George Elliott

The goal for any irrigation system is to deliver water to the growing medium as effectively and efficiently as possible. Effectively means getting the right amount of water into the growing medium. Efficiently means minimizing the amount of water that is lost from the system.  In order to irrigate effectively, an irrigation system must deliver water uniformly to every pot in an irrigation zone. An efficient irrigation system will either deliver water with minimal leaching and runoff or capture and reuse all the water that is not retained in the growing medium. Sub-irrigation systems are generally both more effective and efficient than top-down systems. These systems include capillary mats, troughs, flood and drain trays and flood floors. Capillary Mats The simplest form of sub-irrigation, in these systems water is delivered to a porous mat that is in contact with the bottom of the container. This allows water to move from […]

The amount of water that can be held by the substrate in a given container with a specific irrigation method is the effective water-holding capacity (EWHC). It may be desirable to maintain the moisture content of the medium below EWHC in order to regulate plant growth or reduce the risk of soil-borne diseases. Overall, it is important to irrigate thoroughly. The amount of water applied must be sufficient to re-wet the entire volume of growing medium. If the medium is dry and not enough water is applied, only part of the mix will be re-wetted. In irrigating thoroughly, the method of delivery plays an important role. With top-down irrigation, water will be pulled downward by the force of gravity. As it moves downward, some will be held by the growing medium. Usually, some water will escape from the bottom of the pot before the medium is thoroughly wet. At the […]

The term “stakeholders” calls to mind a scene from a vampire movie, with angry villagers about to go after the monster that has been terrorizing them. At the National Sustainable Agriculture Stakeholders Dialogue, sharpened sticks were not in evidence, but several pointed opinions were expressed in presentations and discussions. The conference, held Feb 29 in Washington, D.C., was organized by the Leonardo Academy and Scientific Certification Systems (SCS). About 120 attendees represented a wide range of commodity groups, processors, agribusiness interests, government agencies and environmental advocacy groups. Floriculture and nursery interests were well represented, by OFA and ANLA, as well as representatives from production and distribution companies. Joyce Latimer from Virginia Tech, Jim Barrett from the University of Florida and myself were the floriculturists among a handful of academics. The meeting opened with a presentation by Michael Arny, president of Leonardo Academy. He explained how the American National Standards Institute […]