Rice water! Have you tried it on your plants? I personally don’t cook rice often but when I remember I use it on my plants. After you wash your rice the water that is left back contains starches and minerals. The minerals contain trace macronutrients of NPK, nitrogen, phosphorus, and potassium that help your plants grow.
Not enough studies have been focused just on plants but the few that are out there show they can be just as powerful as a complete food.
I personally use rice water on my houseplants (my Pothos really made a comeback) and my edible plants too.
I try to use it all at once. If you have any leftover it may be wise to keep it cool, but bring it back down to room temperature when feeding plants to not shock their roots.
Beneficial to soil and stimulating healthy bacteria. On soilless plants the nutrients go directly to the roots.
So have you given it a try? Let me know!