Returning flood-damaged soils to productivity
One of the issues is the loss of phosphate in the soil, and Al-Kaisi said the typical tell tale signs will be purple leaves on plants, but he said corn grown on flooded soil should lose any purple leaves within a week. Additionally, “Flooded fields with weeds or without tillage showed less purpling than those tilled to control weeds.” But he said time is needed for the phosphorous to benefit the soil after it has a chance to aerate. However he said flooded fields may have a normal phosphate test and still have a low degree of AM fungi. To alleviate any phosphorous deficiency, he suggests high banded P rates are needed, at least twice as much as the normal rate.
Land that was flooded extensively may benefit from a soil test which should be conducted after any leveling is done to mitigate gullies and other washes. Soil test results may be surprising if either topsoil has been washed away or other soil has been washed into your field.
Whether you have long flooded river bottomland or pesky ponds that never seem to dry out, the soil can be damaged from the loss of microbial activity. However, that can be restored with growing plants, such as in a cover crop. The plants and the microbial plants will benefit each other to help the soil regain its dynamic capability. Soil tests will help because flooded land may lose nutrients faster, and flood plains may also gain unknown nutrients.