A CROP-SPECIFIC DROUGHT INDEX FOR CORN .1. MODEL DEVELOPMENT AND VALIDATION

Most popular indices in use today that address agricultural drought [e .g., the Palmer Drought Severity Index (PDST) and the Crop Moisture In dex (CMI)] do not consider specific crop responses to the drought even t. Thus, values produced by indices such as the PDSI and CMI cannot be directly linked to drought impacts on crop production and yield since each crop responds differently to moisture and heat stress. This pape r presents a new drought index that, unlike other drought indices, is specific to a single crop (corn-Zea mays L.) and takes into considerat ion water use during specific periods of growth. The Crop-Specific Dro ught index (CSDI) model was developed with 8 yr of data from Nebraska' s East Central Crop Reporting District (CRD), and validated with 10 yr of data from Nebraska's East Central CRD, 9 yr of data from Missouri' s Northeast CRD, 8 yr of data from Wisconsin's South Central CRD, and 9 yr of data from Indiana's Central CRD. Plots of model predicted vs. actual CSDI values yielded coefficients of determination (r2) ranging from 0.32 (Central Indiana) to 0.76 (Northeast Missouri); D-index of a greement values ranging from 0.72 (Central Indiana) to 0.90 (South Cen tral Wisconsin); and root mean square errors ranging from 7.7% (South Central Wisconsin) to 13.4% (Northeast Missouri). The CSDI model may p rovide an effective drought monitoring and assessment tool for the Cor n Belt of the United States.