LOGAN, Utah — Drip irrigation is a highly efficient irrigation method well suited to many fruit and vegetable row crops.
Drip tubing or tape discharges water to the soil through emitters positioned close to the plant. The tubing can be placed uncovered on the soil surface, under plastic mulch, buried in the soil or suspended above the ground. The water-application rate is low and irrigation is usually frequent. Properly designed and maintained drip-irrigation systems can have benefits that help increase the profitability of crop production.
n Reduced water use: Well-designed drip systems save water and money. Drip irrigation can minimize runoff, deep-percolation and evaporation. Irrigation application improves and goes directly to the plants’ roots.
n Decreased weed and disease pressure: Since the inter-row and noncropped field edges are not watered with a drip system, weed growth is limited compared to sprinkler and flood irrigation. Drip irrigation keeps water off the plant canopy, reducing foliar disease development on many plants. Both of these benefits can lead to reduced pesticide use and chemical and labor savings.
n Lower pumping needs than sprinklers: Drip irrigation requires low water pressure (35 to 40 psi for most systems) than sprinkler irrigation (50 to 80 psi).
n Uninterrupted field operations: Traffic rows should remain dry, allowing access to conduct field operations while watering. This simplifies timing of tillage, application of pesticides and harvesting.
n Fertilizer application: Precise fertilizer application is possible through the drip irrigation system due to high irrigation application uniformity and irrigation efficiency. Soluble nutrient losses are reduced due to decreased deep percolation and surface runoff, which reduces fertilizer costs and improves crop yields.
n Adaptable: Drip systems are suitable for odd-shaped fields. This can be an advantage over surface irrigation due to high land-leveling costs and issues caused by disturbing soil profiles. It has advantages over sprinkler irrigation on odd-shaped fields because the poorest uniformity with sprinkler irrigation occurs at field edges due to a lack of proper application overlap.
n Cost: Initial investment in a drip system ranges from $1,200 to $2,000 per acre. Specialized equipment is needed to install and remove the drip tape. Some parts of the system last 30 years or more (filter, pump, delivery line, etc.) Drip tape or drip tubing lasts one to 10 years. For some annual crops, less-expensive thin wall drip tape is used and discarded each year. Replacing drip tape each year can cost about $400 per acre depending on emitter spacing, wall thickness and row spacing. Thicker-walled drip tape or tubing is used in perennial crops and is left in place for several years. While costs are high, the decision to use drip systems should be to increase profitability through better crop quality and yields.
n Need for clean water: Debris and sediments in irrigation water can easily plug small emitters. It is important to use filtered water in order to avoid clogging. Depending on the water source, multiple filtration systems such as a settling pond combined with a media filter and other inline filters, may be needed. Bacteria and algae growth and mineral deposition from irrigation water can plug emitters. These conditions can be prevented with disinfectants such as chlorine to control biological growth and acid to dissolve buildup.
n Leak repair: Drip tape can be damaged by equipment, insects, rodents or even by deer stepping on it. Leaks need to be fixed in order to keep the system running efficiently. In general, leak repair parts are inexpensive but can be costly in labor. Farmers may need to control rodents and insects to protect drip tape. Some farmers have found that using 6 to 8 mil. (1 mil. is 1/1,000 of an inch) wall thickness helps reduce leaks on tubing that is replaced each year. Drip tape installed for multi-year use generally has a thicker wall, such as 10 to 15 mil. Drip tubing with a wall thickness of 50 to 70 mil. is suitable for many years of use above or below the ground with less potential for leaks.
n Plastic disposal: The annual replacement of some types of drip tape results in significant plastic disposal into the landfill, incurring disposal costs and causing environmental concern. Drip tape buried deeper than 5 inches is harder to retrieve. If the tape is in the tillage layer it gets torn-up and incorporated into the soil. The tape does not harm the soil, but can be a nuisance.
n Labor costs: Installation and removal of drip tape requires concentrated labor efforts. However, the total irrigation labor costs may be less because of the automation capabilities of a drip system.
For more in-depth information on equipment and system design, visit tinyurl.com/USUIrrigation.