Introducing permanently an associated crop in rubber plantations may improve biodiversity and soil cover, optimize resource use, and diversify farmer's income. However, the associated crop may also compete with the rubber trees for resources such as space and water. The case of bamboo-rubber agroforestry system is peculiar, as bamboos present features common to both grasses and trees, they grow fast and are considered strong competitors for water. Soil organic matter and water content, bulk density, root distribution, canopy cover, and rain interception were studied on farm to understand the effects of bamboo intercropped in rubber tree plantation, compared with rubber monoculture in southern Thailand. In the rubber-bamboo association, soil water content was lower in shallow depth, whereas it increased in deeper horizons. There was no significant difference in fine root distribution of rubber trees with or without bamboo; therefore, the total root density (rubber + bamboo) was higher in the association. Canopy cover and rain interception were also higher in association with bamboo. Further studies are required to better understand in this system, the balance between higher superficial water use and increased water retention in lower soil depth, together with more specific studies on soil properties, tree development, and latex yield.