Evaluating the effect of pyrolysis temperature on the physio-chemical properties of banana (Musa spp.) peduncle biochar derived from three different cultivars

Introduction

Banana (Musa spp.) is a large, perennial herb cultivated as an annual crop, globally in the tropical and subtropical regions, and belongs to the Musaceae family. The plant is characterized by a succulent pseudostem, broad leaves and a corm with fibrous root system that collectively generate substantial biomass residues during the crop cycle. After the harvest, almost 60% of banana biomass is remains as waste including pseudostem, leaves, peduncle and peels (Acevedo et al., 2021) [3] . Banana cultivation of one hectare generates about 220 tons of biomass residue. India is the leading producers of banana which produces about 190 million MT of biomass residue from banana cultivation (Priyadarshana et al., 2022) [13] . It is a novel approach of valorisation of banana peduncle into biochar. A carbon-rich solid that is produced when organic material is thermally broken down in the absence or with little oxygen is known as biochar. Biochar is mostly used as a soil additive to improve soil functioning (Abdullah et al., 2023) [1] . It has various positive impacts on agriculture such as raising water retention capacity, reduction of nutrient leaching, enhancement of nutrient availability, enhancing soil microbial activity, improve soil quality and plant growth (Islam et al., 2019) [7] . Also, biochar is an affordable, sustainable, and ecofriendly agriculture material. Due to its special ability to both improve soil quality and prevent climate change, it has recently become an important aspect of research. In this study, we selected three different cultivars namely Red Banana, Nendran and Monthan from three different genomes AAA, AAB and ABB respectively (Simmonds and Shepherd, 1955) [16] , to explore the effect of cultivars on biochar properties.

Materials and Methods

The current experiment was conducted at Division of Horticulture, School of Agricultural Sciences, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India located at 10.9362° N, 76.7441° E during 2025-2026. This study used a Factorial Randomized Block Design (FRBD) with nine treatment combinations and three replications.

Feedstock and biochar preparation

Peduncle of three different cultivars namely Red Banana (AAA), Nendran (AAB) and Monthan (ABB) were collected from local fruit market, Coimbatore. The damaged peduncles were discarded and the fresh peduncles were used for further process. The physio-chemical properties of biochar were mostly influenced by process condition. The characteristics of the biochar are significantly impacted by the temperature during pyrolysis (Zhang et al., 2020) [18] . Temperature fixed for pyrolysis were 400, 600 and 800 °C to evaluate its effect on biochar properties. The peduncle was chopped into 2-3inch small pieces. After that, the chopped samples were cleaned of dust and soil particles that had remained to them using distilled water. Following the washing procedure, samples were dried for 48 hours at 60 °C in a hot air oven. The dried samples were collected and converted into biochar using Muffle Furnace (Hasthas Scientific Instruments) at three different pyrolysis temperature of 400, 600 and 800 °C for 2 hours. Biochar was cooled at room temperature within the muffle furnace.

Notations Treatment details C1T1

Red Banana peduncle @ 400 °C C1T2 Red Banana peduncle @ 600 °C C1T3 Red Banana peduncle @ 800 °C C2T1

Nendran peduncle @ 400 °C C2T2

Nendran peduncle @ 600 °C C2T3 Nendran peduncle @ 800 °C C3T1 Monthan peduncle @ 400 °C C3T2 Monthan peduncle @ 600 °C C3T3 Monthan peduncle @ 800 °C

Evaluation of physical and chemical properties

Bulk density (BD), particle density (PD), and porosity were determined by the below equations outlined by Aller et al.

Where, M is the mass of the biochar (g), V is the volume of biochar (ml) and P is the pore volume (ml). Biochar yield, moisture content and ash content were calculated by the following formulas quoted by Nanganoa et al. (2019) [11] .

Where, M b is the mass of the biochar (g), M d is the mass of the raw dried sample before pyrolysis (g), A is the mass of the sample before drying at 105 °C (g), B is the mass of the sample after drying at 105 °C (g) and C is the mass of the ash (g). The pH and EC (Electrical Conductivity) of biochar were determined by a digital pH meter and an EC meter (Labtronics ISO 9001-2008 certified), respectively. The total organic carbon of biochar was calculated using the Chromic Acid Wet Digestion Method as described by Walkley and Black (1934) [17] . CEC (Cation Exchange Capacity) was assessed using the ammonium acetate method as described by Piper (1942) [12] . The factorial and interaction effects of biochar on chemical and physical properties were evaluated using analysis of variance (ANOVA). The differences between treatment means have been analysed by using the least significant difference (CD @ 5%) test.

Results and Discussion

Bulk density and Particle density

The data present in table 1. depicted that the cultivars and pyrolysis temperature had significantly affected BD and PD of the banana peduncle biochar. The highest (0.241 g cm -3 ) and the lowest (0.107 g cm -3 ) BD were recorded in C 2 T 3 and C 3 T 1 respectively. As the temperature during pyrolysis raised from 400 °C to 800 °C, both bulk density and particle density increased. As pyrolysis temperature increased (400 °C to 800 °C), BD increased from 0.161 g cm -3 to 0.193 g cm -3 , and PD also increased from 0.377 g cm -3 to 0.546 g cm -3 , respectively. These findings match with those of Khater et al. (2024) [8] . Their results revealed that the BD raised with increase in temperature during pyrolysis for biochar derived from sawdust (195.0 to 211.9 kg m -3 ), tree leaves (188.0 to 199.4 kg m -3 ), and rice straw (161.5 to 187.1 kg m -3 ), respectively.

