University of Arkansas
Use of agricultural chemicals such as
fertilizers and pesticides benefit mankind by increasing agricultural production
and improving public health. Fertilizers and pesticides improve the production
and quality of food and fiber. Insecticides continue to save lives and
improve living conditions for humans and animals by reducing or eliminating
diseases such as malaria, yellow fever, and typhus.
Because of the benefits and simplicity
of application, both rural and urban users have come to rely on fertilizers
and pesticides. Recently, the extensive use of these chemicals has led
some to question the potential danger to the environment. One area of concern
is the mobility of the chemical from the site of application to ground
and/or surface waters. Runoff and leaching after rain or irrigation can
concentrate soluble nutrients and pesticides from a large landscape, at
a smaller collection point where the concentrated chemicals can be transported
to the groundwater, or as runoff to surface waters. Injurious effects such
as fish kills, growth of unwanted plants, reproductive failures in birds,
and acute illnesses in humans and animals have been correlated with chemicals
in water. The exact sources from which the damaging chemicals come, however,
are not always apparent since natural contaminant sources also may be present.
And because we have a poor understanding of the results of long-term use
of chemicals, the exact identification of hazards is difficult. Understanding
the regional distribution and key scientific factors that affect water
quality in ground and surface waters is critical to implementing and evaluating
cost-effective programs to manage and protect our water resources.
The persistence and movement of chemicals
in the southern region of the United States are influenced by several factors
and practices. These include (1) geographic and geological factors, (2)
climatic factors, (3) landuse/landcover, (4) soil factors, (5) chemical
factors, and (6) management factors. The southern region of the United
States has unique and diverse relationships among these factors. For the
most part, these relationships can be grouped according to the major land
resource areas (MLRA). A MLRA is a geographic associated land resource
area that is characterized by particular patterns of soils, climate, water
resources, and landuses. These MLRAs have been used in important statewide
agricultural planning decisions as well as in regional and national planning.
In this publication, we include a discussion and summary of those factors
that affect the transport of water and chemicals after application to a
land surface in the southern region of the United States. Emphasis is placed
on those soil factors that determine the mobility of water and a chemical
within an MLRA. Examples are presented of the persistence and movement
of water and tracer chemicals in the dominant soils within an MLRA. These
examples serve to illustrate the important principles affecting the persistence
and mobility of water and chemicals in the southern region of the United
This Special Report serves as the latest
in a series on the physical properties of soils in the southeastern United
States. Previous publications on southern regional soils include Southern
Regional bulletins numbered 61, 157, 174, 178,219, 262, 263, 265, 266,
267, and 303 along with Oak Ridge National Laboratory publication 1890.
The last seven of these regional bulletins contain field data on soil physical
properties collected by several of the authors of this publication.
AGENCIES AND PRINCIPAL LEADERS
North Carolina Agricultural Research
North Carolina State University
USDA – CSREES Washington, DC
H. Dane*, B.J. Hajek
– J.E. Hook*; Athens – D.E. Radcliffe*, L. West
Perfect*, R.E. Phillips
North Carolina D.K.
Puerto Rico V.
South Carolina V.L.
Yoder*, G.V. Wilson
Munster*, K. McInnes
– Tifton R.K. Hubbard*, C.C. Truman
USDA Ohio – CoshoctonM.J.
Shipitalo*, W.M. Edwards
Mississippi - Alcorn State University
Tennessee – Oak Ridge National
Laboratory R.J. Luxmoore*
Texas – Texas Tech University
This bulletin is dedicated to Dr. George J. Kriz, our Administrative
Advisor during the past years. Dr. Kriz counseled us in our four southern
regional projects, S-124, S-185, S-225, and S-257, where we explored the
transport and fate of water and solutes in soils found in the various landscapes
of the southern region of the United States. Dr. Kriz has shown exemplary
leadership skills and given continuous encouragement to the regional scientists.
He has almost always been present at our regional meetings and has graciously
shared with the research project leaders the latest philosophy, thoughts
and future trends of state and federal administrators in funding regional
research activities. In addition, Dr. Kriz served as a positive role model
for the long-term administrative support of regional research projects.
We are grateful to him for diligent efforts on our behalf.
The editor would like to thank the cooperating state and federal agencies,
principle investigators and each Agricultural Experiment Station Director
for their support in making this publication possible. I would especially
like to thank Drs. M. Horton (USDA-CSREES) and D.L. Nofziger (Oklahoma
State University) for their leadership and support of this undertaking.
The summary of this work was partially supported by grants from USDA/CSREES
96-35102-3774 and USDA/CSREES 95-34275-1319. Sincere appreciation is expressed
to the many authors who contributed their expertise to make this bulletin
an excellent source of information on water and solute transport in soils
of the southeastern United States. Many thanks are also extended to Barnali
Dixon, Marty McKimmey, and Tina Udouj for their efforts in generating the
necessary graphics and compilation of this regional bulletin.
D. L. Nofziger would like to thank Dr. Horton for his encouragement
and financial support. Special thanks are also extended to Dr. Jinquan
Wu and Dr. John Boren for their help in developing maps, applets, CGI scripts,
and databases used in the interactive portions of this document.