Geoscience Reference
In-Depth Information
Table 6.4 Estimated nutrient loading (ton/year) in the Saginaw Bay Basin
N (Ton) from
P
2
O
5
(Ton) from
Fertilizer application (F)
Atmosphere (At)
Total N
Fertilizer application
Total
Year
Manure (M)
Total
Nonfarm
M + F + At
Manure
Total
Nonfarm
M + F
1987
26,644
97,908
5,429
13,950
138,502
11,390
81,496
2,526
92,886
1992
25,754
100,534
6,894
14,355
140,643
11,210
42,229
2,323
53,439
1997
24,847
108,662
9,036
14,208
147,717
10,142
43,163
2,868
53,305
2002
23,257
91,883
10,188
14,104
129,244
10,174
32,186
2,949
42,360
Notes:
About 1.31 million ha of cropland (3.24 million acres) is available in the Saginaw Bay Basin
Estimated total amounts of nitrogen and phosphate from animal manure were based on the Census of Agriculture Data of 1987, 1992, 1997, and 2002
Atmospheric deposition of N was based on the U.S. Geological Survey estimates (Ruddy et al.
2006
)
