FOREWORD H.D. Scott 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 States.
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.
COOPERATING AGENCIES AND PRINCIPAL LEADERS
Administrative Advisors
G.J. Kriz, Associate Director North Carolina Agricultural Research Service North Carolina State University
and
Maurice Horton USDA – CSREES Washington, DC
State Institutions
Alabama J. H. Dane*, B.J. Hajek
Arkansas H.D. Scott*
Georgia Tifton – J.E. Hook*; Athens – D.E. Radcliffe*, L. West
Kentucky E. Perfect*, R.E. Phillips
Louisiana H.M. Selim*
North Carolina D.K. Cassel*
Oklahoma D.L. Nofziger*
Puerto Rico V. Snyder*
South Carolina V.L. Quisenberry*
Tennessee R.E. Yoder*, G.V. Wilson
Texas C. Munster*, K. McInnes
USDA Georgia – Tifton R.K. Hubbard*, C.C. Truman
USDA Ohio – CoshoctonM.J. Shipitalo*, W.M. Edwards
Other Cooperators
Mississippi - Alcorn State University A. Johnson*
Tennessee – Oak Ridge National Laboratory R.J. Luxmoore*
Texas – Texas Tech University R. Zartman*
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.