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Precision Agriculture:
Opportunities and Challenges
MICHAEL O’CONNOR
O’C and Associates
INTRODUCTION TO PRECISION AGRICULTURE
Precision Agriculture (or Precision Farming) is a term used to describe the
use of technology to better measure and control crop production on a site-specific
basis to improve efficiency. Such improvements include:
• More efficient application of inputs (seed, fertilizer)
• More effective utilization of tillage equipment
• Improved crop and field measurements
• Better farm management decisions
While computers and electronics have been used in crop production since
the 1970s, GNSS has been a key enabling technology for Precision Agriculture
beginning in the mid-1990s.
THE PRECISION FARMING FEEDBACK LOOP
Historically, the process of crop production has been an “open loop” process,
with only qualitative or imprecise feedback methods available to growers. This
process is illustrated in Figure 1.
Growers generally use the best information available to them, including the
crop history on their farm (e.g., for crop rotation); information about available
seed types; the current costs of inputs such as fertilizer, seed, fuel, and labor; cli -
mate history for their area; and the recent weather for their area. This information
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FIGURE 1 “Open loop” crop production.
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is used to make fundamental farm management decisions such as which crop to
plant in each field, which seeds to use, when to plant, how much fertilizer to use,
how to till the ground, and what planting pattern and spacing to use in the field.
These decisions are made with the goal of optimizing the farm’s operation and
maximizing crop production output for the farm. Unfortunately, there are also
several dominant external factors that affect crop production—in particular the
weather and weed and pest infestations.
With the introduction of Precision Agriculture, including advancements in
electronics, computers, software, and sensors, growers now have better tools to
manage their crop production. These tools are shown in blue in Figure 2 and are
described in more detail below.
Yield Measurements
The practice of using moisture and grain flow sensors in combine harvesters
to measure yield was the first precision agriculture practice to become widely
adopted. While the practice of measuring yield on-the-go was introduced in the
1980s, the integration of yield measurements with GNSS in 1994 was a revolution.
GNSS-based yield monitors gave farmers a tool to collect site-specific information
about their crop production and to generate maps showing in-field yield variability
on their farms. Today nearly every combine harvester manufactured and sold in
North America includes a yield monitor.
Soil Nutrient Measurements
Nitrogen, phosphorous, potassium, and other soil nutrients are critical to plant
health. For thousands of years growers have been aware of the importance of soil
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PRECISION AGRICULTURE: OPPORTUNITIES AND CHALLENGES
FIGURE 2 “Closed loop” crop production using Precision Agriculture practices.
nutrients and have used organic fertilizers to amend their soils before planting.
In more recent times, scientists and agronomists have learned more about the
specific chemical needs of crops and have developed specialized fertilizers to
directly target those needs.
Today, growers have access to services that will collect soil samples from
their fields, mail those samples to a chemistry lab, and provide a map showing the
site-specific nutrient levels within the growers’ fields. Unfortunately, this process
is slow, highly seasonal, and labor intensive.
Crop Health Measurements
Growers are now able to better measure the health of their crops during the
season. Field scouting techniques using GNSS are becoming popular in North
America, and growers are beginning to utilize remote imagery from satellites or
aircraft with multispectral imaging cameras. Near-real-time sensing of crop health
can drive in-season management decisions such as pesticide application and in-
season nutrient management (Figure 3).
Crop Selection
While not directly related to computers, electronics, or sensors, crop selection
is becoming one of the most important variables for a grower to manage. Seed
selection has a dramatic impact on input costs as well as yield. Because they are
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202 GLOBAL NAVIGATION SATELLITE SYSTEMS
FIGURE 3 Crop health measurement techniques.
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so effective, genetically modified seeds have become widely adopted in the United
States. These seeds are engineered for characteristics such as higher yields, pest
resistance, and herbicide resistance. These results are highly visible to the grower,
and the economic value is compelling.
Efficient Field Cultivation
In addition to allowing for site-specific measurements within a field, GNSS
has also enabled robotic automation of farm equipment. Products introduced to the
market in the year 2000 enable tractors, sprayers, and harvesters to steer through
a field, hands-free, with sub-inch accuracy.
Automated steering provides clear benefits to growers (Figure 4). It allows
equipment to run around the clock—regardless of visibility—in the daytime,
nighttime, or in the fog. Precision-steered vehicles experience 8 to 10 percent
less overlap between passes than human-steered vehicles, which leads to lower
fuel, labor, and input costs. Also, less overlap results in more rows in the field,
which leads to greater yields. The results of hands-free steering are visible, and
the economic value is compelling.
Seed and Fertilizer Management
In addition to controlling the steering of farm vehicles, GNSS enables solu -
tions that can control the application of field inputs on a site-specific basis.
Powerful tools are now available to growers that allow real-time adjustment of
seed and fertilizer rates. These rates are established by software “prescriptions,”
which are created based on a variety of data, including the yield monitoring and
soil nutrient data described above.
