RELATIVE EFFICIENCY OF AZOLLA AND OTHER ORGANIC MANURES IN WINTER RICE (ORYZA-SATIVA)

An experiment was carried out during July-November 1985 and 1986 at Ka lyani, to study the effect of Azolla, blue-green algae and other organ ic manures on 'Jaya' rice (Oryza sativa L.). Grain and straw yields of rice increased significantly due to incorporation of Azolla, Ipomoea carnea Jacq., farmyard manure, water lettuce (Pistia stratiotes L.) an d water hyacinth [Eichhornia crassipes (C. Martius) Solms-Laub.] compa red with the control. Inoculation with blue-green algae was not benefi cial, but the effect of dual cropping with Azolla was pronounced with 30% more yield than the control. Basal dressing of Azolla was also sup erior to top-dressing and dual cropping. The highest grain yield (6.5 tonnes/ha) was recorded with the application of 15 tonnes/ha Azolla 15 kg N/ha at panicle-initiation stage. The extent of yield increase, compared with the control, due to different treatments, varied from 5 to 107.5%. The treatment with Ipomoea sp proved equal or more efficien t than Azolla. The N status of soil after harvest of crop depended on the uptake of N by the plants as well as contribution of Azolla and ot her manures.