# A Review of Biochar Properties and Their Utilization in Crop Agriculture and Livestock Production
## 2 Biochar Properties  
Properties of biochar have been very well described by [PERSON] and [PERSON] [3] in their review article. In this section, the most important properties of BC from the perspective of agriculture and livestock production have been discussed. BC characteristics are determined by its composition, which depends on the feedstock material used for the pyrolysis and the process parameters themselves, with the feedstock material being the most significant factor [5]. In the process of BC production, the main interest is to obtain the most of a carbonaceous solid-state product. Typical BC pyrolysis time and temperature range from 60 to 240 min and from 300 to 700 \({}^{\circ}\)C; however, those parameters are determined by the desired properties of the final material [3]. Torrefaction, a low-temperature pyrolysis at a range of 200 to 300 \({}^{\circ}\)C, also referred to as \"mild pyrolysis\" or \"high-temperature drying\", has recently gained more interest as it allows a feedstock material with similar properties to be obtained but with simpler technology compared to regular pyrolysis for the same feedstock material, due to the lower temperature of the process [6]. Increasing interest in biochar production has resulted in a demand for a high-quality product and regulatory oversight. The European Biochar Foundation [7], a non-profit institution, provides voluntary quality standards and guidelines to ensure that the manufacturing of BC leads to a material that has satisfactory properties and a positive environmental footprint. The International Biochar Initiative (IBI) [8] is another platform for fostering stakeholder collaboration, best industry practices, and environmental and ethical standards to support biochar systems that are considered safe and economically viable. IBI Biochar Standards provide tools to confirm that biochar possesses the necessary characteristics and meets quality standards for safe use. This is especially important for agricultural uses of BC that could be potentially contaminated with toxics (e.g., heavy metals, polycyclic aromatic hydrocarbons, dioxins, volatile and semivolatile organic compounds). Biochars of unknown origin or produced from contaminated waste substrates are more likely to be of concern, compared to the substrates used for biochar production in agriculture, such as corn stover, pruning residues, or poultry litter. [PERSON] et al. [4] investigated the influence of pyrolysis conditions on date seed BC properties. An increase in pyrolysis temperature and heating time of the same feedstock material, from 350 to 550 \({}^{\circ}\)C and from 1 to 3 h, resulted in a BC characterized by higher C content (from 64.4% to 82.2%), ash  
Figure 1: Summary of the scope and content of review focused on the use of biochar in agriculture. content (from 6.67% to 12.62%) and pH (from 6.95 to 8.58); however, at the same time, BC yield was reduced, from 45.18% to 20.94%. [PERSON] et al. [9] used pitch pine woodchips during a fast pyrolysis (2 s) under different temperatures (300, 400, and 500 \({}^{\circ}\)C) and the increased temperature resulted in a BC with higher C content (63.9%, 70.7%, and 90.5% respectively), but lower H (5.4%, 3.4% and 2.5% respectively) and O (30.4%, 25.5%, and 6.7% respectively) content. BC yields were also decreased with the increase of pyrolysis temperature, from 60.7% at 300 \({}^{\circ}\)C, 33.5% at 400 \({}^{\circ}\)C, to 14.4% at 500 \({}^{\circ}\)C.  
[PERSON] [10] compared effects of slow (heating rate of 50 \({}^{\circ}\)C/min, 60 min of the process) and fast (heating rate of 120 \({}^{\circ}\)C/min, 20 min of the process) pyrolysis of sugarcane bagasse and proved that slow pyrolysis yields a fuel of a higher char content than the fuel obtained from the same material with fast pyrolysis.