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HISTORIC NOTE
The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
of Florida
,3 6 Circular 959
B /April 1991
Ti a Hd E S I T Y 0L1
S ............ INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
Soil ratings for selecting pesticides for water quality goals
Managing pesticides for crop production and water quality protection
A supplement to the IFAS Pest Control Guides
R. B. Brown, A. G. Hornsby and G. W. Hurt*
Florida Cooperative Extension Service / Institute of Food and Agricultural Sciences / University of Florida / John T. Woeste, dean
describes the generalized map units that'are found
Using your county soil survey on the General Soil Map of the County (i.e., the
report to evaluate your soil colored fold-out map that appears near the back of
resources the book). These generalized map unit descrip-
tions, together with the general soil map itself, can
A soil survey is an inventory of the soil resources be very useful in gaining a feel for the overall
of a county or other area of interest. Soil surveys landscape of the county, but they lack the detail
are conducted and published in order to provide necessary to make detailed interpretations of small
information on the nature and occurrence of soils, segments of the landscape. Fortunately, the next
and to help land users understand some of the section of the report gives descriptions of the map
limitations for different land uses that might exist units that are found on the fold-out, photo-based
in various, contrasting segments of the landscape. soil maps that are attached in the back of the book
In conducting a soil survey, soil scientists walk the (or, tn.the pase06fi6nme counties such as DeSoto,
landscape and examine the soil at intervals, observ- Columbia andSumter, the stand-alone maps that
ing color, texture, layering phenomena, water table are held bose in an envelope The detailed soil
fluctuations, slope of the land, kinds of native map uitidecl~ip( ios help the user to envision and
plants, and other features that help to characterize understand hetheree-dimensi nal landscape that
and identify soils. These soil scientists dig many occurs on the property in question. Here one gains
holes, mainly using soil augers about seven feet in a f'elf fi:tl)&h dccurren e, appearance, nature, and
length, to study, classify, and delineate soils on i..behavior of thesoils as well'as the degree of vari-
maps. ability and consequent imprecision that one might
.. .. .., 1 expect in the mapping of soils on this tract.
countyy saurll uLvey ieporuLs are puu iiesu uy Lthe
USDA Soil Conservation Service, with cooperation
from the University of Florida Agricultural Experi-
ment Stations and Soil Science Department, the
Bureau of Soil and Water Conservation of the
Florida Department of Agriculture and Consumer
Services, the Florida Department of Transporta-
tion, and, where national forest lands are involved,
the USDA Forest Service.
Soil survey reports have slightly different
formats depending on the year they were published
and other factors. But they all contain roughly the
same information. The beginning of each report
contains sections dealing with the nature of the
study area, including its history, agriculture,
climate, and major land uses. The following section
*R. B. Brown and A. G. Hornsby are professors, Soil Science
. Department, IFAS, University of Florida, Gainesville, FL 32611;
G. W. Hurt is a state soil scientist with the Soil Conservation
Service, U.S. Department of Agriculture, Gainesville, FL.
I
Next in the soil survey report are discussions of
the use and management of the soils of the county,
and detailed technical descriptions of soil profiles
and the various laboratory analyses and interpreta-
tions that may have been made on the soils of the
survey area. (In some older reports, detailed
technical descriptions of soil profiles are found
earlier in the report along with the soil map unit
descriptions). Finally, there are lengthy tabula-
tions of interpretations, or predictions, of the
behavior of the soil map units in the contexts of a
wide variety of land uses, from agricultural to
nonagricultural.
Every soil survey user should take the time to
become familiar with the contents of the soil survey
report and with the nature of the soils in the
overall survey area as well as those in any specific
areas) of interest. Users should also be sure to
remember that assistance is available to better
understand the nature and use of soil survey
reports and of the lands and soils of the survey
area. Such assistance may be obtained from local
Soil and Water Conservation District offices,
usually listed in the phone book under county
government (or perhaps under U.S. Government-
Department of Agriculture-Soil Conservation
Service, which is the federal agency that staffs
these offices along with county personnel); from
local offices of the IFAS Cooperative Extension
Service; and/or from private firms staffed by
professional soil scientists.
Locating your land holdings in
the soil survey report
A soil survey report has on its inside front cover
a section entitled "How to Use this Soil Survey."
Guidance is given in finding one's property or other
tract of interest on the photo-based soil maps and
in going to other places in the report to gain under-
standing of the occurrence and nature of soils found
there. This "how-to" section, together with guid-
ance from agency personnel and other experienced
makers or users of these reports, will get the user
past the initially daunting task of locating one's self
on the maps and finding the associated text and
tables in the report. One page that the user will
refer to repeatedly in getting familiar with the
report is the "Index to Map Sheets," a fold-out page
that usually follows the General Soil Map but
precedes the photo-based maps. On this page is a
map of the county with superimposed, wide-bor-
dered, numbered rectangles covering it. These
superimposed rectangles correspond with the
similarly numbered, photo-based soil maps them-
selves. Note that the county map itself, "beneath"
the superimposed rectangles, shows state and
county highways, major cultural features (lakes
and communities), and section/range/township
markings. Knowing the location of the property in
question relative to these features will help the
user to identify approximately which photo-based
map sheet or sheets depict the tract. The map
sheets themselves are numbered in circles that
appear in the upper right or left corners of the
maps. Note that cultural and other landscape
features, as well as section corners, are shown in
even greater detail on the photo-based maps.
