           |
|
Cornell’s Hydroponic Lettuce
Facility Provides Prototype
By Ken Thomas
New York Correspondent
Gusty winter winds and mountains of drifting snow are common on the Cornell University campus. Floating islands of bright green lettuce basking in the warm, golden glow of high-pressure sodium lights radiating are not. The exception is a state-of-the-art hydroponic lettuce facility where two varieties of bib lettuce placidly float in stark contrast to the winter scene just beyond the glass.
The $500,000 investment was secured from a partnership that included the New York State Energy and Research Development Authority (NYSERDA), New York State Electric and Gas Corporation (NYSEG), and the National Space and Aeronautics Administration (NASA).
“Our maximum harvest capacity approached 1,400 heads per day, “ said Dr. Louis Albright, Cornell University professor of biological and environmental engineering, who has been a prime participant since the project began. Albright said they have scaled back to about 500 heads per day due to market conditions.
“Ithaca Produce is our marketer and our lettuce is available in the Ithaca area, and throughout the massive Wegman’s super market food chain,” he said.
Available data indicated that annual hydroponic lettuce production exceeds 425,000 five-ounce heads at the year-around Ithaca facility. According to Cornell research data, this compares to 460 to 470 tons per acre per year. Statistics for field-grown Boston lettuce reveal production intensities of only 15 to 25 tons of lettuce per acre.
The planting cycle begins in Rockwool slabs that have been filled with Cornell Peat-lie Mix. Ninety-eight holes are filled employing a vacuum seeder that matches the seed-hole template. One seed is released into each hole.
Germination occurs over 11 days in the ‘growth room’ at the facility. Temperature is maintained at 24°C. Water-cooled high-pressure sodium lights provide 24-hour lighting while seeds are watered by an ebb-and-flow bench watering system. Initial culling of seedlings occurs at day six with removal of seedlings that are too large, or too small. Transplants are then inserted into 60 seedling boards. This critical step allows uniformity of the crop for harvesting on day 35.
On day 11, seedlings are moved to the hydroponic ponds in the greenhouse. There are three 20 feet by 84 feet ponds that use standard hydroponic nutrient solutions originally developed by Sonneveld. Each pond has a 10,000-gallon capacity. Pumps circulate the nutrient. Daily measurements indicate how much additional new nutrient solution needs to be added to the system.
New seedlings arrive at the ponds each day. As the harvest occurs all the trays move appropriately forward from pond to pond toward the harvest end.
A second re-spacing that is needed at day 21 gives more plant space for light reception and growth. Now there are only 20 plants per board. Plants fully mature over the next 14 days until they are harvested on day 35.
The aphid, the scourge of lettuce growers, is managed by the introduction of a beneficial insect, colemani that lay eggs in the bodies of the aphids. To maintain an adequate supply of colemani, a nursery is maintained at the facility.
Throughout the growing period, computers manage light, temperature, and humidity. To regulate the daily light sum (amount and intensity), lights are turned on, or shades drawn across the superstructure.
At day 35, plants are harvested and refrigerated immediately. The breakeven cost factor for hydroponic lettuce is approximately 60 cents. Given current market prices for lettuce, profitability may well be in sight!
|
|
