Biofertilizers enhance dissolved oxygen content (DOC) in water
1993
Lakshmanan, A. | Anthoni Raj, S. | Abdul Kareem, A. (Tamil Nadu Rice Research Inst., Aduthurai 612101 (India))
A study of blue-green algae (BGA) and azolla nurseries under continuous submergence for more than a year, however, revealed an enhanced DOC [dissolved oxygen content] in the water. DOC increased between 0600 and 1600 h but declined thereafter. Between 0600 and 1600 h, DOC ranged from 3.7 to 7.1 ppm in the BGA nursery, from 1.3 to 5.5 ppm in the azolla nursery, and from 3.1 to 5.4 ppm in the control where water was impounded without BGA or azolla. Most samples from the BGA nurseries had higher DOC than did those from the control. DOC in the control was higher than that in the azolla nursery, except at 1600 h. CO2 evolution was 61 mg/h per sq.m. in the azolla nursery, which was more than in the BGA nursery (46 mg/h per sq.m.) and control (10 mg/h per sq.m.). Although CO2 emissions may contribute to atmospheric pollution, increased DOC in water associated with biofertilizers might alleviate problems related to stagnant water. Augmenting DOC in continuously submerged fields where BGA and azolla are grown might also eliminate accumulated reduced iron and sulfides, which are toxic to rice
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