LAHORE - The Agriculture Department has advised cotton growers to select fertile loam for maximum produc-tion of the crop.  Farmers should only use certified cotton varieties for sowing. He said BT variety Ali Akbar-703 could be sown from March till April 15, Nelum-121 from March to April 30, Sitara-008 from March to May 15, MG-6 from April to May 15, IR-3701, Ali Akbar-802 and IR-1524 from April 15 to May 15.