Comparative efficiency of Azolla and chemical nitrogen fertilizers on growth and yield of rice.
In field trials in 1990-91 at Cuttack, Orissa, rice cv. CR-1009 and Kalinga-2 were given various combinations of 0-60 kg N/ha as urea, application of Azolla pinnata green manure incorporated before transplanting rice, or A. pinnata grown with rice for 25 d before incorporating. Grain yield was highest (about 5 t/ha) with a combination of A. pinnata incorporated before planting or 25 d after planting + 30 kg N/ha, or A. pinnata incorporated both before and after planting. N and P uptake by rice were highest with A. pinnata applied before and after planting. Growing A. pinnata with rice reduced weed DM compared with urea application or incorporating A. pinnata before planting.