0 Residue Ain’t Possible!!!<BR>1 ppm = one second in 12 days <BR>1 ppb = one second in 32 years <BR>1 ppt = one second in 32,000 years <BR>1 ppq = one second in 32,000,000 years <BR> <BR>1.0 lb. Ai/acre = 1.0 ppm in upper 3 inches<BR>