Content area
Full Text
(ProQuest: ... denotes non-US-ASCII text omitted.)
INTRODUCTION
Coconut husk is a by-product of coconut growing that has long been used for a variety of purposes. Its fibre is used industrially as a raw material for ropes, mattresses, stuffing for chairs and insulation. Defibring waste (cocopeat) is greatly appreciated as a horticultural growing medium. The hygroscopic properties of coconut husk make it a good water absorbent material that is very effective in increasing the water-holding capacity of a soil in dry periods (Liyanage et al. 1993; Sherin et al. 2004; Subramanian et al. 2006). It can also concentrate nutrients, particularly potassium (K) and chlorine (Cl), which can be recycled in coconut plantations when nuts are dehusked in the field and the husks are left to rot on site (Ouvrier, 1984; Ouvrier et al. 1978; 1985; Teoh et al. 1986).
However, leaving husks to rot at the foot of coconut palms on peat soils has two major negative effects: firstly, it causes a nitrogen (N) deficiency in neighbouring palms, and heaps of husk fragments provide shelter for the insect pest Sufetula, whose larvae attack coconut roots (Bonneau et al., 2007).
In order to benefit from the advantages offered by coconut husk without suffering the drawbacks, we tested coconut husk ash as a fertilizer, and as a possible substitute for imported fertilizers such as KCl.
MATERIALS AND METHODS
The estate (18 000 hectares) is planted on deep peat on the east coast of the island of Sumatra (Riau Province, Indonesia) and belongs to the Riau Sakti United Plantations company (RSUP).
Planting material on the estate consists mostly of PB 121 hybrids (MAWA), at a density of 180 palms ha-1(8 m apart in a staggered equilateral triangle design). The basic unit is a block of 50 ha (500 x 1000 m). The water-table is controlled in the fields by a network of canals and field drains.
Field trials were carried out to test in situ the effect of treatments applied to coconut palms (Bonneau et al. 2007). Coconut husk ash is obtained by simply burning fresh coconut husk, either directly in the field after dehusking harvested nuts, or in an open-air kiln with a roof from which ash is...