Fertilizing of young rubber in the Cameroons.

Abstract

The growth response to (NH₄)₂SO₄, phosphate rock and KC1, given in all combinations at increasing annual rates of up to 24 oz/tree until the seventh year after planting, was measured by the girth increase of Hevea in three soils formed from the same parent material but possessing different nutrient status and depths to the root-impeding layers. Despite poor nutrient supply in the soil, lack of rooting depth had a greater effect on growth than had nutrient availability; while abundant nutrient supply reduced the unproductive period by half a year, this reduction was at least one year in shallow soils. Annual fluctuations in yield were reduced by balanced application of small amounts of fertilizers. Fertilized trees, opened up at 18-inch girth, yielded 430 lb/acre in the first year whether given balanced fertilizer or not; in the second year, trees given balanced fertilizer yielded 700 lb as compared with 580 lb without fertilizer. (Abstract retrieved from CAB Abstracts by CABI’s permission)