Fields Flooded By Tropical Storm Debby? Another Soil Test May Be Necessary
Tropical Storm Debby delivered some much needed rain to many Florida Counties, albeit in a rather short amount of time. These flooded fields may have had their soil chemistry affected, resulting in the need for a new soil test to get a precise determination of nutrient needs.
Soils which have been saturated with water for a prolonged period of time (over two weeks) may experience a permanent shift in the pH reading up to a half unit or more towards neutral (pH 7). This change is related, in part, to the denitrification of soil nitrate to nitrogen gas, which occurs under anaerobic conditions.
Other factors affecting a pH shift via denitrification includes initial soil pH, organic matter, soil inorganic nitrogen content, and temperature. This shift will be more likely if the initial soil pH was above 5.5, it has high nitrogen fertility, it contains high organic matter, and of course, if the soil are warm, as they are now.
Prolonged flooding may also temporarily increase plant-available manganese, phosphorus and iron, but they will decrease again upon soil drying. Additionally, if you plan to apply phosphorus fertilizer to a wet soil, it also may become less available upon soil drying.