Nitrogen Management Options in Winter Rice under Boro- Fallow-T. Aman Cropping System

Abstract Nitrogen (N) is commonly applied in equal split during different growth stages of rice. However, higher requirement of N during panicle initiation (PI) stage emphasizes relatively higher N dose at that particular stage. A field experiment was conducted during dry seasons (November-May) of two consecutive years from ۲۰۱۳ to ۲۰۱۵ to determine appropriate timing and amount of N application and its effect on yield and N use efficiency. Two modern rice varieties (BRRI dhan۲۸ and BRRI dhan۲۹) under six N management options viz. i) One third of N was applied at initiation of tillering (IT) stage + one third at active tillering (AT) stage + one-third at panicle initiation (PI) stage (N۱)(Recommended practice); ii) One-half at IT stage + another-half at PI stage (N۲); iii) One third at IT stage + two-third at PI stage (N۳); (iv) One-fourth at IT stage + one-fourth at AT stage+ half at PI stage (N۴); v) One-half at IT stage + another half at AT stage (N۵); and vi) N-control (N۶)  were evaluated in randomized complete block design with three replications. Recommended practice and application of higher dose at PI stage gave similar yields in BRRI dhan۲۸ and BRRI dhan۲۹ in both the years. Agronomic use efficiency showed similar trend of results. Therefore, inadequate N application at early growth stages for any inevitable circumstances could be compensated by higher N application at PI stage.  

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Keywords: Oryza sativa L , Timing of nitrogen application , Nitrogen rates , Agronomic use efficiency , grain and straw yields