Satellite-Based Mapping of Field-Scale Stress Indicators for Crop Yield Forecasting: An Application across the Corn Belt, USA

Soil moisture deficiency is a major factor in determining crop yields in water-limited agricultural production regions. Evapotranspiration (ET) describes crop water use through transpiration and water lost through direct soil evaporation, which makes it a good indicator of soil moisture availability and vegetation health and thus has been an integral part of many yield estimation efforts. The Evaporative Stress Index (ESI) is ET based crop stress index, which describes temporal anomalies in a normalized evapotranspiration metric as derived from satellite remote sensing. ESI has demonstrated capacity to explain regional yield variability in water limited regions. However, its performance in some regions where the vegetation cycle is intensively managed appears to be degraded. In this study, we have demonstrated field-scale ESI has the advantage of being able to resolve different crop types with varying phenology. In addition, incorporating phenological information significantly improves yield-correlations by accounting for effects of phenology such as variable planting date and emergence date. Work is underway to extend the field-scale mapping ESI and the analysis of ESI-yield correlation to three sites across the Corn Belt: Ames, Bondville, and Mead. This approach prototypes a methodology that could benefit operational yield monitoring using remote sensing based ET estimate.