Questions about Drip Irrigation Design

What You Need to Ask Your Drip Irrigation Designer

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Drip irrigation has grown in popularity as growers continue to look to conserve water and other resources. The idea of greater water use efficiency (WUE) and resource use efficiency (RUE) is enticing growers, while the expectation of greater yields, a proven benefit of drip irrigation systems, is further making the case.

Within the last year, a new single-use drip tape and retrieval service option from RDO Water is further encouraging growers to go the route of drip irrigation. The idea of single-use drip tape offers labor savings, reduced water usage, and improved food quality and safety, while eliminating hassles of removing, storing, and re-using drip tape, common issues when it comes to drip systems.

Once it has been decided to convert a field to drip, growers can expect many questions from the irrigation company designing the system – and it’s equally important growers ask questions of their own. Here are the key questions to ask a drip irrigation designer.

In Good Company
The first and perhaps biggest decision a grower needs to make is which irrigation company to partner with for the drip system. A company that can answer “yes” to the below questions is the difference in overall satisfaction and full ROI potential vs. dissatisfaction and inability to achieve maximum ROI.

  1. Question: Does the company offer a thorough consult to ensure an ideal, customized system is recommended?
  2. Question: Does the company install the system?
  3. Question: Does the company provide service after the sale?

Existing Field Considerations
After the partner company has been chosen, the initial questions to ask the irrigation designer should focus on the grower’s present situation; things that have an impact on the system and that would be difficult to modify once the system is in place.

  1. Question: How will the system affect my crop rotation schedule?

    Imagine the proposed field is primarily a vegetable crop field but will be rotated to berries in the future. A good designer will ensure the system is designed to support this change. The concept of single-use drip tape designs makes it even easier to rotate the crops, as new emitters and spacing can be specified each season and crop rotation.

  2. Question: Do I need to change block size?

    A good designer will evaluate and determine ideal block size for the system, taking into account factors like soil type and water availability. Strawberries are an example of one crop that may warrant smaller blocks, to ensure the water is staying concentrated enough to meet needs, and without pushing the system to or beyond its maximum. There has also been a trend on the coast to switch to growing in substrate, where block size is even smaller, often as small as two acres per block vs. the typical 15-20. 

    Drip systems, while accommodating to various sizes, work best in smaller blocks and with various block shapes, great for growers with irregularly-shaped fields and corners that are challenging for traditional irrigation systems like pivot.

  3. Question: How does my soil type affect emitters?

    One important design parameter affected by soil type is the drip system’s emitter flow. Loamy or clay soil better holds water, so a low-flow emitter is sufficient compared to sandy soils that need a different flow emitter to accommodate the higher flow needed.

  4. Question: Speaking of spacing, how is lateral spacing determined?
    As mentioned in the previous answer, soil type/texture is the primary determinant for emitters, as well as their spacing. A soil that encourages the spread of water can have emitters spaced further apart vs. a soil that holds water close. Light and sandy loam soils require close spacing, medium loam soil require medium spacing, and heavy, silt/clay loam soil farther apart.

Operational Information
Changing an irrigation system certainly affects the day-in, day-out operations of a farm. To be prepared and set up for success, every grower should ask questions about the changes to expect.

  1. Question: How do I control irrigation periods with the new system?

    There are several options for controlling irrigation periods with a drip system. A grower may choose daily intervals in which the system is run for a short period of time every day to put out the daily required amount of water. Another option is running the system every few days, for a longer time period, and put out multiple days-worth of water in a single day.

    Automation systems offer assistance setting irrigation periods. These systems offer time and labor-saving benefits, typically realized sooner and on a greater scale in larger operations vs. small. In the case of a smaller farm, one with five blocks or fewer, an automation system may not be needed or provide enough value to justify the cost. Every grower should analyze the cost/benefit ratio to decide if it makes sense for his/her unique operation.

  2. Question: Does the system affect my fertilizer use?

    All growers have to run some chemicals through the drip lines to prevent emitter clogging. Virtually all have to filter their water, too, again to prevent clogging, so if fertilizer is used, it should be done prior to running filtered water.

    Operations that use highly-acidic fertilizers will require a certain type of pipe, typically PVC or poly, as acid can corrode steel pipes. However, a good designer will ask about fertilizer early-on in the process so there shouldn’t be any need to change it after the system is installed. Those who mix fertilizers should seek information and trainings on the topic to prevent unanticipated side effects. For example, some mixes, combined with rain, can lead to emitter plugging if not managed properly.

  3. Question: Will this new system affect harvest?

    One of the biggest benefits of a drip irrigation system, especially those that use a single-use drip tape setup, is uniformity of plants. Non-drip irrigated strawberries are often harvested four times a year due to plants being at various growth stages. With a good drip system, a grower likely only has to harvest twice a year, yet is getting comparable or better yields thanks to the uniformity. This isn’t exclusive to strawberries; other fruit and vegetable crops benefit from the plants having more uniform growth.

  4. Question: How do I properly maintain the system?
    An integrated, planned approach is advised for all drip systems. A few best practices include:

    During the season, periodic flushing is advised every 2-4 weeks to rid the system of potentially clogging debris. With that, periodic filter maintenance is recommended. Also, regular inspection of the piping system for leaks is advised to avoid water hammers (pressure surges) or air pockets.

    Those who re-use drip tape must carefully remove, ensuring equipment isn’t slicing or puncturing the tape. Next, tape must be properly stored, then checked at the beginning of next season to ensure it’s in good shape to use again.

Understand and Achieve
While a good designer will take into account each unique operation when specifying and installing a drip system, it’s important all growers are proactive and ask questions that ensure a full understanding of the system. The questions above are a good starting point; every grower should feel comfortable asking additional questions as he/she needs. 


About The Author
Carly Koertge is a Designer for RDO Water, based in Santa Maria, CA. Learn more about irrigation solutions from RDO Water or contact your local RDO Water store.