James Heald


Developing a National GIS Data Layer for Agriculture One County at a Time


The USDA Farm Service Agency (FSA), along with partner agencies Rural Development and the Natural Resource Conservation Service (NRCS), is in the process of implementing desktop GIS at over 2500 field service center locations nationwide.  Ultimately, the GIS resources for the Agency will be managed in a distributed database environment.


The most critical component in the successful implementation of GIS for FSA is development of the Common Land Unit (CLU) data layer.  The Common Land Unit layer will ultimately include all farm fields, range land, and pasture land in the United States.   Data is currently maintained at the service centers with annotations on hardcopy aerial photography.  In conjunction with digital imagery and other data, FSA will use the Common Land Unit to manage Farm Service Programs, monitor compliance, and respond to natural disasters, among other tasks.


Due to funding constraints and the need to build support for GIS within FSA, we have had to start slowly, building momentum and developing data and pilot applications in parallel to show results quickly.  Phase One of the data development was the creation of 12 digitizing centers at field office locations in seven states.  These offices are developing the CLU data layer with on-screen digitizing using Arcview in a Windows NT environment.  Customized digitizing and quality control extensions were written for the project.


Pending budget approval, future developments will include a program of outsourcing data production, developing new digitizing centers, upgrading the software environment, and distributing the completed data sets to field service centers with training and tools to maintain the data.  This presentation will discuss the current progress for this effort, methodology, standards, lessons learned, and future directions.



The USDA Farm Service Agency (FSA), along with partner agencies Rural Development and the Natural Resource Conservation Service, is in the process of implementing desktop GIS at over 2500 field service center locations nationwide.  Ultimately, the GIS resources for the Agency will be managed in a distributed database environment. As with many public agencies, “the majority of FSA’s business data is geo-spatial in nature, or referenced to geographic locations (i.e., land records, field locations, soil types, etc.).  The ability to manage this data efficiently and effectively as we move into the next century is essential.”[i]  A report done in 1996 estimated that roughly one-third of FSA’s business directly involved using and maintaining maps and geospatial information.  In those areas, it was estimated that FSA could save approximately 42 percent of its costs by integrating GIS into business processes.


The most critical component in the successful implementation of GIS for FSA is development of the Common Land Unit (CLU) data layer.  The Common Land Unit layer will ultimately include all farm fields, range land, and pasture land in the United States.   Data is currently maintained at the service centers with annotations on hardcopy aerial photography.  In conjunction with digital imagery and other data, FSA will use the Common Land Unit to manage Farm Service Programs, monitor compliance, and respond to natural disasters, among other tasks.


Due to funding constraints and the need to build support for GIS within FSA, we have had to start slowly, building momentum and developing data and pilot applications in parallel to show results quickly.  Phase One of the data development was the creation of 12 digitizing centers at field office locations in seven states.  These offices are developing the CLU data layer with on-screen digitizing using Arcview in a Windows NT environment.  FSA wrote customized digitizing and quality control extensions for the project.  Additional extensions to support FSA program needs are being developed as needed.




FSA faces a number of challenges in developing the Common Land Unit layer.  First is the sheer size of the task.  FSA needs to map all of the farm fields in the country, or at least all the fields involved in agency programs.   Second, the data is constantly changing.  Therefore, it needs to be put in a maintenance program as soon as initial digitizing is completed.  Also, FSA needs to be able to maintain tabular and geospatial time-series information.  Lastly, we have security and privacy issues.  Farm and disaster payments are directly tied to acreage and the crops reported by producers.


Mapping all the Farm Fields in the Country


The Farm Service Agency (FSA) currently maintains records for about 2 million Farms, comprised of about 16 million fields.   Map data is maintained manually on hard copy aerial photographs at more than 2500 local service centers. Tabular data is currently maintained on a System 36 mini-computer at these same local offices.  Some of the tabular data is uploaded to a central mainframe computer.  These legacy systems employ thousands of lines of Cobol code and utilize hundreds of VSAM files.


