All India Coordinated Rice Improvement Project, Rajendranagar, Hyderabad, Andhra Pradesh
*Present address: University of Agricultural Sciences, Hebbal, Bangalore, Karnataka
The combined recovery of N from straw by two crops without application of fertilizer N was 20.6% at Cuttack and 7.2% at Hyderabad. The total recovery increased nearly two-fold when fertilizer N was applied to both crop seasons. On an average, about 57 to 62% of the straw N was left behind in the root zone at the end of the experiment at Hyderabad. The highest recovery of N from FYM (82%) at Cuttack occurred when N fertilization was delayed until the second season.
Under submerged conditions, addition of straw immobilized about 4% of the fertilizer N at Hyderabad and increased its incorporation in the hexosamine fraction of the soil N.
The mineralization of straw N and immobilization of fertilizer N by added straw in this field investigation employing normal application rate and physical condition of the straw were not comparable with those reported from greenhouse experiments elsewhere.
15N straw and FYM, turnover in flooded soils
