Agronomic Services — News ReleaseFOR IMMEDIATE RELEASE
MONDAY, MARCH 10, 2003
Contact: Rick Morris
Regional agronomist, Agronomic Division
Too much lime can cause manganese deficiency in cropsby Rick Morris, NCDA&CS regional agronomist
BLADENBORO — During the 2002 growing season, manganese deficiencies were prevalent throughout southeastern North Carolina, and I expect the problem to continue this season if corrective steps aren't taken. Certain crops—such as small grains and soybeans—are particularly susceptible to lack of this nutrient. Tobacco, peanuts and several fruit and vegetable crops are also sensitive to manganese availability.
A deficiency can occur when manganese levels in the soil are low or when its availability is low due to high soil pH. Overliming can trigger a manganese deficiency. The N.C. Department of Agriculture and Consumer Services' Agronomic Division provides key diagnostic services, such as soil testing and plant tissue analysis, that can identify this problem and provide sound recommendations to correct it.
Soil test report recommendations for manganese take into account several relevant factors: the specified crop's relative need for the nutrient, the amount present in the soil, and the effect of soil pH on manganese availability. Notations of 10, $, $pH or pH$ in the manganese recommendation column on soil test reports indicate either an existing or potential problem. A plant analysis report for a deficient crop will show tissue concentrations of less than 25 parts per million (ppm) manganese.
As a regional agronomist, I encounter manganese problems frequently in the coastal plain when too much lime has been applied. The remedy often involves a foliar application of manganese. Deep tillage can also help by mixing overlimed soil with acid subsoil. In certain situations, elemental sulfur may be applied to lower soil pH. Check with your local agricultural advisor to discern the method best suited for your situation.
Fertilizer dealers can also make special blends of fertilizer for soils low in manganese. When soil test levels are low and pH is not high, a broadcast application of 10 pounds of manganese per acre should correct the problem. Sources of manganese include manganese oxides, manganese sulfate and manganese oxy-sulfates. Since sulfate materials are very soluble in water, they are often the best choice to correct major problems.
If you have experienced manganese problems with the crops you are growing or suspect another nutritional problem, contact your local agricultural advisor. Fertilizer dealers, county Cooperative Extension agents and NCDA&CS regional agronomists are available to assist you with your problem. To identify the regional agronomist for your area, visit the NCDA&CS Web site www.ncagr.com/agronomi/rahome.htm.