Evaluation of Four Soil Conservation Practices in a Non‐Terraced Oil Palm Plantation

Abstract

In Malaysia, four soil conservation practices are often recommended for non‐terraced oil palm (Elaeis guineensis Jacq.) plantations. These practices are oil palm empty fruit bunches (EFB), Ecomat (a compressed EFB mat; ECO), and pruned oil palm fronds. These three oil palm residues are used as organic mulching materials. The fourth method is silt pits (SIL) which are soil trenches to collect nutrients from runoff water and later redistribute them back into the soil. Nonetheless, the relative effectiveness of these four methods in improving soil and oil palm properties have never been studied. A 3‐yr field experiment was consequently conducted to determine their relative effects on increasing soil chemical properties (pH, cation exchange capacity, organic C, total N, available P, and exchangeable K, Ca, and Mg) and oil palm nutrition levels (N, P, K, Ca, and Mg). Biomass decomposition rate and nutrients release rate in the field by the three mulching materials were also determined. Results showed that EFB mulching was significantly better than the other three soil conservation practices in improving nearly all of the measured soil and plant parameters. Empty fruit bunches was most effective partly because of the combined effects of higher amounts of dry matter added and the higher nutrient concentrations in the EFB than in other mulching materials. Silt pitting was found not to be as effective as EFB because SIL could only trap and return nutrients back into the soil, whereas EFB could do both: trap nutrients and release additional nutrients into the soil as it decomposes.