Author : Auxtero, Edgardo A.

Summary : The influence of two terrain classes (i.e. 5 -25 percent and 25 - 50 percent slopes) on soils developed from two parent materials (i.e. granite and sedimentary rocks) on the growth and yield of rubber (Hevea brasiliensis) after four years of tapping was evaluated by using the field data, viz. girth and yield of rubber from 1980 to 1983, obtained from the Federal Land Consolidation and Rehabilitation Authority (FELCRA) Scheme at Sendayan Negri Sembilan. Rubber grown in soils derived from sedimentary rock and located on steep slopes (25 - 50 percent slope) after four years of tapping showed significantly bigger girth than those grown in the same soil on undulating to rolling terrain ( 5 - 25 percent slope). The mean monthly and annual dry weight of rubber after four years of tapping was significantly higher in areas planted in soil derived from sedimentary rock and located on steep terrain. The growth of rubber, as influenced by the interaction of parent material and slope over time, was not significant during the same period of tapping. However, the overall rubber yield was significantly higher for rubber planted in soils derived from sedimentary rocks and located on steep terrain than in soils derived from granite located similar terrain.