring and placed in the top the transparent cylinder. The O ring allowed for exact positioning of the vial above the substrate surface to control hydraulic head. The vial had 5 holes in the bottom and acted as a diffuser for the force of the water as it contacted the substrate. Water went from the funnel through the diffuser, into the substrate and out to the beaker. The flow of water was controlled at 2-3 liters per hour with the funnel stopcock. The water dripped evenly from the five holes in the diffuser onto the substrate. If ponding Proc. IS on Growing Media, Composting and Substrate Analysis Eds.: F.X. Martínez et al. Acta Hort. 1013, ISHS 2013 140 occurred, hydraulic head was kept to 1 to 2 cm. A hydration event used 200 ml water through the substrate with the above conditions. Any water effluent going through the substrate was recorded and the moisture retained was calculated by subtraction. Ten hydration events were performed on each substrate with 4 replications per treatment. Materials tested were coir pith (Densu Coir, Canada), peat moss (Premier Tech, Canada), composted pine bark (Pacific Organics, NC), and sand (Builder’s grade, NC). All substrates were tested at three moisture contents, both with and without wetting agent. Wetting agent was AquaGro-L at 187 ml/m3. Samples were moistened to 1.5 mass wetness (MW), then air dried down to 0.82, 0.43, and 0.18 MW, representing moisture contents of 45, 30 and 15% by weight. These levels were too high for sand and it was wetted and dried to 15, 10 and 5% moisture. Cylinders were filled and firmed to 200 ml of sample and packed to specific target densities for each material. All replications within a substrate treatment were packed to within 5% by weight. As substrate heights changed in the process, heights were recorded at three points on each surface and averaged. The diffuser prevented much unevenness of the substrate surfaces. Maximum hydration was measured in a similar fashion as container capacity. After 10 hydrations, the sample cylinder was removed from the hydration unit, weighed and placed into a Buchner funnel with holes as described in the NCSU Porometer Manual (Fonteno, 2010). Water was slowly added from the bottom in a stepwise manner until it reached the top of the substrate surface. After 15 minutes, the water was drained from the sample, allowed to drain for 30 minutes then weighed. Samples were then placed in a forced-air drying oven at 105°C for 24-48 h until dry. Water retention was used to create hydration curves and expressed as a percent age of the total volume. Hydration efficiency was expressed as the percent volume container water compared to the maximum water content it could hold. Efficiency was examined at three points. Initial hydration (HE 1) was the water held after the first hydration event divided by the maximum hydration. HE 3 was the water held after the third hydration event divided by the max. This was considered the “watered-in” level – a level that is reached after hydrating a substrate for production. HE 10 was the water content held after the tenth hydration event divided by the max. This was used to determine if the substrate ever reached the maximum hydration by irrigation. The experiment was a completely randomized design. Statistical mean separation was done with LSD (p 0.05) using SAS (Cary, North Carolina). RESULTS AND DISCUSSION Hydration curves for coir are shown in Figure 2. Water retention is displayed as percent volume of substrate. For comparison, the moisture contents of 15, 30 and 45% by weight are displayed as 2, 4 and 7% by volume at 0 hydrations. The coir without wetting agent hydrated quickly at the first hydration to over 60% by volume and took up little water afterward. At 30% initial moisture, the uptake was much less (20%) and only increased in 8 to 10% increments with each additional hydration. At 15% initial moisture, the coir took up even less water and never reached the levels of the 30 and 45% treatments. Maximum values for 30 and 45% were the same (~70%) while the 15% treatment was significantly less. With wetting agent, the wetting curve response was similar at 45% moisture although slightly higher. However, both the 15 and 30% treatments reached similar maximum levels. Maximum values for all coir treatments were the same, except for the 15% without wetting agent (Table 1). Peat without wetting agent took up much less water than the coir treatments at 45 and 30% (Fig. 3). The 15% treatment of peat was too hydrophobic to take up water consistently and the data is not shown. With wetting agent, peat took up water similarly to coir with wetting agent at 45% moisture. However, the peat at 30 and 15% took up much smaller amounts at each hydration and never reached maximum hydration. Pine bark reached maximum hydrations by the third hydration event in all treatments except the 15% moisture without wetting agent. Sand wet up to maximum levels at}, booktitle={International symposium on growing media, composting and substrate analysis}, author={Fonteno, W. C. and Fields, J. S. and Jackson, Brian}, year={2013}, pages={139–146} }
