By Siobhan Fathel
Pennsylvania has experienced widespread droughts this year. With persistent dry conditions, keeping fields properly irrigated poses a challenge. Farmers like Bill Mitchell from Mitchell’s Country Market in Middleburg, Pennsylvania, whose farm is pictured here, added drip irrigation this summer to combat the hot, dry weather and provide daily irrigation for his produce crops. Using drip irrigation can provide much needed hydration for crops without requiring significant energy input or high initial cost expenses.
Drip irrigation systems work by applying a small amount of water (and in some cases fertilizer) uniformly across a specific area. There are two common versions of this type of irrigation: a subsurface drip irrigation system and surface drip irrigation system. In a subsurface system, tubing is placed under ground and is most often used for high value produce crops. Whereas a surface drip irrigation system is added after the crops are planted and can provide irrigation support for dry spells. Key benefits of these systems include decreased water use compared to other irrigation methods, targeted water and fertilizer application at the root zone, and importantly energy (and, therefore, money!) savings.
Drip irrigation is used throughout Pennsylvania, often in fruit and vegetable production, within nurseries and greenhouses, and for other high value, commodity crops. Penn State Extension provides resources which more thoroughly discuss the benefits of water use efficiency in these systems (see: Water Use Efficiency in Agricultural Trickle Irrigation Systems ), installation of drip irrigation for vegetable crops (see: Drip Irrigation for Vegetable Production ), and guides to determining how much water to supply your crops using drip irrigation (see : Irrigating Through a Dry, Hot Summer ). This article will focus on energy savings associated with using drip irrigation.
First: Why do drip irrigations systems save energy? Compared to their high-pressure, high-energy counterparts, drip irrigation can cut down energy costs as much as 50% and increase water efficiency up to 40-70%, according to the Natural Resources Conservation Service (NRSC) Irrigation Guide. Energy required in crop irrigation is directly tied to the level of pumping required. Considerations include (1) how much vertical lift from the water source is required, (2) how much water pressure is needed, (3) the depth of irrigation, (4) the frequency of irrigation, and the (5) efficiency of your pumping system. Importantly, drip irrigation helps to mitigate each of these considerations.
Drip irrigation applies water to the surface of crops, which minimizes the amount of vertical lift required, this could be further minimized if water is supplied from a surface source rather than from a groundwater source. As mentioned, the nature of the drip irrigation is to provide a small, focused application of water at the base of the plant which requires less pressure (8-20 psi) than higher pressure alternatives like sprinkler systems (45 -70 psi). This focus water delivery also reduces seepage and evaporation losses compared with systems that water the entire field area.
How much energy savings could this add up to? To better understand potential savings, the NRCS provides a helpful Energy Estimator Tool to get you started on your journey to lowering energy usage for irrigation. Using this tool, we can run through an example for a switch from sprinkler irrigation with a diesel pump to drip irrigation with a more efficient, electric pump. Let’s look at a 5 acre crop of sweet corn planted in Union County. For a sprinkler system, which requires a water pressure of 60 psi, it costs approximately $223 or $44.60/acre in energy costs to irrigate. Whereas, the drip irrigation system, with a 10 psi water pressure, costs approximately $53 or $10.60/acre to irrigate. That’s a 76% savings!
While there are certainly benefits to using drip irrigation systems, there are a few disadvantages to consider. There is an average upfront cost of $500-$1,200 per acre according to one University of Florida study. Regular maintenance and close management will be required to ensure that the system is working properly and is not damaged or leaking. Finally, it might be beneficial to add drip irrigation to a high value crop midseason if the weather dries out, but this adds a more time-intensive step to suppling adequate irrigation compared to more traditional systems.
Installing a low-pressure, water-efficient, drip irrigation system, can significantly reduce energy costs. To better understand potential savings, the NRCS provides a helpful Energy Estimator Tool to get you started on your journey to lowering energy usage for irrigation.
Source : psu.edu