Four different manures were used. In manure 1 (OM) and manure 3 (OM 2x OM),
cattle manure (
local), poultry droppings (local), and mustard oil cake (Double Hiran Mustard Oil-cake,
Malook Chand Food Pvt. Ltd., Aligarh, U.P., India) (1:1:1) were used at the rate of 1.052 and 2.104 Kg/m3 (Srivastava et al., 2006); in manure 2 (IF), urea (IFFCO, Indian Farmers Fertilizer Cooperative Limited, New Delhi, India), potash (Narmada, Gujarat Narmada Valley Fertilizers & Chemicals, Gujarat, India), triple superphosphate (IPL, Indian Potash Limited, Chennai, India) were used at the rate of 15, 3, and 3 Kg/ha/day, respectively, based on the study of DWRP (1998); manure 4 (2x OM+IF) was a combination of manure 2 and manure 3. The amount of IFs was calculated for 10 days and applied in the culture tank. In all these experiments, OMs were applied at the rate of one fourth dose of initial dose at every 10 days interval. In IFs, similar dose (initial amount) of manures was applied at every 10 days interval. Manures for individual tank were mixed with tap water and allowed to decompose for 5 days before application. All manures, except cattle manure were applied in dry conditions. The moisture content of cattle manure was measured and the weight was adjusted.
The production of Lemna spp. in clean water with a known manuring schedule is required for commercial aqua-feed production. Few studies have been conducted to find the best balance of nutrients that may provide maximum growth of duckweed (FAO, 1989), especially for Lemna spp. The requirement to fertilize duckweeds depends on the source of the water. Rainwater collected in ponds may need a balanced NPK application. In Bangladesh, inorganic fertilizers (IFs, urea, triple superphosphate, and potash) were used for the production of duckweeds (DWRP, 1998). Hassan and Chakrabarti (2009) suggested a wide range of organic waste materials viz. animal manure, kitchen wastes, wastes from a wide range of food processing plants, biogas effluents, etc. for the production of duckweeds. A periodic supply of nutrients helped to avoid nutrient deficiency in the culture systems (Sutton and Ornes, 1975; Said et al., 1979). A direct relationship was found between the crude protein content of duckweed and the nitrogen content of the culture system. Although many species survive at extreme temperature, warm and sunny conditions are preferable for faster growth of the plants (Skillicorn et al., 1993). The distribution of various members of duckweed has been influenced by the microclimatic factors such as light intensity, salinity, and regional temperature (Landolt, 1986). The growth of duckweed is largely a function of environmental temperature and light, nutrient status of the culture medium and the degree of crowding of the plants (Hassan and Chakrabarti, 2009).
So higher Urea...
Higher amount of
ash and fiber and lower amount of protein were found in duckweed colonies with slow growth rate (Skillicorn et al., 1993).
https://www.sciencedirect.com/topics/earth-and-planetary-sciences/duckweed
Guerric Kendall wrote:I've been raising duckweed for quite a while now, but with expanded projects, I'd really like to know how to get more out of this plant.
There's plenty of information on feeding duckweed to animals, people on youtube growing thick mats of them that are said to be constantly renewed, and a lot of recommendations for it on forums.
But so far I've found absolutely nothing on what to actually give the duckweed plants themselves. Especially for that much-repeated "doubling in less than 48 hours" thing they can apparently do.
I'm not expecting to get the ideal conditions for that exact result, but certainly more than what I'm getting now which is nowhere near that.
Does anybody know what fertilizer they like best? Comfrey tea? Fish water? Some sort of animal manure maybe?
Also, how often was it added to their water, and how large of an area were you growing the duckweed for that dilution ratio to work?
I tried several small experimental batches with different things last year, but didn't come up with anything conclusive. Thanks!
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