Illinois Environmental Protection Agency Lake Oakland TMDL Implementation Plan
Final Report 19
(Photo Courtesy of CCSWCD)
Figure 4-3. Deep Placement Phosphorus Attachment Unit for Strip-till Toolbar.
For corn-soybean rotations, it is recommended that phosphorus fertilizer be applied once every two years,
following harvest of the corn crop if application consists of broadcast followed by incorporation (UME,
1996). Band placement should occur prior to or during corn planting, depending on the type of field
equipment available. In this watershed, most fertilizer is applied after bean harvest and before corn
planting (Sample, 2007). Fertilizer should be applied when the
chance of a large precipitation event is low. Researchers in
Iowa found that runoff concentrations of phosphorus were 60
percent lower when the following precipitation event occurred
10 days after fertilizer application, as opposed to 24 hours after
application. Application to frozen ground or snow cover
should be strongly discouraged. Researchers studying loads from agricultural fields in east-central
Illinois found that fertilizer application to frozen ground or snow followed by a rain event could transport
40 percent of the total annual phosphorus load (Gentry et al., 2007).
Recent technological developments in field equipment allow for fertilizer to be applied at varying rates
across a field. Crop yield and net profits are optimized with this variable rate technology (IAH, 2002).
Precision farming typically divides fields into 1- to 3-acre plots that are specifically managed for seed,
chemical, and water requirements. Operating costs are reduced and crop yields typically increase, though
upfront equipment costs may be high.
The effectiveness of nutrient management plans (application rates, methods, and timing) in reducing
phosphorus loading from agricultural land will be site specific. Average reductions of total phosphorus
Check the weather forecast before
applying fertilizer. Apply fertilizer only
when the chance of heavy rain is low.
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