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Methyl Bromide Fumigation

September 18, 2009

It’s the time of year we all dreaded as kids. The days have become shorter, the temperatures cooler, and school is back in session. However, for many golf courses this time of year brings with it the opportunity for major renovations. Soil fumigants, such as methyl bromide, can play a pivotal role in the renovation process. The United States Golf Association (USGA) recommends soil sterilization during the renovation and building process in order to reduce competition from weed seed, soil borne insects, nematodes, as well as soil borne diseases. For decades turf managers have relied on the fumigant methyl bromide as an affordable and effective soil sterilant.

Methyl bromide is an organobromine compound with the chemical formula CH₃Br. This compound is produced in nature as well as in the lab. It is estimated that approximately 1 to 2 billion kilograms of methyl bromide is naturally produced by marine organisms annually. In the lab, methyl bromide is produced by reacting methanol with hydrogen bromide. Methyl bromide is a colorless, tasteless, odorless, and nonflammable gas that is registered with the EPA as an herbicide, fungicide, nematicide and insecticide. The chemical chloropicrin is often added to methyl bromide as an odorant, in small amounts, and as a fungicide in ratios containing more than 50% chloropicrin.

There are three main factors that influence the efficacy of methyl bromide; soil moisture, soil temperature, and soil tilth.

· Soil Moisture: Soils with too much, or too little moisture can reduce the efficacy of methyl bromide fumigation. When soils are too wet, the fumigant can become diluted, reducing its sterilizing potential. However, soils that are too dry also pose a problem. Soils that don’t have enough moisture tend to allow the methyl bromide to move through the soil profile too quickly. The soil should be kept wet for at least one week prior to the fumigation to allow for the germination of weed seeds. Just before the fumigation is to take place, the soil should be dried to the equivalent of slight dampness.
· Soil Temperature: The higher the soil temperature, the easier it is for methyl bromide to vaporize. At soil temperatures above 40°F, methyl bromide will readily vaporize and diffuse through the air and soil.
· Soil Tilth: Methyl bromide works the best when applied to loose, tilled soils that are free of weeds and other organic debris. Soils should also be cultivated prior to fumigation. The depth at which the soil is cultivated will be approximately equivalent to the depth at which the methyl bromide penetrates. For the best results, a penetration depth of 8 to 10 inches is recommended. Areas that are under vegetation should be scalped and aerified before the fumigation process.

 

 

 

There are two methods for methyl bromide application; the hot gas method and the tractor applied method. Both methods require a certified applicator and commonly consist of application rates from 100 to 400 lbs of active ingredient per acre. The plastic coverings can be removed from the treated areas in as fast as 3 hours per fairway or 5 hours for 18 greens. The hot gas method was recently used at the ISU Horticulture Research Station to fumigate an area that had previously been established to roundup ready bentgrass.

· Hot Gas Method: The hot gas method is used whenever the mechanical application method is not an option due to space, access, terrene or no till application. Usually treats 120,000 ft² per day.

Step 1: T-tape drip tubing is placed at 6 ft. intervals assuring even distribution of the gas over the entire area to be treated.

 

 

 

 

 

 

Step 2: Hand lay polyethylene tarps over the treated area securing seems with quick dry fumigant adhesive and covering the edges with dirt or a layer of pre-cut sod.

Step 3: Methyl bromide is forced through a heat exchanger and into the drip tubing. Scales are used to determine the precise amount of fumigant used.


 

 

 

Step 4: Polyethylene tarps can be removed after 48 hrs. or when the methyl bromide concentrations are below 5ppm.

· Tractor Applied Method: The tractor applied method is used any time the undulation and area allow for its implication. Each machine is capable of treating approximately 1 large par 5, 2 par 3’s, 250,000 ft² of sports field, or 20 acres of sod farm per day. Each machine injects methyl bromide 8 to 10 inches deep through solid knives. Once the methyl bromide is injected, the machine covers the soil with high barrier polyethylene tarps.

 

Methyl bromide has been a very effective chemical for sterilizing soil systems. However, methyl bromide is currently being phased out due to its potential harm to the ozone layer and human health. Soil sterilization, never the less, will remain a common practice as it promises to prolong the development of problematic weeds, soil borne diseases, nematodes, and soil borne insect problems in newly established turf. For more information on mehtyl bromide fumigation visit http://www.hendrixanddail.com/index.asp

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USING GPS TO MAP SOIL CONDITIONS IN TURF AREAS-ZACH SIMONS

August 10, 2011

The following is a post from Zach Simons. Zach is working on a masters degree through the master of Ag. program with a specialization in turfgrass science. He is working this summer with Dr. Van Cline at Toro in Minneapolis on a very interesting project that involves the mapping of soil conditions in turfgrass areas using remote sensing and GPS (global positioning system) technology. This is part of his creative component for his MS degree.

If you get Golf Course Management, you will find an article on this technology by Dr. Cline and Dr. Carrow of the University of Georgia in the August issue.

From Zach:
The increased emphasis on reducing water usage in the turf industry has increased the need for site-specific management. Toro has been developing a product called the Precision Sense 6000 (PS 6000) that can give site-specific soil information in turfgrass. The PS 6000 is a mobile sensing machine that measures soil moisture, soil salinity, soil compaction, and turf vigor. It is designed to be used on golf course fairways and athletic fields. A sensor that measures soil moisture, soil salinity, and soil hardness is attached to a rotating arm on the machine. A spectrometer measures the turf vigor by measuring reflected energy from the turf canopy at a wavelength in the red area in the visible spectrum and a wavelength in the near infrared portion of the spectrum.

The PS 6000 is pulled by a heavy-duty workman set to a speed of 1.9 miles per hour (mph). The machine moves at a speed of 1.9mph so samples are taken every 8 feet with a spacing of 8 to 12 feet between adjacent passes. Data on an average par 4 fairway can be collected in 45 minutes and it takes a day and a half to 2 days to collect data on an entire golf course.

A GPS system is used on the PS 6000 to give the specific site where data was collected. Once the data is collected and processed the results are displayed on Google Earth. Google Earth allows a person to zoom in on a specific hole on the course to analyze the data. Multiple layers can also be displayed on Google Earth so a person could compare the relationship from soil compaction to soil moisture.

Data collection with the PS 6000 should occur at a time when the golf course or athletic field is relying on the irrigation system to water the turf. This is so the data collected reflects the coverage of the irrigation system. When data is collected at that time, it can show areas on fairways that are getting over-watered or under-watered by the irrigation system. An irrigation audit can be performed with the data collected. The audit is performed by determining if the soil has the desired volumetric water content from irrigation. The audit can show many irrigation heads around the golf course that may have problems and the superintendent can make the proper adjustments.

The service that the PS6000 provides will be sold through Toro distributors once it is ready for commercial use. A distributor will have a machine and when a golf course buys the service the distributor will come to the golf course or athletic field and sample the turfgrass. When the PS6000 is ready for commercial Toro’s distributors in California and in the Carolina’s will offer the service first. Toro plans on expanding this service so that more distributors in the U.S. and worldwide will have machines and more customers will have access to the PS6000.

The pictures attached show the results of the data the PS 6000 collects. The first picture is soil moisture, the second picture is soil compaction, and the third picture is turf vigor.

Soil Moisture and Soil Compaction Data

 

The video attached is of a previous version of the PS 6000. The version of the PS 6000 that will be sent to distributors is equipped with a foamer so the user of the machine can see the previous passes

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