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E. Carmona, J. Ordovás, M.T. Moreno, M. Avilés, M.T. Aguado, and M.C. Ortega

Static hydrological properties [aeration capacity, easily available water, reserve water, water release curves: θvm), and specific humidity curves] and dynamic hydrological properties (saturated and unsaturated hydraulic conductivity) of sub strates based on industrial cork residue (the bark of Quercus suber L.) and cork compost were studied. Samples of similar granulometry have been used to establish the effect of cork composting on the afore mentioned physical properties. Different models were tested to describe the mechanism of water release from these materials. Van Genuchtens model (Van Genuchten, 1978) was the best fit and produced specific humidity curves that revealed slight differences in the ratio of water capacity function. When cork residues were composted for 7 months, important changes occurred in hydrological properties of the material as it became more wettable. Water retention significantly increased from 45% to 54%, at a potential of 5 kPa, although this did not necessarily result in increased water available to plants. A study of the unsaturated hydraulic conductivity (Kunsat) of these materials revealed a significant de crease in the Kunsat water potential at 0-5 kPa, which corresponds to the range in which the irrigation with these substrates was usually carried out. The long composting process resulted in increased Kunsat between 4 and 5 times that of uncomposted material, which would improve the water supply to the plant.

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Michael R. Evans, Giampaolo Zanin, and Todd J. Cavins

Water-holding capacity represents the volume of water retained by a substrate after a saturating irrigation and drainage, and it is often referred to as container capacity. However, water-holding capacity is a time-specific measurement that is limited to the status of the substrate immediately after saturation and drainage. It does not provide information regarding how quickly water is lost from the substrate, the substrate water status over time, or the irrigation frequency required for a substrate under specific conditions. A new procedure was developed that generated a single numeric value that described the wetness of a substrate and in so doing took into account the substrate's water-holding capacity and drying rate. This value was referred to as an E-value. For substrates included in this study, E-values ranged from a low of 6 for parboiled fresh rice hulls (PBH) to a high of 93 for the commercial substrate Metro Mix 360. The procedure was shown to generate E-values that were as would be expected for the evaluated substrates and also ranked the substrates as would have been expected. Over repeated evaluations, the procedure was demonstrated to have a maximum inherent variability of plus or minus one E-value.

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Nathan J. Herrick and Raymond A. Cloyd

insect pests that reside in growing media, including fungus gnat larvae ( Echegaray et al., 2015 ; Helyer et al., 2003 ). Rove beetle adults are mobile but tend to reside in growing media in greenhouse environments. Birken and Cloyd (2007) found that

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Erin James and Marc van Iersel

the Scotts Co. for the donation of the growing media. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this

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James E. Altland and James C. Locke

Byproducts of pyrolysis, known collectively as biochar, are becoming more common and readily available as ventures into alternative energy generation are explored. Little is known about how these materials affect greenhouse container substrates. The objective of this research was to determine the effect of one form of biochar on the nutrient retention and release in a typical commercial greenhouse container substrate. Glass columns filled with 85:15 sphagnum peatmoss:perlite (v:v) and amended with 0%, 1%, 5%, or 10% biochar were drenched with nutrient solution and leached to determine the impact of biochar on nutrient retention and leaching. Nitrate release curves were exponential and peaked lower, at later leaching events, and had higher residual nitrate release over time with increasing biochar amendment rate. This suggests that biochar might be effective in moderating extreme fluctuations of nitrate levels in container substrates over time. Peak phosphate concentration decreased with increasing biochar amendment rate, whereas time of peak release, girth of the peak curve, and final residual phosphate release all increased with increasing biochar amendment. Additional phosphate levels in leachates from biochar-amended substrates, in addition to the higher phosphate concentrations present in later leaching events, suggest this form of biochar as a modest source of phosphate for ornamental plant production. Although there was not sufficient potassium (K) from biochar to adequately replace all fertilizer K in plant production, increasing levels of this form of biochar will add a substantial quantity of K to the substrate and should be accounted for in fertility programs.

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Md. Jahedur Rahman, Md. Quamruzzaman, Jasim Uddain, Md. Dulal Sarkar, Md. Zahidul Islam, Most. Zannat Zakia, and Sreeramanan Subramaniam

availability in the growing substrates. Proper nutrient combinations in the solution may improve the yield and yield contributing characters in the crop. Consequently, the present experiment was aimed to find out a suitable and sustainable growing media mixture

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Patrice Cannavo, Houda Hafdhi, and Jean-Charles Michel

have a considerable impact on plant growth. The hydraulic properties of growing media generally provide precise information about their ability to provide good growth conditions. Peat, especially slightly decomposed sphagnum peat, is a growing medium

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Daniel C. Milbocker

Pyrus calleryana, Decne, `Aristocrat'; Cryptomeria japonica, D. Don; Populus maximowiczii, Henry × `Androscoggin' and Koelreuteria bipinnata, Franch. trees were grown in low-profile containers. The optimum height and width of these containers was 20 to 30 cm and 84 cm, respectively. Pine bark and mixtures containing 50% or more of pine bark were preferable to mixtures containing leaf mold for filling the containers because the former weigh less. Roots penetrated pine bark mixtures better than sphagnum peat mixtures and also retained their shape better during transplanting. When grown in low-profile containers, trees grew fibrous root systems; after transplanting, roots grew downwardly radial and trees were able to withstand extremely difficult landscape conditions.

Open access

Sangho Jeon, Charles S. Krasnow, Gemini D. Bhalsod, Blair R. Harlan, Mary K. Hausbeck, Steven I. Safferman, and Wei Zhang

root system, and dark roots and dispersed growing media are symptoms of root rot. The number is the root rot severity rating. Root rot severity was rated per the following scale: 1 = no symptoms; 2 = mild root rot, less than one-third of plant roots

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Mohammed El-Sayed El-Mahrouk, Yaser Hassan Dewir, and Salah El-Hendawy

of different media on seed germination and seedlings growth of ‘Mrs. Burns’ lemon basil. Fig. 1. Vegetative growth of ‘Mrs. Burns’ lemon basil seedlings 45 d after sowing in 13 different growing media (by volume): M1 = 1 coir : 1 vermiculite, M2 = 3