The impact of biochar amendment on wheat (Triticum aestivum) productivity: A review

Introduction

Biochar's Role in Sustainable Wheat Production: Historical Context, Global Trends, and Objectives

Originating in the Amazonian Terra Preta, biochar is an ancient soil amendment that has recently attracted attention as a carbon sequestration and sustainable agriculture input (Wikipedia, 2025). Early research in the 2000s concentrated on soil conditioning, but throughout the last 20 years, attention has shifted to crop-specific results, especially for wheat, a staple crop that is essential to the world. Wheat yields increased by 13.5%, according to meta-analyses, including the 2021 study by Ma et al., especially on acidic, coarse-textured soils. This demonstrated the agronomic potential of biochar in poor settings. After 2015, research funding and publications increased dramatically due to a range of climatic applications, especially in China, Pakistan, Canada, and Australia. Given the pressing problems facing wheat production, such as soil degradation, water scarcity, and nutrient losses, research into biochar-driven soil improvements (such as improved nutrient retention, water holding capacity, and soil structure) is highly pertinent. The primary goals of this review are to critically evaluate performance outcomes and trends. [11] , there was a 13.5% increase in field conditions, especially in desert and subtropical agroecosystems. This pattern was supported by Xiao et al. (2017) [13] , who discovered a 10% average yield increase across grains, with clay and acid showing the strongest responses. According to Zulfiqar et al. (2022) [3] , drought stress pot experiments using 3-5% wheat-straw biochar showed a 13-16% increase in yield, which was backed by increased physiological resistance. In comparison to organic fertilizers, longer-term field trials in the Yellow River Delta (5-20 t ha⁻¹ annually, over three years) demonstrated improvements in salinity and water status as well as yield increases of 10-14%. Coapplying biochar with NPK fertilizers resulted in 15-30% yield improvements in treatment integration studies conducted in Pakistan utilizing nutrient-rich treatments. All things considered, the statistics continuously show modest but significant yield gains, especially when combined with fertilizer and under stress.

Mechanisms Enhancing Wheat Yield: Soil-Plant-Microbe Pathways

The stimulatory effect of biochar on wheat stems from four interconnected pathways. Biochars made from crop residues and manure offer a continuous release of N, P, and K while lowering nitrate leaching and ammonia volatilization. Grain and shoot N increases of 50-60% are demonstrated by meta-analyses and pot experiments, which directly contribute to the creation of yields (Ali et al., 2022) [1] . Biochar increases plant-available moisture, decreases bulk density, and improves soil aggregation-all of which are crucial in areas that are prone to drought (Hyvaluoma et al., 2018; Zulfiqar et al., 2022) [6,3] . Biochar increased water content and decreased EC and sodium in the saline-alkaline Yellow River Delta soils, improving yield by 0.5 to 0.7 t ha⁻¹ (Lashari et al., 2024) [8] . Research conducted on acidic soils confirms that biochar has an alkalizing impact that promotes nutrient availability. In order to promote plant stress resilience, biochar raises microbial biomass C/N ratios, enzyme activities (like dehydrogenase), and antioxidant enzyme responses (SOD, CAT) (Bilal Zulfiqar et al., 2022; Asai et al., 2011) [3,2] . Under stressful environmental conditions, their contributions help to maintain yield stability. The properties of biochar and its agronomic results are influenced by the feedstock source, pyrolysis temperature, and application rate. Because of their higher nutrition and ash content, cropresidue and animal-waste biochars continuously function better than woody chars (Ma et al., 2021; Xiao et al., 2017) [11, 13] . According to research, pyrolysis between 400 and 550 °C offers the best balance between nutrient release and structural integrity; higher temperatures boost stability while lowering the amount of volatile nutrients (Li et al., 2019; Hyvaluoma et al., 2018) [9,6] . In coarse, degraded soils, application doses of 5-15 t ha⁻¹ optimize yield benefits; greater dosages are not cost-efficient because of diminishing returns (Xiao et al., 2017; Ma et al., 2021) [13,11] . 15 t ha⁻¹ provides the best salt mitigation in saline soils, whereas >20 t ha⁻¹ adds minimal benefit (Lashari et al., 2024) [8] . www.extensionjournal.com

Cooperation with Water-Saving Techniques and Fertilizers

The agronomic benefits of combining charcoal with fertilizers are substantial. In clay-loam soils, nutrient-rich biochars enhanced nitrogen uptake by 16-27% and enhanced wheat biological and grain yield by 26-29% when paired with chemical fertilizers (Improvements via PMB/FM pilot trials). In calcareous soils, co-applying wheat-straw biochar and NPK increased the concentration of nitrogen and grain protein (Ali et al., 2022) [1] . Furthermore, in semi-arid wheat systems, the combination of biochar with conservationtillage and water-retentive polymers greatly increased yield and water-use efficiency (WUE) (Zulfiqar et al., 2022) [3] . These complementary approaches demonstrate how biochar can enhance water management and soil fertility systems.7. Agronomic Guidelines for Effective Biochar Use in Wheat Farming, When using biochar, farmers and agronomists should take into account important considerations. Choose crop-residue or manure feedstocks that have been pyrolyzed at ≤550°C and apply at moderate rates (5-15 t ha⁻¹) that are appropriate for the fertility and texture of the soil. Coapplication of NPK fertilizers is necessary in coarse, acidic, or saline soils in order to maximize nutrient delivery and structural enhancement. Adaptive management is ensured by tracking soil pH (goal range 6.5-7.5), salinity, and nitrogen dynamics. To prevent impurities and guarantee consistent outcomes, quality standards (such as IBI) must be adhered to. Being aware of the risks is essential. Biochar works best on deteriorated or stressed soils, while compost may be more economical in fertile, temperate climates.

