# A Review of Biochar Properties and Their Utilization in Crop Agriculture and Livestock Production
## 2 Biochar Properties
Orange peels, residual wood, and water-treatment sludge BCs obtained through pyrolysis at 300 \({}^{\circ}\)C were characterized by lower pH (8.00, 7.80, and 5.80, respectively), higher N content (1.78%, 1.21%, and 0.23%, respectively) and lower ash content (3.90%, 7.84%, and 82.04%, respectively) compared to the same feedstock material BCs pyrolyzed at 700 \({}^{\circ}\)C--pH (12.30, 10.30, and 6.80), N content (0.67%, 0.45%, and 0.13%) and ash content (8.45%, 12.57%, and 90.70%), respectively. [PERSON] et al. [15] obtained BC through the torrefraction of municipal waste and sawdust at temperatures from 200 to 300 \({}^{\circ}\)C at 1 h and investigated the effect of temperature on the fuel properties of the final products. An increase of the torrefraction temperature contributed to the decrease of the final product mass yield, volatile solids content, and H/C ratio, while moisture, ash, and sulfur contents increased. Biochar mass yield decreased with temperature for both of the feedstock materials, from 89% at 200 \({}^{\circ}\)C to 63% at 260 \({}^{\circ}\)C for municipal waste and from 94% at 200 \({}^{\circ}\)C to 30% at 300 \({}^{\circ}\)C for sawdust; VOCs content decreased from 75% to 57% and from 77% to 40%, respectively and the H/C ratio dropped from 1.4 to 1.0 and from 1.3 to 0.4, respectively. The moisture content of waste BC ranged from 1.4% to 1.9% with no correlation with temperature, while sawdust BC moisture content ranged from 1.5% to 6.0% for 200 and 260 \({}^{\circ}\)C, respectively. Any unusual increase in moisture content with a temperature increase might be caused by the high moisture of the feedstock materials and its condensation in the reactor while the material is in its cooling phase. Ash content increased from 14% at 200 \({}^{\circ}\)C to 24% at 260 \({}^{\circ}\)C for waste BC and from 0.65% at 200 \({}^{\circ}\)C to 1.7% at 300 \({}^{\circ}\)C for sawdust BC, while sulfur content increased from 0.2% to 0.5% and from \(\sim\)0.02% to 0.05%, respectively. In case of the waste-derived BC, a temperature of 260 \({}^{\circ}\)C (instead of 300 \({}^{\circ}\)C) shows the most extreme values, probably due to the high standard deviations, that should be attributed to the high heterogeneity of the feedstock material. The fact that values slightly increase when temperatures exceed 260 \({}^{\circ}\)C also have to be noted. In another research, [PERSON] et al. [16] investigated properties of municipal waste BC, obtained at 260 \({}^{\circ}\)C and 50 min of the torrefraction process. The BC was characterized by C, H, N, O contents of 59.7%, 6.07%, 0.68% and 13.24%, respectively. Moisture and ash contents were 1.54% and 20.14%, respectively. [PERSON] et al. [17; 18] examined properties of BC obtained from torrefraction of Oxytree (_Paulownia Clon_ in Vitro 112) pruning residues as a function of torrefraction temperature and time, with the process temperature also ranging from 200 to 300 \({}^{\circ}\)C and time ranging from 20 to 60 min. Biochar yields ranged from 52% to 98%, with the lowest yield at the highest temperature and the longest time of torrefraction. H, N, and O contents followed the same trend with the percentage ranging from 3.20% to 7.17%, 1.89% to 4.56%, and 14.90% to 42.20%, respectively. Moisture and C contents followed the opposite trend, ranging from 1.22% to 7.58% and 38.1% to 57.0%, respectively. However, there are some exceptions to the general trends (e.g., lower yields at higher temperatures and higher C content at the same time) that concern different types of cultivation of the feedstock trees. [PERSON] et al. [19] torreified sewage sludge for 60 min at different temperatures ranging from 200 to 300 \({}^{\circ}\)C and obtained BC that was characterized by C, H, N, O contents ranging from 28.4% to 12.7%, 2.43% to 0.71%, 4.03% to 2.68%, and 21.31% to 9.02%, respectively, for temperatures from 200 to 300 \({}^{\circ}\)C. Ash content increased with temperature from 43.6% to 73.4%.