Each day we are facing new challenges in floriculture. Most growers are very aware of the current emphasis being placed on water quality, water conservation, and the reduction of runoff from agricultural industries. Another issue that reaches beyond floriculture and affects society as a whole is solid waste management and waste product utilization. Here at N.C. State, these issues are being addressed in an inimitable fashion. Faculty within the Department of Horticultural Science have combined their expertise and formed a powerful research unit, the Horticultural Substrates Laboratory.
For some time, the Department has housed experts in horticultural substrates (for those of you like myself who are behind the times, "growth medium" is passé and "substrate" is the correct term for the "stuff" around your plant roots): Dr. Bill Fonteno has been specializing in physical properties of horticultural substrates, particularly the mixes used in floriculture; Dr. Ted Bilderback also researches physical as well as chemical properties of substrates, primarily for use in container nursery production of ornamentals; Dr. Stu Warren has expertise in amending native soils for landscape use and is also involved with fertilization practices in the landscape and in nursery production; and Dr. Paul Nelson is renowned as a leading authority in floriculture crop nutrition and has a great interest in pursuing alternative fertilization practices for plant production. These four faculty members are assisted in the horticultural substrates laboratory by four technicians and three graduate students. This core of researchers banded together, integrating the strengths of each program into a center of excellence for substrates research. Though in its infancy, the interaction works well; sharing of facilities, sometimes labor, and a constant dialogue of shared ideas allows the group to address issues that no one member could approach alone.
Any plant/water/fertilizer issue that is related to the below ground portion of a crop is a concern of the substrates research group. The issues being addressed and the corresponding research goals can be broken into two groups, those relating to physical properties of a substrate and those relating to chemical properties of a substrate.
Chemical properties of a substrate are concerned with plant nutrition, fertilization practices, and nutrient retention in the container. In the past, most chemical properties research dealt with these issues without addressing how physical properties of the substrate affected plant nutrition. It is hard to separate physical from chemical properties because they are so interrelated. For example, watering habits (based on drainage and water holding of a substrate) drastically affect nutrient levels in the substrate solution.
The physical properties of a substrate are equally important to growers, yet are less understood than chemical properties. A substrate is needed to supply anchorage for the plant, moisture and oxygen to the roots, and to serve as a reserve for plant nutrients. Physical properties dictate how rapidly the container will drain, how often watering is needed, and to a certain extent, how available nutrients will be to plants.
Water quality/water conservation/runoff/groundwater contamination. It is only a matter of time until growers will be forced to change their fertilization and irrigation habits. The amount of water used in production and the quantity of fertilizer running out of the container after a watering must be reduced. In the simplest terms, the goal is to keep the nutrients in the container, reduce the amount that escapes into the environment, and reduce water use in general.
Horticultural Uses of Solid Waste Materials. The increasing problem of solid waste management affects each of us in our personal as well as professional lives daily. The problem is intensifying and society must be prepared with alternatives to landfill disposal. In case you were unaware, you should know that beginning January 1, 1993, it will be illegal to place any yard trash or plant material in a North Carolina landfill. Currently, items such as leaves and yard debris (including plant material from horticulture industries) account for ~30% of the volume of North Carolina landfills. Where will this material go in 1993? Where will you place your poinsettia stock after you have taken all the cuttings you need? This area of waste utilization is being addressed by the horticultural substrates laboratory.
In a time when agriculture is being criticized for environmental
pollution, we are attempting to increase water quality, and we are standing on
the edge of an era when we will become an essential user of society's waste
products (talk about environmental stewardship!) The horticultural substrates
group is researching real issues of real concern for our industry; water
quality and solid waste utilization being emphasized most. Approached by
individual programs, progress in these areas would be slow. However, with the
cooperative additive efforts currently underway, perhaps the general public
will gain a better appreciation for horticulture in the very near
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