Scientists Optimize Nursery Irrigation Practices by Managing Water Output

Edward W. Bush and Jeffrey S. Beasley

Proper irrigation management is essential to producing a quality nursery crop, reducing cost and optimizing plant growth. Many believe the nursery industry uses excessive irrigation when producing a large crop, but irrigation analysis at the nurseries in both Forest Hill and Folsom indicated that in some cases below-optimum irrigation volume was used.

Underwatering crops can be as harmful to plants as overwatering. Physiologically, plants that are underwatered become stunted and lose root and shoot growth. Underwatered plants also become more susceptible to insect pests and diseases. Overwatering crops can leach out necessary elements contributing to nutrient movement and runoff into waterways, while leaving plants deficient in nutrients for normal growth. Several leaf and root diseases are attributed to overwatering, and filling soil air space with too much water can suffocate roots. Managing irrigation requires years of experience and detailed management. The goal of this research was to develop a method of irrigation that would assist growers in determining the proper water requirement needed throughout a changing growing season.

Properly scheduling irrigation for nursery container crops can be difficult in substrates (soils) having low water‑holding capacity. Therefore, a simple, automated, sensor‑driven irrigation system was developed at the LSU AgCenter to better regulate irrigation application volumes. To test the device, known as Switch, researchers evaluated the August Beauty gardenia grown in one of two container sizes (1 and 3 gallons) and two pine bark substrates (fine and coarse) over a four-month period. Gardenias grown using the new irrigation system were compared to plants grown using a traditional timed overhead irrigation system. The traditional timed system applied one inch of water per day. Over the course of the study, gardenia had similar growth between irrigation systems within substrate treatments. Gardenia growing in coarse substrate had higher growth indices and greater biomass compared to gardenia growing in the finer substrate. Within four months of planting, all gardenia had reached marketable size. However, gardenia grown using the new Switch system reduced water application volumes greater than 30 percent compared to the traditional timed irrigation system. A provisional patent was granted on the device in 2015. It is expected that the patent process will be finalized by January 2016. This process was a cooperative effort between the nursery industry and the LSU AgCenter.

Edward W. Bush is a professor, and Jeffrey S. Beasley is an associate professor in the School of Plant, Environmental and Soil Sciences.

The summer 2015 issue of Louisiana Agriculture magazine includes articles on a variety of topics that affect Louisiana’s agriculture industry and the environment – water management at Catahoula Lake, 4-H youth wetland programs, artificial reefs for water conservation, corn nitrogen management in saturated soil conditions, and more. 36 pages

9/14/2015 11:54:10 PM
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