Soils of some Quaternary marine terraces in the British Solomon Islands Protectorate and some problems in their agricultural use

Abstract

The Quaternary marine terraces discussed are formed predominantly from coral, but the soils overlying them are strongly influenced by subsequent volcanic deposits. Six “"land systems"” are defined and morphological, chemical, and physical properties of their main soils are detailed. The mineralogical properties of soils and parent materials indicate varied stages of weathering, and these are reflected in plant nutrient levels.

Agronomically the most important feature common to all the soils is the extremely low level of subsoil potassium. Some of the soils also require sulphur, and possibly manganese, for coconuts. With shifting cultivation, incoi porating long fallows, food cropping can be sustained, but if cultivation is prolonged, potassium fertilising is essential for optimum growth.