# A Review of Biochar Properties and Their Utilization in Crop Agriculture and Livestock Production
## 4 Biochar as a Manure/Sludge Additive  
One of the environmental aspects of BC utilization is its use as manure, or other compostable waste, additive. Biochar with its high porosity and large surface area can be an excellent adsorbent, retaining valuable elements (e.g., N, C, and S) that typically would be lost to the environment as unwanted pollutants, as well as other microelements in a composting mixture. High surface area \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Reference** & **Feedstock** & **Biochar Dose** & **Effect** \\ \hline \multirow{6}{*}{[PERSON] et al. [23]} & & & - Up to 95\% increase in plant total dry matter \\  & & & - Increase in N, P, S, Na, Ca, Mg \\  & & & concentrations in plants \\  & & 10 to 50 tha\({}^{-1}\) & - Increase in soil electrical conductivity, pH, \\  & & & total N, total C, Colwell P, Ca, Mg, Na, K, and \\  & & & effective cation exchange capacity. \\  & & & - The decrease in soil exchangeable Al. \\ \hline \multirow{6}{*}{[PERSON] et al. [34]} & \multirow{2}{*}{Pine woodchips} & \multirow{2}{*}{1 g per 50 g of soil (\(\sim\)20 tha\({}^{-1}\))} & - NH\({}_{3}\)-enriched is a bioavailable N source \\  & & & 1 g per 50 g of soil & for plants \\  & & & (\(\sim\)20 tha\({}^{-1}\)) & - Up to 2 times increase in root dry matter \\  & & & - Up to 3 times increase in leaf dry matter \\ \hline \multirow{6}{*}{[PERSON] et al. [35]} & Pruning residues & 1.5\% and 3\% by dry & - Reduction of heavy metals’ bioavailability \\  & Fir tree pellets & weight of the soil & - Reduction of bioavailability of one element \\  & Manure pellets & (\(\sim\)15 and \(\sim\)30 tha\({}^{-1}\)) & increases the bioavailability of the other \\ \hline \multirow{6}{*}{[PERSON] et al. [36]} & \multirow{2}{*}{Poultry litter} & \multirow{2}{*}{1.5 and 10 tha\({}^{-1}\)} & - Different effects of BC amendment on \\  & & & different types of soil \\  & Wheat straw & & - Lower total plant biomass in acidic aerosol, \\  & & & higher plant biomass in acidic ferralsol \\ \hline \multirow{6}{*}{[PERSON] et al. [37]} & \multirow{2}{*}{Wheat straw} & 3\% by mass of & - Increase in pH, total N, total C, and plant \\  & & the soil & growth yield \\  & & & growth yield \\ \cline{1-1}  & & (\(\sim\)30 tha\({}^{-1}\)) & - The decrease in leaching of nutrients \\ \hline \hline \end{tabular} Note: Values for biochar dose given in parentheses are approximate values in tha\({}^{-1}\), calculated with an assumption that that the biochar has been added to the 10 cm layer of the soil and that the bulk density of the soil is 1 g\(\cdot\)cm\({}^{-3}\).  
\end{table} 
Table 2: Summary of selected data on biochar application to soil. also provides more spacious and aerated habitats for microorganisms, that promote microbial activity additionally stimulated by a relatively high content of less acidic, organic C that is available to the microorganisms [38], thereby having a strong positive influence on composting processes. [PERSON] et al. [39] performed a lab-scale experiment to investigate the effect of BC amendment to dairy cattle slurry in order to preserve the slurry nutrients. Wood shavings BC (2 mm dia.) was added to the slurry at a dose equivalent to 3.96 m\({}^{3}\) ha\({}^{-1}\), resulting in 77% NH\({}_{3}\), 63% N\({}_{2}\)O, and 84% CO\({}_{2}\) emissions reduction. [PERSON] et al. [40] studied the effect of topically applied pinewood BC floating on the surface of swine manure on treating gaseous emissions. Observation showed a 13-23% reduction of NH\({}_{3}\) emission with the highest tested BC application dose of 4.56 kg\(\cdot\)m\({}^{-2}\), a 12-30% reduction for H\({}_{2}\)S at a BC dose of 2.28 kg\(\cdot\)m\({}^{-2}\), and up to a 26% reduction for indole, also with the BC application dose of 2.28 kg\(\cdot\)m\({}^{-2}\). However, the results were not statistically significant. It is worth noting that a 4.56 kg\(\cdot\)m\({}^{-2}\) application dose showed a significant increase of CH\({}_{4}\) up to 24%, which is likely due to the addition of labile C and other nutrients for the methanogens present in the manure.