Effects of Prilled Urea, Urea Briquettes and NPK Briquettes on the Growth, Yield and Nitrogen use Efficiency of BRRI Dhan48

Nitrogen is one of the most deficient plant nutrients in Bangladesh soils. The use nitrogenous fertilizer especially urea is a commonly used fertilizer for rice production but its efficiency very low about 30-40% under traditional broadcast method A field experiment was carried out in the Soil Science Field Laboratory of Bangladesh Agricultural University, Mymensingh during Aus rice growing season of 2014 to investigate the effects of prilled urea, urea briquettes and NPK briquettes on the growth, yield, and nitrogen use efficiency of BRRI dhan48. There were six treatments as T1 [check (N0P16K42], T2 [Urea briquette (one-3.4 g) (N52P16K42)], T3 (Urea briquette (one-2.7 g (N78P16K42)], T4 [NPK briquette (one-3.4g)(N51P13K32], T5 [Prilled urea (N78P16K42)] and T6 [NPK briquettes(two-2.4 g briquettes (N78P15K42)]. The experiment was laid out in a Randomized Complete Block Design (RCBD) with six treatments and four replications. Prilled urea was applied in two equal splits application; at 8 days after transplanting (DAT) and the second dose after 38 DAT, while for urea briquettes and NPK briquettes were deep placed (8-10 cm depth) at 8 DAT between four hills at alternate rows. Water samples were collected for every 7 consecutive days and analyzed for NH4-N. The results showed that the NH4-N concentration in floodwater reached to maximum on day 2 in PU treated plots and then decreased with time, while the urea briquettes and NPK briquettes treated plots slowly produced NH4-N over the growth period. The highest grain yield of 4.75 t ha-1 (69% over control) was obtained in the treatment T3 [Urea briquette (one-2.7g) (N78P16K42)]. The treatment T3 also produced the highest straw yield of 5.49 t ha-1. The maximum apparent N recovery and the maximum N use efficiency were found in the treatment T4 [NPK briquette (one-3.4g) (N51P13K32)]. It appeared that the deep placement of urea briquettes and NPK briquettes reduced N-losses and enhanced the recovery of applied N as well as N use efficiency in comparison with PU application.