The Economics of Planting Density in Rubber Growing

Abstract

i. The plantation rubber industry falls into two fairly distinct sections of about equal size, estates and smallholdings.1 The planting density-the number of trees per surface unit-on smallholdings is much greater than on estates, some 200-300 trees per mature acre against 70-90 trees on estates. It is very generally assumed by European observers,2 and almost universally by European planters, that the higher density on smallholdings reflects the failure of the smallholders to appreciate the adverse effect of this high density on the yielding capacity of the trees. This opinion, which has had important repercussions on smallholders' assessments under rubber restriction, appears to be mistaken. The different planting densities are only one aspect of the fundamentally different economic basis of rubber growing by estates and by smallholders. 2. In the choice of planting density the rational course is not the same for estates and for smallholdings. The latter incur no cash wage costs, being operated by the owner and his family, occasionally assisted by outside labour paid on a share basis. The smallholders attempt to maximise the gross yield per surface unit. On their densely planted holdings the trees are of smaller girth and the yield per tree lower than on the estates, but the yield per surface unit is higher. In Malaya and the Netherlands East Indies (N.E.I.) normal, unrestricted yields on smallholdings are about 475-500 lb. per mature acre, against some 400 lb. on seedling estates. The estate employing paid tappers tries to maximise the cash profit per acre, and it is held that the higher profit per tree resulting from the higher yield per tapper on less densely planted areas more than offsets the reduction in gross receipts due to the lower stand. Indeed, it has been claimed that very low stands, say 40 or So trees per acre, would give such high yields per tree that the profits per acre would be higher than on the more, densely planted areas. There is, however, not enough evidence to support this view, which would be valid only on extreme assumptions. The smallholder would naturally also like to increase the output