Editing Azolla (section)

====Companion plant====
''Azolla'' has been used for at least one thousand years in rice paddies as a [[companion plant]], to fix nitrogen and to block out light to prevent competition from other plants. Rice is planted when tall enough to poke through the ''Azolla'' layer. Mats of mature ''Azolla'' can also be used as a weed-suppressing [[mulch]].

Rice farmers used ''Azolla'' as a rice biofertilizer 1500 years ago. The earliest known written record of this practice is in a book written by Jia Ssu Hsieh (Jia Si Xue) in 540&nbsp;AD on ''The Art of Feeding the People'' (Chih Min Tao Shu). By the end of the [[Ming dynasty]] in the early 17th century, ''Azolla''<nowiki/>'s use as a green compost was documented in local records.<ref>{{cite web |title=The East discovers Azolla |url=http://theazollafoundation.org/azolla/azollas-use-in-the-east/ |website=Azolla Foundation |access-date=18 August 2014}}</ref>