Agronomic Services — News ReleaseFOR IMMEDIATE RELEASE
TUESDAY, OCT. 31, 2000
Regional agronomist solves farm fertility problemHARGETT'S CROSSROADS — Thigpen Farms, located near Hargett's Crossroads in Jones County, is a thriving enterprise and a shining example of precision agriculture, with its 1,200 acres of double-cropped wheat and soybeans as well as tobacco and cucumbers. But that hasn't always been the case.
Six years ago the farm was in decline due to serious soil fertility problems. Owner Marc Thigpen knew he needed help and contacted Bob Edwards, a regional agronomist with the N.C. Department of Agriculture and Consumer Services, serving Jones and neighboring counties.
"Bob's been a big help," Thigpen said. He's my second set of eyes. Sometimes I'll call him 10 times a week. Trust me. I know how to get up with him."
When Thigpen first called Edwards, the farms soil test reports indicated unusually high soil pH, low phosphorus, low manganese and the presence of soybean cyst nematodes. Edwards had seen these kinds of problems before.
Edwards has spent more than 10 years advising growers in the coastal plain about NCDA&CS Agronomic Division services, such as soil testing, nematode assay, plant tissue analysis, waste analysis and solution analysis. Prior to joining the department, he also worked with a fertilizer manufacturer. This combination of experience gives him good insight into soil fertility problems.
Most North Carolina soils tend to be acidic and have low pH values. However, on the Thigpen farm, dust from the marl-covered dirt roads adjacent to the fields had raised the pH of soil along the field borders to 7.0 or more. Changes in soil type seemed to be responsible for other areas of high pH scattered throughout the field.
To complicate the problem, high pH was making the small amount of manganese present in the soil unavailable to plants. And despite the fact the land had been farmed for decades and had phosphorus fertilizer applied annually, the soil test report indicated that phosphorus was abnormally low in certain fields.
Fertilizer was obviously the answer to the problem, but Thigpen had already tried lots of fertilizers. Both men realized they had to find a very specific fertilizer. It needed to provide plant-available manganeseeven in areas of the field where the pH was unusually high.
None of the commonly available manganese fertilizers met this requirement, but Thigpen was certain the product he needed was out there somewhere. "It's like a combination lock," he said. "There is a way to get into that lock."
Edwards kept his eye out for the right fertilizer. The breakthrough came in 1997 when he found out about a fertilizer used in Florida to increase manganese availability on high pH soils where sugarcane was grown. It contained 70 percent elemental sulfur, which acidifies the area around the fertilizer granule, thereby converting its manganese oxide component into 15 percent manganese. The product didn't contain phosphorus, but if it could help make manganese available to the crop when pH was high, then phosphorus could be applied separately.
The promising fertilizer had two drawbacks. One was cost, and the second was the fact it had never been used on North Carolina soils or crops. Even so, Thigpen was willing to try the fertilizer on a few hundred acres.
"We were the first in the state to use this product," Thigpen said. "I had been through some major setbacks, and I didn't want to spend a lot of money, but if I knew then what I know today, I'd have put it out on all my fields."
For the1998 growing season, Thigpen ordered a tractor-trailer load of the fertilizer and applied it at an initial rate of 20 pounds of manganese per acre. In addition, Edwards set out a series of experimental test plots on the farm to compare several rates: two-and-a-half, five, 10 and 20 pounds of manganese per acre.
By the time soybeans emerged in the treated fields, the differences were obvious. The plants receiving the new fertilizer were uniform and green. There were no yellow and stunted plants scattered throughout the field.
On seeing the results, Thigpen's father Mervin remarked, "I don't know what you and Bob have done, but it's turned this farm around in a year."
Thigpen now uses the fertilizer on all of the fields he plans to keep in production. And it has not been as expensive as he originally thought.
Based on results from Edwards test plots, Thigpen now knows he can use a rate as low as five pounds of manganese per acre and still double his yields. That's a big savings over the 20-pound rate he used the first year. Edwards and Thigpen have fine-tuned the application rates over the past several seasons and have found that about seven-and-a-half pounds of manganese per acre works best for his fields.
A new fertilizer is not the only innovation at the Thigpen farm these days. Experience with soil fertility problems led Thigpen to appreciate the benefits of accurate and intensive soil sampling. He invested money he saved by applying the right amount of fertilizer into mapping his fields with global positioning system technology and in the purchase of a lime spreader truck.
Every field is now mapped in detail. Thigpen knows down to the meter which areas need phosphorus, manganese and potassium. He applies lime based on the soil pH maps of his fields.
Thigpen credits Edwards and the Agronomic Division's field services program with many of the changes on his farm. "It's a free service," said Thigpen. "I'm surprised everyone doesn't use it."
Edwards can help other growers protect their investments and improve production. He is available to visit or consult with any grower in Carteret, Craven, Greene, Jones, Lenoir and Pitt counties who needs help taking agronomic samples, adjusting fertilizer programs, pinpointing nutrient deficiencies or toxicities, identifying nematode problems, or interpreting agronomic reports.
The Field Services section of the NCDA&CS Agronomic Division has 14 regional agronomists located throughout the state. For more information or for the name of the regional agronomist for your area, call J. Kent Messick at (919) 733-2655 or refer to the division Web site at www.ncagr.com/agronomi.