The land between row of immature rubber period has a potential to produce soybean. However, this soil type has a high aluminum (Al) toxicity and soil acidity. Soil quality improvement by using liming and introducing adaptable variety are some options to increase soybean yield as rubber intercrops. Field experiment was conducted to study the effect of rubber+soybean intercropping system on the growth of rubber girth and to study the effect of liming and introducing adaptable variety of soybean

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... increase soybean yield as rubber intercrops. The experiment was conducted at the Sembawa Research Station from January to March 2016. The research was arranged in a split-plot design with three replicates. The main plots were two levels of lime i.e. 0 ton/ha and 2 ton/ha, while sub plots were two soybean varieties, i.e. Tanggamus and Wilis. Observation of rubber trees was conducted using simple random sampling method, comparing the rubber trees growth of soybean intercropping system with the rubber trees growth of monoculture system. The results showed that soybean and liming improved soil quality in between row of rubber trees IRR 118 clone. The rubber girth of soybean intercrooping system more significantly than the rubber girth of monocultur system. The liming increased the growth and yield of soybean at two tested varieties and significantly increased soil pH and reduced soil Al saturation. Tanggamus was more adaptive than the Wilis variety on acid soil.