GARDEN TALK

Irrigation

The entire root zone needs to be wet when irrigating, and this could be several inches deep. Irrigating only the top of the soil and not the entire root zone will cause roots to stay near the surface, leading to drought stress if water is not applied. leave one zone on a different amount of time than another. Remember to irrigate early in the morning to decrease the chance of disease problems and never late in the evening or at night. Overhead irrigation is used with turfgrass, but drip Shallow-rooted plants will readily show signs of nutrient deficiencies.

Drought stress can cause a delay in maturity, significantly reduce the harvest in many fruits and vegetables and lead to cracked produce and even blossom end rot in some crops. Therefore, frequent irrigation events are recommended for vegetables and other shallow-rooted crops.

Irrigation is another way of improving your garden, specifically drip irrigation. Drip irrigation conserves water by directing water to the root zone of plants where it is needed. Since the water is displaced down the row, garden chores such as scouting or harvesting can be done while irrigating. Overhead irrigation uses more water, wets row middles where it is not needed, and increases disease problems. Vegetable crops need 1 to 1–1/2 inches of water per week. Every farmer and gardener needs a rain gauge to keep up with how much additional water is necessary. Remember, getting three inches of water one week does not supply adequate water for the next two weeks. In theory, an inch of water was applied per week, but in reality, the plants have been suffering from drought for two weeks.

If possible, turf irrigation is recommended, as well. About 1 to 1–1/2 inches per week is needed there too. The water can be applied simultaneously or split up into two applications of about 3/4 inch each. Put out a rain gauge to determine if the irrigation system needs to be turned on. Do not just have it on a timer that turns on a certain day of the week. The system should be turned on when you know you are not getting adequate rainfall. Put out rain gauges in different areas of the yard to check your system to see if water is being evenly distributed. Is one zone getting 1 inch and another getting only 1/2 inch? Consider making adjustments to the sprinkler if it is not working properly, or Improve your garden irrigation is the recommended practice for fruits and vegetables. Drip irrigation is very economical in price and easy to install. It also uses much less water than overhead irrigation. You can purchase a thin wall irrigation line called drip tape that is cheap and designed to be used in a vegetable garden for one year. I know of people who take care of the drip tape and are able to use it on a small scale for more than a year. It is common to purchase drip tape for vegetables with the emitters spaced twelve inches apart. A thicker walled line is used for blueberry, blackberry, and muscadine plants and can be left in the field for many years. The thicker walled line can also be used in the vegetable garden for many years, but I recommend rolling it up and storing it during the off-season. A line can be purchased, and emitters can be manually installed at any Have a plan distance for plants that may Top: Drip tape conserves water by directing it to not be evenly spaced. With the root zone of the plants where it is needed. Next plants evenly spaced in a row, Page: For the best outcome and healthiest harvests, irrigation should be turned on when there is not adequate rainfall; do not just have it on a timer. it is common to purchase the irrigation line for blueberries and blackberries with emitters already in the line spaced 3 feet apart. Even if muscadines are spaced 20 feet apart, I like to use lines with the emitters 3 feet apart down the muscadine row, as well. Roots will grow in the environment best suited for them, and under the trellis where weeds are managed is typically where most of the roots are found. Rodents can and will chew and damage the line, but it can be easily fixed. With crops that use a trellis, such as muscadines, it is easy to install another wire 10 or so inches off the ground and attach the drip line to the wire. Getting the drip line off the ground will really help the rodent issue. Depending on how many gallons of water per minute is available at the site, the system can run all at once or have more than one zone. A water hose, a known container size such as a 5-gallon

bucket, and a watch are all you need to determine the gallons of water per minute. The most common drip tapes apply 1/2 gallon of water per 100 feet per minute, but 1/4 gallon per 100 feet per minute drip tapes are available. The emitters we use for fruit will drip a certain amount per emitter per hour. It is common to have 1 gallon per hour emitters for fruits, but 1/2 gallon and 1/4 gallon per hour emitters are available, as well as emitters that drip more than a gallon per hour. The water will spread out better with a slow drip, and sometimes we cycle the drip irrigation to help the water cover a wider area. Instead of leaving the irrigation on for an hour, try running it for two 25-minute cycles, which would use less water and provide water over a wider area. This method saves water but can take a little extra time to manage. If the field was on a slope and irrigation water runoff was a problem, I would encourage the use of emitters that apply less water per hour and cycle irrigate. The impact sprinklers commonly used on turfgrass irrigation require a lot of pressure, but the drip systems on fruits and vegetables run on much less water pressure. We still need pressure reducers, water filters, fittings, valves and a supply line to get the water to the field, but all that can be used from one year to the next and makes the system very economical. It takes a lot of work, such as pruning, training, weed management, mulching, staking, etc., to produce fruits and vegetables, and we do not want a lack of water to prevent us from making a crop.

The irrigation system is a wonderful tool to help crops, but do not use it when it is not needed. Too much water, especially overhead, can contribute to disease problems, leach out fertilizer and cost money. I like the idea of irrigating fruits, vegetables and turf; however, I have visited many landscapes over the years that had major problems caused by too much water. I like irrigating ornamentals when needed the first year after planting; however, unless you are in a major drought, the established ornamental plants may not need supplemental water.

If you cannot find the irrigation supplies you need or have additional irrigation questions, give us a call at the Extension Office.

Garden Talk Chip East

~ Chip East is a regional extension agent for commercial horticulture for Alabama Cooperative Extension System.