Tropentag, September 10 - 12, 2025, Bonn "Reconciling land system changes with planetary health"

Enhancing soil fertility and polyphenol composition in highland arabica coffee through agricultural biochar application

¹Chiang Mai University, Dept. of Plant and Soil Science, Thailand
²University of Hohenheim, Inst. of Agric. Sci. in the Tropics, Acrocomia Hub, Germany
³Mahidol University, Fac. of Environment and Resource Studies, Thailand
⁴Chiang Mai University, Dept. of Highland Agric. and Natural Resources, Thailand

Abstract

This study investigated the influence of biochar derived from highland agricultural residues on soil physicochemical properties and the polyphenolic profile of Coffea arabica beans during the harvest season in northern Thailand. The experiment was conducted at the Nong Hoi Highland Agricultural Research Station in Chiang Mai Province, a region renowned for Arabica coffee cultivation. Biochar was incorporated into the soil at a rate of 2.5% (w/w). Five coffee plants received the biochar treatment, while five untreated plants served as controls. Post-application assessments revealed a marked improvement in soil chemistry, with soil pH increasing to 5.99. Additionally, extractable potassium and magnesium concentrations significantly increased to 106.20 ± 3 mg kg^-1 and 29.48 ± 0.15 mg kg^-1, respectively, indicating enhanced nutrient availability. In terms of bean quality, biochar application resulted in a significant increase in catechin content (22.16 ± 0.40 mg 100g⁻¹) compared to the control (19.07 ± 0.75 mg 100g^-1; p≤0.05). This elevation in catechin levels may be attributed to improved micronutrient status and enhanced rhizosphere microbial activity, notably from siderophore-producing and iron-solubilising bacteria, which are known to promote flavonoid biosynthesis. Although not statistically significant, slight increases were also observed in the concentrations of gallic acid (0.36 mg 100g⁻¹), caffeic acid (2.03 mg 100g⁻¹), naringin (0.73 mg 100g⁻¹), rosmarinic acid (0.11 mg 100g⁻¹), o-coumaric acid (0.09 mg 100g⁻¹), and quercetin (0.10 mg 100g⁻¹) in the biochar treatment when compared to the control. In conclusion, the application of biochar not only enhanced soil fertility but also contributed to the improvement of health-promoting compounds in Arabica coffee beans. These findings support the use of biochar as a sustainable soil amendment for enhancing both soil health and bean quality in highland coffee production systems.

Keywords: Arabica coffee, Biochar, Highland , Polyphenolic compounds

Contact Address: Nuttapon Khongdee, Chiang Mai University, Dept. of Highland Agric. and Natural Resources, Huay Kaew Road, 50200 Chiang Mai, Thailand, e-mail: nuttapon.kcmu.ac.th