Chemical and Physical Control of Bracken Fern: Effects on Mulanje Mountain and Nyika Plateau Soils

Pteridium aquilinum (bracken fern), a prevalent invasive species, dominates high‐elevation grasslands on Mulanje Mountain and Nyika Plateau in Malawi, displacing native vegetation, eroding biodiversity, and disrupting soil nutrient cycling within vital Afro‐montane watersheds. This four‐year field experiment employed a randomized complete block design (RCBD) with two sites: Mulanje Mountain and Nyika Plateau, designated as blocks and five replicates per treatment. Each experimental plot measuring 35 × 29 m was subdivided into 30 discrete 5 × 5 m quadrants buffered by 1 × 1 m buffers to minimize edge effects, with treatments comprised physical (mowing, slashing) and chemical (Forester, Eco‐Imazapyr, lime) interventions, alongside untreated controls. Random soil samples (0–15‐cm depth; six subsamples per quadrant) were evaluated pre‐ and posttreatment for pH (CaCl 2 ), soil organic carbon (SOC) stocks via the Walkley–Black titration, total nitrogen (N) by the Kjeldahl digestion, available phosphorus (P) via the Mehlich‐3 extraction and colorimetry, exchangeable Ca and Mg, and C:N ratio. One‐way ANOVA detected significant treatment effects ( α  = 0.05) for pH ( p < 0.01), SOC, available P, and Mg. Lime elevated pH by 14.5% (4.08 to 4.67 in CaCl 2 ), surpassing slashing (11.6%), Eco‐Imazapyr (10.4%), Forester (9.7%), and mowing (7.4%), while SOC stocks increased most under Forester (64.4%; 58.14 to 95.62 MgCha −1 ) and mowing (66.7%); available P rose universally from 3.2 to 3.8 mgkg −1 baselines, peaking at 39.2 mgkg −1 (Eco‐Imazapyr) and 32.3 mgkg −1 (mowing), even in controls (26.7 mgkg −1 ) but Mg declined sharply including Forester 58% from 1.12 to 0.47 cmol(+) kg −1 ), with nonsignificant trends in C:N elevation under physical methods (mowing: 7:1 to 12:1) and N gains under herbicides. These findings elucidate treatment‐specific enhancements in soil fertility (pH, SOC, and P), alongside trade‐offs (Mg), furnishing evidence‐based protocols for P. aquilinum suppression, native grassland restoration, and heightened ecosystem resilience in tropical montane soils.