Farm Progress is part of the Informa Markets Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them. Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Serving: United States

Precision ag on the cheap? Ideas for farmer “hackers”

The tools for precision ag may pay for themselves on the right farm in the right situations. But the one thing you can't say about most of these electronic wonders is that they are cheap. Even if a team of reputable scientists has the research numbers to show that these boxes of wires and software are probably going to be a good investment in the long run, it's often hard for farmers to part with a lot of cash for something they somehow got along without before.

To be sure, plenty of early adopters and innovators already have jumped into precision ag with both feet, hooking up tractors, ATVs and combines with branded and conveniently packaged systems. But for a significant portion of farmers, a spending aversion holds true whether they are looking at a $4,000 GPS-guided lightbar system or a $40,000 RTK system that can steer a tractor hands-free down a field with sub-inch accuracy.

Companies that sell precision ag systems refer to these tough-sell characters as technology laggards. But that’s not really a fair assessment for all cost-averse farmers. Many are still interested in new technology; they are just determined to find a less expensive way to get the job done. Often, these are the same farmers who look for bargains with generic herbicides or a regional seed dealer. To them, technology is just another input to be purchased as cheaply as possible. And they aren’t afraid to spend some extra time and effort figuring out how to capture those savings.

A question e-mailed to Farm Industry News from a farmer who identified himself only as Ray, is typical of a new type of letter we've been receiving in our in-box.

I have a question for you regarding a laptop use and GPS. Is there any way someone could use a laptop for the processor and display for Ag Leader or Greenstar? I talked to someone today who said they have seen someone using just a laptop with GPS software to vary air seeding on the go. If this could be done, it would be far cheaper than buying the complete systems. The problem I see is the hookup for the moisture sensor and grain flow meter. I would also like to use it for putting in my tile. I know there is GPS software available with street maps, but I have never seen anything to use it as a yield monitor. Any information would be appreciated.
Thanks, Ray

To help answer Ray’s question, we called on Daniel Humburg, an ag engineer at South Dakota State University who has written a number of papers on precision agriculture, . Humburg’s answer, which follows with a few added Web link resources, shows that GPS control of machinery via laptop or handheld computer is possible, but not necessarily easy.

It is possible to do some level of variable-rate control with a laptop or even a palmtop device. If someone only wishes to do output control of chemical, or fertilizer, or seeding rate, they can do this with some application machinery and a laptop or palmtop. I will give one example, but please understand that I do not pretend to be aware of all current products on the market and so will not attempt to list all of the systems that might be able to do similar function.
If I wanted to control variable rate of a herbicide across my CRP field, I would require several things:
First, my system must know where it is. Differentially corrected GPS will do this part.
Second, I must have a plan. This is in the form of an electronic map. This may be addressed by the software I purchase to run on the portable computer. It might also be possible to generate a map on my desktop mapping software that can be loaded onto the portable computer in a compatible format.

For a summary of software products ready to use with handheld or laptop computers, go to .

Third, I must have a computer and software combination that can accept the map, accept the GPS signal, make the current output decision, and communicate that output to an application machine.
Last, I must have an application device that will accept the output command from the portable computer.
Here's one example. Note that there is undoubtedly other software and hardware that could also do this:
I am familiar with software called Field Rover II. This is a program developed by Farm Works
( that has utility for GPS-based scouting, and has a variable-rate add-on capability. I use this for teaching with backpack GPS receivers and palmtop computers.
Let us assume that the desktop portion of the program can help generate the desired application map. (This I have not had reason to do, but believe to be possible.) That map is then loaded onto the palmtop device. The palmtop is connected through an RS 232 serial connection to the GPS receiver to obtain input location coordinates from that device, while the transmit wire of the RS 232 serial connection must be connected to the RS 232 input of the chemical application system. I will use a Raven system in this example.
Many of Raven's application controllers now accept dynamic application rate inputs through RS 232. So, once in the field the palmtop computer (or laptop) will monitor its position and send a command for the current rate to the Raven controller, which will set its current rate to the command.
In order for this to work, you would have to build your own wiring harness to get data into and out of the portable computer. Most have only one RS 232 port and we are using it for both incoming and outgoing information. Also, you would want external power provided to the portable computer as continuous serial port use will drain batteries quickly.

