Sustainable agriculture is one that produces abundant food without depleting the world's resources or polluting its environment. Sustainable agriculture follows basic principles such as sustainable systems for sustainable crop production, with considering social values, provide domestic food security, and considering all concerns of small farmers, environmentalists, agricultural scientists as well as the government policy makers.
The increasing land degradation is a necessary problem that impacts many soils in several countries, and in this aspect, the soil organic matter (SOM) has a vital function, because of its progressive biodegradation parallels to the concomitant emissions of CO2 to the atmosphere and desertification (Jimenez-Gonzalez et al., 2022). It is considered that soil quality could be a main cause of yield gaps. Soils also has a significant role in the global carbon cycle and are important to the management of climate change (Farooq et al., 2020; Almagro et al., 2021). Soil C content was protected in subsurface and in the more reliable fractions of soil organic matter (Almeida et al., 2021; Sun, Shahrajabian, 2025). Microbial nitrogen immobilization in soil can be improved by boosting carbon bioavailability (Cao et al., 2021; Che et al., 2021). Several techniques to improve both sustainable agricultural intensification and fertilizer utilization will be more successful, if soil fertility is studied comprehensively (Burke et al., 2022).
Biochar is carbonaceous product obtained from the incomplete combustion of numerous organic materials (Mavi et al., 2023; Sun, Shahrajabian, 2023). Generally, biochar application improves soil N accessibility and retention, reduces soil bulk density, boosts water holding capacity, promotes appropriate microorganisms, increases pH and cation exchange capacity, and decreases the bioavailability of heavy metals (Yuan et al., 2022). Application of biochar into soils alone or combined with fertilizer or manure have been reported to have many notable advantages for soil and environmental attributes (Zhang et al., 2017; Bilgili et al., 2019). Biochar benefits soil by increasing their biological, chemical, and physical properties such as pH, electric conductivity, ion exchange capacity, aggregate structural stability, and water-holding capacity (Cao et al., 2021; Liu et al., 2022; Tian et al., 2023; Xiang et al., 2023).
This article aims to study new sources of biochar effect on crop yield and quality in sustainable crop production. The latest relevant literature has been obtained from scientific databases, such as “PubMed”, “SciFinder”, “Elsevier”, and “Web of Science”.
Biochar is a carbon-rich by-product when biomass is degraded under limited oxygen conditions (Huang et al., 2023a,b). Different biochar substrates are natural vegetative growth, organic wastes and residues (floating plant waste, forest residue), farm and crop residues (agricultural crop residue, animal waste), municipal waste (urban solid waste, urban refuse waste), industrial waste such as food processing waste, and plantation producing energy crops such as plant and tree species (Parmar et al., 2014; Kan et al., 2016; Parwar et al., 2019; Diatta et al., 2020; Gabhane et al., 2020; Kapoor et al., 2020). Pyrolysis, a thermochemical process, involves decomposing organic materials at elevated temperatures in the absence of oxygen, and this process produces a variety of products, including bio-oil, biochar, and syngas, whose properties are significantly influenced by several technological parameters, and key parameters include heating rate, temperature, feedstock composition, residence time, and reactor type (Alkharabsheh et al., 2021; Sharma et al., 2022; Bolan et al., 2023; Tan et al., 2023). Biocarbon exhibits varying chemical compositions and physicochemical properties depending on feedstock and production methods, key components include carbon (44% to 95%), oxygen (0% to 45%), and hydrogen (1% to 9%).
The most important physical and chemical properties of biochar are presented in Table 1. The most notable benefits of biochar application are mentioned in Table 2.
Physical and chemical properties of biochar (Yadav et al., 2023).
| Characteristics | Key-points |
|---|---|
| Porosity | The pore size of biochar changes on the basis of the material applied for biochar production and usually ranges from nano (<0.9 nm), micro (<2 nm), meso (2–50 nm) to macropores (>50 nm). |
| Surface functional groups | Different functional groups (e.g. hydroxyl-OH, amino-NH2, ketone-OR, ester -(C=O)OR, methyl-CH3, nitro-NO2, aldehyde-(C=O)H, carboxyl-(C=O)OH are shaped on biochar surface. |
| Carbon content | Biochar is greatly stable, consisting of more than 65% carbon. Chemical composition is greatly dependent on feedstock and pyrolysis conditions. |
| Cation exchange capacity | Low temperature biochars usually have high CEC as they are rich in oxygenated functional categorizes, indicative of high complex formation intensity with metal cations. |
| Structure | Among elements, C, O, H, and N are the most common elements and usually contribute to the main structures of biochar. |
| pH | Different alkaline salts, alkali metals (Na, K, Mg, and Ca), and CaCO3 are connected with higher pH of the biochars. Generally, biochar pH is found to be >7. |
| Surface area | The surface area of biochar boosts with the improvement in pyrolysis temperature. Highly porous structure, large surface area, and high pore volume are assumed favorable. |
| Non-organic content | The ash constituent is the nonorganic fraction of biochar include elements such as Mg, O, Ca, S, N, K, etc. |
The most important advantages of biochar application.
