DDT moratorium in Arizona-agricultural residues after 1 year.

: The moratorium on agricultural use of DDT in Arizona that began in January 1969 proved very effective during the first 7 years of enforcement. Residues on green alfalfa declined significantly to a probable inherent level of 0.02 ppm wet weight. Soil residues of sigmaDDT-related degradation products declined significantly, averaging 23 percent; residues in desert soils declined 60 percent. The sigmaDDT half-life in irrigated soils was about 7 years; it decreased to 2.5 years in nonirrigated soils.