GPS in Agriculture: 7 Uses, Accuracy and USDA Data

GPS in agriculture is used to steer tractors, map fields, record yields, vary seed and fertilizer rates, and log where every pass and spray went. On US farms, auto-steer and guidance systems now cover more than half of the acres planted to corn, soybeans, winter wheat and cotton, according to USDA’s Economic Research Service. The main benefits are less overlap, lower fuel and input use, less soil compaction and less driver fatigue.

This guide explains how GPS works on the farm, the seven uses that matter most, how accurate each type of receiver is, and who has adopted it, with USDA survey data. It also gives you a calculator to test whether a guidance system pays on your own implement width and costs. Accuracy levels, adoption figures and trade-offs are also covered in GPS use in agriculture.

What is GPS in agriculture?

GPS, the Global Positioning System, is a US network of satellites that sends timing signals. A receiver on a tractor, combine, drone or phone uses those signals to work out where it is. Farm equipment today can also use other satellite systems, such as Europe’s Galileo. The general term for all of them is GNSS (global navigation satellite systems). In farm talk, “GPS” usually means any of them.

A position on its own is not very useful. The value comes when the position is joined to something else: a steering motor, a yield sensor, a rate controller on a spreader, or a photo from a drone or satellite. Then a farmer can treat each part of a field on its own terms instead of treating the whole field the same way.

Guidance is the most common use of that accuracy, and buying a used autosteer system lists what to check before paying.

How does GPS help in farming? Accuracy levels explained

How much GPS helps depends on how accurate the receiver is. The GPS.gov accuracy page says GPS phones are accurate to within about 4.9 m (16 ft) under open sky, and that high-end receivers with corrections can reach a few centimetres in real time. Trees, buildings and hills block signals and reduce accuracy.

Farm receivers fall into three broad groups:

• Uncorrected GPS. Phone and basic handheld level. Good enough for scouting notes, field boundaries you will check later, and finding a spot again. Not good enough to steer.
• Satellite-based corrections (SBAS). WAAS in North America and EGNOS in Europe. These need no subscription. The EU Space Programme’s agriculture page describes EGNOS as an entry-level option with sub-metre accuracy over Europe. An EUSPA brochure on EGNOS in farming puts pass-to-pass accuracy at about 15 to 30 cm.
• RTK and paid correction services. RTK uses a base station or a network of stations. The same EUSPA brochure gives 2 to 10 cm accuracy and pass-to-pass accuracy of about 2 to 3 cm for RTK and commercial services. This is the level needed for planting, strip-till and controlled traffic.

Kansas State University’s guide on field efficiency gains gives typical overlap settings by system: 12 to 15 inches for WAAS, 6 to 8 inches for OmniStar and 3 to 4 inches for RTK. Those settings drive the savings in the calculator below.

Prices for receivers and correction plans change often and differ by dealer, so ask for a written quote and check what the subscription covers.

GPS applications in agriculture: 7 key benefits

Below are the seven main uses of GPS in agriculture, with what each one does and what the evidence shows.

1. Guidance and auto-steer

Guidance shows the driver where to go, and auto-steer turns the wheel for them. The main purpose is to cut “skips” (missed strips) and “overlaps” (double passes). The USDA ERS Amber Waves article on guidance lists the benefits as lower energy costs, lower input use, less soil compaction and less operator fatigue. It also notes that accuracy depends on slope, terrain, the number of satellites in view and ionospheric activity.

The savings come from overlap. The Kansas State guide assumes an unaided driver overlaps by about 10% of the toolbar width. With a 40-foot toolbar and a yearly operating cost of US$100,000, it estimates a WAAS system could save up to US$7,500 a year and an RTK system up to US$9,000. On narrow tools under 10 feet, a WAAS system can do worse than a good driver.

North Dakota State University’s site-specific farming economics guide reports a case where guidance cut planter overlap from an estimated 10% to 0.5%. Guidance also lets crews keep working in dust, fog and darkness, because the machine follows coordinates rather than sight lines.

2. Field mapping and soil sampling

GPS lets you record exact field boundaries, waterways, wet spots, rocks and drainage lines. It also ties each soil sample to a point or zone. When the next sample is taken from the same spot, changes in pH, phosphorus or organic matter can be tracked over years.

Soil maps are less common than guidance. USDA found soil maps were used on 21.5% of corn acres in 2016, 14.3% of soybean acres in 2018 and 5.6% of winter wheat acres in 2017.

3. Variable rate technology (VRT)

VRT changes the rate of seed, fertilizer, lime or pesticide as the machine moves. The controller reads the GPS position, looks up the rate for that zone on a prescription map, and adjusts the flow. USDA put VRT at 37.4% of corn acres in 2016 and 25.3% of soybean acres in 2018.