| Characteristics | Reference |
|---|---|
| Enhance the soil's properties | Oliveira et al., 2017 |
| Improvement in fertility status by increasing nutrient availability | Karimi et al., 2020 |
| Soil remediation | Wang, Wang, 2019 |
| Induces microbial activity in the soil | Hale et al., 2015 |
| Agronomic importance (crop improvement) | Saudy et al., 2021, 2022 |
| Climate change mitigation | Wang et al., 2022a; Shahrajabian, Sun 2023a,b |
| Carbon sequestration | Montanarella, Lugato, 2013 |
| Wang et al., 2023b, Li et al., 2023a |
Biochar has several advantages which predispose it to be used in sustainable agriculture like the potency of sequestering carbon thus inducing to climate change mitigation, improved nutrient retention by soil, sorption or organic contaminants, increase in soil fertility (Shang, Chi, 2023). Biochar can also increase soil microbial activities by providing labile C, mineral nutrients, and habitat as microbes promptly colonizes biochar surface. The addition of biochar as an amendment to soil increases the biological and physicochemical properties of soil, and thereby improves the soil quality (Akhtar et al., 2020; Chen et al., 2023). Due to these properties, biochar may have an impact on crop plants. The scope and direction of the changes it causes were discussed using examples taken from the literature (Table 3).
The impacts of different kinds of biochar on growth and final yield of crops.
| Plant | Treatment | Key points | Reference |
|---|---|---|---|
| 1 | 2 | 3 | 4 |
| Basil (Ocimum basilicum L.) | Biochar (BC) and Chemical fertilizer |
| Pandy et al., 2016 |
| Biochar derived from black cherry wood (1, 2, and 3%) |
| Jabborova et al., 2021 | |
| Cauliflower (Brassica oleracea L.) | Nitrogen compounds (nitrate, ammonium) from biochar-amended soil in comparison to untreated (Control) |
| Losacco et al., 2022 |
| Chicory (Cichorium intybus L.) | Century-old biochar |
| Dehkordi et al., 2020 |
| Chinese cabbage (Brassica rapa) | The biochar was prepared by charring rice hull from Purnnature (Suncheon, Korea) and Yoogi Lnd (Gonchang, Korea) |
| Chun et al., 2022 |
| Chinese ginseng (Panax notoginseng) | Biochar from tobacco stems at the rates of 9.0, 12, 15, and 18 t ha−1 |
| Zhao et al., 2022 |
| Cotton (Gossypium hirsutum L.) | Biochar application rate (BCAR) at 10 t ha−1 |
| Li et al., 2023c |
| Biochar application rate (BCAR) at 4.0 t ha−1 |
| Karthik et al., 2019 | |
| Millet (Panicum miliaceum L.) | Sunflower stem biochar (15 t ha−1 biochar) |
| Taheri et al., 2022 |
| Mint (Mentha crispa L.) | The application rate of biochar and modified biochars with H2O2, KOH, and H3PO4 was 25 g kg−1 soil |
| Ghassemi-Golezani, Farhangi-Abriz, 2023 |
| Radish (Raphanus sativus L.) | Microbial biochar formulations (BCMs) and Bacillus subtilis SL-44 |
| Chen et al., 2023 |
| Red onion (Allium cepa L.) | Different biochar (BC) ratios (2% and 5% w/w) |
| Peiris et al., 2022 |
| Onion (Allium cepa L.) | Three pyrolyzed biochars cotton sticks, wheat straw and poultry litter |
| Arif et al., 2021 |
| Rice (Oryza sativa L.) | Biochar manures were applied at a rate of 12 Mg ha−1 (dry weight) in a rice paddy |
| Canatoy et al., 2022 |
| Combining 20 t ha−1 of biochar with 25% inorganic fertilizer application rate |
| Danso et al., 2023 | |
| Fe-modified and P-rich biochars |
| Yang et al., 2023 | |
| P-rich biochar |
| Yang et al., 2023 | |
| Fresh and aged holm oak biochar (BH) |
| Lopez-Pineiro et al., 2022 | |
| Biochar addition rate at 20 t ha−1 |
| Qin et al., 2016 | |
| Soybean (Glycine max L.) | The application of 2% peanut straw biochar (PSB) in polluted soil |
| Kamran et al., 2022 |
| Sunflower (Helianthus annuus L.) | The optimum biochar concentration at both CO2 levels (420 ppm and 740 ppm) was found to be 15% |
| Wang et al., 2023c |
| Four biochars namely, B1) fast pyrolysis from pine wood, B2) paper-sludge, B3) sewage sludge, B4) derived from grapevine wood. |
| Paneque et al., 2016 | |
