# Agricultural Waste-Based Biochar for Agronomic Applications
## 3 Biochar as a Soil Amendment
### Impacts on Soil Structure and Composition
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Biochar** & **Application Rate** & **Plant** & **Effects on Soil Properties** & **Effects on Crops** & **Ref.** \\ \hline
**Bamboo branch** & \(0,5,10,20\) t/ha & Bamboo & Increase in soil moisture, soil microbial biomass and influence on the mean soil respiration rate & - & [74] \\ \hline
**Olive stone,** & & & Decrease in soil bulk density and increase in soil field capacity & Increase in seed germination, plant dry biomass and crop production & [75] \\ **almond shell,** & & & & \\ **wheat straw, pine woodchips, and** & & & & \\ **olive-tree pruning** & & & & \\ **olive-tree pruning** & & & & \\ \hline
**Pouttry waste** & \(0\)–\(1\%\) (_w/w_) & **Brassicacampestris** & **Improvement in soil physical and chemical conditions Enhancement of nutrients and especially nitrogen & Decrease in metals uptake in Brassica campestris and improvement of growth Increase in photosynthetic and accessory pigments and accessory pigments** & Decrease in metals uptake in Brassica campestris and improvement of growth Increase in photosynthetic and accessory pigments** & Decrease in shoot biomass, root length and volume, tuber yield, photosynthetic rate, midday leaf water potential, and increase in K\({}^{+}\) content in xylem \\ \hline
**Hardwood and** & \(0\)–\(5\%\) (_w/w_) & **Potato** & - & \\ **softwood** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ **wheat** & & & & \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._ \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Biochar** & **Application Rate** & **Plant** & **Effects on Soil Properties** & **Effects on Crops** & **Ref.** \\ \hline Wheat & 12 t/ha & Maize & Significant decrease in soil salinity & Mitigation of salinity stress and improvement in maize grain yield and plant performance in saline croplands Increase in maize leaf sap nitrogen, phosphorus and potassium and decrease in sodium and chloride Improvement in leaf bioactivity related to osmotic stress & [80] \\ \hline Pellets of & 0 or 5\% & Lettuce & Reduced conductivity in biochar-ameliorated soils & Reduced Na uptake of plants & [81] \\ \hline Rice straw & 22.5 t/ha & Rice & -Increase in total C and total N contents -Increase in C/N ratio and moisture of rhizosphere soil & Enhancement in rice yield and N retention in a paddy field & [82] \\  & & & -Increase in soil pH and water retention ability & & \\ \hline Poultry manure & 1\% (\(w\)/\(w\)) & Barley & -Improvement in petroleumhydrocarbons-degradation -Improvement in soil microbial respiration & Increase in dry weight yield & [83] \\ \hline Maize stubble & 3\% & Maize & - & Improvement in chlorophyll content and shoot to root biomass & [84] \\  & & & & Decrease in contaminant retention by shoots & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Cont. Figure 2: Benefits of biochar amendment for soil and plant production. Biochar improves the soil texture and porosity, increases the pH buffering capacity of soils, increases CEC and helps in the binding of important anions and cations [85]. The increase in the soil pH subsequent to the addition of biochar improves the retention of basic cations in acid tropical soils and consequently improves the crop nutrition [86]. Similarly, [PERSON] et al. [87] confirmed that the increase in the soil pH following biochar addition enhances the availability of phosphorous and potassium. Alkaline biochars are more suitable for acidic soils [88], while low-pH biochars could be effectively applied to alkaline soils to lower their pH [89].