Rubber-based Intercropping System in Southern Thailand: Its Constraints and Planting Patterns on Sustainable Productivity

Abstract

Due to the low rubber price crisis, smallholders have decided to improve their rubber plantations
to increase returns by investing in alternative sources to provide an alternative income than by using the
standard rubber mono-cropping system. Especially in the South of Thailand, the largest producer of
natural rubber with intercrops on rubber plantations, the regularly planted intercrops are based on two or
more perennial species to increase the land usage capacity and income opportunities. Various objectives
of intercropping are; to earn extra income before and during rubber tapping, to grow their own food for
consumption, to keep as a source of herbal raw material, to keep for using as woody biomass, for ruminants
feeding and for local traditional activities. Moreover, there are many cash crop classification groups which
could be grown between the inter-rows spacing during the mature period, for examples; ornamentals,
vegetables, herbs, forages, fruit trees and woody plants. In addition to these intercrops, root competition

and light intensity have been major factors limiting plant growth and survival due to intra/inter specific
competitions. Additionally, new planting patterns in which more inter-row space and light transmission
should be provided to improve rubber based intercropping systems during the rubber life span. In practice,
two spatial arrangements of planting pattern could be provided to improve light availability in order to allow
long-term intercropping systems without compromising the rubber planting density. Under single row with
a double space planting pattern, rubber will be planted at a spacing of 3.0 m within, and 16.0 m between
rows. Meanwhile, the double rubber row pattern will be planted with a plant spacing of 3.0 m and a double
row spacing of 4.0 m and separated by 14.0 m between the double rows to allow intercropping. Although
rubber-based intercropping productivity might be higher under the rubber mono-cropping planting pattern,
water and nutrient management practices should be concerned with optimizing either as sole rubber trees
or intercrops. For a successful rubber intercropping policy, practical knowledge could contribute to a
better understanding to overcome the constraints limiting productivity in traditional rubber plantations.
Meanwhile, a suitable planting pattern for long-term rubber intercropping should be established to improve
sustainable rubber plantation management and the well-being of rubber smallholders in the coming decade.