INFLUENCE OF ORGANIC MULCH AND MULCH APPLICATION TIME ON THE GROWTH OF OIL PALM SEEDLINGS

This study evaluated the effectiveness of organic mulches oil palm empty bunch refuse (EFB) and sundried Mucuna bracteata cover crop applied at different times (mulching at planting, Mp, and mulching 3 months after planting, M3mp) on the growth of oil palm seedlings at the Nigerian Institute for Oil Palm Research (NIFOR). The experiment was arranged in a Randomized Complete Block Design (RCBD) with three replications. It was a 5 × 2 factorial design comprising five mulch treatments: zero mulch (M1), EFB (6 t/ha) (M2), Mucuna bracteata cover crop (6 t/ha) (M3), EFB + Mucuna bracteata (6 t/ha) (M4), and EFB + Mucuna bracteata (12 t/ha) (M5), along with two mulch application times: mulching at planting (T1) and mulching at 3 months after planting (T2). The growth variables measured included plant height (cm), collar girth (cm), number of leaves, leaf area (cm²), and soil temperature (oC). Results indicated that mulching generally enhanced vegetative growth and reduced soil temperature compared to the control. Among the treatments, EFB + Mucuna bracteata (6 t/ha) at planting (T1) produced the tallest seedlings (86.7 cm), while Mucuna bracteata (12 t/ha) applied 3 months after planting (M3mp) resulted in the shortest seedlings (17.0 cm). Seedlings mulched with EFB (6 t/ha) at planting exhibited significantly larger leaf area (1613.0 cm²) compared to the control and EFB + Mucuna bracteata (6 t/ha) treatments. Additionally, EFB (12 t/ha) applied 3 months after planting (M3mp) produced the highest number of leaves, although this was comparable to other mulch treatments. At 4 months after planting (MAP), seedlings mulched with EFB (6 t/ha) at planting (T1) had the lowest soil temperature (27°C) and were significantly lower than that of EFB (6 t/ha) applied 3 months after planting (31.67°C). Mucuna bracteata (12 t/ha) applied at 3 months after planting (M3mp) did not reduce soil temperature, and mulching with Mucuna (6 t/ha) at planting also resulted in the highest soil temperature (29.57°C). These findings highlight the importance of timely organic amendments in oil palm nurseries, particularly the use of EFB (6 t/ha) at planting to optimize seedling growth and soil conditions.