Because map data is manually maintained at a large number of sites, the quality of source material available for transfer to GIS varies considerably.  Historically, as new NAPP photography became available, new hard copy photography was prepared and printed by FSA’s Aerial Photography Field Office (APFO) in Salt Lake City and shipped to the service centers.  Employees at the service center were then tasked with transferring their line work and annotations from the old maps to the new maps.  Depending on the county, this has been a massive job.  For example, Kings County, California has over 1150 map sheets.  Given other work demands, the maps have not always been transferred to the latest photography.


Standards for maintaining the hard copy maps exist, but the standards are somewhat flexible.  In part, this has probably been done to alleviate some of the burden of maintaining the maps.  However, local variations in source material will make it more challenging to contract out the digitizing.


In addition, because the maps are critical to conducting business at the service centers, the staff is very reluctant to part with them, particularly for more than a couple of days.  FSA is currently testing out a process for scanning the source documents at APFO.  Scanning can be completed within several days and the original source materials can be returned to the service center.  Scans would be made available to contractors or digitizing centers in either hard copy or digital format. 


Dynamic Data


Farm and field boundaries change constantly.  Tree stands are cleared to create new common land units.  Farmland is sold and subdivided for development and common land units disappear.  Ownership and producer relationships change.  Depending on the growing season, crop data and planting patterns change one or more times a year.


 The Minnesota State office has estimated that, in a typical county, there are between 1200 and 2400 map changes per year.  Workload for these changes is not spread out conveniently throughout the year, but is tied to program signup deadlines, annual acreage reporting, and compliance verification cycles.


As a result, FSA cannot simply digitize the field information for the County and let the data sit on a shelf somewhere until computer hardware, GIS software, and applications are delivered to the counties.  Maintenance is crucial and development of the data layer must coincide with delivery of hardware, software and applications.


In order to properly administer farm programs, FSA is required to maintain time-series information on both attribute and geospatial data.  Eligibility for certain farm programs and disaster payments is dependent upon the historical use of land parcels.  For example, land is not eligible to be enrolled in the Conservation Reserve Program unless it has been farmed in 2 of the 5 most recent crop seasons.  Disaster programs are sometimes initiated for past years.




FSA is responsible for billions of dollars in loans, farm payments, and disaster assistance.  In 1999, Market Loss Assistance Payments totaled over $5.4 billion to over 1 million producers.  In 1998, Crop Loss Disaster Assistance totaled over $1.9 billion. These payments are directly tied to what happens on the land and acreage reported by producers.   Therefore, the GIS data layer needs to have an acceptable level of accuracy.  For many years, FSA has determined field acreage and producers have accepted these measurements.  There is some discomfort within the agency that GIS acreages will deviate too much from the historical acreage and cause problems with producers.  One way to ease this problem is to work with producers to make sure that they agree with where boundary lines are drawn.  Currently, digitizing specifications require all boundary lines to be within 3 pixels of a feature on the DOQ.   In addition, any changes to the data need to meet strict auditing requirements.  When the system is fully implemented, FSA needs to be able to track who made changes, when they were made, and why they were made.  FSA also needs to protect the confidentiality of any sensitive tabular data joined to the GIS data layer.




Creating and maintaining a farm field layer for the entire country is an expensive proposition.  Estimates have ranged from $16 million to $45 million just to create the initial data layer, excluding preparation and distribution costs for managing DOQ imagery.   Because this particular data layer becomes obsolete quickly, software and tools need to be deployed to a large number of sites to ensure maintenance.  While there appears to be broad agreement that this layer is critical to redesigning farm program delivery, very little of this has been included in the FSA budget up to this point.


Creating the Common Land Unit Layer


FSA and its partner agency NRCS have been struggling with implementing the Common Land Unit layer for almost a decade.  The first pilot program to integrate GIS in the service center workflow began in 1991.  This and subsequent pilot programs verified that implementing GIS in local service centers would dramatically reduce workload and improve the quality and consistency of delivered services.   Finally, in 1998 nine pilot sites were equipped as part of a Service Center Implementation program and Common Land Unit layers were developed for these sites.  FSA contracted out most of the digitizing for the nine sites to private contractors.


At the end of FY 1998, funding was obtained to establish 12 digitizing centers in seven states.   The State Directors from Kansas, Minnesota, Nebraska, and Missouri lobbied the Farm Program Administrator to get GIS implemented in their states and proposed setting up two digitizing centers in each state.  The Farm Program Administrator agreed to implement the program, but added an eastern state, Virginia, and a tobacco state, Kentucky.  Oklahoma was later added to the program because of issues involving the Cherokee nation.  The State offices selected the digitizing sites and most were established in local service centers. 


