In 2008 global wheat stocks reached a thirty-year low, and the U.S. wheat stocks fell to their lowest levels since the late 1940s As wheat is the major commodity provided as food aid, wheat shortages not only impact wheat and wheat-product prices, but also have dire implications for ensuring food security in developing countries. Timely and accurate forecasts of wheat production prior to harvest at regional, national and international scales for both developing and developed countries are crucial. Such estimates can help to improve food accessibility risk management, as well as play an important role in global markets, policy and decision making. A range of techniques such as visual field estimates,multiple framebased sample surveys, analog-year approaches, crop-simulation models and regression approaches have been used for forecasting preharvest yield estimates with varying degrees of success. Earth observation data, owing to their synoptic, timely and repetitive coverage, have been recognized as a valuable tool for yield and production forecasting. Agricultural monitoring from space, in particular pre-harvest assessments of crop yield and production, has been a topic of research since the early 1970s.
In the US the Large Area Crop Inventory Experiment (LACIE), a joint effort between the USDA, NASA and the National Oceanic and Atmospheric Administration (NOAA) initiated in 1974, demonstrated that earth observations, could provide vital information on production, with unprecedented accuracy and timeliness, prior to harvest. This experiment spurred many agencies and researchers around the world to further develop and evaluate remote sensing technology for timely, large area, crop monitoring. Remotely sensed satellite data offer timely, objective, economical, and synoptic information. Their utility for crop yield forecasting has been demonstrated across a wide range of scales and geographic locations.