Rainfall throughout most of North Carolina has been at record high levels this growing season, with some areas receiving more than 30 inches.

Most of the state’s crops have struggled because of poorly developed root systems. Because of this agronomists are warning that the growth of upcoming crops is also likely to be affected unless soil-nutrient reserves are monitored and replenished.

David Hardy, chief of the Soil Testing Section with the North Carolina Department of Agriculture and Consumer Services, and Carl Crozier, soil science professor and Extension specialist at North Carolina State University, urge growers to be particularly vigilant about soil sampling this summer and fall.

“Our sandy, light-colored soils have limited ability to hold nutrients to begin with,” Hardy said. “And some of our nutrients are what we call ‘mobile in soils,’ simply meaning they move with excessive water through the soil. Farmers are more familiar with the term ‘leaching.’

“Potassium, nitrogen and sulfur are the most mobile nutrients,” Hardy said, “but even nutrients such as magnesium, which is held more tightly than potassium, can be depleted due to excessive rainfall. This year growers across the state really need to check the nutrient status of soils by soil testing.”

Crozier agrees with this recommendation, but points out another effect of wet soils on nutrient availability. “Poorly drained soils may have been flooded for long periods,” he said. “The problem in areas where water has been standing is more likely to be denitrification than leaching. In that case, nitrogen is lost as a gas to the air.

“Growers need to remember that routine soil testing does not measure soil nitrogen levels,” Crozier said. “The nitrogen recommendations given on a soil-test report represent the typical needs of the crop and do not take into account that residual nitrogen levels might be even lower than expected given the weather this past season.”