Enhancing barren agricultural soil, autumn-grown okra (Abelmoschus esculentus (L.) Moench) yield and mineral content using rice husk biochar and organic fertilisers
Contemporary agricultural systems are increasingly embracing organic inputs as a sustainable and effective alternative. These inputs contribute significantly to agroecosystem health, enhance ecological resilience and support sustained crop productivity. However, limited studies exist regarding the effects of biochar (B) and organic fertilisers (F) on fruit crops when cultivated in the acidic soils of Pingtung, Taiwan. To address this gap, a study was conducted during 2024–25 to evaluate the impact of rice husk B and F on soil properties, yield and mineral content of okra. The experiment was designed using two-factor factorial treatments within a randomised complete block design (RCBD), with 3 replications under greenhouse pot conditions. Treatments consisted of varying combinations in grams of B and F, produced from a mixture of pig, cow and chicken manure: B50 + F0, B0 + F75, B25 + F25, B50 + F25, B50 + F50 and B50 + F75, alongside an unamended control (CK) that received 0 g of either B or F. Following 90 days of amendment, the B50 + F75 treatment significantly elevated soil pH to 5.93 relative to the CK treatment, whereas B0+F75 recorded the highest soil organic matter content of 3.95 %. B25 + F25, B0 + F75 and B50 + F25 significantly increased soil-available phosphorus (P) (253.82 mg/kg), calcium (Ca) (1047.48 mg/kg) and magnesium (Mg) (97.96 mg/kg) compared with the CK respectively. Microbial activity was also enhanced, with bacterial populations peaking at 9.39 log CFU/g in B50+F25 and fungal populations reaching 8.10 log CFU/g in B50+F50. Interestingly, the B50+F75 treatment significantly increased potassium (K) levels in both the soil and okra fruits compared with the CK. In contrast, fruits from the control exhibited higher iron (Fe) content (12.47 mg/100 g). The heaviest fruits (156.13 g plant-1) were harvested under B50 + F50, while fruit number peaked at 9 per plant in B50 + F25. Overall, the combined use of B and F enhanced soil health and boosted okra productivity, demonstrating their strong potential for restoring infertile soils.