 @article{barnes_nelson_fonteno_whipker_jeong_2013, title={Impact of Mature Dairy Manure Compost and Water Content on Wettability and Bulk Density in Peat Moss-Perlite Root Substrate}, volume={982}, ISSN={["2406-6168"]}, DOI={10.17660/actahortic.2013.982.7}, abstractNote={ISHS International Symposium on Responsible Peatland Management and Growing Media Production IMPACT OF MATURE DAIRY MANURE COMPOST AND WATER CONTENT ON WETTABILITY AND BULK DENSITY IN PEAT MOSS-PERLITE ROOT SUBSTRATE}, journal={INTERNATIONAL SYMPOSIUM ON RESPONSIBLE PEATLAND MANAGEMENT AND GROWING MEDIA PRODUCTION}, author={Barnes, J. and Nelson, P. and Fonteno, W. C. and Whipker, B. and Jeong, Ka-Yeon}, year={2013}, pages={75–80} }
 @article{judd_jackson_fonteno_2013, title={Novel Methods for Observing and Quantifying Root Growth of Horticultural Crops (c)}, volume={1014}, ISSN={["0567-7572"]}, DOI={10.17660/actahortic.2013.1014.88}, abstractNote={INTRODUCTION A large portion of the U.S. Green Industry is involved with growing plants in containers, including nursery crops, annual bedding plants and potted herbaceous perennials. With such a large portion of the industry in containers, it is important to understand the factors that influence root growth to attain optimal benefits from container production. Several factors that affect root growth include the physical and chemical properties of substrates. Physical properties include porosity and water holding capacity, percentage of fine particles and bulk density (Mathers et al., 2007). Chemical properties include pH, cation exchange capacity and soluble salts (Mathers et al., 2007). There are several known techniques used to measure these factors that affect root growth, but methods used to measure the whole root system or measure the growth of roots over time are not as widely available. It is also not well understood how roots change and affect the physical properties of substrates in the container over time. The most common root system measurements reported in scientific literature are: (1) subjective root ratings and (2) root dry weight measurements. Root ratings, while being non-destructive, are completely subjective to the person rating the root system and can vary person to person. The second method of root washing is widely accepted as a valid determination of root mass but it is well understood/assumed that a percent of root (particularly fine roots) mass is lost. Oliveira et al. (2000) reported that almost 20-40% of the original root weight is lost during root washing of certain plant species. A non-destructive technique for measuring horizontal root growth (HorhizotronTM) was developed at Auburn University and Virginia Tech that offers a simple, non-destructive technique to measure root growth over time (Wright and Wright, 2004). This HorhizotronTM is constructed out of eight panels of glass attached to an aluminum base to form four wedge-shaped quadrants. The HorhizotronTM was built to fit a plant removed from a 1-3-gal container and placed in the center so the quadrants extend away from the root ball. This technique is most appropriate for assessing/observing root growth from rootballs likely to study post-transplant root response. This technique does not allow for observations and study of small plant root development such as, herbaceous plugs and nursery liners. In order to study root growth of seeds, liners and plugs during production, new techniques need to be developed and evaluated. The objectives of this work were: (1) design and testing of a small scale version of a HorhizotronTM suitable for small plant material and (2) design and testing of the Rhizometer, an in situ technique for determining the influence of plant roots on the physical root environment.}, journal={PROCEEDINGS OF THE INTERNATIONAL PLANT PROPAGATORS' SOCIETY}, author={Judd, Lesley A. and Jackson, Brian E. and Fonteno, William C.}, year={2013}, pages={389–394} }
 @inproceedings{fields_jackson_fonteno_2013, title={Pine bark physical properties influenced by bark source and age (c)}, volume={1014}, DOI={10.17660/actahortic.2013.1014.96}, booktitle={Proceedings of the international plant propagators' society}, author={Fields, J. S. and Jackson, Brian and Fonteno, W. C.}, year={2013}, pages={433–437} }
 @inproceedings{owen_jackson_fonteno_whipker_2013, title={Pine wood chips as an alternative to perlite: Cultural parameters to consider (c)}, volume={1014}, DOI={10.17660/actahortic.2013.1014.77}, booktitle={Proceedings of the international plant propagators' society}, author={Owen, W. G. and Jackson, B. E. and Fonteno, W. C. and Whipker, Brian}, year={2013}, pages={345–349} }
