Advances and prospects of biochar in improving soil fertility, biochemical quality, and environmental applications

Abstract

With the global food deficit increasing and rising climate change issues, there is a need to find green solutions to improve soil fertility and productivity while enhancing soil biochemical quality and reducing the ecological impact of agriculture. Biochar is a potentially cost-effective, carbonaceous resource with many agricultural and environmental applications. As a soil amendment, it improves soil physical and biochemical properties and increases soil fertility and productivity—particularly over the long-term—increasing soil aggregation, water retention, pH, and microbial activities, thus, improving overall soil quality, potentially helping to reduce chemical fertilizer needs over time. The extent of biochar’s impact on soil physiochemical properties varies depending on biochar source, type, size, inherent soil characteristics, cropping system, etc. Moreover, biochar has significant potential in soil and water remediation, especially through its unique adsorption and chemical properties capable to capture and immobilize pollutants such as metal(loid)s, organic pollutants, and hazardous emerging contaminants such as microplastics. Further, biochar has also emerged as a key strategic, cost-effective material to tackle global issues such as climate change mitigation, reducing the net greenhouse gas emission to minimize global warming potential. However, a knowledge gap remains as to understanding the long-term persistence of biochar on agroecosystem, optimal biochar application rate for the diversity of biochar-soil-crop-environmental conditions, interaction of biochar with inherent soil carbon stock, specific mechanisms of biochar’s effect on soil biotic properties, quantification of carbon sequestration, greenhouse gas emissions, synergy or potential antagonistic effects with other carbon sources such as compost, manure, residues, etc., its modification for environmental applications and associated environmental and human risks over long-term. Further research is needed to evaluate the long-term impacts of types and sizes of biochar on overall soil quality to recommend suitable application practices based on soil management and cropping system. Also, its environmental applications need to be finetuned for wider and target specific applications to tackle pressing environmental issues such as soil and water pollution.

Significant Synergy Effects of Biochar Combined with Topdressing Silicon on Cd Reduction and Yield Increase of Rice in Cd-Contaminated Paddy Soil

“…The high CEC, large surface area and pore volume of BC could alleviate the harmful effects of heavy metal on soils and plants, thereby improving crop productivity and environmental sustainability [44]. Rice productivity was increased by 25-26% by the application of BC amendments (20 and 40 t ha −1 ) in heavy metal-contaminated rice fields [45], and the presence of unique surface functional groups of BC increased the contents of soil K and magnesium (Mg), which in turn promotes the increase of rice yield [46].…”

“…In the same way, the application of BC and Si under cadmium-contaminated conditions both increased the concentrations of N, P and K in rice plants in this paper. Many studies have shown that the application of BC facilitates the absorption of N, P and K by crops [11,44,55]. Silicon also benefits crop productivity and the accumulation of plant nutrients [54,56,57].…”

Putting Biochar in Action: A Black Gold for Efficient Mitigation of Salinity Stress in Plants. Review and Future Directions

“…Recently it received attention across the globe for its to improve crop productivity and mitigate the toxic effects of abiotic stresses. ,− BC application improves soil carbon sequestration, soil permeability, soil fertility, and microbial growth, which improves the water holding capacity and nutrient availability and thus ensures better plant growth . Biochar also increases the soil cation exchange capacity and nutrient use efficiency and therefore leads to an increase in crop yield . Biochar application also reduced the toxic effects of salinity by binding Na + on its exchange site and increasing soil K + and moisture contents.…”

Effects of Biochar and Arbuscular Mycorrhizal Fungi on Soil Health in Chinese Kale (Brassica oleracea var. alboglabra L.) Cultivation

“…In terms of sustainable agriculture and the environment, biochar is receiving attention as an environmentally friendly alternative for sustainable agriculture and environmental improvement. It is used as a soil amendment to enhance soil fertility, structure, and biochemical quality while reducing the use of industrial fertilizer and the ecological impact of agriculture [11,12]. Biochar is well known for its unique properties, such as having a high surface area and porosity, low bulk density, high cation exchange capacity (CEC), neutral to alkaline pH, and high carbon content, and it also contains some essential plant nutrients, such as nitrogen (N), phosphorus (P), and basic cations such as calcium (Ca), magnesium (Mg), and potassium (K) that are necessary for crop growth and development [12].…”

“…Biochar is well known for its unique properties, such as having a high surface area and porosity, low bulk density, high cation exchange capacity (CEC), neutral to alkaline pH, and high carbon content, and it also contains some essential plant nutrients, such as nitrogen (N), phosphorus (P), and basic cations such as calcium (Ca), magnesium (Mg), and potassium (K) that are necessary for crop growth and development [12]. Therefore, the addition of biochar to soil can improve soil organic carbon content, CEC, and soil porosity; stabilize soil pH; increase soil microbial activity; enhance moisture retention and availability; immobilize toxic elements like heavy metals; and increase the bioavailability of minerals, resulting in improved root development and nutrient uptake [11][12][13]. Previous studies reported that the application of biochar has been shown to increase soil microbial activity and improve the chemical and physical properties of the soil [14][15][16][17].…”