Afiqur R. Khan, University of California, Riverside, 450 W. Big Springs Rd, Riverside, CA 92507, Husein A. Ajwa, University of California, Davis, UC Davis c/o USDA-ARS, 1636 East Alisal St., Salinas, CA 93905, and Shad D. Nelson, Texas A&M University, Kingsville, MSC 228, Kingsville, TX 78363-8202.
The phase out of methyl bromide (MB) has led to increased use of chloropicrin (CP) for soil fumigation. Drip fumigation is a relatively new practice that involves the use of drip irrigation lines to deliver fumigants into soils. Surfactants (emulsifiers, EM) are needed to keep the fumigant in water suspension for adequate distribution in the irrigation lines. An emulsifier can alter the natural behavior of the pure chemical, thus altering the soil fumigant's physico-chemical properties. This study investigated the influence of formulated CP with 7 different commercial EM on the adsorption and transformation in three different soils. All formulations were weakly adsorbed by soil and showed varying distribution coefficient (Kd) values for the different soils. Degradation of the formulations was affected by temperature following a first-order equation. Degradation half-life (t1/2) varied in different formulations. This study identified several surfactants that will form a stable emulsifiable concentrate formulation of CP, and enhance the distribution of CP in the irrigation lines.
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