Biochar can be a valuable soil amendment for crops. Photo courtesy of

Banana peels – we peel them, we occasionally slip on them, and I’m sure most of us end up throwing them away (unless you compost, in which case you are a credit to society). Researchers in Bangladesh have recently found alternative uses for banana peels that could potentially curb the agriculture industry’s hunger for synthetic fertilizers.

A study conducted at Khulna University in Bangladesh, has demonstrated that biochar made from banana peels can be quite effective at keeping potassium, a key nutrient for plants, in the soil. It’s made through a process called pyrolysis in which biomass is heated to very high temperatures with very little oxygen. The benefits of biochar have already been fairly well-documented, with past research finding that it can absorb toxins like heavy metals, reduce nutrient leaching, increase the soil’s ability to hold water, increase soil microbial activity, and improve soil quality and plant growth. You may be wondering why we would need to develop yet another kind of biochar since it can already be made out of other biomass materials, but much of the significance of this study comes from the fact that it’s place-based. Bangladesh is a country that produces one million tons of bananas every year. The crop is not only economically important, but it’s also a major food source and consumed at a high rate because bananas can be grown year-round. This study sought to fill the knowledge gap concerning banana peel biochar specifically, because it’s such an abundant byproduct in Bangladesh and could be used to replace some synthetic fertilizers if it proves to be beneficial for crops.

This study was composed of two experiments. The first included three replications of four treatments: plants grown with a soil content of 1, 2, and 3% banana peel biochar, and one control treatment. Water spinach was planted in each replicate and harvested after 42 days. The second experiment included three replicates of three treatments of soil amendments: banana peel biochar, potassium applied through conventional fertilizer, and a control treatment. A variety of pumpkin was planted in these treatments. Researchers did not find any significant differences in plant height of water spinach, but they did notice that while the pumpkins in the control treatment exhibited signs of potassium deficiency, those growing with both the potassium amendments and the banana peel biochar did not. It was also observed that the pumpkins growing with banana peel biochar appeared to be greener and healthier compared to the other treatments. This finding could be really beneficial for banana-growing countries like Bangladesh, but it’s also an important lesson for the agriculture industry that the most valuable resources are sometimes the things that you see every day.


journal article: Islam, M et al. (2019). Banana peel biochar as alternative source of potassium for plant productivity and sustainable agriculture. International Journal of Recycling of Organic Waste in Agriculture. Supplement 1, Vol. 8. Pg. 407-413.