Convert Existing Ponds to Duckweed?
Can you take an existing pond or lake and modify it for duckweed production?
I was asked this question recently and my immediate response was please DON’T. Like many aquatic plant species, duckweed can take advantage of available nutrients and grow prolifically, covering the water surface seemingly overnight. This scenario would create an imbalance in the water system, possibly limiting the variety of both aquatic plants and animals and the action would be difficult to reverse.
However, there are many naturally occurring duckweed ponds that could be harvested, as in the picture above. If you’ve got an existing pond on your property with duckweed already growing thickly on it, then you’re in luck. As long as the incoming nutrients are not downstream from an industrial facility, you should be harvesting and feed your duckweed to animals or apply in your garden. Your pond will continue to produce nutritious duckweed on a yearly basis, as long as it continues to receive waste nutrients.
Factoid: Oftentimes, run-off from factories contains trace heavy metals. These can be absorbed by duckweed and concentrated to levels that may become dangerous. If you think your pond may be fed by industrial run-off, have your water checked for heavy metals by your county extension agent.
If you don’t have access to an existing duckweed pond, then you can still take advantage of this crop’s prolific nature and nutrient value in a controlled setting. For small scale production, opt for growing duckweed in shallow, man-made rectangular ponds, approximately 3 by 15 ft, barrels, tubs, wading pools, etc… This allows for easy control of waste nutrient inputs and harvesting. If you are interested in larger scale production of duckweed, and have land and nutrient-rich wastewater available, there are proven pond designs that allow for wind-breaks, light shading, and mechanical harvesting.
Be mindful where you site duckweed ponds, large or small. Insure that during heavy rains, any overflow water will not reach a creek or natural pond. Sustainability includes working in harmony with nature, not using nature against itself.