These sites were equipped with Windows NT servers and between one and four additional workstations.  The GIS software chosen for use at the centers was Arcview.  Hardware and software were ordered in December 1998.  Hardware and software were installed starting in March 1999.  Training began in March and the first site was operational in April.  Deployment and training continued through May.  A thirteenth site (Callaway County, Missouri) was added in January 2000.  Callaway County had been part of an earlier GIS pilot program and had been doing digitizing and other GIS projects using Arc/Info in a Unix environment.




The initial proposal to develop the Common Land Unit data layer outlined a process to transfer data from the hard copy maps using heads-up (on screen) digitizing on a Digital Orthophoto Quad base.  FSA’s Aerial Photography Field Office is responsible for delivering the DOQ to the digitizing centers.  FSA made a policy decision to mosaic the DOQ to create seamless County images, because image quality and edge matching problems made the raw DOQ unacceptable as a base map for this project.  As a result, APFO checks every single DOQQ (USGS only checks 10 percent). APFO has found that approximately 8 percent of the quarter quads have problems: for example, they don’t meet National Map Accuracy Standards, they are projected in the wrong UTM zone, or they contain the wrong photograph.  The mosaics are tone balanced and most common DOQ edge-matching problems are eliminated.  Seam lines are also adjusted so seams do not divide farm fields.  Currently, APFO is delivering full resolution TIF files tiled by quad boundary and a County Mosaic in MrSid compressed format.  Digitizing is only done using the full resolution images.  The MrSid files are used mostly for quick viewing of data.


With current staffing levels and hardware, APFO is only able to mosaic about 200-250 counties per year.  In order to meet development targets, this production level will need to be at least doubled over the next couple of years.


With over 2500 county offices nationwide, FSA has had to establish data development priorities for each state.  Each State Office, in cooperation with our partner agency NRCS, developed a priority list.  Factors considered by FSA in developing the list were; 1) workload, 2) availability of DOQ, 3) agricultural land and crop production levels, 4) expertise and adaptability of the county office staff, and 5) availability of Digital Soil data.  The digitizing centers began by working on data for their own states.  The next phase of the project, starting this summer, will be to begin digitizing top priority counties from other states.




As of May 1, 2000, initial digitizing has been completed for 106 counties.  We estimate the digitizing centers will complete another 8-10 counties every month.   At the present time, only about 20 counties, in addition to the digitizing centers, have the hardware and software to maintain their land units. 



Arcview, out of the box, includes most of the functions needed for creating data.  However, it was necessary to extend and customize the interface to reduce manual setup time and ensure data and procedural consistency between the sites.  The funding obtained for this project did not include a budget for software development.  FSA staff did the original Avenue programming to customize tools for the digitizing project.


Features of the original digitizing extension included the following features:


q      Floating tool bar

q      File creation with defined attributes

q      Scale limitation on editing (1:4800 or smaller)

q      Feature editing with some topological checking

q      Automatic acreage calculation when features are edited

q      Tools for creating inclusions (polygon subtraction) and to streamline the process of combining polygons

q      Attribute editing through dialog boxes



Subsequent updates to the digitizing tools corrected problems, particularly to reduce problems with segmentation violations and file corruption, and added new functionality, including:


q      Integrated Quality Control tools

q      Checks Overlaps, Voids, Slivers, Multi-part polygons

q      Automated Map Layout creation

q      Multi-attribute polygon labeling

q      A simplified search routine

q      Farm, Tract, and Field number search

q      Public Land Survey Township, Range, Section search


Again, most of this functionality was developed in-house.  However, some of the functionality was adapted from user scripts downloaded from the Esri site.  In particular, the shape check and correction program developed by Andrew Williamson has been a lifesaver on numerous occasions.


Where the files are being maintained, most sites are currently using FSA’s standard digitizing extension.  A more user-friendly maintenance tool has been developed and is undergoing final testing.  This tool is very similar to the digitizing extension, but includes stronger data validation and some additional tools.  The maintenance tool also forces attribute data entry when polygons are added or edited.


