The heavy rains this spring and summer have waterlogged many Iowa soils. Waterlogged soils limit soil aeration and will affect the growth and development of lawn grasses. The effects of waterlogged soils on turfgrass growth are a shallow root system, reduced leaf quality, reduced plant vigor, and increased disease activity.
The reduced root system and decreased plant vigor combine to impair the uptake of essential nutrients. Iron is a micronutrient that is commonly deficient in waterlogged soils. Iron is used by the plant in chlorophyll synthesis and is not mobile within the plant. Symptoms will show up as discoloration (yellowing) of the newer leaf tissue.
Plants that have a reduced root system and vigor will be more prone to disease activity. The leaves and stems of turfgrass plants have thinner cell walls during rainy weather. This succulent growth, plus higher humidities, makes disease activity more likely.
The use of core cultivation can help dry out some waterlogged soils. Core cultivation increases the surface area which in turn increases evaporation. This enables oxygen to reach the roots, thereby improving root respiration.
There is no need to add iron to most home lawns. Iron uptake will resume when the waterlogged soils dry out. However, foliar applications of ferrous sulfate in high maintenance turf (i.e. golf course greens and athletic fields) may prove to be beneficial.
This article originally appeared in the July 21, 1993 issue, p. 119.