Environmental Considerations, Economic Feasibility, and Future Research Needs

Economic and environmental obstacles stand in the way of the broad application of biochar, despite its yield improvements. In low-value grain systems, production, transportation, and application can be prohibitively expensive unless localized pyrolysis units are practical. The carbon balances in life-cycle assessments (LCAs) vary based on logistics and scale, and they are constrained. Field experiments must take environmental concerns such heavy metal contamination, pH changes, and disturbance of the soil microbiome into consideration. The majority of positive yield responses decrease in later years, and there are crucially little long-term (>3 years) field data (Xiao et al., 2017) [13] . Standardized reporting on feedstock, pyrolysis, and soil-interaction parameters, multi-year, multi-site experiments, and integrated agronomic-economicenvironmental assessments are all essential components of future study. Meaningful scale will require socioeconomic research and farmer uptake programs.

Conclusion

The idea that properly applied biochar increases wheat yield (8-20%) by improving soil fertility, water status, and stress resistance is supported by a substantial body of evidence from meta-analyses and field studies. Biochar must be made and used with evidence-based feedstocks, doses, and integration techniques in order to fully reap its benefits. Issues including cost, environmental effects, and long-term performance call for methodical research and policy backing. Biochar can only move from a specialized innovation to a widely used sustainable practice in wheat production with an integrated, standardized strategy.

References

1. Ali U, Ali R, Yasmeen T, et al. Biochar optimizes wheat quality, yield, and nitrogen acquisition in lowfertile calcareous soil treated with organic and mineral N fertilizers. Front Plant Sci. 2022;13:879788. https://doi.org/10.3389/fpls.2022.879788
2. Asai H, Samson BK, Stephan HM, Songyikhangsuthor K, Homma K, Kiyono Y, et al. Biochar amendment techniques for upland rice production in Northern Laos: www.extensionjournal.com soil fertility, growth, yield, and yield components. Field Crops Res. 2011;123(2):182-7. https://doi.org/10.1016/j.fcr.2011.05.015
3. Zulfiqar B, Hussain HA, Ishfaq M, Ahmad M, Wasaya A. Biochar enhances wheat yield under drought via improved physiological and antioxidant defense. PLoS One. 2022;17(4):e0267819. https://doi.org/10.1371/journal.pone.0267819
4. Blanco-Canqui H. Biochar and soil physical properties. Soil Sci Soc Am J. 2013;77(5):A1-A11. https://doi.org/10.2136/sssaj2013.01.0023aw
5. Farhangi-Abriz S, Torabian S, Mirzaei A. Metaanalysis on biochar effects on wheat yield and stress tolerance. Sci Total Environ. 2021;775:145869. https://doi.org/10.1016/j.scitotenv.2021.145869
6. Hyväluoma J, Matsiola D, Rasa K. The effects of pyrolysis temperature on biochar physical properties and wheat productivity. J Anal Appl Pyrolysis. 2018;134:516-23. https://doi.org/10.1016/j.jaap.2018.07.003
7. Khan S, Ullah H, Ali H, et al. Biochar improves soil nutrient availability and wheat under saline conditions. Plants. 2024;13(2):166. https://doi.org/10.3390/plants13020166
8. Lashari MS, Ye C, Ji H, Li L, Liu Y. Biochar improves wheat yield in saline-alkaline soils of Yellow River Delta: a 3-year field trial. BMC Plant Biol. 2024;24:45. https://doi.org/10.1186/s12870-024-04521-y
9. Li X, Zhu Y, Wang H, et al. Pyrolysis temperaturedependent changes in biochar properties and its effects on wheat growth and soil nutrient retention. J Clean Prod. 2019;241:118400. https://doi.org/10.1016/j.jclepro.2019.118400
10. Linke R, Tisdall JM. Woody biochars in agriculture: a review of their long-term performance and agronomic limitations. Agric Syst. 2022;195:103299. https://doi.org/10.1016/j.agsy.2021.103299
11. Ma D, Wei Q, Sun J, Zhao X, Lu Y. Meta-analysis of biochar application on cereal crop yields: a global perspective. Sci Total Environ. 2021;775:145869. https://doi.org/10.1016/j.scitotenv.2021.145869
12. Wang D, Zhang Y, Wang Y, Wang S. Effects of biochar derived from wheat straw on soil properties and wheat growth in saline soils. Agronomy. 2020;10(9):1304. https://doi.org/10.3390/agronomy10091304
13. Xiao J, Zhang Z, Lin C, et al. A meta-analysis of biochar effects on wheat yield in China. Sci Agric Sin. 2017;50(10):1827-37. https://doi.org/10.3864/j.issn.0578-1752.2017.10.008
14. Xu G, Quicker P. Biochar properties influence on nitrogen transformation and plant growth: a review. Environ Sci Technol. 2018;52(16):9579-90. https://doi.org/10.1021/acs.est.8b02193
15. Zhang X, Wang H, He L, et al. Effects of biochar feedstock and pyrolysis temperature on soil carbon stability and crop yield: a global meta-analysis. Environ Pollut. 2020;265:114861. https://doi.org/10.1016/j.envpol.2020.114861
16. Zhou H, Liu X, Zhang D, et al. Animal manure biochar improves soil properties and wheat productivity in arid soil in Northwestern China. Field Crops Res. 2018;218:165-73. https://doi.org/10.1016/j.fcr.2018.01.019