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Title: MORE PLANTS PER GALLON: GETTING MORE OUT OF WATER

Author
item BILDERBACK, TED - NCSU
item WARREN, STUART - NCSU

Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2004
Publication Date: 1/1/2005
Citation: Bilderback, T., Warren, S. 2005. More Plants Per Gallon: Getting More Out of Water. HortTech. v.15.p.14-18.

Interpretive Summary: Irrigation of container-grown ornamental crops can be very inefficient, using large quantities of water. Much research was conducted in the 1990s to increase water efficiency. The factors that need to be considered when developing a water management plan for containerized nursery crops includes: method of water application, when and how much water is applied, and the growing substrate. Data suggest that both irrigation volume and time of application should be considered when developing a water management plan for container-grown plants. Amending pine bark substrates with clay may reduce irrigation volume required for plant production.

Technical Abstract: Irrigation of container-grown ornamental crops can be very inefficient, using large quantities of water. Much research was conducted in the 1990s to increase water efficiency. This article examined water management, focusing on three areas: water application efficiency (WAE), irrigation scheduling, and substrate amendment. Increases in WAE can be made by focusing on time-averaged application rate and pre-irrigation substrate moisture deficit. Irrigation scheduling is defined as the process of determining how much to apply (irrigation volume) and timing (when to apply). Irrigation volume should be based on the amount of water lost since the last irrigation. Irrigation volume is often expressed in terms of leaching fraction (LF = water leached ÷ water applied). A zero leaching fraction may be possible when using recommended rates of controlled-release fertilizers. With container-grown plant material, irrigation timing refers to what time of day the water is applied, because most container-grown plants require daily irrigation once the root system exploits the substrate volume. Irrigating during the afternoon, in contrast to a predawn application, may increase growth by reducing heat load and minimizing water stress in the later part of the day. Data suggest that both irrigation volume and time of application should be considered when developing a water management plan for container-grown plants. Amending soilless substrates to increase water buffering and reduce irrigation volume has often been discussed. Recent evidence suggests that amending pine bark substrates with clay may reduce irrigation volume required for plant production. Continued research focus on production efficiency needs to be maintained in the 21st century.