Farmers from large-scale hog farms, rid their waste through large duckweed lagoons. Interesting, eh? Here are a few links for you to study duckweed and its benefits and complexities:. Advice for ridding unwanted duckweed from ponds from the Royal Horticultural Society in London:. Non-chemical controls: Complete control is impossible and growth should be controlled before it reaches nuisance levels.
Try the following for control and prevention of duckweed:. Skip to comment form. Terms of Service Disclaimer Privacy Policy Conditions of Use TAGS agriculture applying existing automation technology has been an easy task and yet it is the semi-skilled worker that is still the key to the success of the aquaponics installations. Made with by Graphene Themes.
Toggle search form. Advice for ridding unwanted duckweed from ponds from the Royal Horticultural Society in London: Non-chemical controls: Complete control is impossible and growth should be controlled before it reaches nuisance levels. Try the following for control and prevention of duckweed: On small ponds repeated raking or netting will keep the weed under control.
Increasing the percentage of area devoted to water treatment will only serve to improve the overall effectiveness of the nutrient removal process. Duckweed culture requires fairly intensive management for optimum production. Daily attention and frequent harvesting are needed to ensure that the crop is productive, healthy and controlled.
The optimal standing crop density of duckweed is between to grams per square meter. Colonies can be effectively managed using floating PVC structures, giving the farmer a dense yet manageable crop. Daily harvesting of the incremental growth is a standard practice. Co-cropping with another water-loving plant provides an added dimension to this highly managed and sustainable system.
The chosen plant is planted along the waters edge to serve as wind and direct sunlight barriers for the floating duckweed plots. The shade offered by the waterline plants aids in keeping water temperatures in a favorable range for the duckweed. Either taro, which produces a tuber known as "yucca" or banana plants are ideal crops for many tropical locales. Importantly, these plants can provide additional revenues to the operation and further maximize the utilization of the farm's valuable water resources.
One of the most important benefits of the duckweed produced in the integrated system is that it can be used as a readily accepted supplemental feed for the tilapias. Duckweed protein has high concentrations of the essential amino acids lysine and methionine and is also high in trace minerals and pigments. Generally speaking, the overall nutrient characteristics are quite similar to those of soybeans. Fresh duckweed can be fed directly to the tilapias or it can be dried and incorporated into a custom pelleted feed.
As shown below, the cost savings associated with utilization of duckweed as an alternative food source can be very significant. While many of the proposed solutions for sustainability in the aquaculture industry are conveniently being criticized for being too costly, here is a system that has the potential to pay for itself through significant and sustainable reductions in operational expenses. This is the beauty and promise of the integrated tilapia and duckweed culture system. Search form Search this site.
Often the question is like, How many square feet of duckweed do I need to feed some number of tilapia? I once set up a duckweed tank. It was 16 feet long by about 30 inches wide and 18 inches deep. It had shade cloth over it and started out as part of a pee ponics system hooked to a barrel ponics system. The pump was down in the barrel that was set a few inches into the ground so the top of the barrel and the top of the duckweed tank were about the same level. The pump was in the barrel and lifted water to the top bed, then it went to the flush tank and into the half barrel beds which actually drained over to the duckweed tank and the far end of the duckweed tank drained back to the barrel tank.
System was running on a 30 watt water pump and a 5 watt air pump. Duckweed can use up a great amount of ammonia but if it dies off, sinks and decomposes it will give off much ammonia and other nasty stuff if the decomposition goes anaerobic. Also duckweed can clog filter screens, pump intakes drain grills etc so keep that in mind.
Once it is in a system it tends to get everywhere. Unless of course you are trying to grow it. See Duckweed seems to grow best as a weed. What does that mean? That is just my experience, ya have to trick it if you really want to grow it. Anyway, So I had this duckweed tank and we gathered wild duckweed and kept it in this separate system for a while. Then I decided I would put some tilapia in the duckweed tank.
I put 12 tilapia between fingerling and breeder size into this 16 foot by 30 inch by 18 inch deep tank covered with a thick growth of duckweed. I was feeding the fish daily over by the aerator where there was a circle of clear water to drop the feed in.
The cover of duckweed remained good. Well they did survive but by the time I got home there was no duckweed for them to be under. So that was less than a week for 12 small to medium size tilapia to clean up almost 40 square feet of a thick growth of duckweed. So, how much duckweed do you need to feed tilapia. However, if your not running aquaponics and you need an ammonia sink, then perhaps recirculating water from the fish tank through a large shallow pond plant bed in a shady location and a little aeration will grow a good amount of duckweed that you can then scoop off and give to the fish regularly.
I do not think duckweed will provide a huge benefit of aeration to the fish tank since by covering the surface of the water the duckweed will impede a good amount of the natural passive aeration available to the fish tank so during the day the duckweed may break even on the amount of aeration available to the fish tank but at night, the duckweed will more likely produce a loss of oxygenation to the fish tank since plants only give off oxygen in the light.
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