COUNTY AG NEWS

Wet Fields, Fertilizer, Cultivator

Recent rains have caused flooding and ponding in many cornfields and we now have numerous fields that have turned yellow as a result.

The extent to which flooding injures corn is determined by several factors, including timing of flooding during the life cycle of corn, frequency and duration of flooding, and air-soil temperatures during flooding.

Respiration is the plant physiological process most sensitive to flooding. Flooding reduces the exchange of air (oxygen) between soil and atmosphere eventually leading to decreased total root volume, less transport of water and nutrients through the roots to the shoot, and formation of sulfides and butyric acid by microorganisms that are toxic compounds to plants. Soils contain pores filled with gas and/or water.

The two main gases important for respiration are oxygen and carbon dioxide. The pathway for oxygen into the plant is from the atmosphere through soil pores to a thin water film surrounding plant root hairs. It is relatively easy for oxygen to diffuse into soil when pores are filled by air, but oxygen does not easily diffuse in water so the main constraint to oxygen movement is the thin water film surrounding root hairs.

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