Banana peel biochar as alternative source of potassium for plant productivity and sustainable agriculture

Biochar addition to soil is immensely beneficial for increasing plant productivity and C sequestration, attenuating nutrient leaching loss, counteracting heavy metal contamination and organic waste triggered environmental pollution. To understand the sustainable benefits of biochar, two pot experiments were conducted under net house condition in Khulna University, Bangladesh.

Biochar was prepared from banana peel waste through slow pyrolysis process under limited oxygen condition. Three lower rates (1, 2 and 3%) of banana peel biochar (BPB) were added with agricultural soil along with control with three replications for each. After incorporation of BPB into soil, pots were kept under field condition for 7 days and then the seeds of Ipomoea aquatica were sown. Plants were harvested after 42 days from seeds sowing and plant height, leaf number, fresh weight, and dry weight were measured. Another pot experiment was also conducted under sand medium to test the BPB as K-rich soil amendment where K was applied from two different sources (KCl and BPB) along with control. Seeds of Cucurbita moschata were sown and 40 days after seed sowing, K deficiency was observed in control treatments.

Banana peel biochar was found to be rich in K content. Plant productivity and above-ground biomass were reduced in 1% BPB treatments, but increased in 2 and 3% BPB treatments as compared to control but statistically insignificant (p < 0.05). In case of second experiment, K deficiency symptoms were observed in 40 days aged Cucurbita moschata seedlings under control treatments, whereas no K deficiency symptom was noticed in plants grown under K supplied from both KCl and BPB. Moreover, the plant grown with BPB was found healthy, stronger and greener in appearance.

This positive influence of BPB on plant growth suggests the alternative way to overcome the use of chemical fertilizer and effective way of utilization of agricultural wastes through recycling.