A Crop Stress Index to Predict Climatic Effects on Row-Crop Agriculture in the U.S. North Central Region - The Ecology of Agricultural Landscapes - page 90

Figure 4.7 . Distribution of accumulated (A) growing season degree-days and (B) precipita-
tion (mm) by county in the NCR from May through July (1971-2001). See Fig. 4.6 for data
sources.

temperatures during flowering and pollination depress yields in both, but because
corn has a shorter reproductive period—on the order of only 1 week—corn is espe-
cially sensitive to short-term heat waves (Hatfield et al. 2011).
Incorporating both year and climate into multiple regression analyses significantly
improves the prediction of corn ( r 2 = 0.80) and soybean ( r 2 = 0.79) yields in the NCR:

Corn yield

=− + 135 00 . 717 year − 00 . 955 CSI

Soybean yield =− 432 . + 00 . 23 year 0 − 0 0 . 238 CSI

where year = calendar year and CSI = Crop Stress Index.