Effect of Preplant Irrigation, Nitrogen Fertilizer Application Timing, and Phosphorus and Potassium Fertilization on Winter Wheat Grain Yield and Water Use Efficiency
Table 9
Water use efficiency (WUE) 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)
Fertilizer treatment
Year
2003
2011
WUE (kg ha−1 mm−1)
Irrigated
1
2.7
3.8
2
4.7
4.7
3
4.6
5.2
4
5.8
4.6
5
6.3
3.9
6
4.7
4.2
7
5.9
3.7
Rain-fed
1
4.2
4.8
2
5.5
5.6
3
6.1
4.6
4
5.9
4.3
5
6.3
4.4
6
6.2
4.8
7
6.2
3.5
SEDa
0.3
0.3
(b)
Contrasts
Year
2003
2011
Sig
Dif
Sig
Dif
P fertilizer added irrigated versus rain-fed
***
−0.5
ns
−0.1
K fertilizer added irrigated versus rain-fed
***
−0.9
ns
−0.2
45 kg N ha−1 irrigated versus 45 kg N ha−1 rain-fed
***
−0.8
*
−0.4
90 kg N ha−1 irrigated versus 90 kg N ha−1 rain-fed
***
−0.6
ns
0.1
45 kg N ha−1 versus 90 kg N ha−1
**
−0.4
***
0.5
Irrigated 45 kg N ha−1 versus 90 kg N ha−1
*
−0.5
ns
0.3
Rain-fed 45 kg N ha−1 versus 90 kg N ha−1
ns
−0.3
***
0.7
Irrigated P fertilizer added versus no P fertilizer added
***
1.4
**
−0.7
Rain-fed P fertilizer added versus no P fertilizer added
ns
0.3
**
−0.7
Irrigated K fertilizer added versus no K fertilizer added
**
−0.8
ns
−0.3
Rain-fed K fertilizer added versus no K fertilizer added
ns
0.1
ns
−0.2
Irrigated, 90 kg N ha−1and P fertilizer added versus no P fertilizer added
***
1.7
***
−1.3
Rain-fed, 90 kg N ha−1 and P fertilizer added versus no P fertilizer added
ns
0.3
ns
−0.2
Irrigated, 90 kg N ha−1 and K fertilizer added versus no K fertilizer added
ns
−0.5
ns
−0.2
Rain-fed, 90 kg N ha−1 and K fertilizer added versus no K fertilizer added
ns
−0.1
**
−0.9
Standard 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.
