Evaluation of Clean Chip Residual as an Alternative Substrate for Container-Grown Plants
Abstract
Clean chip residual (CCR), a forestry by-product, could become an important replacement for pine bark in containerized nursery and greenhouse crop production. Rising costs of pine bark (PB) due to reduced production, increased importation of logs (no bark) and increased shipping costs have placed a large financial burden on the nursery and greenhouse industries. The objective of this work is to determine if nursery and greenhouse crops grown in CCR can be produced with similar growth to plants grown in traditional PB substrates. Additional objectives include surveying the forest industry to determine availability and potential supply of CCR. If CCR, a local (to the Southeast U.S.), sustainable, and economical forest by-product can be used to amend or replace PB and/or peat, the benefits to grower’s bottom lines and the environment could be tremendous. A variety of nursery and greenhouse crops were evaluated for growth in CCR over the course of this investigation. Chapter two evaluated the annual crops ageratum, salvia, and impatiens in a greenhouse setting. At the study termination two out of three annual species tested had similar growth when compared to standard PB substrates. Chapter three evaluated eight perennial species including buddleia, gaura, coreopsis, verbena, scabiosa, dianthus, rosmarinus, and salvia for growth in CCR on an outdoor container pad. There were few differences in growth at the conclusion of the study for most species. However, shoot dry weight tended to be greater in substrates containing peat. Peat amended treatments produced similar growth in five of seven species at Auburn, AL and two of eight species at Poplarville, MS. Chapter four evaluated growth of woody ornamental crops including crapemyrtle, loropetalum, buddleia and azalea. Data for all species indicated that plants grown in CCR had similar or greater growth than plants grown in PB. Chapter five involved surveying loggers in order to characterize the potential supply of CCR to horticultural industries. Samples from this survey revealed the approximate composition of component particles (wood, bark, needles). Chapter six investigated the potential of CCR to immobilize nitrogen during a 60-day crop cycle. Results showed that CCR does not immobilize nitrogen differently than PB except at higher supplemental nitrogen rates. In general, most plants grew as well as those grown in control treatments for annuals, perennials and woody ornamentals. These studies have demonstrated that CCR is a viable alternative substrate in nursery and greenhouse production of ornamental crops.