Research Paper

Comparing impact of Biochar conditioned with Organic inputs and Inorganic fertilisers

Biochar has been widely recognized as a soil enricher, offering several benefits such as improved soil quality, increased crop yield, enhanced solubility of nutrients by raising soil pH, carbon sequestration to mitigate climate change, and the production of compost from organic matter decomposition. Compost, like biochar, provides advantages like increased water holding capacity, enhanced micronutrients and microbial activity, and reduced soil erosion. When agricultural waste is used to produce biochar and combined with both organic and inorganic fertilizers, it offers additional benefits to cropping systems, soil health improvement, and biodiversity promotion, leading to overall healthier ecosystems. Recent studies have estimated that converting agricultural residues to biochar globally could prevent the release of 331 million tonnes of carbon dioxide equivalent, which is equivalent to the emissions produced by over 88 coal-fired power plants in one year.

The addition of biochar during the composting process alters compost properties, resulting in improved quality, pH, moisture content, and nutrient availability. Co-composting also forms an organic coating on biochar particles, reducing hydrophobicity and improving nutrient retention conditions, ultimately enhancing agronomic performance. This article aims to compare the effects of biochar combined with organic fertilizers versus biochar combined with inorganic fertilizers, analyzing their impact on soil nutrition levels, climate mitigation, and crop yields. The analysis is based on a review of seven different studies conducted in various climatic and agricultural zones.

A study conducted by Ming Liu demonstrated that biochar application modifies the soil environment, promoting crop root growth and nutrient absorption. The study found that biochar improved the absorption and utilization of nitrogen and potassium in rapeseed, while organic and inorganic fertilizers improved the absorption and utilization of nitrogen and phosphorus. Additionally, organic fertilizers significantly enhanced potassium absorption and utilization. These findings establish a strong relationship between biochar application and soil fertility. The study also indicated that biochar combined with organic and inorganic fertilizers promotes nutrient uptake in rapeseed, improving soil fertility and the microbial environment. However, excessive biochar application was found to be detrimental to sustainable farming.


This figure by Zhiyong Zhang depicts the benefits of organic manure combined with biochar to root growth and yield under continuous cropping system in China. Here, M represents organic manure levels (M3,M6); B represents biochar levels(B1,B3) .We can very well see that 3% organic manure when combined with biochar could significantly increase the root surface area specifically in the bud stage but not as much in the harvesting stage. From this study we also find that the highest root growth, total root volume, and the surface area of roots were the highest when treated with M6B1 which is with 6% manure and 1% biochar addition to be specific in this study. This proves that a detailed understanding of the proportions are essential to get the appropriate result that we desire which infact requires repeated trial testings. -Zhang, Zhiyong & Dong, Xiuxiu & Wang, Shaoming & Pu, Xiaozhen. (2020). Benefits of organic manure combined with biochar amendments to cotton root growth and yield under continuous cropping systems in Xinjiang, China. Scientific Reports. 10. 4718. 10.1038/s41598-020-61118-8.

Another study by Mohammad Ayaz revealed that biochar application significantly reduced CO2, N2O, and CH4 emissions from soil in the second year compared to the first year in non-biochar-treated plots. This suggests that swine manure digestate biochar can effectively mitigate emissions, especially in temperate climatic conditions. The study also found a positive correlation between greenhouse gas emissions, soil moisture, and temperature.

A study conducted by Hardy Schulz demonstrated that biochar stabilizes compost-derived organic matter, leading to synergistic carbon sequestration when biochar and compost are applied together. The addition of mineral fertilizer to biochar, however, may accelerate biochar degradation during the second growth period. The study showed positive effects of biochar on plant growth, plant-available potassium content, and total organic carbon level, but no effects were observed on cation exchange capacity and leaching of nitrogen and phosphorus. The combination of biochar with compost showed the best results in terms of plant growth and carbon sequestration, but no effects on nitrogen and phosphorus retention were observed.

Observations from long-term studies suggest that the effectiveness of biochar treatments changes over time. Some studies reported a decrease in vegetable yield after several years of application, indicating a decline in biochar’s ability to increase crop yields and reduce nitrogen losses. However, aged biochar still showed improvements in soil fertility and crop growth. Changes in temperature, precipitation, tillage practices, and microbial activities can affect biochar’s physical and chemical properties over time, impacting its carbon storage capacity while enhancing soil fertility and reducing pollutants. The properties of biochar, such as pH, ash content, and functional groups, also change with aging due to prolonged exposure.

In conclusion, biochar as a soil amendment provides substantial benefits, such as improved soil fertility, increased crop yields, and carbon sequestration. However, it is most effective when combined with organic fertilizers and, to a lesser extent, inorganic fertilizers. It is important to consider soil types, cropping patterns, and pH levels, as biochar may not be suitable for all soils and can negatively affect crop yield in high pH ranges. Additionally, biochar can degrade over time due to exposure, chemical oxidation, and physical fragmentation. Further research is needed to fully understand the long-term effects of biochar applications in different agroecosystems.

— Written by Rakshitha Naik Consultant, IBBN

The IBBN Secretariat is hosted by the Revitalizing Rainfed Agriculture Network and Snehakunja trust, and supported by GIZ  – The Deutsche Gesellschaft für Internationale.

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