The historic drought afflicting South Africa has already cut its corn crop in half. Although the country is typically a net corn exporter, the crop losses already incurred this year will have it seeking to import several million tonnes of the grain.
But the drought itself might spell even more trouble for corn, especially for those fields that were planted late. Overly dry conditions encourage a large range in daily temperature, especially in autumn, South Africa's current season.
If temperatures get low enough, both yield and quality could be affected. As such, South African corn production could take a devastating blow since the current estimate of 6.5 million to 7 million tonnes has been driven downward mostly by losses to area and not as much yield. So any considerable hits to yield or quality could have South Africa importing even more corn than originally thought.
The reason drought and temperatures are closely linked brings us back to high school science and the concept of specific heat capacity. Because water's heat capacity is very high, it takes much more energy to change the air temperature when moisture is present, resulting in lower daily temperature ranges.
But dry conditions lack the temperature "moderation" from moisture, meaning that high temperatures can soar and low ones can plummet. And on a cloud-free, windless night, the earth rapidly radiates heat back to space, further dropping the temperatures. This is very commonly observed in desert climates.
The coldest months in South Africa are June and July, and in its interior, where the corn belt lies, it is not uncommon for temperatures to approach freezing during this time. But given the current drought, nights could become even colder more often.
The corn harvest has already begun for farmers who were able to plant last October, on the early side of the calendar. But many farmers planted late or even past the recommended early-January cutoff, so some corn fields could still be in critical development stages by June.