 @inproceedings{bilderback_riley_jackson_kraus_fonteno_owen_altland_fain_2013, title={Strategies for developing sustainable substrates in nursery crop production}, volume={1013}, DOI={10.17660/actahortic.2013.1013.2}, abstractNote={A comprehensive literature search of industrial and agricultural by-products to replace or extend existing soilless substrate components would produce a seemingly endless list of materials from “garbage” to a plethora of manure-based composts that have been tested both in the laboratory and in crop response studies throughout the world. Many of these alternatives have shown promise, but limiting factors for integration and use of the alternatives substrate components continue to include: regional or national availability; transport costs; handling costs; lack of a uniform and consistent product; guidelines for preparation and use of materials or impact on current crop production practices. If a product can overcome the above limitations, then researchers are tasked with documenting substrate physical or chemical characteristics. The objective in all studies is to maintain or increase growth of nursery crops and to extend the longevity and acceptable physical properties for long-term woody ornamental crops. Proof of results is determined using laboratory analyses and crop growth studies. Physiochemical properties are monitored over days, weeks, and months to ensure stability. Particle size distribution and varying ratios of substrate components are manipulated to achieve optimal air filled porosity and available water content. Soilless substrates are amended with lime, sulfur and nutrients or blended with other substrate components to provide optimal chemical characteristics. Additionally, substrates are evaluated under industry conditions to determine impact on water, nutrient and pest management to better understand obstacles to commercial adoption.}, booktitle={International symposium on growing media, composting and substrate analysis}, author={Bilderback, T. E. and Riley, E. D. and Jackson, B. E. and Kraus, Helen and Fonteno, W. C. and Owen, J. S. and Altland, J. and Fain, G. B.}, year={2013}, pages={43–56} }
 @article{altland_owen_fonteno_2010, title={Developing moisture characteristic curves and their descriptive functions at low tensions for soilless substrates}, volume={135}, number={6}, journal={Journal of the American Society for Horticultural Science}, author={Altland, J. E. and Owen, J. S. and Fonteno, W. C.}, year={2010}, pages={563–567} }
 @article{clark_dole_carlson_moody_mccall_fanelli_fonteno_2010, title={Vase life of new cut flower cultivars}, volume={20}, number={6}, journal={HortTechnology}, author={Clark, E. M. R. and Dole, J. M. and Carlson, A. S. and Moody, E. P. and McCall, I. F. and Fanelli, F. L. and Fonteno, W. C.}, year={2010}, pages={1016–1025} }
 @article{dole_viloria_fanelli_fonteno_2009, title={Postharvest evaluation of Cut Dahlia, Linaria, Lupine, Poppy, Rudbeckia, Trachelium, and Zinnia}, volume={19}, number={3}, journal={HortTechnology}, author={Dole, J. M. and Viloria, Z. and Fanelli, F. L. and Fonteno, W.}, year={2009}, pages={593–600} }
 @article{dole_fonteno_blankenship_2005, title={Comparison of silver thiosulfate with 1-methylcyclopropene on 19 cut flower taxa}, ISBN={9066056487}, DOI={10.17660/actahortic.2005.682.123}, abstractNote={The effects of silver thiosulfate (STS; AVB) and 1-methylcyclopropene (1-MCP; Ethylbloc) were determined on 14 commonly-grown cut flower species, represented by one to three cultivars per species. Stems were unpacked, sorted, and placed in either deionized water (DI) and subjected to 1-MCP (740 nL L') or ambient air for 4 h or DI plus STS at either 0.1 mM (Alstroemeria) or 0.2 mM (all other species) for 4 h. After treatment, stems were removed, placed in polyethylene sleeves and stored either wet in DI water or dry in plastic-lined floral boxes at 5°C in the dark for 4 days. After storage bunches were placed in DI water under 12 h (76 to 100 μmol m -2 s -1 ) light per day. Flowers were monitored daily to determine the end of wholesale vase life, which was designated as the first day a change was noticed in the flower or inflorescence that would typically prevent it from being sold by a wholesaler or retailer. The consumer vase life was also recorded for each stem and was designated as the day a typical consumer would dispose of it. The 19 cut flower taxa could be organized into four groups based on effectiveness of STS and 1-MCP: (1) Both STS and 1-MCP increased vase life but STS was more effective: Dianthus caryophyllus (all three cultivars), Bouvardia, Lilium (Asiatic), and Lathyrus odorata. (2) Both STS and 1-MCP prevented the negative effects of dry storage: Freesia (both cultivars) and Chamelaucium (one cultivar). (3) STS increased vase life while 1-MCP did not: Alstroemeria, Delphinium, Matthiola, and Gypsophila. (4) STS and 1-MCP either had no effect or a negative effect: Consolida, Eustoma, Ranunculus, Antirrhinum, and Chamelaucium (one cultivar).}, journal={Proceedings of the 5th International Postharvest Symposium : Verona, Italy, June 6-11, 2004}, publisher={Leuven, Belgium : International Society for Horticultural Science}, author={Dole, J. M. and Fonteno, W. C. and Blankenship, S. M.}, editor={F. Mencarelli and Tonutti, P.Editors}, year={2005} }
