Backyard Aquaponics
A place to discuss aquaponics

hi, i planted some bean sprouts (mung beans) because i love them, cause i planted some in a plastic cup when i was in school.

i threw alot of bean sprout seeds in my grow bed, but i heard they do not use nitrate and is that true?
do they produce nitrate or they dont use nitrate?

if they dont use or produce nitrate, i want to take it out, cause i want plants that use up nitrates so it can help filter my aquarium and fish.

thank you,

beansproutboy1998.

please can someone answer >.<

I have grown a lot of bean sprouts,but never in a grow bed,as with all seed everything they need to start there life is held within the seed up to the cotyledon leaves,so they dont need nitrogen or produce nitrogen.bean sprout are germinated in the dark so there is no or very little root growth,you just have the sprout which is stretching out looking for light and until it does root growth is inhibited.So in answer to your question they neither need or produce nitrate,but you aren't growing sprouts more so the plants they come from.

I'm no expert but a few minutes of research on google suggests that mung beans and soy beans (which is what most bean sprouts are) generally use up more nitrogen than they fix. So I'm guessing that, if you grow the plants to a mature size, they'll use at least some of your nitrates.

For those that haven't come across this before - here is some information on Nitrogen Fixation in legumes

http://aces.nmsu.edu/pubs/_a/A129/
http://www.public.iastate.edu/~teloynac/354n2fix.pdf

From what I could tell additional nitrogen isn't needed but will result in better growth so at least some does get used. They won't use as much as other crops though because they get much of their nitrogen by nitrogen fixation.

hi, thank you all for the replies. i understand now.

Beans are not going to fix atmospheric nitrogen unless they've been inoculated with the appropriate bacteria (rhizobia). I can't think of any reason your aquaponic system would have those bacteria in it. You can check by pulling out a bean plant and seeing if there are nodules on the roots. If there are nodules, try crushing one. If it turns pink, then your beans are fixing nitrogen from the air.

Short answer: No, your beans are not "creating" or "adding" nitrogen.

There are a lot of these bacteria around and over time the right strain might find it's way into the grow bed and gradually build up sufficient numbers but it is unlikely that sufficient numbers exist initially. Bacteria that exist in the soil can blow in just like dust and these do exist as free living organisms not just in concert with the plants.