Drought Vulnerability

Drought is the primary contributor to crop failure in the United States, resulting in estimated annual losses between $6 to 8 billion. The USDA Farm Service agency estimated that the 1999 drought alone resulted in $500 million in associated crop losses in Pennsylvania, and in some counties crop losses reached unprecedented levels of 70 to 100 percent.

About the Project

Agricultural drought occurs when there is inadequate soil moisture to meet a plant’s needs, ultimately resulting in a reduction in crop yields. Consequently, an agricultural drought vulnerability assessment tool should have the ability to account for the sensitivity of crops to soil moisture deficit conditions during critical stages of crop development. Unfortunately many drought indices and assessment methods widely used today fail to provide an accurate assessment of soil variability across the landscape and may neglect the interaction of crops with soil moisture reserves.

Project Goal

The goal of this research project was to develop a long-term agricultural drought risk assessment tool for Pennsylvania that was applicable at the field scale to help farmers make educated decisions based on their potential vulnerability to agricultural drought. The assessment tool was developed using field-based variables and a crop growth model and was structured to have limited data requirements to allow for a regional and statewide implementation.

Crop Simulation Model

A crop simulation model was utilized to simulate the effects of soil moisture stress on corn production under a variety of soil and climate conditions over a span of thirty years. The effects of soil moisture stress on corn production were quantified to develop a worst-case scenario baseline drought vulnerability index with the ability to capture the vulnerability of Pennsylvania’s diverse soils to agricultural drought under an assortment of climatic conditions. An index representing conditions likely to occur once every four years was mapped over a subset of nine Pennsylvania counties to provide farmers with a tool to detect potential problematic conditions. A relationship was developed between the index and relative yield reductions to put the index in terms more meaningful to farmers. The relative yield reductions likely to occur once in four years were then mapped over the nine county study area. The results indicated that the drought vulnerability of a given location stems from the complex interaction of both climate and soil properties.

Contact Information

Rick Day, Ph.D.
  • Associate Professor of Soil Science and Environmental Information Systems
Phone: 814-863-1615