Journal of the NACAA
Volume 3, Issue 1 - July, 2010
Drip Versus Sprinkler Irrigation In A 4-H Community Youth Garden
- Stephen Sagers, Extension 4-H Assistant Professor, Utah State University
Linden K. Greenhalgh, Extension Agricultural Agent, Utah State University
ABSTRACTAbstract: Sprinkler and drip irrigation methods were compared in the Tooele City 4-H youth garden. A one acre site, subdivided into 8 x 15 garden plots was used by 4-H youth and their families. Forty-three plots were recently converted to drip irrigation; eighty-six plots continued to use sprinkler irrigation. Comparisons between the two methods were observed. Drip irrigation helped reduce weed growth and used less water, but when installed incorrectly or damaged, coverage was inadequate. Sprinkler irrigation used more water and also had inadequate coverage due to spacing design and frequent high winds.
Beginning in 2007, Tooele City Youth garden wanted to introduce another method of irrigation to the large community garden. When the program began, city personnel installed overhead sprinklers. The program grew rapidly during the next seven years, which led to an increase in the garden’s square footage. Due to the increase in use, the water pressure decreased in the sprinkler lines and some garden areas were not receiving adequate moisture. Besides being inefficient, it became a source of frustration to the youth and adult participants because produce quality and production dropped substantially in certain areas. In order to overcome the challenge, Tooele City asked for the help of the local cooperative extension office, and the water supply line was split to water two separate garden sections.
Club leaders in the 4-H youth garden were trying to solve several challenges with the irrigation system in the garden plots. They needed an efficient and user friendly method for the youth to adequately water plants and manage their garden plots. The original sprinklers that were installed had inherent difficulties because they increased the weed population. The land area of the one acre garden sloped so irrigation coverage was not uniform. The Utah State University Extension Service proposed converting to drip irrigation to increase water efficiency. Drip tape was installed to help with water coverage by increasing the pressure in each line and observing the difference in coverage rates during this observational study.
Climatic and Geologic Conditions
Tooele City is located at the edge of the Great Basin Desert and the climate is very arid from May to September. On average the county receives less than 6” of precipitation during those 5 months. Tooele County also has no major freshwater rivers or lakes, so most of the water is pumped from deep wells since the water table is low. The nearby mountains receive significantly more snowpack than the valleys which, creates some runoff in the form of mountain streams. All of these factors make irrigation necessary in this location, and the water used is a precious resource.
In these climatic conditions most garden fruits and vegetables in the state require regular irrigation, since the average rainfall is around 12 inches. The elevation of the garden sits at 5163 feet, making the growing season shorter than many other places throughout the United States and limiting the options of plants that can be grown. It sits at the base of the Oquirrh Mountains and was once covered by Ancient Lake Bonneville that dried up around 14,000 years ago. Since it is the bottom of ancient lakebed the soils is not well drained, it is very alkaline and significant amounts of organic material and preparation are required to generate a productive garden. The garden is mainly for kids and their parents so the optimal method of irrigation is always under experimentation (USDA, 2000).
An observational study was conducted to determine the effectiveness, affordability, and user-friendliness of two separate systems. A new irrigation plan was laid out through a cooperative effort with USU Extension and Tooele City. Approximately 2/3 of the 4-H community garden remained under overhead sprinkler system, and the remaining 1/3 that had the most serious issues of sprinkler coverage were converted to drip lines. This was done for two reasons: to examine the costs and benefits of using this type of irrigation system with 4-H youth and to improve the coverage in the garden. Other irrigation methods were considered that may have been more efficient, but the drip tape was selected because it was the most economical for this area. The cost was an issue since this project was designed to help all individuals regardless of socio-economic status.
During the past two years more than 200 youth and their parents worked the two garden areas in their individual plots. This provided a good test for the drip irrigation system because garden operations of planting seeds, weeding and harvesting used the common garden tools including rakes, shovels and hoes. The care and maintenance of the plots tested the durability of the drip irrigation equipment.
