72nd SWCS International Annual Conference July 30-August 2, 2017 Madison, WI

1. Soil Vulnerability Index (SVI):
Introduction
Lisa F. Duriancik, Lee Norfleet, Kevin Ingram, Maxine Levin
USDA Natural Resources Conservation Service (NRCS)
Resource Assessment Division

2. Variability and vulnerability within
and across fields

3. Background – CEAP origin of SVI
 CEAP quantified the relationship between inherent
vulnerability to nutrient and sediment loss and the effects
of farming and conservation practices on those losses.
 Significant portion of vulnerable cropland acres remain
under-treated
 Treating with a system of practices could be more cost
effective
 CEAP SVI helped determine scenario selection for Cropland
modeling

4. Background – SVI
 Not practical to run models on every field and not possible
for every field to be visited
 Developing assessment information to support broad sacle
field and landscape planning, necessitates qualifying
relationships between conservation, management and
vulnerability.
 SVI based on applying field level assessment results from
the CEAP Cropland modeling on average losses to inherent
soil characteristics from NRCS Soil databases.

5. Cultivated Cropland*
Soil Vulnerability Classifications
Each SVI uses 5 categories
SVIcult-leaching
SVIcult-leaching-managed*
SVIcult-runoff
Note: ”0 - Unclassified” means soil information needed for
classification is not available.
0 - Insufficient Data
1 - Low
2 - Moderate
3 - Moderately High
4 - High

6. Cultivated Cropland
Soil Vulnerability Index (SVI) Classes
*Soil Properties Considered
 Hydrologic soil group
 Soil k factor
 Slope
 Rock Fragment Content (soil surface)
 Soil Taxonomic Classification (Organic vs. Mineral)
 Soil Drainage Class
* Soil properties are for SSURGO/gSSURGO map unit components

7. Uses of SVI
 Determine primary vulnerabilities and loss pathways for a field to
help “screen” fields for TA, conservation planning
 Could be used as part of screening and ranking of applications (FA)
 Field level index results can be rolled up at the watershed level
(through quartile analysis) to identify watersheds that may require
higher priority for further evaluation
 Along with other information, it can be used to help prioritize
watersheds for targeting program efforts for greater effects.
 An interagency process and discussion with State Tech Committees,
States, Tribes and partners at several levels is always a critical
aspect of the NRCS process to evaluate priority watersheds.

8. Soil Vulnerability Index (SVI)
 The CEAP Soil Vulnerability
Index (SVI) identifies
vulnerable soils to
 Leaching, managed
leaching and runoff
 for phosphorus,
nitrogen, and sediments
 Based on the potential
inherent vulnerability of
the soil
 Cannot account for
management influence
or conservation
treatment that adjusts
inherent vulnerability
 Only for cultivated cropland
 SVI factors are combined
with watershed
delineations
 SVI can reveal areas that,
due to inherent
vulnerability, could benefit
from conservation.

9. Review and Input- an evolving product
 Initial evaluation project for one CEAP watershed in MO
 Recommendations were part of the basis for this project
 Broader evaluation, field and watershed-scale where
possible under broader scope of conditions
 …This project
 More recommendations, insights
 NRCS Soil Scientist review
 Further refinement for Cropland, potential for further
development (e.g. other ag land uses?)

10. “People here in the United States – and in many other countries – are
learning that we must have soil conservation if we are to have
continuous, abundant agricultural production. We are fast learning, too,
that it must be effective conservation…”
Dr. Hugh H. Bennett, 1946, JSWC 1 (1): 21-24.
Lisa Duriancik@wdc.usda.gov