Everybody want to eat fresh, but the yen gets way bigger on a submarine. Hydroponic gardening could do a lot to boost morale when you haven’t seen a crisp salad in weeks. Even unprocessed onions and potatoes run out long before the end of a 3 month deployment. There’s not a lot of opportunities to restock the galley from the ocean floor in open waters. Which is what led engineering technician Don Holman with the Combat Feeding Directorate to take on the project of investigating the possibilities. He’s been in their shoes. As a retired command master chief, he’s keenly aware how much anything not canned, frozen, or dehydrated means to a sailor on a sub.
His mission for the past 11 months has been testing hydroponic gardening at the Natick Soldier Research, Development and Engineering Center in Massachusetts. Holman also grew up on a farm, so he’s an old hand at growing veggies. But hydroponics? That’s a whole new adventure for him.
U.S. Military Farm Lab
While the goal is to grow inside a sub, learning the ropes, and testing what crops will work best, his lab is a Freight Farms container system. Once the research is completed, they’ll have to specially design the garden to fit available hull space. It’s not a lot of room, but vertical farming will allow them to max out productivity in a small footprint.
Don’s using ZipGrow Towers, which are great for making every inch count. On top of huge space limitations, the amount of power hydroponic gardening uses on a sub is also critical. So the farm box is outfitted with a curtain of LED grow lighting strips running from ceiling to floor. This ensures plants at all positions on the towers are bathed in the light needed to perform. The setup can produce harvests equivalent to growing the same crops on 1 acre of land. It’s very energy conservative, using only 8 kilowatt-hours of electricity in 24 hours.
Fresh water is also a limited resource at sea. However, hydroponic gardening uses 90% less water than traditional growing. It makes the impossible very possible in such a situation. The military’s farm lab has 280 gallons circulating through the system, but the plants only use up 10 gallons a day.
Resource consumption details are as important to the future of deployment farming as being able to grow a good assortment of fresh produce. It’s all part of the required data reported when Don’s year-long research project ends this September. Freight Farms outfit their containers with Wi-Fi and Bluetooth capability, and an infrared camera. The system has automated controllers, and it’s instrumentation makes data collection simple.
Testing Hydroponic Gardening Limits
Holman planted his first crops last August. He started with just lettuce, because that’s an easy and fast thing to grow in hydroponics. Probably the best thing to work with while learning how your system works, and making modifications if needed. The seed is started in peat plugs, and transferred to towers when ready for nutrients.
They have tested growing 83 different crops, but as any seasoned indoor grower will know, not every plant does well in this kind of setup. Still, over 50 different crops were successful. You can’t grow all fruits and vegetables in the straight up design of ZipTowers. However, surprisingly, root veg like radishes and carrots did well. But shallow growing conditions made for smaller than normal mature sizes.
One System Doesn’t Fit All
Tomatoes need more light and more heat to bear fruit than Don’s lab provides. Cucumbers without trellising were, well, everywhere. Zucchini naturally didn’t do work out either, because of its massive leaves. These are huge plants better suited to Dutch buckets and more powerful lights. The tomatoes need that heat a lot more watts generate. Strawberries and rhubarb were also a disappointment. I don’t think there’s not enough light energy from LED strips for strawberries to produce well. Rhubarb only produces ample harvests with a large, mature root system. Besides that, the huge leaves creates the same problem as zucchini.
Supplying a crew of 130-170 people with fresh tomatoes, cucumbers, and zucchini might require more space than is available on a sub. Even if they grew compact tomato varieties, the energy consumption of lights that make them productive might be a problem for available resources.
Though the military’s experiment is just weeks away from ending, we won’t know if they’ll outfit subs for hydroponic gardening for a while. It depends on what the brass decides after weighing the data in Holman’s report. If they do proceed, indoor farming won’t be limited to underwater vessels, or to the Navy. U.S. Marine and Army installations will have fresh, home grown produce too.
Anyone stationed at Natick has been enjoying Don’s harvests in the mess hall through most of his research growing. The food was thoroughly tested first though. As if hydroponic fruits and vegetables have harmed anyone in all the years it’s been used for growing food. Something one can’t say about produce grown in soil. And with so many farms using sewage sludge for fertilizer those E. coli outbreaks are common occurrences anymore. This will also be safer than taking in fresh produce from many places in the world a sub happens to be.
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