Bt Katie Black and Bailey Tangen el.at
Drought has defined five of the last six summers in Minnesota, with below-normal precipitation and above-normal temperatures contributing to the spread of D1, D2, and D3 drought conditions across more than 75% of the state this summer. August is normally one of Minnesota's wettest months, but rainfall totals have continued to fall short. Drought is expected to persist in much of the state through the end of the growing season. While impacts on corn yield are expected to be minimal across much of the state, seeing fields across the state recently had us wondering – beyond looking dry and cracked, what happens to our soils during a drought?
Drought and soil health
Healthy, productive soils have good soil structure, can cycle nutrients, can filter and retain water, are easily penetrated by plant roots, and support a variety of organisms living in them. Large soil pores, organic matter, and diverse soil microbiota are critical to functioning soils (see Figure 1 below). Drought affects all of these.
The fungi, roots, bacteria, and animals living in the soil depend on having adequate water to survive and perform their “jobs” of recycling nutrients and improving soil structure. In a dry growing season, biological binding agents like roots, microbial glues, and fungal hyphae break down without an environment that protects them from drought, reducing soil structural stability. Microbes’ ability to mineralize nutrients declines, which can negatively affect plant growth. It may not be just temporary – drought can leave a legacy effect of persistent changes in microbial community composition and activity. However, much of the long term research about legacy impacts of drought on soil biology has taken place in grasslands, and more work is needed to understand if there are lasting impacts specifically to productivity.
Source : umn.edu