METHYL-BROMIDE EMISSION REDUCTION WITH FIELD MANAGEMENT-PRACTICES

Current methods of soil fumigation may allow up to 65% of the applied methyl bromide (MeBr) to escape to the atmosphere. To protect stratosp heric ozone and prevent economic losses from MeBr phaseout there is an urgent need to find alternative fumigation techniques that can reduce MeBr emission. A field experiment was conducted to study and compare the effect of different management methods on MeBr emission reduction. Tested parameters included injection depth (0.25 and 0.6 m), use of p olyethylene or a high-barrier plastic, bare soil, and irrigation. MeBr emission was estimated by sampling for the increase in soil bromide i on. Deep injection increased MeBr degradation and reduced total emissi on. Compared to bare soil, covering with plastic tarp significantly re duced MeBr emission. MeBr emission was reduced to <15% with the high b arrier plastic. Irrigation and tarping enhanced MeBr containment and d egradation. Effective treatment of citrus nematodes,fungi, and yellow nutsedge seeds was achieved for shallow injection with tarp or deep in jection with the high-barrier plastic. The optimal method for pest con trol and MeBr emission reduction appears to be a combined use of the h igh-barrier tarp, irrigation, and deep injection.