How drought affects soil health
In order to grow, crops need adequate moisture, soil temperatures, and biological activity within the soil. Drought conditions can throw everything off-kilter.
Mahdi Al-Kaisi is a soil management professor at Iowa State University. He says changes in soil temperature during a drought can affect soil organic matter decomposition and increase the release of carbon dioxide. Minerals such as nitrates are also released, but the plants are unable to use it.
"There’s no water to facilitate the nutrient uptake by the root system," says Al-Kaisi. "Basically, these nutrients are going to stay in the soil system and that’s going to affect the plant health because it doesn’t have the medium to transport these nutrients to the root system.
He says nitrates held in the soil this year can become a problem next year if we have a wet spring. We could have a flood of nitrates going into the environment.
The increase in soil temperature associated with a lack of soil moisture during drought also has an impact on microbial activity.
"To function you need about 70, 80 (degrees), you know the optimum. When you increase it above that level, then you’re going to shut down these microbial activities because there’s a lack of moisture," he says. "And, the microbes to function need water, they need oxygen, and they need moderate temperature."
Al-Kaisi says no-till and residue cover can mitigate these effects.