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When rice is washed, the wash water becomes whitish due to the starchy powder in the skin of unwashed rice. I've often heard or read, usually in water-saving, money-saving, or gardening tips, that the water used to wash rice is beneficial for plants as it fertilizes the soil. There are also various anecdotes on the internet suggesting the use of rice water to water plants:

Surprisingly though, given how often I've heard this claim, I hadn't been able to find much serious researches regarding this topic.

Are there any truth to this claim? Does watering plants with rice water produces better plants than watering plants with plain tap water? How does it compare with regular, commercially produced fertilizers?

  • I think the first part is on-topic (does rice water have plant nutrients), but the second part (is it better than other products) is subjective so off-topic. My Japanese wife swears by this, but I wonder if it might be that Japanese rice used to be fertilizer-ridden, so washing it washed off the fertilizer? – Ken Y-N Jan 14 '15 at 5:15
  • I typed "rice water" in Google, and got sites about "rice water for hair growth." – GEdgar Dec 8 '18 at 20:41
  • Can't find a thing except some guy trying to start a business selling rice water who thinks it's great. Oh, and the odd blog by students doing show-and-tell growing beans in the stuff. – 011358 smell Dec 12 '18 at 13:28
  • One reason for soaking and rinsing rice is to reduce the arsenic content. (See: Arsenic in Rice: Everything You Need to Know to Stay Safe) So using rice water as fertilizer will add arsenic to the soil. That might be fine for flowers, but I'd avoid it for food plants. – Ray Butterworth Aug 19 at 13:38

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