Site-Specific Farming Comes of Age
Managing Field Variability
California
FarmTech Conference – Santa Barbara, California – January 26-27, 1998
Presentation
by Joseph K. Berry
(Article for FarmTech online
communication, Rincon Publishing, Carpinteria, California, January, 1998. For
more information on related activities access
http:/www.rinconpublishing.com/farmtech.html on the worldwide web)
…the farm community doesn’t want
to be entrapped by a new technology, it wants to be empowered by useful new
tools. Site-specific
management, often referred to as "precision farming," means different
things to different people— from the pinnacle of farm efficiency, to a vast
array of new products and services, to the techno-deaththrows of indigenous
insight and quite possibly, farming as we know it. In reality, it is likely
none of the wealth of individual perspectives, but an amalgamation of them all.
All parties, however, appear to agree that this emerging technology is
intimidating, confusing, and often misunderstood. This presentation attempts to
remove some of the mysteries and misconceptions by outlining the elements of
site-specific management, the technical issues surrounding its development, the
legal issues and their impacts, and important extended issues and trends
driving site-specific management. But first a brief discussion of what
site-specific management is (and isn’t) is in order.
What Site-specific Management Is (and Isn’t)
In essence, site-specific
management is about doing the right thing, in the right way, at the right
place and time. It involves assessing and reacting to field variability and
tailoring management actions, such as fertilization levels, seeding rates and
variety selection, to match changing field conditions. It assumes that managing
field variability leads to both cost savings and production increases.
Site-specific management isn’t just a bunch of pretty maps, but a set of new procedures
that link mapped variables to appropriate management actions. This conceptual
linkage between crop productivity and field conditions requires the technical
integration of several elements.
Elements of Site-Specific Management
Site-specific management consists
of four basic elements: global positioning system (GPS), data collection
devices, geographic information systems (GIS) and intelligent implements.
Modern GPS receivers are able to establish positions within a field to
about a meter. When attached to a harvester and connected to a data
collection device, such as a yield/moisture meter, these data can be
"stamped" with geographic coordinates. A GIS is used to map
the yield data so a farmer can see the variations in productivity throughout a
field. The GIS also can be used to extend map visualization of yield to
"map-ematical" analysis of the relationships among yield variability
and field conditions. Once established these relationships can be used to
derive a "prescription" map of management actions required for each
location in a field. The final element, intelligent implements, reads
the prescription map as a tractor moves through a field and varies the
application rate of field inputs in accordance with the precise instructions
for each location. The combining of GPS, GIS and IDI (intelligent devices and
implements) provides a foothold for both the understanding and the management
of field variability.
Smart Farmers, Dumb Maps
To date, most analysis of yield
maps have been visual interpretations. By viewing a map, all sorts of potential
relationships between yield variability and field conditions spring to mind.
These visceral visions and explanations can be drawn through the
farmer’s knowledge of the field— "I bet this area of low yield aligns with
that slight depression," or "maybe that’s where all those weeds
were," or "wasn’t that where the seeder broke down last spring?"
Data visualization can be extended through GIS analysis directly linking yield
to field conditions. This map-ematical processing involves three levels:
cognitive, analysis and synthesis. At the cognitive level (termed
desktop mapping) computer maps of variables, such as crop yield and soil
nutrients, are generated. These graphical descriptions form the foundation of
site-specific management. The analysis level uses the GIS’s analytical
toolbox to discover relationships among the mapped variables. This step is
analogous to a farmer’s visceral visions of relationships, but uses the
computer to establish mathematical and statistical connections. To many farmers
this step is an uncomfortable "leap of scientific faith" from pretty
maps to pure, dense techy-gibberish. However, map-ematical analysis greatly
extends data visualization and can more precisely identify areas of
statistically high yield and correlate them to a complex array of mapped field
conditions. The synthesis level of processing uses spatial modeling to
translate the newly discovered relationships into management actions
(prescriptions). The result is the prescription map needed by intelligent
implements in guiding variable rate control of field inputs. Admittedly, the
juvenile science of site-specific management is a bit imprecise, and raises
several technical issues.
