Abstract
A field experiment was carried out at the Agricultural Engineering Department, Indian Institute of Technology, Kharagpur, for three consecutive years, 1979-1982, to evaluate the use of azolla to meet at least a part of the N requirement of a rice-wheat cropping system. Preplanting incorporation of azolla proved to be superior to postplanting. Fresh azolla at the rate of 10 t ha-1 + 30 kg N ha-1 as urea was found to be the best treatment and recorded maximum grain yield of rice as well as maximum residual effect on wheat. The results indicated that azolla could be utilized as a substitute to N-fertilizer; about 30 kg N could be supplemented through preplanting incorporation of 5 t fresh azolla.