| Wheat (Triticum aestivum L.) | 2% (w/w) bamboo biochar (BB), coconut shell biochar (CB), and maize straw biochar (MSB) |
| Wang et al., 2023a |
| 10 t ha−1 and 20 t ha−1 biochar |
| Li et al. 2023b | |
| Wheat (Triticum aestivum L.) |
| Qiu et al., 2022 | |
| Abburuzzini et al., 2019 |
Studies on the effects of biochar application on different plant species show a mix negative, positive, and neutral responses, commonly influenced by parameters like application rate, biochar type, and plant species, while some studies highlight significant increases in nutrient uptake, root growth, and biomass, and others indicate potential negative effects on plant health and growth, especially at higher biochar concentrations or with specific biochar types (Xiao et al., 2016).
Many publications refer directly to the impact of biochar on plant yields. Azeem et al. (2019) indicated that sugarcane-bagasse biochar utilizations in arid soils with low organic carbon may increase crop productivity and N2-fixation of legumes while decreasing the net ecosystem CO2 exchange (NEE) of legume-cereal cropping systems. It has been reported that application of straw-derived biochar to amend soil could be the suitable technique for sustaining soil fertility and crop yield in wheat-maize rotation systems in the Loess Plateau of China (Hu et al., 2021). Farhangi-Abriz et al. (2021) reported that biochar increased grain yield of maize (by 14–35%) and wheat (13.5%), and rate of biochar >30 t ha−1 did not influence crop yield substantially. Pandit et al. (2018) recommended 15 t ha−1 biochar for a maize-mustard field cropping system. For maize yield the effect of biochar depended on the dose (Kim et al., 2016; Jia et al., 2020). Biochar application significantly influence cotton yield and production (Karthik et al., 2019; Li et al., 2023c). Biochar addition boosted crop yield of arugula (Eruca sativa L.) (Zhou et al., 2017). In the case of cauliflower plants the highest values of curd size and weight were obtained at the biochar rate of 3% (Losacco et al., 2022). Biochar can be regarded as a potential soil amendment for an increased red onion growth (Peiris et al., 2022). Poultry litter biochar increase onion productivity (Arif et al., 2021). Poultry litter biochar with manure and NP fertilizer increased plant growth and yield of cucumber (Solaiman et al., 2020).
Sometimes biochar application has negative impact on crop plants. Yin et al. (2023) reported that the biochar application reduced the root weights and fresh shoot of corn and rice seedlings, but there was no significant impact on wheat seedlings. Century-old biochar enrichment in soil increased crop canopy, but had an adverse effect on plant greenness over the maturity period of chickory (Dehkordi et al., 2020). Orchard prune residue biochar amendment did not influence biomass yield and decreased germination without nutrient supplement of tomato plants (Beesley et al., 2013). Lai et al. (2013) showed no impact of biochar application on rice and leaf beet yield, pine hardwood biochar had even negative effect on cotton yield (Bohara et al., 2018).
Biochar affects also composition, development, physiological parameters and quality of plants. The combined application of chemical fertilizer and biochar improved crop and essential oil yield of basil plants, but without effect on aroma compounds (Pandy et al., 2016). Biochar from tobacco stems reduced vanillic acid and syringic acid constituents of Chinese ginseng plants (Zhao et al., 2022). Biochar derived from black cherry wood boosted plant height, increased leaf length and width, as well as leaf number of basil, moreover, the chlorophyll content, total sugar, flavonoids were increased significantly (Jabborova et al., 2021). Wood chip biochar increased the photosynthesis and decreased the oxidative stress of ice plant (Mesembryanthemum crystallinum L.), (You et al., 2021). Biochar had no effect on cotton fiber quality indices (Li et al., 2023c).
