Potato Grower

24 POTATO GROWER | JULY 2019 THE BEST OPTION Determining your ideal pivot sprinkler package The sprinklers on a center pivot are a lot like the tires on a truck. Maintaining the right air pressure and selecting a quality model directly impacts your vehicle's fuel economy. Likewise, when you opt for a professionally designed sprinkler package, you'll optimize the performance of your irrigation system and maximize your investment. However, it is important to understand that determining the best irrigation system design can be a little more complex than choosing a tire. A sprinkler package cannot be designed without first considering crop requirements, field characteristics, environ- mental conditions and the pros and cons of the sprinkler model selected. An irrigation professional can work with you and your dealer to design the ideal irrigation system based on those considerations. This data will lead to further considerations and sprinkler options based on: Droplet Size You should take the soil's characteristics into account to get bet- ter infiltration and maintain good soil structure. Ideally, droplets should be large enough to combat the effects of strong winds, but not so large as to disrupt the soil. • Application Intensity While larger droplets resist wind and evaporation, their higher kinetic energy can lead to surface sealing and erosion on tighter soils. Smaller droplets are suitable for tighter soils, while looser soils can utilize larger droplets. • Application Rate The application rate can be adjusted to the specific crop and growth stage. Considering only the needs of the crop—while neglecting the soil—could result in lower yields. The application rate of a sprinkler must match the infiltration rate of the soil to prevent runoff and over- or under-watered areas within the field. • Sprinkler Height The proper sprinkler height will help to ensure maximum water application uniformity based on crop height. • Distribution Pattern It is important to know how far apart on the span your sprinklers should be to ensure water is applied evenly over the entire field. What Sprinkler Options Work Best for My Field? Once you get a diagnosis of your field, you can get a more accu- rate answer to this question. There is a wide array of sprinkler options available to address many of the challenges growers face, including water runoff, wind drift and evaporation, as well as uneven water distribution on sloping fields. The options available include fixed sprays, directional sprays, bubblers, moving deflector heads and even high-pressure impact sprinklers. Sprinklers can be installed in various ways—from the top of the pipe to just inches above the ground. Top-of-pipe sprinklers for high-profile crops are often preferred by growers who want to apply chemicals above the crops using their irrigation system. Sprinklers with moving deflectors, like wobblers, are recom- mended for sloping terrains since they decrease the potential for runoff thanks to their low application intensity and instantaneous distribution pattern. There are multiple factors that influence distribution uniformi- ty including the sprinkler irrigation pattern, appropriate pressure, nozzle configuration, weather conditions and overlap. Narrower spacing increases overlap and makes it more difficult for wind to alter the water application uniformity. The sprinkler system design must also consider soil type and texture to protect the soil structure. These characteristics de- termine the ideal droplet size of the sprinkler. In general, larger droplets can benefit lighter soils while smaller droplets are more

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