Flooded fields affect crops

Farming is a business that cannot avoid weather risks. A significant challenge farmers face is dealing with excessive water, especially flooded and saturated soil. The impact of excess water on crop growth and yield is influenced by crop type, soil characteristics, duration of excess water or flooding, initial soil water and nitrogen status of the soil before flooding, crop stage, soil and air temperature, and other factors.

An ideal soil for crop production has 50 percent pore space, 45 percent mineral and five percent organic matter. Ideally the pore space is occupied by 50 percent air and 50 percent water space. When excessive rain occurs, saturated soil refers to a soil in which the pore space is fully occupied with water. Sandy soils can typically hold one inch of water per foot of soil. Medium and fine-textured soils- hold 2.5 to three inches of water per foot of soil. When soils reach capacity, the water ponds and floods areas of the field, which were usually dry. It can result from one extreme event or occur over several days or weeks of excessive rainfall.

Flooding limits the amount of oxygen and nutrients available to plant roots. Whether a seed or seedling survives flooding is based on the length of time that flooding lasts and the soil temperature. Seed and small seedlings can usually survive two to four days, or more than a week if temperatures are cool and leaves are exposed above the water. Plants respire faster at elevated temperatures -- 80s and 90s -- and can be killed in as little as a day.

There is more detailed crop information.

Corn

• V1-V6 can tolerate flooding for two to four days.
• After V6 are more tolerant -- four to six days.

Soybean

• Seedlings can survive flooding for two to four days.
• Older soybean plants can tolerate five to seven days of flooding.

Wheat

• Young wheat plants can die within one to three days of flooding.
• Mature wheat plants cannot withstand more than three to five days of flooding.

Expect all of the factors to be worse in warmer temperatures and heavy clay soils.