FOR IMMEDIATE RELEASE
MONDAY, JULY 14, 2014
||Michelle McGinnis, Field Services Section chief
NCDA&CS Agronomic Services Division
Hydroponic lettuce takes root in eastern NC
Agronomists help new grower manage water and fertility issues
Agronomists Chris Jernigan, left, and Aaron Pettit, center, check the progress of Jedd Koehn's lettuce crop.
AYDEN — Jedd Koehn is a young and innovative agricultural entrepreneur. Raised on an organic row-crop farm in western Kansas, he moved to North Carolina about nine years ago, wanting to live “where it was green.”
Last November, his Pitt County company, Coastal Plains Produce, harvested its first crop of hydroponic lettuce. Now he finds himself surrounded by lots of green: 13 kinds of lettuce, plus watercress, arugula and dandelion greens.
Hydroponic lettuce offers several advantages over field-grown lettuce. First of all, it can be grown and harvested all year. Secondly, it is cleaner — no soil on the roots or in the leaves, no worries about contamination with E. coli. The greenhouse environment provides more control over temperature fluctuations and cuts down on pest problems. Heads of lettuce with roots still attached stay fresher longer as they go to market protected individually in clamshells.
Still, there are challenges involved with hydroponic production. The plants grow in water that has to be constantly monitored. Is there enough water in the float beds? Is the pH within an acceptable range? Are optimal amounts of nutrients being provided?
To get a handle on these issues, Koehn has been sending samples of his well water and float-bed nutrient solution to the N.C. Department of Agriculture and Consumer Services for solution analysis. This test, which costs $5 per sample, provides useful information on the properties and nutrient content of water used for specific agricultural purposes. It is useful in evaluating the suitability of source water, irrigation water and nutrient solutions.
“I found that my well water has a naturally high pH of about 7.3,” Koehn said, “and the float-bed water was low in micronutrients.”
Fortunately, solution reports provide recommendations for alleviating any problems detected. They also provide contact information so growers who desire more specific advice can consult with experts. Koehn has been consulting closely with department agronomists Aaron Pettit and Chris Jernigan.
Pettit, an agronomist at the Agronomic Services Division’s laboratory in Raleigh, explained how high pH in a float-bed solution could reduce availability of micronutrients to the crop. He provided instructions for correcting the situation by adding sulfuric acid to the float beds. Pettit also suggested that Koehn contact regional agronomist Chris Jernigan, who covers Pitt County and could work more closely with him.
Frequent sampling is beneficial
Koehn started out collecting solution samples about once a month, but now he sees the benefit of sampling more often. Summer heat, which causes evaporation, and the addition of acid to lower pH make it necessary to keep close tabs on float-bed solution quality. Since it only takes about five-and-a-half weeks to produce a crop of lettuce in the summer, as opposed to eight weeks in the winter, he must check the nutrient solution more frequently to ensure optimal production.
“When I receive a solution report, I usually spend a day adjusting fertility based on the report data and recommendations,” Koehn said. “I’m particularly interested in pH and EC.”
EC, or electrical conductivity, is one of the measurements provided on the solution report. It is a general indicator of the amount of fertilizer dissolved in solution. When it is above the range indicated as acceptable on the report, then too much fertilizer is present and plants may become dehydrated or show salt injury.
“Jedd is very much on the right track,” Jernigan said. “He’s battling some new situations this summer, but he’s staying on top of it. He’ll call me and say ‘I’ve calculated my fertilizer rate to be this. Will you check behind me?’ He’s determined to get it right. He’s not taking chances.”
Because Koehn is relatively new to hydroponic production, the agronomic advice has been important. “I’m learning all the time,” he said, “and these guys (Jernigan and Pettit) are helping me along. They’ve helped me with the sampling and with getting my nutrients right. They’ve been a lifesaver.”
Koehn sells lettuce through wholesaler Blue Sky Farms in Wendell. The Chef and The Farmer restaurant in Kinston also features “Jedd’s lettuce” on its menu. Koehn hopes the quality of his lettuce will make it compete successfully with field-grown lettuce throughout summer.
The Agronomic Services Division has a staff of regional agronomists who can make on-site visits and help growers solve nutrient-related problems. Contact information is available online at www.ncagr.gov/agronomi/rahome.htm.