For technical information on how to expand the utility of a RS 232 serial connection, visit .

While the example I gave is possible, it is certainly not as robust a system as you would get from Greenstar, or CNH AFS products, or AgStar, or AgLeader. The RS 232 serial standard was not developed with agriculture in mind. The commercial systems are designed to be much more foolproof, and since many are now using CAN technology based on the ISO 11783 standard, they can handle a lot more information, very reliably. For example, they are likely to provide you with an ‘as-applied’ map that is based on information sent back by the Raven controller on actual rates achieved. This is not possible with the one-way communication flow in my example.”

Determined to use a laptop computer in the field? Consider the Panasonic Toughbook, designed for extreme duty in military and industrial applications:

Variable-rate manure, cheap
Shortly after we received Humburg’s reply, the University of Illinois posted a press release about a new low-cost system it is developing to calculate and record how much manure farmers spread and where they spread it.

“We're building a low-cost yet effective system that will incorporate a handheld, consumer-available GPS (global positioning system) unit, a portable computer and mapping software such as FarmWorks or ArcPad ( ," said Jay Solomon, an Extension educator from East Peoria, IL (

The test system records the application path and when the applicator was on or off. A background map of the field with buffer (non-application) zones marked can be pre-loaded into the computer. This provides the operator with a visual representation of the field and his location in the field on the computer screen. By watching the screen, the operator can manually turn off the applicator as a buffer is approached. Once the applicator is outside of the buffer area, the operator can then turn the system back on. Ultimately, the goal is for the system to use the GPS unit data to sense when to turn the applicator off and on automatically when approaching non-application zones, such as near a stream or well.

Researchers also want to put a flow meter in the system to collect flow data for liquid manure.

“We're working with a producer who has a flow meter and a GPS unit on a tractor, and we're trying to build the components to go between them," Solomon said.

The "where and how much" data that are collected from this system will generate as-applied maps for producers, animal waste haulers, individuals who do custom application or bigger producers who use their own equipment.

Although there are other systems on the market that are capable of this type of data collection, Solomon said they are extremely cost-prohibitive. Some of the high-precision units can cost upwards of $20,000. Although Solomon does not yet have a final price on their data collection system, he believes that producers can achieve results similar to the high-precision equipment for around $2,500, a much smaller investment.

Because many of the newer tractors come with a GPS unit already on board, Solomon said another option is to find a way to tap into that system.

“But we're mainly looking at a system for the producer who wants to use an older tractor," Solomon said. "Most of the time, farmers aren't going to use their brand-new equipment to apply manure. So we're looking at a way to put consumer-available technology on an older tractor to collect the data."

Solomon said this type of data will give producers an accurate record of manure application from year to year that can then become a piece of their geographic information system (GIS) documentation.

“The more information farmers can get into a GIS format, the better able they are to analyze a yield problem or variation across the field," Solomon said. "Was it caused by drainage patterns? Was it a weed or an insect problem? Or was it fertilizer?"

Solomon said that although the system's primary function is to provide the producer with useful information, it is also helpful from a regulatory standpoint, because stricter government regulations are holding producers increasingly accountable for their manure management practices.

"What if a neighbor files a complaint against a farmer with the EPA because manure was applied in a waterway or close to a well?" Solomon asked. "Instead of pulling out a hand-drawn map that's got some numbers scribbled on the side, the producer can go to the computer, pull up records and say 'Here's how much I applied and here's where I put it.'"

Finally, Solomon said, much of what has been learned about mapping manure applications can be applied to other, similar systems, such as chemical spraying.

"We may be starting with manure," Solomon said, "but once we get the system worked out, there will be any number of ways we can use it."

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.