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Excessive P buildup in soil has become major agricultural
non-point pollution. The Phosphorus Loss Assessment Tool (PLAT) was developed to
evaluate the P loss potential in different pathways. While most parameters
required are discrete data, many occur in spatial data formats that may enable
the use of PLAT over variable spatial scales. The objective of this research is
to evaluate the potential of using spatial data to estimate P loss. Preliminary
results show PLAT outputs using elevation, soil type, and other spatial parameters
in a Geographic Information System similar to those using field average data. An
important parameter not directly available is the average annual soil loss,
which is obtained by the Revised Universal Soil Loss Equation (RUSLE). We are
evaluating the potential of obtaining a RUSLE estimate that would not require field
assessment. *Erosivity*
and *Cropping Practice *factors are
constant over the field, but *Erodibility*, *Slope Length
(L)*, *% slope(S)*, and *Conservation Practice* factors vary spatially.
Our current efforts are developing an algorithm to estimate all necessary
parameters, especially *L* and *S* using spatial data. Success of the GIS
modeling will provide a valuable computer-based application of RUSLE. Further, it
is essential to evaluate the potential of using PLAT spatially to estimate of P
loss.