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Copper & Boron

Starting October 1, 1996, the Clemson University Agricultural Service Lab began sending out soil test reports with a revised format. In addition, more soil test information has been added to the reports in response to requests from farmers, fertilizer dealers and several county agents.

The two micronutrients which have been added to the soil test report are copper (Cu) and boron (B). Neither of these have a sufficiency rating.

Research and experience have shown that copper deficiency is rarely a problem in South Carolina. There is also limited research data to interpret soil test results. Soils where copper deficiency may be a problem are the high organic soils (gre ater than 10% organic matter) or very sandy soils with a high pH value and subsoil clay deeper than 20 inches. Recommendations for copper should be based on plant tissue analysis.

Boron deficiency is a concern for certain crops on Coastal Plains soils. The appropriate comment will be triggered in the soil test recommendation according to the specified crop and soil type. For example, comment 103 for commercial watermel ons says that applying 0.5 to 1.0 pounds of boron per acre as a foliar spray prior to bloom MAY help fruit set. For cotton, comment 12 says to apply 0.4 pounds of boron per acre in the fertilizer or in the insecticide spray in either one or several appl ications so long as the total amount applied does not exceed 1.0 pounds per acre.

Since boron is mobile in the soil like nitrate, a blanket recommendation is given with the assumption that at the beginning of the cropping season, most of the residual bor on from the previous year's crop will have leached through the soil past the root zone. As with copper, a tissue test will give the best assessment of available boron.

We hope that those who have requested this additional information will find it helpful. For those who have been satisfied with the soil test reports issued by the Agricultural Service lab in the past, they will be pleased to find the same information still on the new reports.