Effects of Heavy Applications of Lime to Soils Derived from Volcanic Ash on the Humid Hilo and Hamakua Coasts, Island of Hawaii

Abstract

Soils derived from volcanic parent material are of considerable agricultural importance in the humid tropics. Abundant sources of lime in the form of coral stone often occur in the vicinity of these acidic soils; thus, an understanding of the effects of lime application to such soils is desirable. The soils used in this study are derived from volcanic ash and are located on the humid Hilo and Humakua coasts on the island of Hawaii, where they are used for growing sugar cane. A series of lime phosphate experimental plots was installed on the Hilo and Hamakua coasts, with the aim of increasing the yields of sugar cane. The high aluminum content and the low pH values of these soils present the possibility that toxic amounts of aluminum may be a limiting factor in plant growth. These soils are highly amorphous and have a high capacity to fix phosphates, thus making them sparingly soluble for plant use. It is suggested that benefit to sugar cane because of heavy liming of these soils is due either to the reduction of the toxic effects of aluminum or to improved phosphate availability.