Growth of immature rubber trees planted in abandoned paddy field and upland areas in relation to soil properties and leaf nutrients

摘要

Although lowland area is not suitable for rubber production, rubber trees are currently extended into abandoned paddyfields. This study investigated rubber growth, soil properties and leaf nutrients of immature rubber trees planted in lowlandand upland plantations. Nine soils (0-30 cm depth) in both poor and good productive lowland and upland plots from threedistricts in Songkhla province were sampled for some physical and chemical analysis and leaf samples were also performedfor nutrient analysis. Growth of rubber trees was recorded. Results showed that soil in the lowland had finer texture comparedwith the upland soil, resulting in tendency of higher organic matter, total N and CEC. In addition, high DTPA Mn and soilmottles are generally found in a profile of the lowland soil. However, immature rubber trees planted in the good productivelowland plot grew as similar as in the upland soil. Whereas, in the poor productive plot, rubber growth was limited andconcentrations of leaf N, P and K tended to be lower than those in the upland soil, in contrast to leaf Mn. These findingsrevealed that soil mottles within 0-30 cm are markedly indicator of limitation of the lowland for rubber cultivation.