By Paul Kassel
A quick review of subsoil moisture during the fall of 1999 and the spring of 2000 shows that subsoil moisture did not recharge much from October 30, 1999 to April 10 of 2000 (table 1). The five subsoil moisture sites gained from 0.6 to 4.2 inches of moisture during the late fall and early spring.
Table 2 shows the April 11 to September 30 rainfall was almost normal in Milford, Estherville, Spencer and Pocahontas. However, rainfall in Storm Lake was 9.5 inches below normal.
This information shows the effect on corn yields from below normal subsoil moisture (4.3 inches at Newell site on April 10) and below normal summer rainfall in Storm Lake . The USDA NASS Buena Vista county corn yield was about 20 bushel per acre below the levels in other area counties (table 3).
Source : iastate.edu