# A Review of Biochar Properties and Their Utilization in Crop Agriculture and Livestock Production
## 3 Biochar as a Soil Amendment
[34] investigated plant bioavailability of BC-adsorbed ammonia by the determination of NH\({}_{3}\)-BC complex stability. NH\({}_{3}\) was isotopically labeled with 15N, and 15N-labelled and unlabeled BC materials were placed into a soil sown with pasture grass seeds, at a BC rate of 1 g per 50 g of the air-dried soil. Four BCs used in the study were manufactured from Monterey pine woodchips at 300, 350, and 500 \({}^{\circ}\)C. After 25 d from the addition of the NH\({}_{3}\)-enriched BCs to the soil, leaf dry matter yields had increased by 2 to 3 times, and root dry matter yields by 2 times, when compared to treatments receiving non-enriched BC. Biochar pyrolyzed in the lowest temperature contributed to the highest N uptake of the plants. However, no differences in plant yield were observed due to the addition of the non-enriched BC. An increase in dry matter yield in the case of the NH\({}_{3}\)-enriched BC shows that biochar is a very good carrier of a bioavailable N source for plants. [PERSON] et al. [35] investigated the amendment of BCs from three different feedstock materials to mine tailings. The effect on the bioavailability of toxic inorganic elements in the tailings and the potential to utilize BC in a phytoremediation process was evaluated. Biochars were obtained from orchard pruning residues pyrolyzed at 500 \({}^{\circ}\)C, fir tree pellets, and manure pellets mixed with fir tree pellets; both pyrolyzed at 400 \({}^{\circ}\)C. The BCs were mixed with the mine tailings at a rate of 1.5% and 3% (by dry weight), and the mixtures were planted with seedlings of three different plants. After 90 days, the plants were dried, and their shoots and roots were analyzed for the content of toxic metals. In general, the BC application reduced the bioavailability of heavy metals. However, the results are not unequivocal as there is strong significant interaction between the plant species and the dose of BC, regardless of its feedstock material, and while a particular type of BC reduces the bioavailability of one element, at the same time it increases another. The research has shown that BC obtained from manure performs best in the stimulation of plants growth (likely due to the higher N content in the feedstock material) and the immobilization of toxic elements. [PERSON] et al. [36] applied poultry litter and wheat straw BCs at rates of 1, 5, and 10 t-ha-1 and investigated the wheat growth response on four different types of soil. The effects of BC amendment were different when considering different types of soil, with a lower total plant biomass in the acidic aerosol at the highest application rate; higher plant biomass in acidic ferralsol, increasing with the  
Figure 2: Summary of the overall concept of biochar application to the soil. dose of BC applied; and no significant impact at all in neutral vertisol and alkaline calcisol. Thus it is suggested that the use of BC is not limited only to a basic use as a carrier for nutrients and requires a more sophisticated approach concerning soil type in a particular agricultural system that is being amended, with a potential influence on the microbial community of the soil. [PERSON] et al. [37] researched the impact of wheat straw BC on the yield of rice grown on Psammaquent and Plinthudult soils, as well as on the properties of those soils. Biochar was applied to the soils at a rate of 3% (by mass), increasing their pH, total N, and C content, and decreasing the leaching of nutrients from the BC amended soils. The application of BC also increased rice plants growth yield, including their height, leaf length, and grain yield--grain yields were increased by 32% and 41% for Psammaquent and Plinthudult soils, respectively. The use of BC as a soil amendment is a vast field of study (Table 2) that attracts the attention of a considerable number of researchers.