As you work with these photo-based maps, you
will notice that there are many sorts of map sym-
bols employed to identify landscape features,
including streams, roads, boundaries of soil delin-
eations, soil map unit symbols (one in each delinea-
tion), section corners and numbers, and a variety of
spot symbols representing small but significant
features such as sinkholes, sandy spots, wet spots,
rock outcrops, and so forth. In addition, around the
borders of the individual maps there are map
scales, township and range numbers, and other
information. These symbols and other information
are described and defined on the fold-out Index to
Map Sheets page and/or on its reverse, which
contains the Soil Legend and the Conventional and
Special Symbols Legend.
Once you have determined the soil map unit
symbol or symbols that are in the delineations
shown for your field, you should go first to the Soil
Legend (on the back side of the fold-out Index to
Map Sheets) to learn the full name of the soil map
unit(s) found in your field. For a description of the
nature and range of soils likely to be found in areas
thus mapped, read the full map unit descriptions)
in the text of the report.
For tabulations of various soil physical and
chemical properties and of interpretations of the
soil map units for different uses, peruse the tables
in the report, looking especially for the soil map
unit symbols) and names(s) that are of interest to
you. Contrast them with other soils found in the
various contrasting regions of your county.
Remember, the purpose of the soil and land
resource inventory that has been conducted and
made available to you in the form of this report is
to inform you and others about your lands and
soils. You will discover that this soil survey report
is the most complete and comprehensive inventory
available of the soil and land resources of your
county.
You will also learn, however, in reading the
report and in comparing its contents with your own
experiences and observations, that the inventory is
not perfect. Soil survey reports tend to be accurate
but imprecise. Intricate details of the land cannot
be completely depicted and described on maps of
this scale or in text of this length. You should be
aware of the consequent imprecision of the maps
and accompanying documentation. If you have
reason to believe or suspect that the maps and/or
descriptions of your land are imprecisely depicted
to the point that your decisions on pesticide use will
be wrong or biased as a result, contact your local
Soil and Water Conservation District for assistance
in determining the correct soil map unit name(s)
and characteristics to use in your decision-making.
Similarly, if you are in a county or area that has no
published or interim soil survey, contact your local
Soil and Water Conservation District for assistance
in obtaining a soil survey of your land.
Dealing with more than one
soil in your field or other
management unit
When two or more soil map units are found in
the field of interest, you will want to make your
decisions by working up your information sepa-
rately for each such map unit. Only after doing so
will you be able to see whether these map units are
sufficiently contrasting to justify (1) different
management decisions and practices on the various
parts of the field, or (2) selection of one set of
practices for the whole field, based on the more
problematic, environmentally sensitive parts) of
the field, even though such practices may not be
entirely necessary on the rest of the field.
Where two or more soils make up the name of
one of your map units (e.g., Pedro-Jonesville
complex, 0 to 5 percent slopes), a similar dual
workup should be made for all the soils in every
map unit in the field. Here, however, you will not
have the luxury of using option "1" from the previ-
ous paragraph, because the soils in a multiple-
named map unit have not been delineated sepa-
rately from each other. You may need to go with
something like option "2," and select a management
system keyed to the most limiting conditions)
found in that map unit.
Rating soils for leaching and
runoff potentials for pesticides
An indicator is needed to determine which of the
two pathways, leaching or runoff, will be the most
likely pesticide loss pathway. Selected properties of
soils have been used to develop a rating system for
runoff and leaching potential of soils. The USDA
Soil Conservation Service has rated soils according
to this system in counties having published soil
survey reports. If your county has a published
report, you can obtain a copy of the soil ratings
from either the County Cooperative Extension
Service or the local USDA Soil Conservation
Service office. Ask for the document entitled
"[Name of your county]: Soil Ratings for Selecting
Pesticides."
The following criteria were developed by the Soil
Conservation Service in collaboration with the
Florida Cooperative Extension Service to rate soils
for leaching and runoff.
Leaching
Factors that determine the soil leaching rating
are the soil permeability and the occurrence of
mucky layers in the upper 80 inches of the soil, as
follows:
RATING
HIGH
MEDIUM
LOW
Exceptions:
1.
2.
CRITERIA
Slowest permeability is
6.0 IN/HR or more.
Slowest permeability is
between 0.6 and 6.0 IN/HR.
Slowest permeability is
0.6 IN/HR or less.
Soils with a muck or peat layer are rated
LOW.
Soils with a mucky layer are rated MEDIUM
unless the soil has a slowest permeability of
less than 0.6 IN/HR; then the soil is rated LOW.
Note: Permeability estimates needed in entering
and using this table may be found in one of the
tables of data in most soil survey reports. In recent
reports (since about the mid-1970s), that table is
usually entitled "Physical and Chemical Properties
of Soils." In older reports, the same information on
permeability may be in tables having a different
title, such as "Estimated Soil Properties Significant
in Engineering."
