What is in this article?:
- Record rainfall has depleted soil nutrients in Southeast
- Soil sampling a critical issue
- Testing not an option
- Impact on humans
• One thing for sure is that farmers better soil sample more thoroughly than ever, because this past year has depleted soils of nutrients more than ever.
SOUTH CAROLINA Peanut Specialist Scott Monfort shows effects of nutrient deficiency on peanuts at a recent field day.
Soil sampling a critical issue
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 says.
“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 says, “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.”
In some areas of the Piedmont Region of North Carolina, growers have been dealing with flooded fields since April.
Though spring months were more soggy, continuous heavy rainfall throughout the growing season has left many fields constantly wet for long periods of time. Soggy isn’t a scientific term, but Crozier says it can cause real problems with plant nutrients.
“Poorly drained soils may have been flooded for long periods,” he says.
“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. 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,” he explains.
Even soil pH levels that have been relatively stable for many years, even the lifetime of some growers, may be knocked out of kilter by the heavy rainfalls.
“On especially sandy soils, I expect there may have been considerable changes in pH over the past four to five months,” Hardy says.
“If a field was borderline in needing lime last year and none was applied, it definitely needs to be tested this year.