Mulching polybag oil-palm seedlings with bunch refuse, shredded polythene, sawdust, grass, wood shavings and kernel shells ‘all-year’ or throughout the nursery period (May–May), in the ‘wet-season only’ (May-November), and in the ‘dry-season only’ (November–May) resulted in soil temperature differences which did not exceed 1 °C at 5 cm polybag depth. This was attributed to the high rainfall which reduced considerably the soil temperature differences between mulched and unmulched soil in the wet season and to the enhanced leaf canopy in ‘all-year’ and ‘wet season only’ mulchings which shaded soil in polybags in the dry season.
The mulch materials and times of their application significantly influenced growth variables like number of leaves, plant height and stem girth, and number of blast-affected seedlings at 6 months after sowing (wet season). By 12 months after sowing, all growth characters measured were similar in the various treatments, indicating compensatory growth at the latter half of the growing period (dry season).
N, P, K, Mg and Ca contents of seedlings were not significantly affected by either mulch materials or times of their application. The results emphasize that mulching for at least 6 months during the early or late nursery period and the use of various mulches may be beneficial to oil-palm seedling growth.