Porosity and moisture content

According to the data in Table 1, there is a significant effect of cultivars and pyrolysis temperature on porosity and moisture content of banana peduncle biochar. The highest (68.28%) and the lowest porosity (40.65%) were found in C 2 T 3 and C 3 T 1 , respectively. The highest (14.49%) and the lowest (8.20%) moisture content were found in C 3 T 3 and C 2 T 1 , respectively. Pore size and porosity are inversely proportional to each other; as pore size decreases, micropore volume increases while total porosity declines (Gray et al., 2014) [6] . Porosity is inversely proportional to water permeability (Rizwan et al., 2023) [14] . These results agreed with those obtained by Sathyabama and Firdous (2025) [15] . They found that when the temperature elevated from 250 °C to 350 °C during pyrolysis, the moisture content in rice husk, sugarcane bagasse, and groundnut shells decreased from 7 to 9.5%, 10.2 to 13.6%, and 11.2 to 13%, respectively.

Biochar yield

Biochar yield was significantly affected by cultivars and pyrolysis temperature as described in Figure 1. Biochar yield decreased from 42.52 to 37.46%, with raise in pyrolysis temperature from 400 °C to 800 °C, respectively. When compared to other cultivars, Nendran showed the highest biochar yield (43.23%). The highest (45.27%) and the lowest (33.95%) biochar yield were obtained from C 2 T 1 and C 3 T 3 , respectively. This finding was similar to Babu et al. (2024) [5] in coconut husk waste biochar. They reported that the highest (41.28%) and the lowest (28.92%) biochar yield were recorded in the highest (800 °C) and the lowest (400 °C) pyrolysis temperatures, respectively.

pH and Electrical Conductivity (EC)

According to the data in Table 2, there is a significant effect of cultivars and pyrolysis temperature on pH and EC of banana peduncle biochar. Both EC and pH were raised with increase in temperature during pyrolysis. The highest (pH-12.580, EC-2.380 dS m -1 ) and lowest (pH-10.437, EC-1.340 dS m -1 ) were recorded in C 2 T 3 and C 3 T 1 . These results related with those reported by An et al. (2025) [4] . They revealed that the highest pH (9.23), EC (2278 μS cm -1 ) were obtained in the highest pyrolysis temperature of 700 °C from hemp stalk-derived biochar.

Cation Exchange Capacity (CEC)

Cultivars and pyrolysis temperature had a significant effect on CEC of banana peduncle biochar as presented in Table 2. The CEC decreased from 34.95 cmol (+) Kg -1 to 25.73 cmol (+) Kg -1 , when pyrolysis temperature climbed (400 °C to 800 °C), respectively. The highest (36.75 cmol (+) Kg -1 ) and the lowest (24.65 cmol (+) Kg -1 ) CEC were found in C 2 T 1 and C 3 T 3 , respectively. This result agreed with those obtained by Melo et al. (2013) [10] , who reported that the CEC was lowest (18 mmol (+) kg -1 ) in their highest pyrolysis temperature of 600 °C from sugar cane straw derived-biochar.

Ash content and total organic carbon

The data in Table 2. illustrated that the ash content of banana peduncle biochar was significantly affected by the cultivars and pyrolysis temperature. Figure 1. shows the effect of cultivars and pyrolysis temperature on the total organic carbon. The highest (ash content-65.53%, total organic carbon-36.64%) and the lowest (ash content-45.81%, total organic carbon-18.61%) were recorded in C 2 T 3 and C 3 T 1 , respectively. These results agree with those obtained by Li et al. (2022) [9] , who reported that the highest ash content (8.01%) and biochar carbon (79.32%) were found in the highest pyrolysis temperature of more than 500 °C, in wood biochar.

Conclusion

Under various temperatures during pyrolysis of 400 °C, 600 °C, and 800 °C, the chemical and physical characteristics of the biochar derived from the peduncles of three different banana cultivars, viz., Red Banana (AAA), Nendran (AAB), and Monthan (ABB), that correspond to three different genomes, were assessed. The results revealed that the highest bulk density (0.241 g cm -3 ), particle density (0.753 g cm -3 ), porosity (68.28%), pH (12.58), electrical conductivity (2.38 dS m -1 ), ash content (65.53%) and total organic carbon (36.64%) were found in C 2 T 3 (Nendran peduncle biochar obtained at 800 °C). Further soil application and adsorption studies are recommended to evaluate the efficiency of biochar produced from different feedstocks and pyrolysis temperatures.

Acknowledgement

The authors thank the Division of Horticulture, School of Agricultural Sciences, Karunya Institute of Technology and Sciences, Coimbatore for their help with laboratory activities for this research work. Conflict of interestThe authors declare no conflicts of interest regarding the content of this publication.

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