Pakistan Gardening Forum

Can I use 20-20-20 NPK fertilizer for hydroponics?

No

Izhar wrote:No

And why not?

Due to Urea presence...

Izhar wrote:Due to Urea presence...

Is it the nitrogen loss due to Ammonia formation?

No.. urea requires soil microbes to get converted to ammonium and nitrate form... hydroponics dont have bacteria...

Thank you Izhar

Sir, when we supply nitrogen in our hydroponic solutions there are always a several ways in which we can fulfill our plants’ needs for this nutrient. The traditional way is to supply nitrogen solely as nitrate (NO3-) salts, something which is well proven to give good results, high yield crops and better than soil growth.

Urea is an organic molecule which slowly decomposes in water to yield ammonia and carbon dioxide. If the media is slightly acidic, the ammonia released will get protonated to form ammonium, a form of nitrogen which can be readily absorbed by most plants. Moreover, this form of nitrogen can also be processed by bacteria to yield nitrate, providing us with an additonal – slow release- mechanism for nitrate supplementation. There was a study published by Oda et al, dealing with the effects of Urea and nitrate fertilization in hydroponics crops using both organic (peatmoss and baggasse), inorganic (rockwoll and sand) media and pure hydroponics systems.

After doing a study with several concentrations of Urea and Nitrate -both by themselves and combined – this research group found out that Urea does not improve crop yields in hydroponics systems and indeed pure nitrate does the best job when no media is in place. When media is introduced, organic media shows a faster Urea to Ammonia conversion but Ammonia to nitrate conversions are faster in inorganic media. However, the effect of Urea remains poor in the sense that nitrate-only crops outperformed almost all crops except for some plants grown with small quantities of Urea which proves to be beneficial in the same way as small additions of ammonia are already known to be.

So in the end, is it worth to add Urea to a hydroponic formulation ? The scientific evidence says that Urea does not have any clear beneficial effect that could not be gained by a small addition of ammonium salts, something which has already been confirmed by several studies done on different plant species. If you are planning on starting a new hydroponics crop adding about 5-10 percent of your total nitrogen as ammonium may prove to be beneficial but any addition of Urea seems completely unecessary.

Of course, further research on this subject would be needed to know the effect of nitrate/ammonium/urea combinations to know if the beneficial effects are a sole consequence of the presence of small quantities of ammonia or a virtue of the “regulatory” effects introduced by Urea as a slow release ammonium fertilizer.

(Source: Google search)

Thanks again, you know my main interest is Hippeastrum, Daylily and Liliums, would the Hydroponic be of any use to me.

I dont think so...