Adoption of these techniques has been relatively slow compared to geneti -
cally modified seeds and automated steering, primarily because the soil nutrient
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PRECISION AGRICULTURE: OPPORTUNITIES AND CHALLENGES
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FIGURE 4 Example of the benefits of hand-free precision steering.
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measurement process is slow and tedious, and the results of performing these
variable rate application techniques are difficult to measure because of the influ -
ence of so many other variables on crop output (such as weather).
TODAY’S LEADING CHALLENGES FOR PRECISION AGRICULTURE
Adoption rates of seed genetics and precision steering have exceeded
50 percent in several geographic markets because of their visible and compelling
value. However, grower adoption of seed and fertilizer management continues
to lag.
More efficient use of field inputs—particularly nitrogen fertilizer—is essen -
tial for several reasons. For one, fertilizer costs are rising. Fertilizer sales now
exceed $18 billion annually in the United States and represent between 30–50 per-
cent of the cost of production for wheat and corn on most farms. In addition,
worldwide fertilizer use is on the rise. Globally, the rate of nitrogen use is out -
pacing increases in population and in arable land. Oxygen depletion triggered by
excessive nitrogen and phosphorous levels, primarily caused by fertilizer runoff,
is becoming a serious problem in several major waterways. The U.S. National
Academy of Engineering has listed “Managing the Nitrogen Cycle” as one of its
14 grand engineering challenges for the 21st century.
It is the author’s belief that adoption of Precision Agriculture for seed and fer-
tilizer management will improve when three key challenges have been overcome:
• Improving GNSS signal availability
• Improving the efficiency of soil measurements
• Analyzing data across multiple farms
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204 GLOBAL NAVIGATION SATELLITE SYSTEMS
Improving GNSS Signal Availability
GPS alone does not provide sufficient field coverage in many farm environ -
ments. Hilly or mountainous terrain is rare, but tree lines are a common issue, as
shown in Figure 5. Reliability of the signal has been a barrier to adoption in areas
such as the southwestern United States. The majority of growers in the United
States 10 years ago were unfamiliar with GPS. Today many growers are educated
enough in GNSS to ask about signal availability and reacquisition.
Most high-precision systems sold in North America now offer GLONASS
capability to augment GPS for signal availability. As more satellite signals-in-
space become available, availability will continue to improve in these difficult
environments, and more growers will view GNSS as a reliable solution for their
needs.
Improving the Efficiency of Soil Measurements
As described above, current soil nutrient measurement techniques are slow,
expensive, and inaccurate. To reduce costs, many growers employ “zone” sam-
pling techniques, in which one to five samples are collected across an entire field
(typically 80 to 160 acres) based on soil texture zones. More progressive growers
who practice “high density” sampling typically collect samples on a grid at one
sample per 2.5 acres. Studies show that, given the spatial decorrelation of soil
nutrients, sampling to at least one sample per acre is required to accurately inter-
polate nutrient levels across a field.
Unfortunately, the financial cost of applying extra fertilizer in a field is sig -
nificantly lower than the potential yield reduction caused by an under-application
of fertilizer. Until growers can measure nutrients affordably and at higher density
in near-real-time (particularly nitrogen, which is water soluble and highly time-
dependent), they will continue to over-apply fertilizers to ensure high yields.
FIGURE 5 Farm fields lined with GNSS-barriers.
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PRECISION AGRICULTURE: OPPORTUNITIES AND CHALLENGES
Data Analysis Across Multiple Farms
As described above, many variables affect crop yield. These include rainfall,
temperature, humidity, wind, soil type, and tillage practices, just to name a few.
Unfortunately, today, farms are “islands” of information. For a single farm to
collect enough information to measure the value created by a new farming practice
or a particular seed hybrid would take many years. A single farm cannot produce
enough data to provide meaningful statistical significance.
Dramatic improvement in data analysis will be possible when information can
be correlated across many farms. The wireless data connections and software tools
to enable such analysis are just coming into practice now on farms. Once these
practices become more widespread, the value of Precision Farming will become
clearer to growers and adoption of these practices will increase.
SUMMARY
Precision Agriculture is enabling more efficient application of inputs (seed,
fertilizer), more effective utilization of tillage equipment, improved crop and
field measurements, and better farm management decisions. With advancements
in electronics, computers, software, and sensors, growers now have better tools
to manage their crop production.
In the United States, adoption rates have been very fast for some of these
technologies, such as seed genetics and precision steering, because of their high
visibility and compelling value. However, grower adoption of seed and fertilizer
management continues to lag. This is a serious problem because improper use
of fertilizer is economically wasteful for growers and is also causing harm to
waterways and underground water sources.
It is the author’s belief that adoption of Precision Agriculture for seed and
fertilizer management will improve when three key challenges have been over-
come: (1) improving GNSS signal availability, (2) improving the efficiency of
soil measurements, and (3) when growers take advantage of the ability to perform
data analysis across multiple farms.
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