## 2 Materials and Methods
### Nitrogen Adsorption and Desorption Determination  
Two grams sample of each treatment was weighed into a 250 mL centrifuge bottle. Each treatment had three replicates. Nitrogen solutions (0, 50, 100, 200, 300, and 400 mg N L\({}^{-1}\)) were prepared by dissolving ammonium chloride (NH\({}_{4}\)Cl) in a 0.2 M NaCl solution after which 20 mL of these isonormal N solutions were added to the centrifuge bottles to give 0, 500, 1000, 2000, 3000, and 4000 ug of added N sample\({}^{-1}\). Isonormal solutions were used in this adsorption study to preserve constant ionic strength in the mixture (adsorbent and solution) and also to provide competing ions for exchange sites [23]. Two drops of toluene were added to each sample to suppress microbial activities [13]. The samples  
\begin{table}
\begin{tabular}{l c c} \hline
**Property** & **Chicken Litter Biochar (CLB)** \\ \hline pH & 9.54 \\ EC (mS cm\({}^{-1}\)) & 3.50 \\ Moisture (\%) & 46.08 \\ CEC (cmol (+) kg\({}^{-1}\)) & 59.27 \\ Molarity (M) & nd \\ Organic matter (\%) & 71.67 \\ Total organic carbon (\%) & 41.57 \\ Humic acids (\%) & nd \\ Crude humins (\%) & nd \\ Total N (\%) & 2.39 \\ Total P (\%) & 4.52 \\ Total K (\%) & 6.05 \\ Total Ca (\%) & 4.80 \\ Total Mg (\%) & 1.77 \\ Total Na (\%) & 1.75 \\ Total Fe (mg kg\({}^{-1}\)) & 0.49 \\ Total Zn (mg kg\({}^{-1}\)) & 772 \\ Total Mn (mg kg\({}^{-1}\)) & 1479 \\ Total Cu (mg kg\({}^{-1}\)) & 264 \\ \hline \end{tabular} Note: nd is not determine.  
\end{table}
Table 2: Selected chemical properties of chicken litter biochar.  
\begin{table}
\begin{tabular}{l c c} \hline
**Property** & **Current Study (\(\pm\)S.D)** & **Range * (0-36 cm)** \\ \hline Cation exchange capacity & 11.97 (\(\pm\)0.68) & 3.86–8.46 \\ Exchangeable K\({}^{+}\) & 0.10 (\(\pm\)0.01) & 0.05–0.19 \\ Exchangeable Ca\({}^{2+}\) & 0.25 (\(\pm\)0.01) & NA \\ Exchangeable Mg\({}^{2+}\) & 0.34 (\(\pm\)0.01) & NA \\ Exchangeable Na\({}^{+}\) & 0.22 (\(\pm\)0.01) & NA \\ Exchangeable Fe\({}^{2+}\) & 0.19(\(\pm\)0.01) & NA \\ Exchangeable Cu\({}^{2+}\) & Trace & NA \\ Exchangeable Zn\({}^{2+}\) & 0.01 (\(\pm\)0.00) & NA \\ Exchangeable Mn\({}^{2+}\) & 0.02 (\(\pm\)0.00) & NA \\ Total titralite acidity & 0.86 (\(\pm\)0.02) & NA \\ Exchangeable H\({}^{+}\) & 0.22 (\(\pm\)0.01) & NA \\ Exchangeable Al\({}^{3+}\) & 0.64 (\(\pm\)0.01) & NA \\ Sand (\%) & 71.04 (\(\pm\)0.14) & 72–76 \\ Silt (\%) & 14.58 (\(\pm\)0.38) & 8–9 \\ Clay (\%) & 14.38 (\(\pm\)0.50) & 16–19 \\ Texture (USDA) & Sandy loam & Sandy loam \\ \hline \end{tabular} Note: the values given are on dry-weight basis; NA: not available; * subjected to the soil development, range as found in Paramananthan [18].  
\end{table}
Table 1: _Cont._were shaken 24 h at 180 rpm using an orbital shaker. Afterwards, the samples were centrifuged at 10,000 rpm for 15 min. Nitrogen in the supernatants (equilibrium solutions) was determined using steam distillation method [24]. The amount of N adsorbed per gram soil was calculated as the difference between the initial amount of N added and the amount in the equilibrium solution. The adsorbed N was calculated in \(\mu\)g g\({}^{-1}\) soil. The sediments in the centrifuge bottles) were washed with ethanol and centrifuged at 10,000 rpm for 10 min [24]. Thereafter, the ethanol was discarded. A 20 mL of 2 M KCl was added and shaken for 24 h at 180 rpm using an orbital shaker. Afterwards, the samples were centrifuged at 10,000 rpm for 15 min. The supernatants were collected and their N contents were determined using steam distillation method [24].