Figure 3

Multiple regression coefficients between crop yields and dry and humid heat days for all the counties with crop yield data. (a,b,d,e) Multiple regression coefficients between detrended corn (a,b) yields with detrended extreme dry (a) and humid (b) heat days (using the 95th percentile threshold) in bushels per acre per one heat day exposure for the period 1979–2019. (d) and (e) are the same as (a) and (b) but for detrended soybean yields. Significant values using a two-sided Student t-test at the 5% significance level are indicated in solid filled circles and triangles and non-significant values in open ones. Circles indicate non-irrigated yields and triangles indicate irrigated yield. (c and f) Box plots showing the interquartile range (boxes) and the data range (solid vertical lines, whiskers) of the regression coefficients for irrigated yields with dry heat (Irr/dry), non-irrigated yields with dry heat (Non-Irr/dry), irrigated yields with humid heat (Irr/humid) and non-irrigated yields with humid heat (Non-Irr/humid) for corn (c) and soy (f). The cross and horizontal line inside the box indicate the mean and median of the regression coefficients, respectively, and open circles in (c) and (f) indicate outliers. The maps are made with ArcGIS Pro 2.2.0 with the US base map downloaded from Census Bureau, https://catalog.data.gov/dataset/2019-cartographic-boundary-shapefile-current-census-tract-for-united-states-1-500000.