
Algae and Bacteria Influence Herbicide Fate
By Tara
Weaver-Missick June 4, 1999Species of green algae that help break
down soil-applied herbicides could lead to improved soil and water quality,
Agricultural Research Service scientists
report. Microbiologist Robert M. Zablotowicz, with ARS
Southern Weed
Science Research Unit in Stoneville, Miss., discovered the one-celled
organisms while studying microbial populations in three Mississippi watershed
lakes--Beasley, Deep Hollow and Thighman. The study is part of the USDA-ARS Mississippi Delta Management Systems
Evaluation Area (MSEA)
project, which is evaluating farming practices in the 7,320-acre area
surrounding the three lakes. The projects goal is to improve farming
techniques and ultimately enhance soil and water quality in the area. Studies conducted by Zablotowicz and his colleagues indicate that management
practices influence lake microbial populations and their impact on water
quality. Deep Hollow watershed, where intensive conservation practices such as
winter cover crops and reduced tillage are employed, had the lowest sediment
and highest algal populations. These algae, Selenastrum and
Ankistrodesmus, can absorb and break down herbicides, such as atrazine
and fluometuron, commonly used in corn and cotton production. Another major finding, according to Zablotowicz, is that a specific group of
bacteria, called fluorescent pseudomonads, can degrade metolachlor, propanil
and trifluralin--three commonly used herbicides in the MSEA area. These
bacteria and algae can reduce herbicide longevity in Mississippi Delta lakes. Zablotowicz and other ARS scientists will continue to study how microbes,
like algae and bacteria, help improve soil and water quality. Knowledge gained
from the MSEA study will ultimately be used to develop management techniques
that help maintain diverse aquatic microbial populations that can degrade
agrochemical pollutants. ARS is the U.S. Department of
Agricultures (USDA) chief scientific research agency. Scientific contact: Robert M.
Zablotowicz, ARS Southern Weed Science Research Unit, Stoneville, Miss.,
(phone) 601-686-5260, (fax), (601) 686-5422, [email protected]. U.S. Department of Agriculture | |