Technical Issues
The accompanying figure identifies the four basic processing steps in
site-specific management. Data collection for site-specific management can be
divided into two broad areas: continuous data logging and discrete point
sampling. Data logging continuously records measurements, such as crop
yield, as a tractor moves through a field. Point sampling, on the other
hand, uses a set of dispersed samples to characterize field conditions, such as
phosphorous levels. The nature of the data derived by the two approaches are
radically different— a "direct census" of yield versus a
"statistical estimate" of phosphorous. In data logging, issues of
accurate measurement, such as GPS positioning and material flow adjustments,
are major concerns. In point sampling, issues of spatial interpolation
(estimating between sample points), such as sampling frequency/pattern and
interpolation technique, are the focus of concern. In both cases, the
resolution of the analysis grid used to geographically summarize the data is a
critical concern. If the analysis grid is too course, information is lost in
the aggregation over large grid spaces; if too small, measurement and
positioning errors are influential.
The technical issues surrounding mapped data analysis and spatial modeling involve the validity of applying traditional statistical techniques to spatial data. For example, regression analysis of field plot data has been used for years to derive crop production functions, such as the corn yield versus potassium curves you might recall from college. In a GIS, you can regress a entire map of corn yield on a map of potassium (they’re just spatially organized sets of numbers) to derive the production curve relating the two mapped variables— but should you? Technical concerns, such as variable independence and autocorrelation, have yet to be thoroughly addressed. Statistical measures assessing results of the analysis, such as a spatially responsive correlation coefficient, await discovery and acceptance by the statistical community. Spatial modeling uses the relationships established during the data analysis phase to determine the "optimal" actions, such as amount of phosphorous to be applied to each location in the field. The issues surrounding spatial modeling are similar to data analysis and involve the validity of using traditional "goal seeking" techniques, such as linear programming or genetic modeling, to generate maps of the optimal actions (prescription maps). At present, the full map-ematically based approach to site-specific management is in the hands of the researchers. Like the "chicken or the egg" dilemma, the skeleton of the site-specific management process is being put in place by a variety of vendors, thus enabling researchers to continuously refine the analytical/modeling meat. Putting aside the considerable technical challenges, what are the major social implications of site-specific management?
Legal Issues and Impacts
Four important social issues
surround site-specific management: intellectual property rights, intellectual
property wrongs, who owns the data, and data haunting. From the vendor’s point
of view intellectual property rights are a major concern. The issuance
of broad patents to individual companies, such as linking GPS to GIS and
variable rate control, reward innovative thinking, yet generate market
uncertainty and stifle open development of an emerging technology. Intellectual
property wrongs refer to the validity of site-specific management systems.
They all generate pretty maps, but whose map is best? And what recourse do you
have if you follow a bum prescription map and lose the farm? The need for
standards in site-specific management reach far beyond the developer’s concern
for compatible wiring harnesses and data exchange, to end user needs for
assessing system performance and results. Who owns the data derived
through site-specific management is another important issue. If a farmer pays
for the collection, analysis and synthesis of site-specific management data
about his farm, who owns, and possibly even more importantly, controls access
to these data? Can the analyst use or sell the information without the farmer’s
consent? Or, as with data haunting, can the data be used in court
against the farmer— sort of a high-tech self-incrimination? As with any new technology,
site-specific management is pushing at the envelope of our traditional social
beliefs and legal doctrine.
Extended Issues and Trends
Site-specific management is
pushing, as well, at current definitions of agricultural research and markets.
Historically, agricultural research involved controlled studies on a few
plots in a couple of fields at a university or experiment station hundreds
miles away, involving different soils, climatic conditions and plant varieties.
The data was analyzed and the findings published. With the advent of
site-specific management, a farmer has access to thousands of "plots"
in his own backyard (the analysis grid used in establishing yield and field
condition maps). What is needed is a switch in emphasis from publishing research
findings to transferring research methodologies so farmers can apply them to
their own extensive data sets. Changes in the agriculture market place and the private/public
sector’s use of GPS/GIS are just as dramatic. A clamor for digital mapped
data is causing mapping agencies, such as the USGS and the NRCS, to change data
collection, map preparation and distribution procedures. Downloading map
digital products over the Internet is already a reality, such as maps from the
National Wetlands Inventory. A booming cottage industry has sprung up for
developing the data bases needed in site-specific management, such as soil
nutrient maps. A growing array of options for the tractor, such as GPS and
notebook computers mounted in the cab, are rapidly appearing. The proliferation
of hardware and software has resulted in a desperate need for standards—
hardware and data exchange standards are obvious, but data processing standards
addressing data errors, conditioning and analysis verge on proprietary
"secrete formulas."
