Evaluation of soil fertility and erosion in oil palm lands post-replanting: A case study in Sungai Muluk Village, Tanjung Jabung Barat Regency, Jambi Province

Abstract

Oil palm replanting often increases the risk of soil degradation due to soil disturbance, nutrient depletion, and erosion, particularly in highly weathered Ultisols. This study aimed to evaluate soil fertility status and erosion risk across different slope classes in post-replanting oil palm plantations and to assess the implications of conservation practices for sustainable land management. Soil samples were collected from three slope classes (3-8%, 8-15%, and 15-30%) at two soil depths (0-20 and 20-40 cm) for soil physico-chemical analysis. Erosion estimation was predicted using the Universal Soil Loss Equation (USLE). In addition, a conservation scenario analysis was conducted to evaluate the potential effectiveness of improved conservation practices in reducing erosion risk. The results showed that soil fertility status ranged from low to moderate across all slope classes, mainly due to low cation exchange capacity and base saturation. Soil organic carbon, total nitrogen, and available phosphorus generally decreased with increasing slope and soil depth. Predicted erosion rates varied among slope classes, with the highest erosion occurring in the 3-8% slope class (141.48 t/ha/year), primarily due to inadequate conservation practices. Conservation scenario analysis demonstrated that conservation practice improvement, factor (P) from 0.35 to 0.04, reduced predicted erosion up to 88.6% (16.17 t/ha/year), which is below the tolerable threshold. These findings indicated that integrating soil fertility improvement through organic matter management with effective conservation measures can substantially reduce land degradation risks and support the sustainable management of post-replanting oil palm plantations on Ultisols.

Keywords

• erosion hazard
• oil palm replanting
• soil fertility
• Ultisol
• USLE method