VRT only pays when the field really varies and the prescription is sound. A sampling plan, a good soil map or several years of yield maps come first. Check the product label and local nutrient rules for any rate you set.

4. Yield monitoring and mapping

A yield monitor on a combine measures grain flow and moisture every second. GPS tags each reading, so the result is a yield map. Over several seasons, these maps show which zones always yield well, which always lag, and which change with the weather.

Yield maps also save labour. In the USDA report, a study of 2010 corn fields found total labour hours per bushel were 35% lower for adopters of yield and georeferenced soil maps than for non-adopters. The same review cites a finding that GNSS mapping raised operating profits by almost 3% on corn farms.

5. Remote sensing with satellites and drones

Satellite and drone images are only useful when every pixel sits in the right place on the ground. GPS gives drones that position, and satellites use their own precise orbits. Multispectral images show crop vigour (NDVI), water stress and uneven growth, often before you see it from the road.

A GPS-tagged map also tells you exactly where to walk. Scouts can go straight to the weak patch, check for pests, disease, waterlogging or nutrient shortage, and record what they found at that point. Farmonaut, for example, shows satellite crop-health maps for fields you draw once on a phone or computer.

6. Fleet tracking and logistics

GPS trackers on tractors, sprayers, grain carts and trucks show where each machine is, how long it idles and how many hours it runs. At harvest, this helps line up grain carts with combines and trucks with the bin site. Over the year, hour logs make service planning easier.

Livestock farms use the same idea. The EUSPA agriculture page lists livestock positioning and virtual fencing among the farm uses of Galileo and EGNOS.

7. Records, compliance and traceability

Modern sprayers and spreaders log where and when each product was applied. Those as-applied maps help prove that buffer zones near water were respected, support crop insurance and audit records, and help answer buyers who ask where and how a crop was grown. GPS data also anchors field-level carbon and sustainability reports, because each practice can be tied to a mapped area.

Rules on record keeping and buffer zones differ by country, state and product. Check the label and your local rules, and get professional advice before you rely on a log for a legal or financial claim.

Does a guidance system pay on your farm?

Use the calculator to estimate the yearly saving from cutting overlap. It follows the Kansas State method: the saving is the overlap you remove, divided by the toolbar width, times the yearly cost of that field operation. Then it subtracts what the system costs you each year.

The default values are examples set near break-even, not benchmarks. Enter your own implement width, your current overlap, the overlap of the system you are looking at, and your costs.

Try the numbers for your own farm below.

How widely farms use GPS: USDA adoption data

USDA’s Economic Research Service tracks how many US acres use these tools through its farm survey (ARMS). Its February 2023 report, Precision Agriculture in the Digital Era, found:

• Auto-steer and guidance were used on 5.3% of planted corn acres in 2001 and 58% in 2016.
• By 2019, guidance was used on 72.9% of sorghum acres and 64.5% of cotton acres.
• In 2019, GPS applications were used on 40% of all US farm and ranchland acreage for on-farm production.
• Yield maps, soil maps and VRT were used on only 5% to 25% of planted acres of winter wheat, cotton, sorghum and rice.

The pattern is clear. Guidance, which saves money mainly by cutting overlap, now covers most row-crop acres. Tools that need data work, such as yield maps and variable-rate prescriptions, are used on far fewer acres.

Chart

Share of US planted acres using auto-steer or guidance

Percent of planted acres, latest USDA survey year for each crop

Who uses GPS: farm size makes a big difference

Large farms adopt guidance far more often. USDA’s chart of note on farm size and guidance and the Amber Waves article give the figures: 73% of the largest corn farms used guidance in 2016, against 10% of the smallest. For winter wheat in 2017 it was 82% against 7%, and for soybeans in 2018 it was 68% against 11%. Cotton is the exception, with 50% of the smallest cotton farms using guidance in 2019.

Chart

Guidance adoption: smallest vs largest farms

Percent of farms using guidance, smallest and largest of five size groups, by crop

One likely reason is cost spread: a guidance kit or correction subscription costs much the same however many acres it covers, so larger farms get more saving per dollar. USDA notes this pattern points to scale benefits. USDA also notes that guidance systems can be moved between vehicles and paired with tablets, which lowers the entry cost for smaller farms.

Service matters too. A farmdoc daily analysis from the University of Illinois found that states with higher precision agriculture use tend to have more farm technicians per farm, although the link was weak. Check who will support the system near you before you buy.

GPS in agriculture outside the US

The same tools are used across Canada, Europe and Australia, with local differences in correction services and connectivity.

