Geology Reference
In-Depth Information
alternatives. Thus they provide documentation
of the 'before' and 'after' soil losses.
As indicated earlier, a feature added to the
RUSLE2 program that greatly eased the database
development effort was the inclusion of the
Rotation Builder. This allowed the management
scenarios to be developed as single crops, allow-
ing the user within the program to 'paste' these
together into the desired sequence. For example,
the long growing seasons in the southeast US
allows for multiple vegetable crops to be grown
in sequence, resulting in a huge number of per-
mutations requiring a large number of database
descriptions. The Rotation Builder allows for lim-
iting the descriptions to the single vegetations,
which the RUSLE2 user can then combine within
the program run as desired. If a specific combina-
tion is used frequently, the program allows users
to save the combination as a single management,
allowing for easy re-use.
Another RUSLE2 enhancement, developed
with the support of the Wisconsin Department of
Natural Resources and Dane County Land
Conservation, is that the erosion and sediment
delivery no longer need to be summed for the
year. Conservationists working on construction
sites are often interested in what happens only
during some accounting period, over which the
site operator is liable for erosion and sediment
control. For example, the Wisconsin project
defined a successful management plan as that
which would keep the total sediment delivered
from the site under 11 Mg ha
−1
(5 US t ac
−1
) during
the period from the time of first soil disturbance
until either placement of some non-erodible
cover, or 60 days of growth of a permanent peren-
nial vegetation. RUSLE2 allows for flexible defi-
nition of the accounting period, and of the target
that must be achieved.
RUSLE2 also allows for printing a report
describing the inputs and outputs of a RUSLE2
calculation. The form of the report is user-config-
urable, allowing users to define what they would
like to see and in what form in a Microsoft Word
®
document. The resulting document can then be
locked so that the user cannot change the results,
and the associated RUSLE2 inputs can be saved
into the document, allowing for a regulator to
inspect the underlying information.
8.3.5
NRCS tools added to the NRCS
RUSLE2 interface
Several additional calculations have been added
to the NRCS RUSLE2 interface. The most promi-
nent of these is calculation of the Soil Conditioning
Index (SCI) (USDA-NRCS, 2002, examined by
Zobeck
et al
., 2007), which provides a rough esti-
mate of whether a specific location/management/
soil combination will tend to cause an increase or
decrease in soil organic matter. One component
of the SCI that has also proved useful is the Soil
Tillage Intensity Rating (STIR), which makes use
of the tillage type, tillage depth, operation speed,
and percentage surface disturbance as a rough
estimate of the soil disturbance cause by the
operation. The STIR value is used as a criterion
for NRCS's National Residue Management
Practice Standards (available for download at
http://www.nrcs.usda.gov/Technical/Standards/
nhcp.html, accessed 3 September 2008). The STIR
and SCI calculations have no impact on the
RUSLE2 erosion/delivery calculations, but make
use of the management operation and erosion
results.
NRCS has added a calculation of management
fuel usage based on the sequence of operations to
the RUSLE2 interface. Several state phosphorus
index calculations have also been added to the
interface. Other tools were added to the NRCS
RUSLE2 interface to compute a Nitrogen Leaching
Index and an Energy and Fuel Use Calculator
based on the tillage operations. Examples of the
SCI and the Fuel Use Calculator results are shown
in Plate 4.
8.3.6
Future of the technology
The science supporting RUSLE2 continues to
advance and will be incorporated into future
releases of the model. Two active areas of
research include (1) residue production in peren-
nial systems, and (2) ephemeral gully erosion
estimation.
