Summary of the rate and timing of N-(n-butyl) thiophosphoric triamide (NBPT)-coated urea for four nitrogen (N) fertilization treatments added to tubs of a silt-loam soil managed in the greenhouse to mimic a furrow-irrigated rice production system..

Table 2: Summary of the rate and timing of N-(n-butyl) thiophosphoric triamide (NBPT)-coated urea for four nitrogen (N) fertilization treatments added to tubs of a silt-loam soil managed in the greenhouse to mimic a furrow-irrigated rice production system.

Treatment	4- to 5-leaf stage	Weeks after first application			Total^†
Treatment	4- to 5-leaf stage	1	2	3	Total^†
	^{__________________} g urea tub^{-1 __________________}
Optimum plus one split (OPOS)	9.9	0	0	7.6	17.5
Half optimum plus two splits (HOPTS)	5.0	0	5.0	7.5	17.5
Optimum plus two splits (OPTS)	9.9	0	3.8	3.8	17.5
Unamended control (UC)	0	0	0	0	0

	^{__________________} kg N ha^{-1 __________________}
Optimum plus one split (OPOS)	177	0	0	133	310
Half optimum plus two splits (HOPTS)	89	0	89	132	310
Optimum plus two splits (OPTS)	177	0	66.5	66.5	310
Unamended control (UC)	0	0	0	0	0

†The 17.5 g urea tub-1 were equivalent, on an area basis, to a field fertilization rate of 258 kg N ha-1 plus 20% on account of the limited soil depth in the tubs (~10 cm) for a total of 310 kg N ha-1