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

Table 6

Grain yield means and selected contrasts by year for plots with different fertilizer treatments and those either received a flush of irrigation prior to planting or did not receive irrigation.

(a)  

			Year
	Fertilizer treatment	2003	2008	2011
			Grain yield (kg ha^−1)
	1	1452	2726	1097
	2	2508	3900	1369
	3	2465	3887	1512
Irrigated	4	3126	4112	1344
	5	3393	4623	1129
	6	2541	4158	1229
	7	3152	4488	1079
	1	1811	2757	923
	2	2408	3541	1076
	3	2641	3536	873
Rain-fed	4	2579	3809	823
	5	2763	3720	840
	6	2710	3576	911
	7	2713	3542	677
	SED^a	169	235	72

(b)  

Contrasts	Year
	2003		2008		2011
	Sig	Dif	Sig	Dif	Sig	Dif
P fertilizer added irrigated versus rain-fed	***	362	***	684	***	382
K fertilizer added irrigated versus rain-fed	ns	135	***	764	***	360
45 kg N ha^−1 irrigated versus 45 kg N ha^−1 rain-fed	*	159	**	415	***	377
90 kg N ha^−1 irrigated versus 90 kg N ha^−1 rain-fed	***	298	***	734	***	443
45 kg N ha^−1 versus 90 kg N ha^−1	**	−210	ns	−117	***	107
Irrigated 45 kg N ha^−1 versus 90 kg N ha^−1	*	−279	*	−276	*	74
Rain-fed 45 kg N ha^−1 versus 90 kg N ha^−1	ns	−140	ns	43	**	140
Irrigated P fertilizer added versus no P fertilizer added	***	772	**	474	***	−204
Rain-fed P fertilizer added versus no P fertilizer added	ns	146	ns	226	**	−142
Irrigated K fertilizer added versus no K fertilizer added	**	−413	ns	−44	ns	−83
Rain-fed K fertilizer added versus no K fertilizer added	ns	41	ns	−206	ns	39
Irrigated, 90 kg N ha^−1, P fertilizer added versus no P fertilizer added	***	928	**	736	***	−383
Rain-fed, 90 kg N ha^−1, P fertilizer added versus no P fertilizer added	ns	121	ns	184	ns	−33
Irrigated, 90 kg N ha^−1, K fertilizer added versus no K fertilizer added	ns	−241	ns	−135	ns	−50
Rain-fed, 90 kg N ha^−1, K fertilizer added versus no K fertilizer added	ns	−49	ns	178	*	−164

aStandard error of the difference for the interaction of fertilizer treatment and water treatment.
*, **, and *** are significant at the 0.1, 0.01, and 0.001 level, respectively.
ns: not significant at the 0.1 level.