Using Cow Manure on Immature Rubber (Hevea brasiliensis Muell. Arg.) (Supervised by YAKUP and TEGUH ACHADI). Fertilization is an important component for growth of rubber plants, application and doses of fertilizer should to increase girth, bark thickness, growth of lateral roots, and decrease weeds to supporting that growth. The research was doing on September 2014 to February 2015 in the Ibul …