Precision agriculture integrates information technology and data to improve agricultural production decisions that enhance farm profitability and deliver environmental benefits
Much of the promise of this technology depends on soils information (See PrecisonAg.com article, “Top 5 Tech Trends in Precision Ag for 2012.”) However, the soils information available through USDA’s Natural Resources Conservation Service (NRCS) Web Soil Survey Site is often inadequate for the needs of precision agriculture. In most cases, the higher resolution soils data needed for precision agriculture requires additional field soil mapping, which farmers may not want or be able to acquire.
Enter a relatively new technology that can materially change the availability of soils data for precision agriculture and help realize its potential economic and environmental benefits. That technology is LiDAR—Light Detection and Ranging. LiDAR provides important environmental background data for the modeling of high resolution soil information. In addition to the increased resolution, modeled soils data that incorporates LiDAR as a “backdrop” has the potential to dramatically increase the precision and accuracy of soils data on the landscape.
Aerial LiDAR is an aerial mapping technology that uses reflected laser pulses to estimate precise elevation and location data. The resulting LiDAR data “cloud” can be used to create elevation data for such purposes as engineering and conservation. LiDAR-based digital elevation data is available at some scale and in some parts of the United States, however, at the current acquisition rate it is estimated that it will take 35 years to provide complete coverage of the nation.
Recently, the U.S. Geological Survey (USGS) contracted an assessment of digital elevation needs in the United States. This 2012 report not only assessed the needs for better digital elevation data, it also estimated that LiDAR-related benefits from all sources could be valued at up to $13 billion per year. These benefits range from improved natural resource conservation to improved flood risk assessment and forest management. The report also estimated a cost of $1 billion to acquire LiDAR data for the United States at the one-foot contour level of accuracy. That cost, while not insignificant, could be manageable if spread across 15 or more federal agencies and over a three- to five-year period.
The elevation data LiDAR provides is the most important factor for making existing soil survey data useful to farmers in precision agriculture. It is estimated that the best resolution for a soils grid produced from LiDAR would be 5 or 10 meters. This would be an enormous increase in resolution of the soils information given the smallest delineation we can show on a traditional soil map is about 1 hectare. At a resolution of 10-by-10 meter cells, there would be 1,000 data points per hectare. A traditional map has 1 data point per hectare. The LiDAR data allows for very accurate spatial accuracy even at these fine resolutions, which means a fertilizer spreader could be continually adjusting application as it moves across a field, based on soils information.
The red lines in the soils map shown below are soil delineations based on existing elevation data. The black lines are derived from LiDAR-based elevation data from a NRCS Soil Survey Program LiDAR-based soil mapping pilot. The greater soil mapping detail provided by LiDAR-based data—which is understated in this map because it doesn’t display the 5 or 10 meter soil grid—would help farmers optimize the application of precision agriculture technology.
Without a nationally coordinated acceleration of LiDAR-based elevation data, the United States not only foregoes a wide range of benefits detailed in the USGS LiDAR Assessment, it also delays fully realizing the environmental and economic benefits of precision agriculture.
Precision Agriculture in the 21st Century, a 1997 National Academies Press publication.
LiDAR overview: http://en.wikipedia.org/wiki/Lidar
Soil Survey LiDAR Pilot in Illinois: https://prod.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs141p2_030186.pdf