A pot experiment was conducted to test the hypothesis that application of biochar and compost improve soil fertility and plant growth. Application of compost with fertiliser significantly increased plant growth, soil nutrient status and plant nutrient concentration. Maize shoot biomass was significantly correlated with chlorophyll content, root biomass, plant height, and specific leaf weight. Compost and biochar additions significantly reduced leaching of nutrients, improved the retention of water and nutrients by the soil and thereby uptake by the plants.

We evaluated the change in water extractable organic carbon (WEOC) and microbial PLFAs of biochar during incubation with an acidic paddy soil, suggesting that the WEOC quickly change and interact with soil components, and that the PLFAs profile is significantly affected by biochar chemical properties. The findings contribute to revealing the interaction mechanism between biochar and soil, and to the proper utilisation of environmental residues.

Wet chemistry and spectroscopy methods assessed the functional groups in the carbonaceous surface of wood biochars. The amount of acidic groups in biochar decreased with increasing pyrolysis temperature. Besides, the presence of a low amount of inorganic fraction caused a “masking effect” on the determination of surface acidity of biochar. This can be partially solved by using potentiometric titrations after acid-washing pretreatment to quantify biochar acidity.

This review paper examines the various uncertainties related to soil quality that exist with biochar amendment. Crop yield can be reduced by biochar application, and increases in greenhouse gas emissions with biochar amendment have also been observed. Farm investment risks with biochar need to be evaluated before field application may be recommended to growers.

Biochar applications potentially can improve soil quality and sequestrate carbon in soils. The effects change with biochars produced with different feedstock materials and under different temperatures. The information from this study should be useful to design soil carbon sequestration strategies with different biochars.

It has been suggested that biochar develop negative charge with ageing in soils. In this study, we investigated the effect of aged biochar on surface charge characteristics and adsorption behaviour of cadmium and arsenate. We did not observe any change in the cation exchange capacity of aged biochars. However, Cd adsorption increased in the presence of aged biochars, whereas the adsorption arsenate varied with soil type. Our results suggest that aged biochar may be suitable for the remediation of contaminated soils.

Biochar, a charcoal-like material produced from the waste biomass by thermal treatments under no or low O₂ conditions, has been promoted as a soil amendment to enhance carbon storage and to improve soil functions. In this study methodologies were developed to quantify the carbonate-C in biochars which is essential to understand both biochar liming properties and longevity in soils. Our results will contribute to a better characterisation of biochars, as needed if biochar technology is adopted as a climate change mitigation strategy.

Biochar application in poor or acidic soils has often shown amazing effects on crop yield, which seemed a win-win strategy for ensuring food security and mitigating global climate warming. We studied the effects of biochar on alkaline soils in high-yielding agricultural fields which was poorly understood. However, the limited effects of biochar on soil nutrient, water and crop yield suggest that the positive effects of biochar application may only occur in some special conditions.

Nitrogen (N) leaching frequently leads to productivity losses and negative environmental consequences. Two amendments, clay and biochar were investigated to ameliorate N leaching from coarse-textured soils. There was no difference in NH₄⁺ or dissolved organic N leaching between the amendments but a significant difference in NO₃^– leaching was detected. We conclude that to decrease N leaching, land managers should apply the most readily available of the amendments in the most convenient manner.