Interactions of Nitrogen Source and Rate and Weed Removal Timing Relative to Nitrogen Content in Corn and Weeds and Corn Grain Yield
Table 5
Nitrogen content in corn plants when weeds were removed at a height of 16 cm compared with weed-free corn as a result of the interaction of environment, N source, and N rate.
Nitrogen content in corn plants
Average weed height at timing of removal (cm)
Nitrogen
2011
2012
Clayton
Rocky Mount
Clayton
Rocky Mount
Source
Rate
0
16
0
16
0
16
0
16
kg ha−1
kg ha−1
Urea ammonium nitrate
68
11.8
7.0
10.2
9.7
6.6
6.0
5.8
3.5
Urea ammonium nitrate
135
19.3
3.5
18.2
9.7
11.2
10.0
6.3
4.1
Urea ammonium nitrate
202
20.5
9.7
23.7
11.3
11.1
9.0
2.7
4.7
Sulfur-coated urea
68
8.9
4.5
—
7.4
9.4
4.8
3.2
2.5
Sulfur-coated urea
135
18.5
10.0
—
8.1
9.0
10.9
3.6
3.4
Sulfur-coated urea
202
27.7
5.0
21.3
12.4
6.5
10.8
6.0
5.1
Composted poultry litter
68
9.3
4.2
11.1
7.1
7.2
5.6
4.7
3.7
Composted poultry litter
135
16.4
6.5
11.5
8.4
11.3
7.7
6.4
4.9
Composted poultry litter
202
16.6
7.2
16.2
9.9
11.5
10.1
8.0
5.2
Means within a year and location followed by the same letter are not significantly different according to Fisher’s protected LSD test at .
