Effect of Preplant Irrigation, Nitrogen Fertilizer Application Timing, and Phosphorus and Potassium Fertilization on Winter Wheat Grain Yield and Water Use Efficiency

Table 4

Grain yield and water use efficiency (WUE) interaction means by year for plots that received either irrigation or were rain-fed and received their total N fertilizer preplant or topdressed midseason.

	Year			Year
	2003	2008	2011	2003	2008
	Grain yield (kg ha^−1)			WUE (kg ha^−1 mm^−1)
Irrigated
Preplant	2730	4213	1397	5.1	9.0
Topdress	2596	3757	1106	4.8	8.0
Rain-fed
Preplant	2438	3355	849	5.6	9.1
Topdress	2598	3640	900	6.0	9.9
SED^a	56	161	65	0.1	0.4

aStandard error of the difference for the interaction of water and N application timing.