Articles
USE OF GAS-TIGHT PLASTIC FILMS DURING FUMIGATION OF GLASSHOUSE SOILS WITH METHYL BROMIDE – I. SIGNIFICANCE OF PERMEATION AND LEAKAGE FOR THE EMISSION INTO THE OUTSIDE AIR
In the first trial, Saranex 11 plastic film1 and low density polyethene (LDPE) were compared.
The dose of methyl bromide was 103 g m-2 and the cover time was five days.
The emissions of methyl bromide for the Saranex film and the LDPE film after one day were 11% and 33% of the dose, respectively.
For the total cover period of five days these percentages were 20% and 56%. The total emissions to air after 21 days, based on measurements of methyl bromide and bromide in the soil, were 83% and 87%, respectively.
In the second trial only Saranex 11 was used.
The methyl bromide dose was reduced to 20 g m-2 and the cover time extended to 10 days.
The losses of methyl bromide to the air after the first day and after 21 days were 5% and 21% of the dose, respectively.
In the third trial 5 new gas-tight films1 (Waloplast Combi XX 433B, Zeelon 305, Saranex XZ 86 156, Hostaphan RWN 23 and SBW CX 4-Y181) and Saranex 11 were compared.
The methyl bromide dose was again 20 g m-2 and the cover time was 10 days.
The total emission of methyl bromide to air after 21 days, based on measurements of bromide in the soil, ranged from 29% to 48% of the dose.
The losses of methyl bromide to the air could be attributed to the permeability coefficients for methyl bromide of the films and to the rate of air exchange under the films.
From the experimental data and additional computations it was concluded that the dose of methyl bromide can be substantially reduced, without affecting the concentration-time product in the soil if properly laid down gas-tight films are used instead of LDPE.
1) Mention of company names or trade names does not constitute endorsement or recommendation for use.