When it comes to the use of biochar in agriculture, the majority of research conducted in the last decade has focused on its application as a soil amendment and for soil remediation. This treatment improves soil quality, increases crops yields, and sequestrates atmospheric carbon to the soil. Another widely studied aspect connecting biochar with agriculture is the composting processes of various agricultural waste with the addition of biochar. Obtaining the material via the pyrolysis of agricultural waste, including animal manure, has also been investigated. However, given the remarkable properties of biochar, its application potential could be utilized in other areas not yet thoroughly investigated. This review paper summarizes the last decade of research on biochar and its use in crop agriculture and livestock production. Knowledge gaps are highlighted, such as using biochar for the mitigation of odorous emissions from animal manure and by feeding the biochar to animals.

Managing the environmental impacts associated with livestock production is a challenge for farmers, public and regulatory agencies. Sustainable solutions that take into account technical and socioeconomic factors are needed. For example, the comprehensive control of odors, ammonia (NH₃), hydrogen sulfide (H₂S), and greenhouse gas (GHG) emissions from swine production is a critical need. Stored manure is a major source of gaseous emissions. Mitigation technologies based on bio-based products such as biochar are of interest due to the potential benefits of nutrient cycling. The objective of this study was to test non-activated (non-functionalized) biochar for the mitigation of gaseous emissions from stored manure. Specifically, this included testing the effects of: (1) time; and (2) dosage of biochar application to the swine manure surface on gaseous emissions from deep-pit storage. The biochar surface application was tested with three treatments (1.14, 2.28 and 4.57 kg·m⁻² manure) over a month. Significant reductions in emissions were observed for NH₃ (12.7–22.6% reduction as compared to the control). Concomitantly, significant increases in CH₄ emissions (22.1–24.5%) were measured. Changes to emissions of other target gases (including CO₂, N₂O, H₂S, dimethyl disulfide/methanethiol, dimethyl trisulfide, n-butyric-, valeric-, and isovaleric acids, p-cresol, indole, and skatole) were not statistically significant. Biochar treatment could be a promising and comparably-priced option for reducing NH₃ emissions from stored swine manure.

The aim of this research was to evaluate the effect of biochar diet supplementation for broiler chickens on (1) ammonia and odor emissions from manure, (2) feed conversion ratio and daily weight gain, and (3) selected meat quality and sensory parameters. Beechwood biochar (BC, 2 and 4%) and BC–glycerin–aluminosilicates mix (BCM, 3 and 6%) were tested as dietary additives. A total of 750 chicken broilers (Ross 308) were divided into five dietary groups with five replicates per group (n = 5, 30 birds in each replicate) and reared on a littered floor for 5 weeks. Both feed additives showed a significant reduction of ammonia emissions by up to 17%, while the reduction of odor emissions was not statistically significant. The feed conversion ratio increased by 8% for the highest concentration of the mixture. The change of the treated broilers’ average body weight ranged in the last week of the experiment from 0 to −7%, with the most negative effect for the highest dose of the mixture. Sensory analysis of the sous-vide cooked breasts showed no significant differences.

Sustainable solutions for intensive poultry production can help farmers, rural communities, consumers, and regulatory agencies. This study assessed supplementation of laying hens diet with beechwood biochar (BC, 1~2%) and BC–aluminosilicates–glycerin mixture (BCM, 1.5~3%) to lower the environmental impact while maintaining egg quality. The effect on feed intake, laying performance, egg quality, the sensory quality of hardboiled eggs, ammonia (NH₃) and volatile organic compound (VOC) emissions from excreta, and the excreta composition, were evaluated. A total of 90 hens were distributed into 30 cages and divided into five groups (n=6 replications). BC addition increased daily feed intake, while 1.5% BCM addition reduced it. The influence on egg parameters was positive, with a 6% increase in laying performance, up to 10% and 6% increase in shell resistance to crushing and shell thickness, respectively. The sensory analysis demonstrated no significant differences between all treatments. Excreta total N content was numerically lower due to the treatments (by 4~20%); its pH increased (not significantly), while no effect on ammoniacal N and dry matter content was observed. Most of the investigated treatments had a numerically positive (not statistically significant) effect on NH₃ reduction. The reduction of VOC emissions was ambiguous and not statistically significant.