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Agronomic Services — News Release

TUESDAY, MAY 20, 2003

Contact: Tim Hall
Regional agronomist, Agronomic Division
(910) 324-9924

Check zinc levels for new peanut fields

by Tim Hall, NCDA&CS regional agronomist

RICHLANDS — Current contract prices may be enticing some growers to consider peanuts. Anyone thinking about cultivating new fields where peanuts have never been grown needs to consider the history of those fields. In some areas, soils may have high levels of zinc that could interfere with peanut production.

For plants, zinc is an essential micronutrient. In general, elevated levels of zinc in the soil pose no risk to humans or livestock or to the production of most other crops. Peanuts are the big exception.

Cropland in eastern counties, especially Duplin and Sampson, may have elevated levels of zinc due to long-term fertilization with poultry litter. Some fields that have received heavy litter applications now have zinc-index (Zn-I) values approaching or exceeding the toxicity thresholds for peanuts: Zn-I=300 and Zn-I=500.

On peanut fields with Zn-I values of 300, waste applications should be limited. A better course of action would be to find an alternate site to grow peanuts. Toxicity can occur even when Zn-I values are below 300 if the soil pH is less than 6.0. Growers need to be aware that toxicity is more likely under low soil pH conditions.

A Zn-I value of 500 is the established critical toxic level for peanuts. Once zinc reaches this level in the soil, peanuts should not be grown. Growers are advised to take a cautious, conservative approach at sites where zinc levels are elevated.

Growers who are interested in peanut production should always consider the history of the field they select. That means reviewing recent soil-test zinc levels or double-checking that history by having the soil tested again. Samples and completed information forms should be sent to the N.C. Department of Agriculture & Consumer Services’ Agronomic Division, Soil Testing Section, 4300 Reedy Creek Road, Raleigh, NC 27607.

For assistance with nutrient-related crop problems, contact your local NCDA&CS regional agronomist or your county Cooperative Extension agent. Growers in Duplin, New Hanover, Onslow, Pender or Sampson counties can call me — NCDA&CS Regional Agronomist Tim Hall — at (910) 324-9924. Visit the Web page to identify the regional agronomist assigned to other counties or call J. Kent Messick at (919) 733-2655.


Last Update August 1, 2007



NCDA&CS Agronomic Services Division, Colleen M. Hudak-Wise, Ph.D., Director
Mailing Address: 1040 Mail Service Center, Raleigh NC 27699-1040
Physical Address: 4300 Reedy Creek Road, Raleigh NC 27607-6465
Phone: (919) 733-2655; FAX: (919) 733-2837