Runoff
The factors that determine the soil runoff rating
are hydrologic group, permeability, and slope, as
follows:
RATING
HIGH
MEDIUM
LOW
Exceptions:
1.
2.
3.
CRITERIA
Soils in hydrologic group D in their natural,
undrained state.
Soils in hydrologic group C; and any soils in
hydrologic group B (in their natural, undrained
state) that have a permeability of less than 6.0
IN/HR within 20 inches of the soil surface.
Soils in hydrologic class A; and any soils in
hydrologic group B (in their natural, undrained
state) that have a permeability of 6.0 IN/HR or
greater in all of the upper 20 inches of the soil
profile.
Soils that are frequently flooded during the growing
season are rated HIGH.
Soils rated LOW are changed to a rating of MEDIUM
where the slope is greater than 12 percent.
Soils rated MEDIUM are changed to a rating of HIGH
where the slope is more than 8 percent.
Note: The various hydrologic soil groups (A, B, C,
D) are used to cluster soils having similar runoff-
producing characteristics. The chief consideration
is the inherent capacity of bare soil to permit
infiltration. Native soil permeability and prior
wetness are considered in assigning soils to hydro-
logic groups. Simplified definitions of the groups
are: A-high infiltration and low runoff potential;
B-moderate infiltration and slight runoff poten-
tial; C-slow infiltration and moderate runoff
potential; D-very slow infiltration and high runoff
potential. Some soils that have a high seasonal
water table but can be artificially drained are
assigned to two hydrologic groups, such as B/D-
very slow infiltration and high runoff potential in
the natural, undrained state, but moderate infiltra-
tion and slight runoff potential when artificially
drained. The more modern soil survey reports
(since perhaps the mid-1970s) are likely to have
hydrologic group listings in the table entitled "Soil
and Water Features." Earlier reports may show
this information elsewhere or not at all. Fortu-
nately, most users will not need such primary
information, because the final workups of leaching
and runoff potentials are provided by the Soil
Conservation Service.
The above schemes for generating runoff and
leaching potential ratings for soils are offered here
primarily for information, to help the reader
understand the origins of such ratings as provided
by the Soil Conservation Service and Cooperative
Extension Service in Florida. Most users will be
able to bypass these steps, because, as indicated
above, listings of actual leaching and runoff ratings
for every soil in a county are available from local
Cooperative Extension Service and Soil and Water
Conservation District offices.
Soil ratings for use with
TRIUMPH and TEMIK
pesticides
Ciba Geigy Agricultural Division and Rhone-
Poulenc Ag Products have determined that product
stewardship must include restrictions on applica-
tion of some of their products on certain soils.
These companies have worked with the Florida
Department of Agriculture and Consumer Services
and the Soil Conservation Service in Florida to
identify those soils which are particularly vulner-
able to leaching of TRIUMPH and TEMIK. As a
result of this effort, the labels or supplementary
information on these products indicate the soils and
conditions under which these products may be
used.
For TRIUMPH, county specific lists of soils on
which the product may be applied have been
developed by the product manufacturer and are
available from the County Extension Offices or the
product dealers. TRIUMPH should not be applied
to soils that are not included on these lists.
In the case of TEMIK, the product label con-
tains a list of Florida soils which have special
shallow drinking water well set-back requirements
(see label for definition of "shallow well"). Labels
for TEMIK should be carefully read before using
the product.
Conclusion
Your decision of which pesticides to use should
be arrived at by using leaching and runoff potential
ratings for map units, in combination with informa-
tion derived from your soil survey report and from
commodity-specific information given in the Exten-
sion Circulars entitled "[Crop Name]: Managing
Pesticides for Crop Production and Water Quality
Protection" companion to this one. Special addi-
tional considerations must be given to TRIUMPH*,
TEMIK, and other pesticides that carry groundwa-
ter warnings on their labels.
Remember, there are county-specific soil ratings
that you must use in formulating your pesticide-
selection plan. For those counties with a published
or interim soil survey, the USDA/SCS has provided
listings that show leaching and runoff potentials of
map units. These ratings are contained in a fact
sheet entitled "[Name of your county]: Soil Ratings
for Selecting Pesticides." A copy of these ratings for
your county is available from your local Coopera-
tive Extension Service or Soil and Water Conserva-
tion District office.
Acknowledgement:
The development of this document was sup-
ported by the USDA/ES Water Quality Initiative
Project # 89EWQI-1-9134.
COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, John T. Woeste,
director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of the May 8 and June
30, 1914 Acts of Congress; and is authorized to provide research, educational information and other services only to individuals and institutions that
function without regard to race, color, sex, age, handicap or national origin. Single copies of extension publications (excluding 4-H and youth
publications) are available free to Florida residents from county extension offices. Information on bulk rates or copies for out-of-state purchasers
is available from C.M. Hinton, Publications Distribution Center, IFAS Building 664, University of Florida, Gainesville, Florida 32611. Before publicizing
this publication, editors should contact this address to determine availability. Printed 6/91.
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