## 3 Results
### Characteristics of Silage Chemical and Fermentation Characteristics
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Treatment**} & **Alfalfa DM Yield** & **Corn DM Yield** & **Alfalfa CP Content** & **Corn CP Content** & **Alfalfa CP Yield** & **Corn CP Yield** \\  & **(h ha\({}^{-1}\))** & **(h ha\({}^{-1}\))** & **(g kg\({}^{-1}\) DM)** & **(g kg\({}^{-1}\) DM)** & **(kg ha\({}^{-1}\))** & **(kg ha\({}^{-1}\))** & **(kg ha\({}^{-1}\))** \\ \cline{2-11}  & **2017** & **2018** & **2017** & **2018** & **2017** & **2018** & **2017** & **2018** & **2017** & **2018** \\ \hline \multicolumn{11}{c}{Crow} & & \multicolumn{6}{c}{Cropping system} \\ \multicolumn{11}{c}{AC} & & 17.86 & 19.30 & 62.50 & 60.19 & & 1114.70 & 1161.83 \\ \multicolumn{11}{c}{AC} & & 13.35 & 12.09 & 73.77 & 62.47 & & 986.08 & 756.23 \\ \multicolumn{11}{c}{N application rate} \\ \multicolumn{11}{c}{CK} & & 17.86 a & 19.30 a & 62.50 c & 60.19 ab & & 1114.70 a & 1161.83 a \\ \multicolumn{11}{c}{N0\({}^{\text{a}}\)} & 0.93 a & 1.27 & 11.75 d & 9.63 c & 175.35 ab & 167.24 & 66.18 bc & 59.02 b & 162.96 a & 212.93 & 778.32 b & 567.31 c \\ \multicolumn{11}{c}{N60} & 0.82 a & 0.72 & 12.95 cd & 12.51 b & 165.38 b & 169.57 & 74.44 ab & 60.31 ab & 135.29 ab & 122.60 & 963.14 ab & 749.01 b \\ \multicolumn{11}{c}{N120} & 0.89 a & 0.96 & 14.07 bc & 12.66 b & 181.77 a & 169.05 & 76.59 ab & 64.66 ab & 162.23 a & 162.67 & 1072.96 a & 818.77 b \\ \multicolumn{11}{c}{N180} & 0.65 b & 0.85 & 14.63 b & 13.56 b & 177.92 a & 174.55 & 77.84 a & 65.88 a & 116.47 b & 146.94 & 1129.90 a & 889.84 b \\ \multicolumn{11}{c}{CK} & & 17.86 a & 19.30 a & 62.50 b & 60.19 & & 1114.70 a & 1161.83 a \\ \multicolumn{11}{c}{D30\({}^{\text{b}}\)} & 1.07 a & 1.24 a & 11.74 c & 10.15 c & 178.28 & 173.35 & 77.60 a & 64.46 & 191.79 a & 214.38 a & 913.87 b & 655.99 c \\ \multicolumn{11}{c}{D45} & 0.78 b & 0.87 b & 13.46 bc & 12.59 bc & 173.75 & 168.51 & 72.29 ab & 61.31 & 135.16 b & 146.61 b & 979.34 b & 776.99 bc \\ \multicolumn{11}{c}{D60} & 0.61 b & 0.73 b & 14.86 b & 13.52 b & 173.28 & 168.44 & 71.41 ab & 61.64 & 105.77 b & 122.90 b & 1065.03 ab & 835.71 b \\ \multicolumn{11}{c}{Overall} & 0.82 & 0.95 & 13.69 & 12.64 & 175.10 & 170.10 & 72.90 & 62.30 & 144.24 & 161.29 & 995.98 & 787.43 \\ \multicolumn{11}{c}{Mean c} & 0.05 & 0.06 & 0.35 & 0.47 & 1.97 & 1.70 & 1.26 & 0.73 & 8.6 & 11.07 & 27.31 & 30.23 \\ \multicolumn{11}{c}{SEM c} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} \\ \multicolumn{11}{c}{AC vs. CK} & & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} & \multicolumn{6}{c}{} \\ \multicolumn{11}{c}{NR} & \textless{}0.001 & ns & \({}^{\text{d}}\) & 0.001 & 0.001 & 0.003 & ns & 0.001 & \textless{}0.001 & ns & \textless{}0.001 & 0.001 \\ \multicolumn{11}{c}{PD} & \textless{}0.001 & 0.001 & \textless{}0.001 & ns & ns & 0.037 & 0.030 & \textless{}0.001 & \textless{}0.001 & 0.003 & \textless{}0.001 \\ \multicolumn{11}{c}{NR \(\times\) PD} & \textless{}0.001 & ns & ns & 0.008 & ns & ns & \textless{}0.001 & ns & ns & ns \\ \hline \hline \end{tabular} †: Different letters in the same column within the same treatment indicate significant differences (\(p<0.05\)). \({}^{\text{a}}\) N0, N60, N120 and N180 mean N application rate of 0, 60, 120 and 180 kg N ha\({}^{-1}\). \({}^{\text{b}}\) D30, D45 and D60 mean corn plant density of 30, 45 and 60 thousand plants ha\({}^{-1}\). \({}^{\text{c}}\) Standard error of the overall mean. \({}^{\text{d}}\) ns indicates not significant at \(p<0.05\).  
\end{table} 
Table 2: Forage dry matter (DM) yield, crude protein (CP) content, CP yield of alfalfa–silage corn relay intercropping (AC) and silage corn monoculture control (CK) as affected by nitrogen application rate (NR) and corn plant density (PD).