The Journal of Degraded and Mining Lands Management published a study by lead author Hidayatuz Zu’amah and a team of researchers investigating how sugarcane bagasse waste can be repurposed to support shallot farming. Shallots are a vital commodity in Indonesia, but intensive cultivation often leads to soil degradation through the excessive use of agrochemicals. By testing biochar and compost derived from bagasse on Inceptisol soil—a common but often nutrient-poor soil type—the researchers aimed to identify sustainable practices that maintain high productivity while preserving the environment.

The research team found that different methods of processing bagasse waste yield distinct benefits for the soil. Biochar features a highly stable and porous structure that acts as a reservoir for water and nutrients. Meanwhile, compost made by fermenting bagasse with cow manure provides a more immediate supply of organic carbon and essential macronutrients. When applied to the shallot fields, these amendments significantly altered the soil’s chemical profile. For instance, the use of synthetic NPK fertilizer often lowers soil pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More, but the addition of organic matter helped steer the soil toward the neutral range optimal for shallot growth.

A primary finding of the greenhouse experiment was the clear synergy between organic amendments and chemical fertilizers. While biochar alone improved the soil’s cation exchange capacity—enhancing its ability to retain nutrients—the highest crop yields were achieved when bagasse compost was paired with a full dose of NPK fertilizer. This combination resulted in shallot plants with the greatest height and the most leaves. The data suggests that while compost provides long-term stability and improves soil structure, the chemical fertilizer ensures that plants have an immediate supply of the nitrogen and phosphorus needed during their peak growth stages.

The study also measured how well the shallot plants absorbed nutrients from the soil. The researchers discovered that the combination of compost and full NPK dosage was the most effective at increasing the concentration of potassium in plant tissues. Furthermore, nitrogen and phosphorus uptake reached their maximum levels under this specific treatment. Interestingly, using a mixture of biochar and compost—known as biocompost—also showed promising results, performing better than using biochar or compost separately when no chemical fertilizer was added.

Ultimately, the results demonstrate that agricultural waste like sugarcane bagasse can be successfully integrated into a circular economy to restore soil health. By combining bagasse compost with balanced mineral fertilizers, farmers can improve the fertility of Inceptisol soils and achieve higher shallot yields. While a full dose of NPK fertilizer provided the absolute best results, the study noted that a 50% dose still produced competitive yields and could be a more cost-effective option for farmers looking to reduce their input costs while maintaining sustainable practices.

Source: Zu’amah, H., Handayani, C.O., Dewi, T., Arianti, F.D., Beti, J.A., Jufri, A., Rosjidi, M., Sahara, D., Maro’ah, S., & Syamsiyah, J. (2025). The potential of biochar and compost from sugarcane bagasse on growth, yield, nutrient uptake of shallot, and properties of an Inceptisol. Journal of Degraded and Mining Lands Management, 12(3), 7559-7569.