Volume 64 - Proceedings samples for non-member viewing
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An optimum rooting substrate for propagation should always consist of the proper levels of air and water (balanced levels), along with an adjusted proper pH level for nutrient uptake. The base of this substrate can be peat, coir or a combination of both. By providing an optimum rooting substrate for cuttings or finished growing containers, it will ensure that these items will get off to a strong start, while reducing or minimizing cultural issues that may arise over time in production due to the compaction of the substrate.
As with hydroponics, this holds true to the popularity that coir has gained in today’s greenhouse and nursery industry, not only as a standalone growing medium for vegetables and cut flowers, but for production and propagation due to its organic origin. It is produced around the world in locations like Mexico, Dominican Republic, India, Sri Lanka, and Central South America. Coir in its raw form must be treated differently than other growing components. In its raw form, coir can have EC levels up to 8.0 mmhos· cm-1. This is why proper care and treatment must be taken to reduce the amount of excess elements that can be harmful to crops, eventually leading to higher input costs. These elements must be balanced to provide an optimum level of guarantee that crop performance will be maximized.
The development of controlled release fertilizers (CRF) parallels the progress of container growing with most of the advances being made in the 1980s and 1990s. The first CRF sources to become commercially available were only nitrogen (N) but the technology has expanded to include potassium (K), phosphorus (P), and other nutrients, including micronutrients.
Controlled release fertilizers use several mechanisms to limit the amount of nutrient made available at any one time. In the first types, nutrient prills were coated with materials as molten sulphur, clay, and wax. The problem with these materials was that cracks in the coating meant the release-rate was not uniform. Today this problem has been overcome by using other materials. For example, Osmocote® uses a resin coating of an alkyd-type, while Multicote® and Plantacote® use a polyurethane-like coating and Ficote® uses thermoplastic resins. All these materials allow a controlled release of nutrients by osmosis, where the thickness of the coating determines release timing and rate.
Today CRF fertilisers are widely used in container production of nursery stock all over the western world and in Japan. Growers in Sweden started to use them in the early 1970s. At that time the only available product was Osmocote. Today we also use Multicote, Plantacote, Ficote and Basacote®.
A number of factors over the past several years have forced container-grown plant producers to alter production practices. Increasing labor cost and new immigration laws have forced growers to rely more on herbicides for weed control. Problems associated with herbicide use in container production include non-target loss, achieving correct calibration, and the expense of repeat applications a year (Case and Mathers, 2006). Non- chemical weed control methods could diminish non-target herbicide loss and reduce potential environmental concerns. Data from this study reveals that one application of various mulch species at a depth of at least 5 cm (2 in.) will provide long-term control of spotted spurge, phyllanthus, and eclipta.