Water-conserving irrigation strategies minimize overwatering, runoff

Nov 05, 2009
Overhead irrigation system used to irrigate the three-gallon container-grown landscape shrubs in the experiment. Credit: Photo by Aaron Warsaw

Conserving water and reducing the environmental impact of runoff are two of the most important issues confronting container nursery operations. Current regulations and laws in five states limit water consumption by container nurseries, and some states also limit nutrient concentrations in runoff. Excessive runoff from container plants often results from poor irrigation efficiency; in some cases as little as 13% to 26% of overhead irrigation is retained in the container.

When runoff is not properly managed, water, fertilizers, and other agricultural chemicals can end up in surrounding water resources, with the potential for environmental contamination. Facing predictions of increased water costs, lower water availability, and increasingly stringent legislation, nursery owners have a keen interest in implementing irrigation practices that conserve water and reduce runoff without adversely affecting crop quality.

Aaron L. Warsaw, R. Thomas Fernandez, Bert M. Cregg, and Jeffrey A. Andresen of Michigan State University published a research experiment in HortScience that investigated whether irrigation scheduling based on daily water use (DWU)—the combined loss of water from plant transpiration and substrate evaporation—could conserve water without negatively impacting plant growth. The researchers set out to determine the effect of scheduling irrigation according to DWU on water conservation and plant growth, determine DWU and water use efficiency (WUE) of several types of common container-grown woody ornamentals, and evaluate the effect of irrigation volume on substrate soluble salt levels.

Fernandez explained the significance of the experiment, remarking; "Applying irrigation based on plant demand or daily water use is a key concept in water conserving irrigation scheduling. However, scientific information regarding the water use of woody ornamentals is limited. Quantifying the DWU of a wide range of container-grown woody ornamentals will allow various species and cultivars to be categorized by water use so those with similar water uses can be grouped together, thus minimizing overwatering and excess runoff."

Ten different woody ornamental plants were grown in containers in 2006 and 2007, and five in 2008. Overhead irrigation was applied in four treatments: a control irrigation rate, irrigation scheduled to replace 100% DWU per application, irrigation alternating every other application with 100% replacement of DWU and 75% DWU, and irrigation scheduled on a three application cycle replacing 100% DWU followed by two applications of 75% DWU. Irrigation applications were separated by at least 24 hours during the experiment.

Daily water use was calculated by measuring the difference in volumetric moisture content 1 hour after irrigation and just prior to irrigation the following day. Species were classified as low, moderate, and high water users with six low, five moderate, and 13 high water users in the study.

According to the study, "scheduling irrigation according to plant DWU substantially reduced the amount of irrigation applied compared with a control for 23 of the 24 species of container-grown ornamentals evaluated in this experiment while producing larger or the same sized plants for all species."

The authors note that the best DWU treatment to use will depend on a number of factors. The ideal irrigation regimen should provide the most economical balance between crop returns and water management concerns; the cost of water, type of irrigation system, and programming capabilities of the system should all be considered when deciding which regimen to use. "For example, a nursery in close proximity to a large urban area in a state where water use and runoff are highly regulated may elect to irrigate at a slight deficit using either the 100-75 or 100-75-75 irrigation schedules to minimize extraction and runoff. However, using deficit or DWU irrigation techniques requires monitoring of soluble salts, which, although not found in our study, may build up under these regimes depending on climatic factors."

More information: The complete study and abstract are available on the ASHS electronic journal web site: http://hortsci.ashspublications.org/cgi/content/abstract/44/5/1308

Source: American Society for Horticultural Science

Explore further: Organic apple orchards benefit from green compost applications

add to favorites email to friend print save as pdf

Related Stories

Crop models help increase yield per unit of water used

May 04, 2009

Crop water use efficiency (WUE, or yield per unit of water used), also known as crop water productivity, can be improved through irrigation management and methods, including deficit irrigation (irrigating less than is required ...

Water-stingy agriculture reduces arsenic in rice markedly

Jul 28, 2008

A new farming method first developed to conserve precious irrigation water may have the added benefit of producing rice containing much less arsenic than rice grown using traditional rice-farming methods, researchers in the ...

Reclaimed wastewater benefits Florida's citrus orchards

Jul 17, 2008

The Sunshine State has seen rapid growth in population during the last 50 years. The 1997 U.S. Census showed that the population of Florida increased more than five-and-a-half times from 1950 to 2000. Naturally, ...

Recommended for you

Giant anteaters kill two hunters in Brazil

Jul 26, 2014

Giant anteaters in Brazil have killed two hunters in separate incidents, raising concerns about the animals' loss of habitat and the growing risk of dangerous encounters with people, researchers said.

Rising temperatures can be hard on dogs

Jul 25, 2014

The "dog days of summer" are here, but don't let the phrase fool you. This hot time of year can be dangerous for your pup, says a Kansas State University veterinarian.

User comments : 0