However, data processing is what
makes radically different maps, and they both can’t be right. Without
techniques for empirical verification GIS mapping is "like buying a pig in
a poke." Consulting services specializing in the analysis of site-specific
management data are forming. To date, however, the justification of all this
excitement has been on cost efficiency and crop productivity. However, the natural
resources experience with spatial technologies is much longer and has
evolved into a different set of applications. In the beginning, forestry had an
operations-centric view similar to the current site-specific management one (in
many respects, trees are just 120-foot corn stalks that are harvested every 60
years or so). GIS’s automation of mapping and inventory activities promised
great savings, and many systems were justified through cost/benefit analysis of
operational efficiency. However, the view of GIS as a "tool"
expediting traditional management procedures quickly evolved into a different
perspective as a radically new "technology" providing entirely new
approaches to resource management.
Foresters became familiar with such
foreign concepts as optimal path analysis and visual exposure density surfaces,
and began applying these tools in innovative ways. More recently, the value of
GIS is viewed as not only making more efficient and well-informed management
decisions, but as a "revolution" in the decision-making process
itself. With the advent of the environmental movement, a forester (vis. farmer)
can’t harvest a single timber stand (vis. crop) without a thorough analysis of
its environmental impacts, such as sediment loading to streams and the
health/welfare of wildlife in the area. From this perspective, spatial analysis
moves from a cost/productivity focus to a required "license to do
business," and bazaar maps, such as the "propensity for
litigation," are now as important as timber inventory maps. It’s greatest
return is as a communication tool in substantiating good stewardship of the
land. As increasing environmental regulations loom in agriculture, such as the
T-factor in soil loss and nitrogen allocations by watershed, the spatial
technologies in site-specific management might become as much a necessity as a
tractor— it already has for your backwoods cousins.
Conclusions and Some Good Advice
Site-specific management extends
our traditional understanding of farm fields from "where is what" to
analytical renderings of "so what" by relating variations in crop
yield to field conditions, such as soil nutrient levels, available moisture and
other driving variables. Once these relationships are established, they can be
used to insure the right thing is done, in the right way, at the right place
and time. Common sense leads us to believe the efficiencies in managing field
variability outweigh the costs of the new technology. However, the enthusiasm
for site-specific management must be dampened by reality consisting of at least
two parts: empirical verification and personal comfort. To date, there has not
been definitive studies that economically justify site-specific management. In
addition, the technological capabilities (cart) appears to be ahead of
scientific understanding (horse) and a great deal of "spatial
research" lies ahead. That brings us to personal comfort. If you are
skeptical of site-specific management and/or feel "cyber-challenged,"
you should wait to fully adopt the technology. However, keep in mind, that if
site-specific management proves to be more than a passing fad, its most
important ingredient is a robust database— each year that data collection is
postponed it puts a farmer farther behind. In the information age, a farmer’s
ability to react to the inherent variability within a field might determine
survival and growth of tomorrow’s farms.
Joseph K. Berry is a leading consultant and educator in the
application of Geographic Information Systems (GIS) technology. He has written
over two hundred papers, several books and presented hundreds of workshops on
the subject. He is a contributing editor and author of the "Beyond
Mapping" column for GIS World magazine and the "Inside the GIS
Toolbox" column for Successful Farming’s ag/INNOVATOR newsletter. Dr.
Berry is the president of Berry and Associates // Spatial Information Systems,
consultants and software developers in GIS technology. Also, he is a Special
Faculty member at Colorado State University, and the author of the Tutorial Map
Analysis Package (tMAP) used by universities worldwide for instruction in map
analysis principles. Formerly, he was the president of Spatial Information
Analysis Corporation and an Associate Professor and the Associate Dean at Yale
University's Graduate School of Forestry and Environmental Studies. He holds a
bachelor's degree in forestry, a master's degree in business administration and
a doctorate emphasizing remote sensing and land use planning. …for more
information see our web pages at http://www.innovativegis.com/basis
Berry & Associates // Spatial Information Systems, Inc.
2000 S. College Avenue, Suite 300
-- Fort Collins, Colorado USA 80525
Phone: (970) 490-2155 -- Fax: (970) 490-2155 – Email joeb@innovativegis.com