• Europe and the UK. EGNOS gives sub-metre correction across Europe with no fee, and Galileo’s High Accuracy Service aims at under 20 cm horizontal accuracy without an internet link, according to the EU Space Programme’s agriculture page.
• Australia. An nbn report on connecting Australian agriculture says research found 75% of the extra NSW/ACT production from full digital agriculture adoption needs internet connectivity. RTK networks and data uploads depend on mobile coverage, so check signal maps for your paddocks.
• Canada. Large grain farms on the Prairies use the same guidance, section control and yield mapping tools; WAAS covers Canada as well as the US.

Environmental benefits and limits

Less overlap means less fuel, seed, fertilizer and pesticide per acre. Guidance also lets farms run every pass on the same wheel tracks (controlled traffic), which keeps compaction to fixed lanes. SARE’s chapter on addressing compaction explains how heavy traffic on wet soil damages structure and root growth.

The gains are real but they vary. A USDA ARS study of tractor guidance on pasture found guidance reduced gaps by 7.6% and 10.1%, and overlaps by 32.5% and 4.2%, during herbicide and fertilizer applications. Under an assumed 15% yield gain, it estimated 8% to 12% lower environmental impacts, but the yield estimates were highly uncertain and tractor fuel use rose when guidance was on.

Common limits to plan for:

• Signal loss near tree lines, buildings and in steep valleys.
• Subscription and replacement costs for correction services and displays.
• Data that sits unused: a yield map only helps if someone reads it and acts.
• Different brands’ files that do not always load into each other’s software.
• Patchy mobile coverage for RTK networks and cloud uploads.

▶ How the NDWI satellite index shows crop water content for irrigation planning. · 7:57

Benefits comparison table

Chart

GPS tools on US corn acres, 2016

Percent of planted corn acres using each technology

How to start with GPS on a farm

1. Start with what pays quickest. For most row-crop farms that is guidance on the widest, most-used implement, often the sprayer.
2. Match accuracy to the job. WAAS or EGNOS can be enough for wide booms; planting and strip-till need RTK.
3. Turn on logging from day one. As-applied and yield data cost little to keep and are hard to recreate later.
4. Add maps before VRT. Grid or zone soil sampling and two or three years of yield maps make better prescriptions.
5. Use satellite images between passes. Crop-health maps show where to scout between the times machines are in the field.
6. Check support and file formats. Ask your dealer who calibrates the system and whether files export in standard formats.

Steering systems vary widely in accuracy, so what tractor guidance costs is a practical place to compare setups. Anyone weighing receivers and guidance kits can compare GPS systems built for farm use and what each one actually does.

▶ Six plain steps to start precision farming without buying a robot. · 4:18

What comes next for farm GPS

Three trends stand out. First, better signals: GPS is adding new civil signals at L2 and L5, which GPS.gov says will improve performance, and Galileo now offers its own high-accuracy service. Second, more automation: once a machine knows its position to a few centimetres, driver-assist features, autonomous carts and robotic weeders become possible. Third, more data joined together: satellite crop maps, yield maps, soil tests and as-applied logs can sit on one field map, which makes decisions faster.

The constraint is often people, not hardware. Someone still has to calibrate the monitor, clean the data and decide what to do with it.

Related pages on our site: mobile and web app · fleet tracking · carbon footprint tracking · product traceability · multi-farm management · satellite data API · API developer docs

▶ A walk-through of a satellite crop-monitoring web app: drawing fields and reading crop-health maps. · 8:02

How we checked the numbers

Adoption figures come from USDA ERS reports based on the Agricultural Resource Management Survey, with the crop and survey year stated for each number. Accuracy figures come from GPS.gov and the EU Agency for the Space Programme. Savings figures come from Kansas State University and NDSU Extension guides. Each figure in the charts carries its source line.

FAQ

What is the main use of GPS in agriculture?

Guidance and auto-steer. USDA ERS found auto-steer and guidance on more than half of US acres planted to corn, soybeans, winter wheat and cotton as of 2019. Mapping, variable-rate application and yield monitoring follow, on fewer acres.

How does GPS help in farming?

It cuts overlaps and skips, so you use less fuel, seed, fertilizer and pesticide. It lets you work at night or in dust, ties soil samples and yield data to exact points, and records where every product went.

How accurate is GPS for farming?

A phone is accurate to about 4.9 m in open sky (GPS.gov). WAAS or EGNOS corrections give sub-metre accuracy, about 15 to 30 cm pass to pass. RTK gives about 2 to 3 cm pass to pass (EUSPA).

Is GPS worth it on a small farm?

It can be, but the case is weaker. USDA found 10% of the smallest corn farms used guidance in 2016, against 73% of the largest. Low-cost options include WAAS-level guidance, moving one kit between machines, and phone apps for mapping and scouting. Try the calculator with your own numbers.

Can GPS help with environmental rules?

Yes. As-applied maps show where and when products were applied, which helps prove buffer zones were kept. Rules differ by place, so check the label and local rules and get professional advice.