# Agricultural Waste-Based Biochar for Agronomic Applications
## 2 Physiological Characteristics of Biochar
Organic phosphorus is converted to inorganic form, which is not volatilized at a pyrolysis temperature below 700 \({}^{\circ}\)C. The phosphorus content is enriched within the biochar and could serve as a source of phosphorus for the plant [53]. Generally, the content of phosphorus, as well as that of other elements such as Ca, Mg, K, Fe, Si, S, Zn, Cu, and Mn, increases as the pyrolysis temperature increases; however, these elements' bioavailability is reduced due to their insertion into highly aromatic structures within biochar. Contrary to this, at lower pyrolysis temperatures, an improvement in the bioavailability of these nutrients is observed. [PERSON] et al. [54] showed that exchangeable K in maize straw-derived biochars produced at 300 and 400 \({}^{\circ}\)C was more available to plant roots than that in biochars pyrolyzed at 500 \({}^{\circ}\)C. In addition to pyrolysis temperature, the nature of feedstock also affects the chemical properties of biochar. For instance, biochars derived from wood-based biomass are reported to be more resistant to biodegradation than biochars obtained from crop residues and animal manures [27; 55]. Contrary to this, biochar produced from manure contains more nutrients [56; 57]. Elemental composition and some other characteristics of biochar derived from different feedstocks and at different pyrolysis temperatures are listed in Table 1. The main properties of biochar and various forms of its application in agriculture are summarized in Figure 1.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline
**Feedback/Typolysis Temperature** & \multicolumn{6}{c}{**Characteristics**} & \multicolumn{6}{c}{**Ref. **} \\ \cline{2-13}  & **Ster [m\({}^{2}\)gl]** & **Ash [F\({}^{3}\)]** & **pH** & **C [F\({}^{3}\)]** & **N [F\({}^{3}\)]** & **H [F\({}^{3}\)]** & **F [F\({}^{3}\)]** & **K [\({}^{3}\)]** & **C/N** & **OIC** & **HVC** & **CEC [cm/kg]** \\ \hline Shterup half/500 \({}^{\circ}\)C & 13.3 & 83.5 & 10.3 & - & - & 2.08 & 1.98 & - & - & - & 389 & [58] \\ Oak vocod/200 \({}^{\circ}\)C & - & - & 4.6 & 48.8 & 0.2 & - & 0.03 & 0.13 & 257 & - & - & 54.2 & [44] \\ Oak vocod/400 \({}^{\circ}\)C & - & - & 6.9 & 42.7 & 0.3 & - & 0.06 & 0.38 & 130 & - & - & 61.1 & [45] \\ Oak vocod/400 \({}^{\circ}\)C & - & - & 9.5 & 45.5 & 0.4 & - & 0.06 & 0.44 & 111 & - & - & 97.0 & [45] \\ Wheat atma/250 \({}^{\circ}\)C & - & - & - & 55.7 & 0.98 & - & 0.01 & 1.51 & 57 & - & - & 68.7 & [59] \\ Wheat atma/300 \({}^{\circ}\)C & - & - & - & 68.4 & 1.03 & - & 0.03 & 2.12 & 57 & - & - & 56.6 & [59] \\ Wheat atma/300 \({}^{\circ}\)C & - & - & - & 66.65 & 1.06 & - & 0.02 & 2.02 & 63 & - & - & 40.5 & [59] \\ Wheat atma/500 \({}^{\circ}\)C & - & - & - & 69.18 & 1.02 & - & 0.01 & 2.1 & 68 & - & - & 22.0 & [59] \\ Corn-straw/400 \({}^{\circ}\)C & 7 & 18 & 10.4 & 58.6 & 2.0 & 2.0 & - & - & 34.7 & 0.48 & 0.41 & 20.1 & [40] \\ Wheat atma/500 \({}^{\circ}\)C & 111 & 11 & 8.3 & 70.3 & 1.4 & 2.9 & - & - & 57.8 & 0.38 & 0.49 & 5.1 & [40] \\ Wheat atma/400 \({}^{\circ}\)C & 177 & 12 & 9.2 & 73.4 & 1.4 & 2.1 & - & - & 62.0 & 0.31 & 0.35 & 1.3 & [40] \\ Corn-straw/400 \({}^{\circ}\)C & 319 & 5.7 & 7.7 & 45.5 & 0.63 & 5.4 & - & - & - & - & - & [61] \\ Corn strow/400 \({}^{\circ}\)C & 31.7 & 12.5 & 8.8 & 64 & 0.42 & 3.9 & - & - & - & - & - & - & [61] \\ Cornstrow/400 \({}^{\circ}\)C & 4.58 & 18.7 & 9.8 & 64.5 & 0.25 & 2.7 & - & - & - & - & - & - & [61] \\ Rice husk/300 \({}^{\circ}\)C & - & 21.8 & 6.8 & - & - & - & - & - & - & - & - & - & [61] \\ Rice husk/300 \({}^{\circ}\)C & - & 23.8 & 10.4 & - & - & - & - & - & - & - & - & - & [62] \\ Rice husk/700 \({}^{\circ}\)C & - & 35.6 & 10.7 & - & - & - & - & - & - & - & - & - & [62] \\ Spaquetage bages/30 \({}^{\circ}\)C & - & 11.0 & 7.8 & - & - & - & - & - & - & - & - & - & [62] \\ Spaquetage bages/300 \({}^{\circ}\)C & - & 11.5 & 9.2 & - & - & - & - & - & - & - & - & - & [62] \\ Spaquetage bages/300 \({}^{\circ}\)C & - & 12.8 & 9.7 & - & - & - & - & - & - & - & - & [62]