Chapter 4.30
4.30 - Banana peduncle as a source of organic potassium fertilizer/biochar for small scale African farmers
Jean-Vianney M. Kabamba, University of Guelph, Canada
Suggested citation for this chapter.
Kabamba,M,JV. (2022) Banana peduncle as a source of organic potassium fertilizer/biochar for small scale African farmers . In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org
Introduction
Potassium is critical to many plant growth traits, and plants display different symptoms when in deprivation of it (Prajapati & Kalavati, 2012). Potassium helps with enzyme activation, stomatal activity (water use), photosynthesis, transport of sugars, water and nutrient transport, protein synthesis, starch synthesis, and overall crop quality (Prajapati & Kalavati, 2012).
Figure 1: Banana peduncle (see red arrow) (Source: The Boyds, 2013).
A peduncle is the stalk that supports the inflorescence and the individual fruits of a plant. (Balajii et al., 2022). In bananas and plantains, the peduncles comprise approximately 13% of the inflorescence biomass (Balajii et al., 2022). It is crucial to note that the banana and plantain peduncle is rich in potassium (Ngoh et al., 2014), and hence could serve as a rich source of organic potassium fertilizer, which is the topic of this chapter. Currently, most of the time, peduncles are wasted at banana distribution points, markets, and on farm (Bhardwaj et., 1981). Banana farming generates huge amounts of biomass. In most cases, it goes to waste because of a lack of suitable technology for its re-use. In the worst cases, after removing the bananas from the peduncle, the remaining banana peduncles are dropped off in areas around markets which causes nuisance problems (Bhardwaj et al.,1981).
Farmer adoption of banana peduncle as a mulch or compost
The steps to use banana peduncle as mulch or compost based fertilizer consist of the following steps:
Step 1: Preparation of the Peduncles: Stack the peduncles together (Karim et al., 2019).
Step 2: Chopping: In this step, the peduncles are chopped into smaller parts. This process helps making the decomposition faster and helps increase nutrient liberation into the soil (Karim et al., 2019).
Step 3A: Spreading: Apply the chopped peduncles onto the soil around the targeted plants, forming a coat of mulch. It is important to spread them evenly and avoid overloading the plant, as this could decrease irrigation effectiveness and air from circulating towards the soil (Karim et al., 2019).
Step 3B: Adding compost: As another option, you can mix chopped peduncles to your compost stack. Associate them with other organic materials such as kitchen scraps, grass clippings, and dried leaves. Mix the compost usually allow air flow and to favor decomposition (FAO, 2015).
Step 4: Allow decomposition: Using peduncles as mulch or compost, it is crucial to allow to decompose completely. This procedure can require weeks to months, depending on factors such as temperature, humidity, and the dimension of the peduncles (FAO, 2015).
Step 5: Manage moisture: Be attentive to the moisture levels of the peduncles. They must be humid but not watery. Irrigate the mulch or compost pile as necessary to preserve appropriate moisture levels (FAO, 2015).
Figure 2: Mulch spread around banana trees (Source: Australian Banana Growers, 2024).
Farmer adoption of banana peduncle for biochar production
Alternatively, banana peduncles can be used to produce biochar. In simple terms, ‘‘biochar is a solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment” (IBI, 2013). It is a material rich in carbon, used as a renewable gas or as soil fertilizer to increase soil effectiveness (Maniscalco et al., 2021). It can improve relations between soil and plants and constitutes a promising management option to combat soil degradation and anthropogenic climate change effects (Xu et al., 2023). It comes from organic matter like wood chips, agricultural waste, or even animal manure. It is obtained through a process called pyrolysis, which consists of heating the organic matter under low oxygen conditions (Xu et al., 2023). It is important to note that its attributes mostly rely on the chemical composition of feedstock and the environment in which it was produced (Nanganoa et al., 2019).
The steps to produce banana peduncle as biochar consist of the following:
Step 1: Collection and Preparation: Collect banana peduncles. Remove any unnecessary parts (Karim et al., 2019).
Step 2: Drying: Let the banana peduncles dry properly. This helps reduce the moisture content, therefore making it more suitable for pyrolysis (Karim et al., 2019).
Step 3: Pyrolysis: Pyrolysis is the process of heating organic material in the absence of oxygen to produce biochar. Place the dried banana peduncles in a pyrolysis reactor or kiln and heat them to temperatures typically ranging from 300 to 700 degrees Celsius (572 to 1292 degrees Fahrenheit) (Karim et al., 2019).
Step 4: Cooling: After pyrolysis, allow the biochar to cool down. This step stabilizes the material and prevents it from further reactions (Karim et al., 2019).
Step 5: Grinding (optional): Depending on the intended use, you may choose to grind the biochar into finer particles. Grinding increases the surface area, making the biochar more effective for certain applications such as soil improvement (Karim et al., 2019).
Step 6: Application: Use the banana peduncle biochar in various applications such as soil amendment, water filtration, or as a component in compost (Nanganoa et al., 2019).
From a quantitative point, the available potassium (K) content of banana peduncle is (66.3 g/kg) (Karim et al., 2017). The Karim et al. (2017) study shows us that it increased to 86.2, 163.5 and 258.5 g/kg in biochar produced by argon plasma processing for 3, 5 and 7 min respectively. For clarity, 66.3 g/Kg means that if we have 1000 Kg of starting banana peduncle, we will have 66.3 Kg of potassium available. And when turned into biochar, 258.5 g/Kg means that 1000 Kg of Biochar would be equal to 258.5 Kg of potassium (Karim et al., 2017).
