In recent years, several peat and pine bark (PB) alternative substrates have been developed and researched in the United States and throughout the world. The interest in new substrates is in response to the increasing cost and environmental issues
Brian E. Jackson, Robert D. Wright, and Mark M. Alley
U. L. Yadava and S. L. Doud
Trunk bark thickness of 6 peach clones was significantly affected by seedling root-stocks of peach (Prunus persica (L.) Batsch). Of the 7 rootstocks tested, Siberian C invariably induced the thickest bark in the scion while Lovell and Halford induced the thinnest scion bark. However, Siberian C grown as unbudded seedling trees did not produce thicker bark than the other rootstocks, similarly grown. The effect was not site- or cultivar-dependent.
Donald J. Cotter
Yields of greenhouse tomato (Lycopersicon esculentum Mill.) increased in bark or sawdust when the media had been prior cropped. Bark produced more marketable fruit than sawdust No unusual plant diseases were noted and root-knot nematode symptoms (a chronic problem in soil) were not observed on roots in either sawdust or bark.
Mary Lewnes Albrecht, Maurice E. Watson, and Harry K. Tayama
No differences were observed in the level of total acidity, total N and phenolic hydroxyl groups for samples of composted hardwood bark (fresh composted hardwood bark) and composted hardwood bark which had undergone further decomposition (aged composted hardwood bark). Humic acid was extracted from both fresh and aged composted hardwood barks. Yield of humic acid was greater for the aged bark, and there was an increase in the reactive functional groups which are involved in micronutrient chelation (carboxyl groups increased from 2.69 to 3.59 meq/g; phenolic hydroxyls increased from 7.82 to 10.29 meq/g). Alcoholic hydroxyl groups in fresh composted hardwood bark decreased from 2.03 to 0.01 meq/g with aging. From leaching studies it was determined that 0.5 meq/g Cu+2 was bound per gram of dried, fresh bark. Nutrient uptake studies showed that there was a reduction in the foliar nutrient concentration for Lolium multiflorum Lam. for increased cropping time when grown in aged, composted hardwood bark.
D. L. Airhart, N. J. Natarella, and F. A. Pokorny
Water absorption curves were developed for air dry peat-vermiculite and pine bark media. Data indicated 70-78% of moisture saturation was attained within 5 days with a peatvermiculite medium while 48 days were required to achieve 58-70% saturation with a milled pine bark medium. Increased water absorption of pine bark after 10 days of wetting suggested that a threshold moisture level within the bark particles is necessary if water uptake is to be enhanced. The threshold moisture content was established at 35% (wet wt basis).
F. A. Pokorny and Hazel Y. Wetzstein
Internal porosity, availability of internally adsorbed water, and root growth within a pine bark particle were studied. Internal pore spaces comprised about 43% to 44% of the volume of a pine bark particle. Scanning electron microscopy (SEM) of Coleus blumei Benth. and Vaccinium ashei Reade showed roots anchored on the exterior surface and developing within the bark particle. Seedling development (Raphanus sativus L.) in water-saturated pieces indicated that internally adsorbed water was available provided that roots developed within the bark particle. The quantity of available water remains to be determined.
Steve Thomas and Fred B. Perry Jr.
When a 200 ppm N solution as (NH4)2SO4 was percolated through a wet pine bark medium, 6 times the medium volume of the N solution was required to reach an equilibrium of N in the bark. Once equilibrium was reached, the water added, leaching of the ammonium ion was rapid. When twice the medium volume of water was passed through the medium, 85% of the ammonium ions were leached. After analysis of the leachate indicated no N being leached from the bark, 60 ppm of N remained in the bark.
Shiv K. Reddy
Various barks, aged and composted to different degrees, are used in potting mixes. These differences have different effects on plant growth. It was observed that electrical conductivities (ECs) of the bark mixes that reduced plant growth were lower when compared to the ECs of the mixes that did not reduce growth, despite the same fertilization. This difference in EC diminished over time, differently for different barks. The decrease in EC was mainly due to a decrease in N. Apparently, nutrients were adsorbed or immobilized, which decreased their availability to the plants. This observation may be used to assess the suitability of a bark. The relative decrease in EC or N of similarly fertilized bark mix vs. no bark, peat mix (that does not reduce EC) may indicate the relative unsuitability of the bark, as related to nutrition. The amount of decrease in EC may also indicate the amount of additional fertilization to be provided to the bark mix during its use. The same method may also be applicable to other wood wastes, such as kenaf, sawdust, etc.
R. Crofton Sloan, Richard L. Harkess, and William L. Kingery
Urban soils are often not ideal planting sites due to removal of native topsoil or the mixing of topsoil and subsoil at the site. Adding pine bark based soil amendments to a clay soil altered soil bulk density and soil compaction which resulted in improved plant growth. Addition of nitrogen (N) or cotton gin waste to pine bark resulted in improved plant growth compared to pine bark alone. Growth of pansies (Viola × wittrockiana) during the 1999-2000 winter growing season was enhanced by the addition of pine bark plus nitrogen at 3- and 6-inch (7.6- and 15.2-cm) application rates (PBN3 and PBN6) and pine bark plus cotton gin waste at the 6 inch rate (CGW6). Plant size and flower production of vinca (Catharanthus roseus) were reduced by pine bark amendments applied at 3- or 6-inch rates (PB3 or PB6). Crapemyrtle (Lagerstroemia indica) grown in plots amended with 3 or 6 inches of pine bark plus cotton gin waste (CGW3 or CGW6) and pine bark plus nitrogen at 3- or 6-inch rates (PBN3 or PBN6) produced greater shoot growth than other amendment treatments. In some instances PB3 treatments suppressed growth. High levels of N and soluble salts derived from CGW and PBN soil amendments incorporated into the soil probably contributed to the improved plant growth observed in this experiment.
H. E. Wave and W. C. Stiles
Formulations of superior oil applied to the developing buds and bark of ‘Delicious’ apple trees in the greenhouse inhibited bud break and growth. Bud break was significantly affected by oil concn, viscosity, and unsulfonated residue (UR). Total fresh wt of shoots was adversely affected by increasing concn and decreasing UR. Severity of bark injury increased with decreasing viscosities and increasing concn.