Satellite and ground data track status of the nation’s food supply
USDA’s National Agricultural Statistics Service (NASS) and Economic Research Service (ERS) track U.S. crop production each year, relying in large part on producer surveys and ground observations to estimate acreage and yields at state and county levels. During the growing season, production data inform estimates of crop acreage and yields that help farmers and traders set prices. Satellite data offer a useful method for validating statistics collected on the ground, and can help fill in gaps in ground observations, particularly in years where planting is delayed or disrupted due to weather or climate extremes.
NASS uses data from the USGS/NASA Landsat 8 and the European Union Copernicus Sentinel 2 A/B satellites, which provide data at a fine enough scale to distinguish individual fields, to identify where particular crops are growing. Sensors aboard NASA’s Aqua and Terra satellites also monitor daily vegetation health and growth stage, which are indicators of crop yield. For example, in 2019, heavy spring rains flooded millions of acres of cropland around the Mississippi, Wisconsin, and Missouri Rivers, delaying planting for many farmers. Landsat 8 and Sentinel 2 data helped NASS state officials observe which fields and areas were most impacted by the floods and determine which fields had planted crops.
NASS’s Cropland Data Layer datasets are released to the public at the end of each year. The site’s historic data are used by disaster managers to evaluate crop damage from floods and other natural disasters. Resource managers also use historic data to monitor crop rotation, study land-use change and crop migration, and monitor water use.
Three moments in a year of farming north of St. Louis, Missouri, as seen in USGS/NASA Landsat 8 data. On the left is May 7, 2019, as heavy rains delayed planting for many farms. September 12, in the middle, shows bright green signifying growing vegetation, although with a fair amount of brown, bare fields. On the right, October 14, the light brown indicates harvested fields, while darker brown indicates fields that had not been seeded or were fallow all summer. Source: USGS/NASA.