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New Land F/X Feature: Center Pivot Design

Sep 03, 2014
Video Length:  54:35
Presented By:  Jeremiah Farmer



Jeremiah shows off the latest addition to Land F/X: a Center Pivot designer. Center Pivot irrigation has become no less than a mainstay of feeding the planet since its inception in 1948. Yet surprisingly, its design has traditionally relied upon pencil-and-paper illustration, multiple manual calculations, various spreadsheets and forms, and the occasional manufacturer-provided software tool – until now. You will be among the first to witness the unveiling of this new Land F/X capability, and your input is most welcome in guiding its future development.
Webinar Content

(note: The following catalog of content covered in this webinar is time stamped to allow you to follow along or skip to sections of the video that are relevant to your questions, You can also search for content on this page using the FIND command in your browser (CTRL + F in Windows, Command + F in Mac OS.)

  • Intro and Overview of Center Pivot Design
  • Setting Up the Site
  • Intro to The Land F/X Center Pivot Tool
  • Adding and Placing an End Gun/Overhang System
  • Adding and Placing a Custom Center Pivot System


0:00 – 9:50: Intro and Overview of Center Pivot Design


9:51 – 12:44: Setting Up the Site

Pulling a Google Earth aerial site view into AutoCAD (10:00)


Scaling the site image (example: 1 inch =500 feet) (11:00)


Checking the Source Data and placing a point of connection (P.O.C.) (11:40)


Checking the Pipe Data and specifying the mainline (12:10)


12:45 – 26:19: Intro to The Land F/X Center Pivot Tool

Accessing the Center Pivot tool from the flyout on the F/X Irrigation ribbon (12:45)


The Center Pivot Designer dialog box with preset common center pivot configurations (12:55)


Specifying the radius to the end tower in the Radius field (13:40)


Placing a center pivot component into the drawing (Example: ¼-mile full circle) (14:15)

  • Right-clicking to specify a full-circle (14:35)


The Center Pivot Calculator dialog box (14:39)

  • Setting the Area, Precip Rate, Run Time, End Tower Speed, and GPM of the system (14:39)


Once we set the system specs using the Center Pivot Calculator dialog box, Land F/X assigns these specs to the system in the drawing. A schedule showing the specs appears within the center pivot system we placed. (16:50)


Drawing the mainline (17:20)


Verifying the mainline with the Highlight Station tool (17:45)


Sizing the mainline (17:59)


Checking the hydraulic calculations in the Critical Analysis (18:08)


Placing a second, smaller center pivot component and mainline (18:30)


Question: How do I design the pump for the center pivot system? (20:21)

Answer: The pump is a factor of the pressure required and the pressure available. Land F/X is demand based in terms of pressure. So you’ll design your system starting with your desired pressure and work backward to the source. Once you know the available pressure and the pressure you need, you’ll specify a pump that makes up the difference and enter it into the system. (The current default pressure is 25 psi – the industry-standard pressure.)

Adding a pump:

Select the Auxiliary Equipment radio button in the Irrigation Manager for the current project.

  • Click the New button.
  • In the Select Type dialog box, select Booster Pump and then click the OK button.
  • In the Select Manufacturer dialog box, select Custom.
  • The Equipment Info dialog box will open. Here you can set the Pump Pressure Increase (example: 10 psi) and the Pump Maximum Flow. (example: 1,400 GPM) (You would determine these amounts by interfacing with the manufacturer of the pump.)

Question: How many pivots typically run on one mainline? (22:45)

Answer: It depends on a number of factors, including the size of your pipe, your location, the plants or crops you plan to water, whether the source is a well or a pump. The average ¼-mile pivot runs in the range of 400 to 1,200 GPM. How many mainlines you can run on your mainline will depend on all of these factors.


Question:Do I have to match the precipitation rate among pivots? (24:40)

Answer:That will again depend on the crops you are watering. If you are watering all the same crop, you will likely want similar irrigation rates throughout the irrigation site. However, if you are splitting crops, you might need different rates. And some farmers will plant different crops in different seasons and set the irrigation rate accordingly each season.


26:20 – 42:59: Adding and Placing an End Gun/Overhang System

The Center Pivot Span Configuration dialog box (27:35)

  • Setting the Number of Spans (example: 11)
  • Setting the Span Distance, Pipe (i.e., type of pipe), Emitter (type), and Number of emitters
  • Note that the GPM, Precip rate, and Target Precip rate autofill once we have specified the pipes and emitters. (29:30)


Sizing the mainline for the end gun component and checking the Critical Analysis (32:20)


Question: In generating the schedule, can I factor in your ET so it adjusts your run times with local climactic conditions? (34:35)

Answer: Great idea. We could potentially add a button to the Center Pivot Calculator dialog box that opens a Web-based dialog box where you can enter local information. For now, the workaround involves adding manual calculations in the center pivot dialog boxes.


Question: Does “span” refer to the arc of the irrigation system? Are the spans from tire to tire or nozzle to nozzle? (37:45)

Answer: Yes, “span” refers to the arc. The spans are currently measured from tire to tire.


Question: How much pressure loss occurs from the tower to the end gun? How does the end gun handle the corners in the span? (40:00)

Answer: Many end guns have a booster pump that boosts the pressure up 25 PSI or so, which handles the corners. Using large, smooth, metal pipes prevents significant pressure loss in an end gun configuration.


43:00 – 44:59: Adding and Placing a Custom Center Pivot System

Use the Polyline (PLINE) function to draw the unusual shape you’d like to achieve with the Custom center pivot irrigation system. (Make sure the shape is closed.) (43:13)


Select Custom in the Center Pivot Designer dialog box (43:41)


The cursor will turn into a pickbox, and the Command line will prompt you to Select polyline. Use the pickbox to select the polyline you just drew. (43:44)


The Center Pivot Calculator dialog box will open. Configure your settings, and click the OK button. (Note that the Area is calculated automatically.) (43:47)


Click the OK button in the Center Pivot Designer dialog box. The closed polyline will become the center pivot system. (43:55)



45:00 – 47:10: Demonstration of how quickly you can place a number of different center pivot systems into a site design and determine the flow needs


More Questions

Question: How do I account for the water needs of different crops? (47:11)

Answer:Check the myriad charts and websites available that show different crops’ water needs.


Question: Do you see much potential for landscape architects to be hired by NRCS or others to do this kind of system design? (48: 27)

Answer: Yes, that’s definitely a possibility, although distributors may not want to give up that type of power. However, distributors often take several hours or days to design their systems, and run into inaccuracies in their system designs, which costs time and money. Our software’s center pivot design capability means a quick design time and an accurate design. Distributors may want to start contracting out to landscape architects who have experience with CAD and can design this type of system quickly, accurately, and efficiently.


Question: Is it possible to incorporate the ET function into the drip icon for orchard crops? (52:04)

Answer: Another great idea. We will look into that. And as always, we welcome user input for how we can continue to make our software work for you.

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