Biochar can also affect phytosanitary status of soil. Biochar combined with Bacillus subtilis enchanced growth and plant health of radish (Chen et al., 2023). Poultry litter biochar can suppress Stemphylium leaf blight on onion (Arif et al., 2021). Zhou et al. (2021) concluded that biochar improved the yield of cucumber under continuous cropping system, because of soil microbial community regulation.
Soil biochar application boost the resilience of vineyards to water shortages, and soil biochar addition improves the soil water-holding capacity in vineyards, so it could be an important strategy for climate change adaptation (Baroneti et al., 2022). Biochar application is a factor of improvement of WUE of maize (Faloye et al. (2018) and fenugreek (Bitarafan et al. 2020).
The effect of biochar on plants under different stress conditions was also studied. Biochar has the capability to boost crop yields on degraded, tropical soils (Elias et al., 2020; Tan et al., 2023). Sunflower stem biochar improved millet yield in saline and sodic soil (Taheri et al., 2022). Rice straw biochar stimulated crop performance of cotton and wheat under saline water irrigation (Singh et al., 2021).
P-rich biochar limits Pb accumulation in rice on Pb-contaminated soils (Yang et al., 2023). The application of biochar and modified biochars with H2O2, KOH, and H3PO4 could increase mint growth and productivity under fluoride and cadmium toxicities (Ghassemi-Golezani, Farhangi-Abriz, 2023). Zeeshan et al. (2020) concluded that the lower size biochar particles were notably more effective for potential agronomic and soil fertility advantages of tomato crops of biochar under heavy metal contaminated soil conditions. Biochar decreases the heavy metal accumulation in roots and seeds of sunflower (Wang et al., 2023c). Biochar application can ameliorate rice yield and reducing the accumulation of As in rice grain (Sun et al., 2024a,b). Peanut straw biochar used on arsenic polluted soils increased size and weight of soybean plant, as well as chlorophyll and soluble sugars content (Kamran et al., 2022).
The application of biochar with swine manure and sawdust mixture increase the content of nutrients and reduce the level of phytotoxicity in vegetable crops such as carrot (Daucus carota), radish (Raphanus sativus), tomato (Lycopersicon esculentum), cabbage (Brassica oleraceae), and napa cabbage (Brassica rapa) (Milon et al., 2022). Erdem (2021) reported that corn cob and rice husk biochar reduced Cd uptake of tobacco plants, and the effect of corn cob biochar was better because of its higher specific surface area. Biochar amendment reduce phytotoxicity of herbicide sulfentrazone on wheat seedlings (Wang et al., 2022b).
Biochar is the solid, carbon-rich product of the pyrolysis of biomass. It is potentially valuable and important soil amendment with tremendous agricultural benefits. Pyrolysis conditions like reactor shape and type, feedstock particle size, biomass type, heating rate, chemical activation, residence time, etc., influence the physical parameters of biochar. The benefits of biochar are increasing soil nutrients and soil organic matter content, improving soil chemical, physical and biological properties. It can reduce pollution by binding heavy metals and other contaminants. Biochar application is an effective management practices to reduce the negative impacts of climate change, which is a great challenge for human society and a pressing global issue. The interaction between plants, soil, and biochar is multifaceted, involving chemical physical, and biological processes. Biochar can positively influence both crop yield and quality. The examples from the latest literature on the subject given in the study confirm the beneficial effect of biochar application on wheat, rice, millet, soybean as well as radish, onion, cucumber, basil, mint, but they also show the possibility of negative impact on crop plants.
According to the results, future researches are important to study the mechanisms containing the microbiological and chemical nature of the synergistic and antagonistic interactions between organics and biochar so that efficient guidelines can be progressed to assure trustworthy performance of biochar treatments on crop productivity in various agricultural methods. Researches are needed to analysis and evaluate the applications of biochars with considering both its advantages and disadvantages in both plant health and soil quality.
Future studies and researches should consider long-term effects of biochar application on both plants and soil, optimizing biochar for specific goals, and improving new strategies for biochar quantification and characterization, and considering the importance of effectiveness of biochars in arid and semi-arid regions.