The Effects of Shelterbelt-Planting on Crop Production (2SLS)
| Variables | log(Yield of Wheat / Acre) (1) | log(Yield of Corn / Acre) (2) | log(Yield of Hays / Acre) (3) | log(Irrigated Acreage) (4) | log(Revenue from Crops / Cropland) (5) |
|---|---|---|---|---|---|
| Prop. protected by shelterbelts* | −1.147*** | −0.448** | 0.407 | −5.213** | −0.748*** |
| 1945-1950 | (0.350) | (0.204) | (0.438) | (2.437) | (0.283) |
| 1954-1959 | −1.132** (0.499) | −0.256 (0.298) | −0.380 (0.273) | −3.572* (1.830) | −1.377*** (0.435) |
| 1964-1969 | −0.422 (0.356) | −0.705* (0.412) | −0.104 (0.216) | −5.867*** (2.144) | −0.941*** (0.313) |
| 1978-1982 | 0.0558 (0.264) | −0.515** (0.232) | −0.128 (0.189) | −1.938 (1.770) | −0.321 (0.298) |
| 1987-1992 | 0.203 (0.233) | −0.0711 (0.253) | −0.102 (0.197) | −1.425 (1.622) | −0.0130 (0.290) |
| Year and county dummies | Yes | Yes | Yes | Yes | Yes |
| Outcome variables in 1910-1930 | Yes | Yes | Yes | Yes | Yes |
| Other control variablesa | Yes | Yes | Yes | Yes | Yes |
| Erosion from the Dust Bowla | Yes | Yes | Yes | Yes | Yes |
| Proportion above the Ogallala Aquifera | Yes | Yes | Yes | Yes | Yes |
| Observations | 2,411 | 2,122 | 2,326 | 2,264 | 2,427 |
| Number of counties | 222 | 233 | 233 | 234 | 234 |
| R-squared | 0.904 | 0.934 | 0.918 | 0.832 | 0.937 |
Note: Yield of corn in column 2 is missing for 1969 and 1974; yield of all hays in column 3 is missing for 1945; irrigated acreage in columns 4 is also missing for 1945 with its baseline year 1935 (1930 for other variables).
↵a “Other control variables” include rainfall and temperature for each year and all the other variables listed in Table 1 from 1910–1930; “Erosion from the Dust Bowl” from Hornbeck (2012) include proportions of high- and medium-eroded as in Table 1; “Proportion above the Ogallala Aquifer” is from Hornbeck and Keskin (2014). All these variables are time invariant and all interacted with year-dummies. Standard errors clustered at county level in parentheses:
↵*** p < 0.01
↵** p < 0.05
↵* p < 0.1