A major advantage of drip tape in Utah’s climate is that it saves water. The drip tape used about 50% less water than sprinkler irrigation. This is something that we continue to monitor and using recent grant funding are now setting a system to monitor sub surface moisture to determine the systems efficiency. (Wilson and Bauer, 2005.) Results of this will not be known until the fall of 2010.
In addition to saving water, this plan also educated both youth and parents that participated about the benefits of using drip irrigation in landscape and gardens in the city. Drip tape is not new equipment, but it is not as widely available locally as overhead sprinklers. Many of the gardens participants had not used this method before, so the introduction to this irrigation method educated participants about the importance of effective water conservation methods to community members. Another advantage was better weed control since they not grow well in the unrelated areas between the rows making control of unwanted plants much easier.
Irrigation uniformity was also an advantage. The garden is located near the mouth of a canyon, and due to local weather patterns, the wind blows consistently blows hard during certain seasons. Due to the unpredictable airstreams, water from the sprinkler irrigation is diverted or blown away so many plants never receive adequate moisture. Large plants, such as tomatoes or sunflowers, block the sprinkler stream from the heads, but this was not a problem for the drip hose since the water leaked right at the base of the plants. The uniform drip watering also helped the plants grow and produce faster throughout the hot summer months. Plants grown with drip irrigation tolerated the heat better due to optimal soil temperatures combined with adequate moisture around the roots.
There was inadequate coverage because of the increased demand on water pressure after the growth of the club. Drip tape was put in, but it was hypothesized that it would be very fragile. After some observation, this theory was confirmed. The drip tape was rather fragile for kids to use and was often punctured as they worked the soil with sharp metal garden tools. This created additional maintenance since the lines constantly required repairs with electrical tape. Though the lines wore out and had to be replaced this option still remained the most economical choice. The availability of the drip line was also an issue since it was not readily available from local businesses.
The study concluded that while there were inherent problems with overhead sprinklers in a youth garden, the drip irrigation hose was not a perfect solution to handle the issues. It was fragile for youth as they cultivated plots with rakes and hoes. It was a time-consuming ordeal for garden administrators to fix each line after youth damaged them. Though electrical tape patched small punctures, the holes were often too big to patch. The lines with multiple small punctures eventually became ineffective and needed replacement. Since the hoses were frequently replaced, there was another challenge; the availability of the hose was a problem due to it not being in stock at local businesses.
The drip tape became popular for those who used it and learned to avoid damaging it while weeding. The lines, when functioning correctly, allowed the plants to grow better in all areas, reduced the amount of weeding, and provided adequate water in the summer months. The education provided to the youth and parents regarding alternative methods of watering in arid climates were also very helpful to the community members.
Another challenge is to persuade families that have only used sprinklers, to try this type of irrigation system. A large majority of the 200 individuals that have used it, request it when they return the following year. They have cited the weed control and uniform method of watering as a reason for wanting to use it again. They also liked how the plants fared in the summer heat with this method.
USU Extension and Tooele City have concluded that though there are significant challenges associated with the drip hoses in a youth garden, the project has been worthwhile. Some of the members now request it. Due to the high cost of completely redoing the sprinkler irrigation system, this is found to be the most cost efficient and effective way to water areas not reached by sprinklers. Though caps now exist on enrollment so that membership will not grow bigger than 120-130 youth, this method has been ideal for the environment and situation for the garden. Its results of uniform coverage and easier weed control led those who have previously used it to request it again.
USDA. 2000. Soil Survey of Tooele Area, Utah. United States Department of Agriculture-Natural Resources Conservation Service.
Wilson, C., Bauer M. 2005. [Online]. Drip Irrigation for Home Gardens. Colorado State University Extension Available: http://www.ext.colostate.edu/PUBS/Garden/04702.html [2010, March 5th]