High Nitrogen Fertilization of Tobacco Crop in Headwater Watershed Contaminates Subsurface and Well Waters with Nitrate
Table 3
Nitrate concentration in soil solution under different conditions of land uses and landscape positions in the watershed.
Transect
Position/use
Depth (m)
Date of collection
November 10, 2005
November 28, 2005
December 9, 2005
January 6, 2006
January 20, 2006
January 27, 206
February 10, 2006
Mean
N- (mg L−1)
1
1, tobacco
0.2
0*
0
4.3
0
10.3
9.8
14.2
5.5
0.5
19.0
0
4.8
0
8.7
5.3
21.0
8.4
1
2, tobacco
0.2
11.9
0
0
9.8
11.8
11.8
28.1
10.5
0.5
56.1
0
0
0
0
5.1
0
8.7
1
3, tobacco
0.2
31.8
0
1.5
3.6
16.0
19
32.8
15.0
0.5
28.9
0
1.6
0
13.8
15.1
0
8.5
1
4, tobacco
0.2
0
0
0
0
36.4
40.1
15.9
13.2
0.5
79.9
37.6
2.0
4.4
19
24.2
18.5
26.5
2
1, tobacco
0.2
33.7
0
5.6
13.0
7.2
9.2
0
9.8
0.5
0
0
0
0
0
21.5
0
3.1
2
2, tobacco
0.2
43.7
0
0
0
0
0
0
6.2
0.5
52.8
17.6
4.7
0
33.3
0
0
15.5
2
4, tobacco
0.2
158.4
4.8
4.1
0
0
0
23.8
27.3
0.5
52.0
0
19.5
0
26.2
27
30.0
22.1
3
1, tobacco
0.2
0
0
0
0
14.5
17.6
0
4.6
0.5
0
0
0
0
0
10.9
0
1.6
3
2, tobacco
0.2
71.2
0
3.2
0
5.1
14.3
16.4
15.7
0.5
19.5
0
0
0
0
13.5
23.5
8.1
4
1, tobacco
0.2
17.1
6.4
2.3
2.9
8.3
1.2
1.0
5.6
0.5
0
7.0
4.2
0
29.8
31.6
2.3
10.7
4
2, tobacco
0.2
29.5
11.3
3.7
0
3.8
4.9
2.6
8.0
0.5
39.5
0
3.3
0
6.5
7.8
1.0
8.3
4
3, tobacco
0.2
0.0
11.7
10.8
13.1
10.2
11.2
13.2
10.0
0.5
24.2
17.8
6.3
0
1.8
9.3
6.6
9.4
Mean
32.1
4.8
3.4
2.0
10.9
12.9
10.5
10.9
3
3, grassland
0.2
7.3
0.9
0
0
0
0
0
1.2
0.5
0.0
0
0
0
0
0
0
0.0
3
4, grassland
0.2
0.4
0
0.3
0
0
0.1
0
0.1
0.5
0.0
1.6
1.1
4.8
4.9
3.1
3.5
2.7
Mean
1.9
0.6
0.4
1.2
1.2
0.8
0.9
1.0
2
3, forest
0.2
0
0
0
0
0
0
0
0.0
0.5
39.1
0
24.8
0
0
1.3
0
9.3
4
4, forest
0.2
7.5
7.6
6.7
8.5
10.8
11.5
9.7
8.9
0.5
8.4
9.3
9.2
10.0
9.8
10.9
11.0
9.8
5
1, forest
0.2
9.3
21.1
16.5
0
1.7
0
0
6.9
0.5
0
0
0
0
0
0
0
0.0
5
2, forest
0.2
4.3
27.6
14.1
0
2.5
0
1.0
7.1
0.5
25.8
0
15.4
0
4.0
0.7
0
6.6
5
3, forest
0.2
8.1
2.8
0
0
2.0
0.7
1.0
2.1
0.5
0
2.5
2.6
0
0
0.1
1.0
0.9
Mean
10.3
7.1
8.9
1.9
3.1
2.5
2.4
5.7
The periods without data represent dates when it was not possible to collect the soil solution due to low soil moisture at these points. Position: 1: upper slope, 2: mid slope, 3: lower slope, and 4: plateau.
