High soil Mn and Al, as well as low leaf P concentration, may explain for low natural rubber productivity on a tropical acid soil in Vietnam

The aim of the current study was to identify major soil and leaf factors accounting for low natural rubber (NR, Hevea brasiliensis) productivity on tropical acid Acrisols in Vietnam. Twenty NR plots were measured with NR productivity, leaf factors (N, P, K, Ca, Mg, Mn, Cu, Fe, and Zn), soil factors (pH, particle size distribution, total C, N, P, K, exchangeable K, Ca, Mg, Al, Mn, Fe, Zn, available P). Cluster analysis showed that NR productivity could be separated into three clusters with low (23.2), medium (38.2), and high (61.3 g tree−1 harvest−1) yield. High-yield cluster had higher leaf P concentration and soil pH, while low-yield cluster had higher leaf Mn, soil exchangeable Al, and Mn concentration. Simple and multiple linear regression analysis applied with backward elimination procedure suggested that leaf and soil toxic concentration may be responsible for low NR productivity in the study soil.