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

Table 1

Fertilizer rates and average soil test P and K for treatments in this study. N fertilizer was applied as urea (46-0-0) either preplant or midseason depending upon subplot assignment. P and K fertilizer treatments were all applied preplant as triple super phosphate (0-20-0) and muriate of potash (0-0-50), respectively.

Treatment				Soil test values^a
	Fertilizer treatment			Irrigated		Rain-fed
	kg N ha^−1	kg P ha^−1	kg K ha^−1	mg P kg^−1	mg K kg^−1	mg P kg^−1	mg K kg^−1
1	0	0	0	6	302	4	334
2	45	0	0	6	319	6	350
3	90	0	0	6	320	7	350
4	45	20	0	21	322	19	337
5	90	20	0	19	312	27	337
6	45	20	37	19	328	19	368
7	90	20	37	17	320	19	373

aSoil test 𝑃 and 𝐾 values derived from Mehlich 3 solution extraction (Mehlich, 1984 [30]).