Soil Health 101
If you’re a flower or vegetable gardener like I am, you’ve likely been scratching your head lately. From drought to deluge – what does it mean for the soil beneath our feet?
According to Steve Pahs, Rice County Soil and Water Conservation District Manager, about 15” of rain fell in the month of June in SE Minnesota. That’s more rain than fell from mid-April through mid-September in 2023. He said, “The soil is so saturated that roots can't access the oxygen they need to take up nutrients, and oxygen is essential for proper root function.”
Looking at the mildew on my bee balm (too much rain in June), and kicking at the dry, crusty soil (too little rain in July), I was encouraged by several visiting pollinators in a few moment's time.
All of the organisms that live in soils need to breathe, and saturated soils quickly become anaerobic environments. The pores in the soil that are normally somewhat open for air to move get filled with water. In the absence of oxygen, respiration still occurs, but toxic substances like ethanol and organic acids start to build up in the soil. Prolonged oxygen deprivation can lead to cell death, root death, and eventual plant death.
In addition, strong winds, high temperatures, and sun following a heavy rain can cause soils to form a hard surface crust. Pahs said, “If soils are bare and exposed to the weather, the fine particles of clay and silt will harden as they dry.”
What can gardeners do?
According to Pahs, “Any time soils are really muddy and wet, don’t walk in the garden to avoid further compaction. Give the garden rows time to dry out.” These are some of the signs that indicate your garden soil is saturated. Above the soil line, you’ll see:
Overall poor growth
Wilting and yellowing leaves
Soft, dark, or rotting areas on the stems or leaves
Absence of flowers or fruits
Leaf drop
Ideally, soil contains about 50% solid materials and 50% pore space that can be filled by air and water. Poorly drained soils have much of that pore space filled with water, leaving little room for airflow. In compacted soil, solid materials pack into larger pore spaces, slowing down water drainage and air movement.
All of this can lead to runoff. Adding organic matter to the soil can help reduce erosion and surface crusting caused by too-quick drying. The more organic matter your garden soil contains, the better.
One farmer’s perspective
Mike Peterson, along with his wife Kay and their two sons, owns and operates Twin Oaks Farm in Northfield. The Petersons take their job of stewarding topsoil seriously. A host at one of three stops on the recent Clean River Partner’s Soil Health Tour, Peterson said, “With all of the rain we got, nitrogen fertilizer percolated right down past the roots. Because corn has shallow roots, there’s a lot of yellowing in the fields even though we applied nitrogen fertilizer.”
Peterson takes a long view when it comes to farming. He said. “A year like this reminds you that there many factors over which we have absolutely no control. That may sound stressful, but I think most farmers take it as a challenge.”
Margie O’Loughlin is a Clean River Partners board member in Northfield, Minnesota. CRP works at the community level to protect and improve the Cannon River Watershed.