Ensuring the Transition to GIS


Over the last several months, it has become increasingly apparent that the only way to ensure a successful transition to GIS is to eliminate any need for the hard copy maps.  Among several problems with initial data modeling efforts was the failure to include all of the data elements in the CLU table that are currently being captured on the hard copy maps.  Tools are currently in development to allow service centers to capture these additional data items and link them to the basic CLU data file.  The bottom line is that no matter how inherently useful the data, applications for making use of the data are necessary to ensure use.


One of the major hurdles to eliminating the hard copy maps involves the farm program compliance process.  Every growing season, producers report their growing intentions (crops and acreage) to FSA at the field and sub-field level.  At the peak of the growing season, most county offices have 35mm aerial color photography flown.  They receive this photography as slides.  Computer programs on the System 36 legacy system generate a random sample of farms, which are to be checked for compliance.  The appropriate slides are inserted into a projector attached to a planimeter and manually rectified to the hard copy maps.  Field and sub-field boundaries are measured and compared to the reported acreage. 


We have distributed Arcview Image Analysis software to four of the digitizing centers and they are rectifying digital copies of the slides to the DOQ.  One county in Minnesota did a test by redoing their compliance from 1999 using rectified 35mm slides and the digitizing tools to measure compliance with farm programs.  Measurement differences between GIS and the planimeter were within an acceptable tolerance (generally less than 5 percent) and the Compliance process took about 15 days (including slide rectification) instead of 30 days using current manual methods.


Minnesota is aggressively pursuing a strategy of doing digital compliance in all counties where hardware, software and data are available.  That could be as many as 20-30 counties in FY 2000, although funding delays may significantly reduce that number.  We are also planning to pilot a program of contracting out the rectification and mosaicking of 35mm slides to create countywide seamless images that match the county DOQ mosaics created by APFO. 


FSA is currently developing a more automated process for compliance, which will include sharing data with the System 36 to eliminate as much data entry as possible.   This process will take the Farm Sample list generated by the System 36 and automatically select Common Land Units, based on the farm number, and copy them to a compliance layer.  Where necessary, sub-fields will be added to the layer based on the 35mm photography.  The acreage will be generated for each field and sub-field automatically by the tools. 


Another data set from the System 36 legacy system, containing the reported acreage and crop information will be linked to this compliance layer, allowing comparison of reported and actual acreage.  Visual interpretation will be needed to verify that the reported and actual crop types are the same.  The generated acreage will then be fed back into the System 36.  Where farms are out of compliance, a map will be generated using a predefined template and a notification letter will be generated using existing software.   FSA is also planning to cut out countywide sections of Landsat TM data to send to our compliance sites during the growing season to see how this might aid them.  Use of these new tools and digital datasets should further reduce the amount of time taken by the compliance process, while improving consistency, and creating a permanent digital record of compliance activities.


It is important to note here that the System 36 is a legacy environment and that any applications developed to tap into its data resources are interim applications.  Recently, the manufacturer withdrew its maintenance support for the platform, making it essential for FSA to move more quickly towards a permanent solution.  However, it is our belief that it will take at least several years to replace these applications with fully re-engineered database products.  Moving forward with interim solutions, which have the potential to significantly reduce manual workload and improve customer service, appears to be well worth the effort.


Lessons Learned


In addition to the data that has been created, digitizing centers have been very valuable for increasing the GIS literacy within FSA.  The centers have become a fertile laboratory for generating ideas on how to transfer FSA program functions from manual and outdated automated technology to GIS.  Staff from the centers also have developed the capacity to train employees at nearby counties and can fulfill a “help desk” function for common problems.  These side benefits could be a major factor in recommending expansion for the program.


Larger digitizing centers appear to work better than smaller ones.  Sites with four workstations are significantly more productive than sites with only two digitizing stations.  They also seem to place fewer trouble calls and have less staffing turnover problems.  


Support from the State office is also very important.  Sites with strong State office involvement are more successful.  The four states that originally proposed the project have been more successful than the other three states.  They were up and running faster and have had fewer overall problems.


