## 2 Materials and Methods
### Germination Assay  
A germination assay was practiced to evaluate biochar effect on germination of maize seeds and seedling growth. For this purpose, sandy loam soil was filled in plastic trays. Before sowing, developed biochar was manually mixed in sand at the rates of 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, and 3% (\(w/w\)) in triplicates. Twelve seeds of maize (_Zea mays_ L.) variety Syngenta NK-6621 were seeded in each tray to calculate germination percentage and rate. Thus, a total of 21 experimental units were assorted using completely randomized design (CRD) and the method described by International Seed Testing Association (ISTA) was used seven days after sowing (DAS). Seed germination percentage (GP), germination rate (GR), mean emergence time (MET), and seed vigor (SV) were calculated using following formulas:  
\[\text{Germination Percentage }(\text{GP})=\left(\text{SNG}\big{/}_{\text{SN0}} \right)\;\times\;100\]  
where, \"SNG\" represent germinated seeds in total and \"SN0\" represents total number of viable seeds [32].  
\[\text{Germination Rate}=\frac{\sum\text{ N}}{\sum\text{ (n }\times\text{g)}}\]  
where, \"N\" is the number of germinated seeds, \"n\" is the seeds germinated on growth day, \"g\" is the total number of germinated seeds.  
\[\text{Mean Emergence Time }(\text{MET})=\frac{\sum\text{ Dn}}{\sum\text{ n}}\]  
where, \"n\" is the germinated seeds and \"D\" represents total number of days [33].  
\[\text{Seed Vigour }(\text{SV})=\text{GP}\times\text{Seedling length}\]  
where, \"GP\" is germination percentage.  
An equation by AOSA [34] was used to calculate emergence index (EI):  
\[\text{Emergence index}=\frac{\text{Germinated seeds}}{\text{No of days of first count}}+\frac{\text{Germinated seeds}}{\text{No of days of final count}}\]  
Time required for 50% emergence of seeds (E50) was determined using equation given by [PERSON] et al. [35]:  
\[\text{E}_{50}=\text{ti}+\left[\left(\left.\frac{\text{N}}{2}-\text{ni}\; \right)\left(\left.\left.\left.\left.\left.\left.\left.\left.\left.\left. \left.\left.\left.\left.\left.\left.\left.\left.\left.\left.\left.\left. \left.\left.\left.\left.\left.\left.\left.\left.\left.\left.\left.\left. \left.\left.\left.\left.\left.\left.\left.\left.\left.\left.\left.\left.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\right.\]\]  
Here, in the equation, \"N\" is the final number of germinating seeds, while nj and nj are the cumulative number of seeds germinated by adjacent counts at times tj and ti, respectively, when ni < N/2 < nj.  
\begin{table}
\begin{tabular}{l l l} \hline \hline
**Parameters** & **Units** & **Pyolysis Temperature (350 \({}^{\circ}\)C)** \\ \hline Yield & \% & 43–46 \\ pH\({}_{1:20}\) & - & 7.10 \\ EC\({}_{1:20}\) & dS m\({}^{-1}\) & 0.73 \\ Ash content & \% & 13.2 \\ Moisture content & \% & 2.49 \\ Cation exchange capacity (CEC) & cmolc kg\({}^{-1}\) & 43–45 \\ Carbon & \% & 58.23 \\ Nitrogen & \% & 1.33 \\ Phosphorus & \% & 0.43 \\ Potassium & \% & 1.02 \\ Sulphur & \% & 0.93 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Physicochemical properties of biochar produced at 350 \({}^{\circ}\)C.