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In recent years, soybean acreage has become equal to that of corn and since about the year 2000, corn and soybean acreage substitute for one another – when one goes up, the other goes down (Figure 1).

Figure 1: Temporal patterns in harvested acres of corn and soybean grown for grain, 1924-2008 (USDA-NASS).

Corn yield and total production have both exhibited exponential growth (Figures 2 and 3). Soybean yield and total production have grown linearly. In the last 10 yr, the maximum regional average corn and soybean yields were 152 and 43 bu/A, respectively. Average maximum total production during that time was 6.5 and 1.6 billion bu for corn and soybean.

Figure 2. Temporal patterns in yield of corn and soybean grown for grain, 1924-2008 (USDA-NASS).

Figure 3. Temporal patterns in total production of corn and soybean grown for grain, 1924-2008 (USDA-NASS).