Some additional benefits of biochar are that it:
-Helps combat the global food security crisis and helps conserve the soil by increasing soil fertility and crop and agroforestry productivity. It increases the fertility of degraded and marginal soils, and favors mitigation and adaptation to climate change in agricultural systems (Balajii et al, 2020).
-Helps combat the global climate change crisis by decreasing greenhouse gas emissions safely and effectively in stable soil sinks. It lessons greenhouse gas emissions related to decomposition of waste from urban and rural uses (Balajii et al, 2020).
-Helps make agricultural production more sustainable at all levels by transitioning farmers to lower chemical fertilizer inputs. It more effectively recycles agricultural and organic waste materials and helps in land recovery. It improves water quality by reducing nutrient filtration into water bodies and supplies (Balajii et al, 2020).
Critical analysis
To produce biochar, the most common option is to buy pyrolysis machines, which would be costly for a small-scale farmer in Africa (Chen et al., 2022). Constructing a kiln is an alternative option to make biochar. Instead of constructing a big kiln, it is possible to construct one using a metallic barrel and a cylindric piece of metal, which is more affordable. The only problem related to this kind of construction is the durability, as mentioned in the video in the Practical Resources to Get Started section (below).
Figure 3: Example of a homemade kiln (Source: Flomaton Famous, 2022).
Therefore when deciding whether to re-cycle banana/plantain peduncles as compost/mulch or as biochar, pricewise, compost/mulch would be the best option since it does not require any heating or energy like biochar production does (Maniscalco et al., 2021). The opportunity cost is that the potassium composite is lower when used as a compost/mulch; some studies also show that spreading banana peduncle on a plantation can cause mealy-bug infestation (Nanganoa et al., 2019). In terms of the merits of biochar, it is important to note that the efficacy of biochar is highly dependent on soil fertility and fertilizer management practices. Nanganoa et al. (2019) shows that different temperatures can impact the composition of the biochar, and furthermore, inorganic fertilizer input is needed for the biochar to be effective as a soil amendment. However, the use of biochar can significantly reduce the need for fertilizer. The efficacy of biochar is highly dependent on the soil fertility and fertilizer management practice (Nanganoa et al., 2019).
Practical Links & Resources to get Started
https://www.youtube.com/watch?v=PxrsBQDBQOk&t=2s : Construction of homemade pyrolysis barrel.
https://www.permaculturenews.org/2022/02/09/bananas-for-mulch-production-and-erosion-control/ : Mulching tips
https://www.youtube.com/watch?v=rozuOdbZvWU : Mulching instructions
https://www.thepostsonmission.com/2013/06/going-bananas/ : banana peduncle representation
https://www.fao.org/3/i3388e/I3388E.pdf: FAO’s farmer’s compost handbook (tips, practices, etc.)
References
1. Australian Banana Growers. (2024). Mulch Banana 2. https://abgc.org.au/2019/04/18/wanted-dead-or-alive-ground-covers/mulch-banana-2/
2. Balajii, M. and Niju, S. (2020) Banana peduncle – A green and renewable heterogeneous base catalyst for biodiesel production from Ceiba pentandra oil. Renewable Energy 146, 2255-2269.
3. https://www.sciencedirect.com/science/article/abs/pii/S0960148119312480
4. Bhardwaj, K. K. R. (1981). Potential and problems in the recycling of farm city waste on the land. In: Recycling Residues of Agriculture and Industry (Ed. M. S. Kalra). P.A.U., Ludhiana, India, pp. 57-76.
5. Chen, M., Hu, C., & Myers, R. J. (2022). Understanding transient technology use among smallholder farmers in Africa: A dynamic programming approach. Agricultural Economics, 53(S1), 91–107. DOI: 10.1111/agec.12721
6. Flomaton Famous. (2022). How to Make a BioChar Retort Kiln | Make Charcoal at Home [Video]. YouTube. https://www.youtube.com/watch?v=PxrsBQDBQOk&t=2s
7. Karim, A. A., Kumar, M., Mohapatra, S., Singh, S. K., & Panda, C. R. (2019). Co-plasma processing of banana peduncle with phosphogypsum waste for production of lesser toxic potassium–sulfur rich biochar. Journal of Material Cycles and Waste Management, 21(1), 107–115. DOI: 10.1007/s10163-018-0769-7
8. Karim, A. A., Kumar, M., Singh, S. K., Panda, C. R., & Mishra, B. K. (2017). Potassium enriched biochar production by thermal plasma processing of banana peduncle for soil application. Journal of Analytical and Applied Pyrolysis, 123, 165-172.
9. Maniscalco, M., Infurna, G., Caputo, G., Botta, L., & Dintcheva, N. T. (2021). Slow Pyrolysis as a Method for Biochar Production from Carob Waste: Process Investigation and Products’ Characterization. Energies (Basel), 14(24), 8457-
10. Nanganoa, L. T., Yinda, G. S., Ndande, E. J., Mounoumeck, P. V., Levai, L. D., Okolle, J. N., & Ngosong, C. (2019). Integrated application of banana peduncle-derived biochar and fertilizer affects soil physicochemical properties and plant nutrient uptake. Fundamental and Applied Agriculture, 4(4), 1008–1018
11. The Boyds. (2013). The Boyds. https://pngboyd.blogspot.com/2021/03/