Crop-Area Estimates from LANDSAT; Transition from Research and Development to Timely Results

The utility of LANDSAT data in developing data in crop-area statistics has been demonstrated by a number of investigators. Generally such studies have had "proof of concept" in a research and development (R&D) mode as their primary objective. Obtaining timely results for consumption by agricultural data users has been of secondary importance in most R&D studies. In contrast, this paper describes recent efforts by the Economics, Statistics, and Cooperatives Service (ESCS) of USDA in developing timely crop-area estimates from LANDSAT with measurable and improved precision. The 1978 Iowa corn and soybean crops were the key items of interest for this project.One of the functions of ESCS is to estimate crop areas planted at national and state levels. These estimates are published by ESCS's Crop Reporting Board starting on June 30 of the crop year. Estimates are updated monthly up until mid-January at which time final national and state estimates for the crop year are made. Estimates for individual counties and in some states for multi-county areas, called Crop Reporting Districts, are made by ESCS's State Statistical Offices (SSO's) in cooperation with state government agricultural agencies. Small area estimates, however, are often not published until April of the year following the crop year.From 1972 to 1977, ESCS has investigated the ability of LANDSAT data to improve crop-area estimates at state, multi-county and individual county levels. The results from these studies have been mixed. For winter wheat, substantial improvements in the precision of crop-area estimates were obtained in Kansas. For corn and soybeans, however, good results were obtained only for a subset of investigation areas. These previous R&D efforts took over a year on the average to complete and thus the results were not useable for setting final area estimates for the current crop year. In 1978, on the other hand, ESCS strove to develop timely LANDSAT-based crop-area estimates to supplement current area survey estimates. These estimates were then input to the 1978 Annual Crop Summary released by the USDA'S Crop Reporting Board on January 16, 1979. The estimates were also used by the Iowa SSO in making multi-county estimates.