 @article{cavins_whipker_fonteno_2005, title={Timing of PourThru affects pH, electrical conductivity, and leachate volume}, volume={36}, ISSN={["0010-3624"]}, DOI={10.1081/CSS-200059076}, abstractNote={Abstract The time between irrigation and PourThru sampling had not been extensively examined for affects on pH, electrical conductivity (EC), and leachate volume in greenhouse production. A greenhouse study with 16.5 and 19.2 cm wide containers using Fafard 4P and Metro Mix 320 soilless substrates was implemented, and PourThru leachates were extracted and tested for pH, EC, and volume at 15, 30, 60, 120, and 240 minutes after irrigation. Substrates and pot sizes affected PourThru pH and EC; however, timing did not affect these values in this study. The elapsed time between irrigation and sampling affected leachate volumes and mass wetness of the substrates such that values decreased when 120 or 240 minutes elapsed from irrigation to sampling. Based upon the fluctuations in leachate volumes and mass wetness values, it is recommended that 60 minutes elapse from time of irrigation to PourThru sampling. Sixty minutes is sufficient time to allow for nutrient equilibration so the greenhouse crop producers can obtain a representative sample of the plant available nutrient status, yet maintain sufficient moisture status to prevent EC shifts due to moisture content variation leachate volumes from becoming too low. *This research was funded in part by the North Carolina Agricultural Research Service (NCARS), the Fred C. Gloeckner Foundation, Ohio Florist Foundation, and the North Carolina Flower Growers' Association.}, number={11-12}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, author={Cavins, TJ and Whipker, BE and Fonteno, WC}, year={2005}, pages={1573–1581} }
 @article{cavins_whipker_fonteno_2004, title={Establishment of calibration curves for comparing pour-through and saturated media extract nutrient values}, volume={39}, number={7}, journal={HortScience}, author={Cavins, T. J. and Whipker, B. E. and Fonteno, W. C.}, year={2004}, pages={1635–1639} }
 @article{huang_nelson_bailey_fonteno_mingis_2002, title={Assessment of the need for nitrogen, phosphorus, potassium, and sulfur preplant nutrients for plug seedling growth}, volume={37}, number={3}, journal={HortScience}, author={Huang, J. S. and Nelson, P. V. and Bailey, D. A. and Fonteno, W. C. and Mingis, N. C.}, year={2002}, pages={529–533} }
 @book{whipker_fonteno_cavins_bailey_2000, title={PourThru nutritional monitoring manual}, publisher={Raleigh, N.C. :  North Carolina State University}, author={Whipker, B. E. and Fonteno, W. C. and Cavins, T. J. and Bailey, D. A.}, year={2000}, pages={40} }
 @article{fonteno_bailey_1997, title={How much water do your plugs really want?}, volume={61}, number={7}, journal={GrowerTalks}, author={Fonteno, W. C. and Bailey, D. A.}, year={1997}, pages={32} }
 @article{fonteno_nelson_bailey_1996, title={Testing procedures for bedding plants}, volume={41}, number={2}, journal={North Carolina Flower Growers' Bulletin}, author={Fonteno, W. C. and Nelson, P. V. and Bailey, D. A.}, year={1996}, pages={1} }
 @article{fonteno_bilderback_1993, title={Impact of hydrogel on physical properties of coarse-structured horticultural substrates}, volume={118}, number={2}, journal={Journal of the American Society for Horticultural Science}, author={Fonteno, W. C. and Bilderback, T. E.}, year={1993}, pages={217} }
 @article{fonteno_1993, title={Problems and considerations in determining physical properties of horticultural substrates}, ISBN={9066054352}, DOI={10.17660/actahortic.1993.342.22}, abstractNote={The establishment of research protocol for horticultural substrates must include the measurements of physical and hydraulic properties. Both empirical and mechanistic approaches must be utilized in protocol development. The steps in establishing a protocol should be: 1) the development of standard definitions for properties and terms, 2) development of a mechanistic framework based on modeling, and 3) development of procedures for data collection. Pore space diagnostics and available water determinations must be reexamined to more appropriately describe these terms. The concept of hydraulic status is introduced as one diagnostic protocol for physical and hydraulic properties.}, number={342}, journal={Acta Horticulturae}, author={Fonteno, W. C.}, year={1993}, pages={197} }
 @article{fonteno_nelson_1990, title={Physical properties of and plant responses to rockwool-amended media}, volume={115}, number={3}, journal={Journal of the American Society for Horticultural Science}, author={Fonteno, W. C. and Nelson, P. V.}, year={1990}, pages={375} }
 @article{fonteno_larson_1983, title={Flowering control for Non Stop tuberous begonias}, volume={27}, number={3}, journal={North Carolina Flower Growers' Bulletin}, author={Fonteno, W.-C and Larson, R. A.}, year={1983}, pages={1} }
 @article{fonteno_larson_1982, title={Photoperiod and temperature effects on NonStop tuberous begonias}, volume={17}, number={6}, journal={HortScience}, author={Fonteno, W. C. and Larson, R. A.}, year={1982}, pages={899} }
 @article{fonteno_cassel_larson_1981, title={Physical properties of three container media and their effect on poinsettia growth}, volume={106}, number={6}, journal={Journal of the American Society for Horticultural Science}, author={Fonteno, W. C. and Cassel, D. K. and Larson, R. A.}, year={1981}, pages={736} }