Abstract
Extensive oil palm plantations have great potential for intercropping systems. One promising legume compatible with oil palm is
Canavalia ensiformis
(jack bean), due to its strong agronomic characteristics on marginal land. It tolerates arid and acidic conditions, possesses deep rooting ability, and contributes to nitrogen fixation, thereby improving soil structure. The advantages of
Canavalia ensiformis
were evaluated using an intercropping model with different fertilizer combinations on oil palm replanting land after coal mining. A completely randomized design was used to assess three fertilization treatments: F0 (control, no dolomite or manure), F1 (2 t dolomite + 5 t layer manure ha
-1
), and F2 (4 t dolomite + 5 t layer manure ha
-1
). Soil sampling was conducted before planting and after seed harvest (150 days after planting). Samples from nine points per plot were homogenized into three composite samples per treatment, with each plot serving as the experimental unit (n=3 per treatment). Intercropping combined with F2 fertilization enhanced soil pH to a neutral level of 7.20, increased organic carbon to 0.65% with carbon sequestration reaching 37.76 t ha
-1
, and improved total nitrogen to 0.07%. Phosphorus availability also increased (Bray P: 6.4 ppm; potential P: 33.1 mg 100 g
-1
). Exchangeable bases showed positive changes (K: 0.08 cmol kg
-1
, Ca: 3.03 cmol kg
-1
, Mg: 0.54 cmol kg
-1
), while CEC reached 4.19 cmol kg
-1
. Applying F2 effectively restored soil fertility by improving pH, nutrient availability, and carbon sequestration, aligning with regenerative agriculture principles for reclaiming degraded post-mining oil palm land. However, these findings represent preliminary evidence from a single location and short-term observation; longer-term, multi-location studies are needed for validation.