What is drip irrigation?
Drip irrigation, or SDI, is irrigation that is installed underground. Drip tape is plowed into the ground across the field, then connected by pipes to a water source.
Water or fertilizer is pumped from the water source through a filter system, then through pipe into the irrigation tubing. The water or fertilizer drips out through emitters into the root zone of the crop planted in the field. This system can be automated to ensure the pressure doesn’t get too high and cause damage. It can also be monitored and run remotely.
How deep is the tape buried?
Installation depth should range between 10-16 inches.
Different factors that go into deciding depth if drip tape installation include the following:
Not too deep: Installing drip tape deeper than 16 inches causes the water and nutrients to be dispensed below the root zone, decreasing nutrient effectiveness.
Tillage practices: drip tape should be installed about 6 inches below the deepest tillage pass, but no deeper than 16 inches.
Soil erosion: It’s essential to determine if soil movement could eventually expose the drip line. Fields will be evaluated topographically to identify the best approach, and soil horizons will also be assessed to ensure the drip line is consistently installed in the A horizon.
How much flow do I need?
Five gallons per minute per acre is ideal; two gallons per minute per acre is the bare minimum but requires intensive management.
Five gallons per minute per acre allows growers to apply one inch of water every four days. This is approximately 0.25 inches per day which will counterbalance the average maximum ET (evapotranspiration) rate of corn in the Midwest. In contrast, two gallons per minute per acre allows for one inch of water to be applied every 10 days. Water needs will vary based on crop rotation and crop mix. Soil type also impacts water requirements, as different soils have different water-holding capacities. For instance, sandy soils generally require more water per minute per acre, whereas heavier soils like loam, silt, or clay can often manage with less water per minute per acre.
Water availability influences how the grower manages the irrigation system. When less water is available, growers need to start irrigation early to prevent the soil from drying out and ensure they don’t fall behind. With more water available, they can wait until the soil dries out before irrigating, allowing them to meet the crop’s immediate water needs.
What is the life expectancy for the tape?
The life expectancy of a drip irrigation system depends on water quality and proper care of the drip system. There are multiple drip systems that have been operational for 25-30+ years.
For example, a system in York, NE, has been operating for 39 years with its original drip line, and the K-State research farm in Colby, KS, installed tape over 30 years ago that still functions within design parameters.
A system’s lifespan depends on water quality and consistent maintenance. Minerals like iron and manganese, if present, need management to prevent clogging, as do bicarbonates, which can also impact system longevity. Preventative maintenance, such as acid flushing or chlorine treatment, is essential for keeping emitters clean and operational. Monitoring flow rates and pressure is crucial; if flow rates drop or pressure rises over time, it may be time for an acid flush. For instance, if a zone starts at 100 gallons per minute but drops 10–20% by mid- to late season, with a corresponding pressure increase, an acid flush is recommended. Generally, a 20% reduction from the system’s designed flow rate is a good trigger point for flushing. Proper design, operation, and maintenance are key to maximizing the system’s longevity.
Can I install on slopes, hilly, or terraced ground?
Absolutely.
These installations require tape with pressure-compensating emitters, which deliver a consistent water output. This allows for effective irrigation even on rolling topography. A diaphragm within each emitter regulates the size of the opening—when pressure increases, the opening narrows, ensuring uniform water output regardless of location. This means that whether at the top of a hill with 8 psi of pressure or at the bottom with 30 psi of pressure, the same amount of water is allowed through the emitters, resulting in uniform irrigation throughout.
What is my investment cost?
The cost ranges from $1,700 to $3,000 per acre.
Cost depends on field shape, size, topography, water quality, and total acreage. Larger fields or square, flat fields typically have a lower cost per acre. Irregularly shaped or highly contoured fields will likely be on the higher end of the cost spectrum.
What about rodents?
If rodents are present, they need to be scouted and eradicated as they can cause many problems with the irrigation tubing.
Field edges and areas with perennial crops, like alfalfa, are more prone to rodent issues, as are loose, sandy soils that rodents tend to prefer.
Control measures include trapping, bait, owl nesting boxes, and ensuring that soil packing during drip system installation is done well.
