In an article published in Agronomy, Mingyu Wu and his co-authors present a greenhouse experiment investigating how biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More influences soil quality and microbial communities. Biochar, a carbon-rich material produced from biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More, is gaining recognition as a soil additive that goes beyond its initial purpose of carbon storage. The study examines how biochar, when applied alone or in combination with organic materials like straw and manure, affects soil properties and the intricate world of soil bacteria.

The experiment used lime concretion black soil from Xiping County, China, and tested six different treatments over a 12-month period: a control (CK), straw addition (S), manure addition (M), biochar addition (B), biochar with straw (BS), and biochar with manure (BM). The researchers found that treatments containing biochar (B, BS, and BM) had a significant positive impact on soil chemical properties. For instance, the B treatment increased 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 and the content of soil organic carbon (SOC), available phosphorus (AP), and available potassium (AK) compared to the control.

The most notable improvements were seen in the combined treatments. Compared to the straw-only treatment (S), the biochar-with-straw treatment (BS) significantly increased SOC by 115.14%, AP by 107.14%, AK by 95.43%, and pH by 24.55%. Similarly, the biochar-with-manure treatment (BM) significantly increased SOC by 61.58%, AP by 12.58%, AK by 33.83%, and pH by 6.85% compared to the manure-only treatment (M). These increases are attributed to biochar’s liming effect, which helps raise soil pH and improves nutrient availability in acidic soils. However, the study also found that biochar treatments reduced available nitrogen content by 18.15% in the manure-amended soil, likely because the stable, aromatic carbon in biochar is not easily used by microbes as an energy source, which can impact nitrogen availability.

The researchers also investigated the effects of these treatments on soil microbial communities using high-throughput sequencing of the 16S rRNA gene. While some studies show biochar can decrease overall microbial diversity, this study found that biochar treatments, especially the biochar-with-manure (BM) treatment, significantly increased bacterial diversity and richness as measured by the ACE, Chao 1, and OTU indices. The Shannon diversity index, which also accounts for the uniformity of species, did not change significantly, suggesting that while the number of bacterial species increased, the most dominant groups remained consistent.

At the phylum level, the dominant bacterial groups were Proteobacteria, Acidobacteria, Actinobacteria, and Gemmatimonadetes. The relative abundance of the phyla Actinobacteria and Gemmatimonadetes increased in soil treated with biochar, which the authors suggest may be key to long-term soil health. The study’s correlation analysis showed that soil pH was a major factor driving changes in bacterial communities. The relative abundance of several phyla, including Bacteroidetes, Proteobacteria, and Nitrospira, was positively correlated with soil pH, SOC, and available P and K, while others like Acidobacteria and Actinobacteria showed a negative correlation with these parameters.

The study’s redundancy analysis (RDA) further supported the strong link between soil properties and microbial communities. The analysis found that soil pH was the most influential factor, accounting for 58.60% of the variation in bacterial communities, followed by available nitrogen at 6.40%. The authors note that the soil’s initial acidic nature (pH 6.04) likely contributed to pH being a dominant driver of microbial changes, distinguishing this study from research on alkaline soils where other factors like available potassium and organic matter may be more influential.

In conclusion, the study highlights that biochar, particularly when combined with manure, is an effective solution for enhancing soil fertility and microbial activity in acidic soils. This combined treatment significantly improves soil properties and enriches specific bacterial communities that are important for nutrient cycling. The findings provide a foundation for further research, suggesting that while this short-term greenhouse study offers strong evidence, long-term field experiments are needed to confirm these results and better understand the complex interactions between biochar, soil chemistry, and microbial communities.

Source: Wu, M., Wang, M., Shi, W., Zhang, Q., Guo, T., Li, P., Han, Y., & Li, H. (2025). Biochar-Mediated Effects on Changes in Soil Quality and Microbial Communities. Agronomy, 15(1861).