Residues and Persistence of Azadirachtin in Cotton Lint Seed Oil and Soil

A commrcially available neem formulation (0.3%) was sprayed on cotton kapas and soil samples @ 20 ppm and 40 ppm of azadirachtin. Analysis of the cotton kapas samples revealed the presence of 0.18 to 0.2 mg g⁻¹ and 0.38 to 0.40 mg g⁻¹ of residues at 20 ppm and 40 ppm dosage, respectively, after 2 hours. After 12 h, the residues dissipated to below detectable level (<0.02 ppm). Analysis of soil samples collected 2 h after the spray showed traces of azadirachtin in all treatments, subsequently, after 6 h became below detectable level. The DT₅₀ in different substrates observed were in the range of 3.03 h and 3.72 h in fourth spray and 2.38 h and 4.32 h in fifth spray.