MANASOTA & PEACE RIVER BBDs Meeting Notebook 10-21-09.docx

B240
Reducing Water Consumption in Polyethylene-Mulched Tomato and
Pepper Fields after Methyl Bromide Pha
Project Type Basin Initiatives
AOR(s)
Water Supply
Basin(s) Alafia River, Peace River, Manasota
Cooperator(s)
University of Florida
Project Manager COHEN, RON
Task Manager(s)
Status Ongoing
Description
Tomato and pepper producers use methyl bromide (MBr) to fumigate their beds before production. About 50 to 95% of
the MBr that is injected in to the soil can eventually enter the atmosphere and damage the earth's ozone layer. EPA's
Clean Air Act (Amendments of 1990) requires that MBr and other similar chemicals be phased out. The loss of MBr
has a major impact on the production practices of tomato and pepper producers in our District and can cause an
increase in their water use. This project will provide the water use information needed to address this change in
technology.
Benefits
Water use information from this project will be used by growers to save water and in the District's conservation,
planning and permitting programs. This will help preserve ground water, reduce off-site discharge of pesticides and
nutrients and flooding and improve water quality. Currently there are about 152,000 acres in the District that are
permitted for the production of tomatoes and peppers. These sites are permitted for about 335 Mgd. The number of
acres planted and their water use will change annually based on market and climatic conditions. Assuming that results
from this project will help reduce at a minimum 5% of the permitted water, the savings would be about 17 Mgd.
Costs
This project will cost $150,000. About 98% of the permitted tomato and pepper production is divided between three
basin boards. Project costs have been prorated between the Alafia (22%), Manasota (67%), and Peace River (11%)
Basin Boards. Funds will be budgeted in FY2007 and FY2008, Alafia will budget $33,500, Manasota will budget
$11,000 and the Peace River will budget $5,500 each year.
Additional Information
Tomato and pepper production relies on a relatively large quantity of water to provide the necessary soil moisture to
establish, grow and harvest both crops. These commodities are grown with either seepage or seepage plus drip
irrigation. Both systems require constant irrigation to maintain the water table relatively shallow during crop
establishment, which reduces the soil storage, increases the risks of flooding, off-site discharge and nutrient leaching.
A quick calculation of the irrigation volumes required to produce one acre of tomato indicates that between 4 and 6
ac-inches per acre of water are used to establish and maintain the crop with seepage irrigation. Most existing
recommendations for tomato and pepper production were generated when MBr was a viable option for bed
fumigation. Also, relatively inexpensive low density-polyethylene mulch (LDPE) was used and current environmental
regulations about water run-off and nutrient leaching were not always considered in research projects. Current
production practices have changed considerably since past water and production requirements were developed. This
project will look at the new technology and changes in growing practices. The University of Florida and the State of
Florida have started a vigorous campaign to address the phase out of MBr and the development of Best Management
Practices (BMP). Within that context, the use of new developments in fumigation techniques and mulch materials that
tend to reduce water use makes sense. Current MBr alternatives, such as 1,3-dichloropropene + chloropicrin (1,3-D +
Pic; Telone C-35) and methyl iodide (MI; Midas), have poor efficacy against soil borne pests when applied in saturated
soils, as it was customary for MBr, because these molecules can bind more tightly to water molecules than MBr.
Another reason that justifies exploring reduced water irrigation programs is the use of higher retentive mulch films
(virtually impermeable (VIF) and metalized films). These mulches retain more moisture in the planting beds than
previous materials, which adds another component to fumigant and water management in tomato and pepper
production. No defendable scientific research has been conducted in Florida to reduce water irrigation volumes for
tomato and pepper by combining the lower water requirement of new fumigants and the higher water retention of new
mulch films. This project will determine the effect of varying water management regimes on tomato and pepper
production, and assess the effect of high retentive mulches and MBr alternatives on the water volumes necessary for
tomato and pepper irrigation.
021 - Manasota Basin 149