Access to other sources of local support, such as universities, also enhances the success of the digitizing centers.  Universities can help as both GIS resources and sources of temporary staff for the digitizing centers.   At least half of the digitizing centers have some kind of relationship with local universities and community colleges.  FSA is currently talking with a number of universities and, if funding becomes available, will actively pursue formal partnerships.


However, in-house digitizing centers are, at best, only a part of the solution to developing the Common Land Unit.  The job is too big and FSA is not really interested in being in the digitizing business.  Even if FSA doubles the number of digitizing centers it will not finish the CLU layer for the entire country for about 10 years at the current rate of production. It would be advantageous to accelerate the program by contracting out digitizing for at least 500 counties over the next two years.  If we can get budget commitments, we will be contracting out as much digitizing as we can manage over the next several years.


On a regular basis, we become aware of other groups – federal, state, and local – who are digitizing farm field boundaries for their own purposes.  FSA needs to find ways to develop partnerships with these other groups to effectively pool our resources to ensure the sharing of data and applications. 


We are also aware of projects going on within FSA and our partner Agencies to digitize field boundaries outside the umbrella of this project.  Our biggest concern about these projects is that they will not meet the standards developed for the national program.  It would be a shame if they could not take advantage of tools that we are developing, but I can certainly understand their frustration with how slowly the wheels seem to be turning at the national level. 


As indicated previously, maintenance is critical to the CLU development process.  By the end of FY 2000, FSA will need to deploy Arcview, maintenance tools, and hardware upgrades (additional disk space is crucial for the imagery) to as many as 160 sites to keep the data from becoming obsolete.   If we increase production, either with additional digitizing centers or by outsourcing, we increase the need to deploy maintenance hardware and software.  We also put pressure on our operations at APFO to mosaic and distribute DOQ.


In order to keep up with production, FSA will need to find a cheaper and easier way to deliver maintenance tools and other related functionality.  One way we have looked at and will look at more closely in the coming months is using ArcIMS to deliver applications.  Limited bandwidth probably precludes delivering data over the web to some of our service centers, at least in the short-term, but we might be able to use the Internet as a software delivery mechanism.


Maintaining this data as shape files also presents challenges, but appears to be unavoidable in the short term.  One problem that we have already had at numerous sites is getting staff to understand that more than one person cannot edit a shape file at the same time.  Another problem is that current data for the counties will not be readily accessible at either the State or National level.  One way that FSA can solve these problems is by managing the CLU in a distributed database environment. 


FSA and the partner agencies are currently evaluating database software and hardware systems to replace the System 36 and our other legacy systems.  Using SDE and an Enterprise Database System will allow us to develop seamless, integrated applications utilizing GIS as the front-end.  Database versioning may be a solution to the problem of managing time-series information such as our annual compliance layer.  But this may be a very costly solution implemented nationwide.


Future Developments


Obviously, FSA has a long way to go before all farm fields in the country are digitized and GIS is fully deployed at all of our Service centers nationwide.  Without additional funding, we will have completed the digital layer for 180-200 counties by the end of the year.  But FSA currently does not have the budget to deploy Arcview in all of those counties.  If we do not find additional funds soon, the data will not be maintained and will eventually become obsolete.


For the current fiscal year, FSA has requested a supplemental budget appropriation for a number of projects, including the Common Land Unit project.  With regard to CLU, the following areas are covered in this budget request:


q      Contract digitizing for about 200 additional counties

q      Hardware and Software for Maintenance sites

q      Hardware and Software for 10 new Digitizing Centers

q      Hardware and Software for Image Processing at APFO

q      Software development and Research and Development


Future funding for a project of this magnitude is always in jeopardy and FSA needs to develop a more coherent strategy for meeting the funding needs of this project.  As GIS practitioners, our first priority has been getting GIS software and tools to those counties where we have completed the basic data layer.  Our second priority, in concert with departmental reengineering efforts, has been prototyping software to meet FSA program needs in the field.  Both of these will allow us to better showcase the benefits of GIS on field operations and highlight the time and budget savings that GIS can generate. 


[i] Farm Service Agency: GIS Business Case, September 1996.



James Heald
GIS Specialist
USDA Farm Service Agency
Information Technology Services Division
Software Development Branch, Remote Sensing Section
Washington, DC 20250

(202) 720-0787