Duckweed blooms plague many waterways about the country during summer months. These infestations foul the water, the shorelines and deplete oxygen levels. Removing duckweed from lakes and ponds is either done with herbicides or by mechanical means. The herbicides do nothing about the nutrients in the water so repeated blooms are common. Not to mention the effect of chemicals on other plants and animals in the system.
Mechanical removal is a better choice as it also removes the nutrients.
The weed can then be composted and fed to livestock. Duckweed is high in protein. Some studies show that one hectare of duckweed can supply enough food for over 4000 chickens and ducks. 10 acres of duckweed could supply over half the nutrients needed for 100 dairy cows. Then the cow manure can be used to fertilize more duckweed.