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Agronomic Services — News Release

TUESDAY, JUNE 20, 2000

Regional agronomist helps optimize fertilizer use on potatoes

PLYMOUTH — When the first regional agronomist for the North Carolina Department of Agriculture and Consumer Services stepped out on the field more than 26 years ago, he soon discovered many growers over applied fertilizer, and began a career-long effort to educate growers on the optimal use of nutrients.

At that time, many potato growers in coastal plain counties routinely applied 1700 pounds of 10-20-20 per acre. This translated to 170 pounds of nitrogen, 340 pounds of phosphate, and 340 pounds of potash per acre. Phosphate happens to be the most expensive component of fertilizer, and growers were applying up to eight times more of it than any potato crop could use. Roger Sugg, NCDA&CS agronomist, immediately recognized the potential savings. But he also realized that before growers would change, they would have to be convinced.

With help from the state agricultural extension service, Sugg set out test plots on farms in several counties. He compared the traditional fertilizer regimes with new ones that contained significantly less phosphate and potash. In almost every case, the lower rates of fertilizer produced higher yields. Armed with this evidence, Sugg was ready to carry his message to the growers.

Durwood Cooper, who grows hundreds of acres of potatoes in Tyrrell County, was among the first to follow Suggs advice, but not without caution. He switched his fertilizer application from 1700 pounds of 10-20-20 to 1200 pounds of 15-15-15. That meant a 160-pound per acre reduction in his phosphate application: from 340 pounds to 180 pounds per acre. Not bad for a first step, but Sugg knew that phosphate could be cut even more.

Sugg began suggesting that Cooper and other growers fertilize their crops based on the results of NCDA&CS soil test reports. More than 80 percent of the blackland potato soils tested had high or very high phosphorus and potassium indexes. Recommendations indicated that little or no phosphate or potash was needed, but growers still resisted the idea that this could be true.

Having had success with Sugg's earlier advice to reduce phosphate, Cooper felt comfortable going one step further. Sugg advised Cooper to switch to a "prescription-grade" fertilizer, a custom blend for potatoes based on soil nutrient content. They came up with a 24-12-19 grade to be applied at 775 pounds per acre, which reduced phosphate application to 93 pounds per acre.

The prescription-grade fertilizer is not a permanent recommendation. It changes with each soil test report and requires adaptability on the part of the grower. Many potato growers in the tidewater region now use this approach to potato fertilization.

A prescription-grade fertilizer may still put out more nutrients than the immediate crop can use, but there is some rationale for this. Potatoes are often rotated or double-cropped with corn or soybeans, which require additional phosphate and potash. By applying extra nutrients to potatoes, a reserve is built up that carries over and benefits subsequent crops.

Roger Sugg calls the blackland farmers "innovators." Unlike most North Carolina farmers, they have never benefited from tobacco income and allotments. Their profits depend on sound and economical production practices and on being receptive to new and better ways of doing things.

Durwood Cooper, who has been farming for 47 years, said his uncle should be credited with teaching him "the business end of what to do" and Roger Sugg with helping him improve his agronomic practices. If so, Coopers impressive farm and state-of-the-art potato grading facility are a credit to all of them.

"If you do what you like and love what youre doing, why should you change?" Cooper asks. "Only to make things even better."

Sugg enjoys his role in helping growers improve their operations. He was raised on a farm near Snow Hill in Greene County and participated in Future Farmer of America field crop projects to help subsidize his college education. He graduated from N.C. State University in 1969 with a degree in crop science and a minor in agricultural economics. He now advises growers in Beaufort, Dare, Hyde, Martin, Pamlico, Tyrrell, and Washington counties.

The Field Services Section of the NCDA&CS Agronomic Division has 14 regional agronomists located throughout the state. These agronomists are available to visit or consult with growers in their regions who need help taking agronomic samples, adjusting fertilizer programs, pinpointing nutrient deficiencies or toxicities, identifying nematode problems, or interpreting agronomic reports. For more information or for the name of the regional agronomist for your area, call J. Kent Messick at (919) 733-2655 or check out the website at


Last Update June 1, 2009


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

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