# Urbanization and Grain Production Pattern of China: Dynamic Effect and Mediating Mechanism
## 4 Results
### Mediating Paths of Urbanization's Effects on the GPP
The mediating effect of PS is \(-0.001\times 0.417=-0.000417\), accounting for \(13.90\%\) of the total effect, which makes it a partial mediating role. The mediating effect of PS significantly alleviates the decrease in the GPCI due to urbanization, exhibiting a transmission path of \"urbanization \(\rightarrow\) planting structure \(\rightarrow\) GPP\". Thus, H3 is verified. 3. Urbanization significantly affects GPCI through agricultural technology progress (ATECH) characterized by the level of the comprehensive mechanization rate. The increased level of urbanization significantly promoted ATECH (Model 10), while the promoted ATECH significantly decreased the regional GPCI (Model 13). The negative effect of urbanization considering the ATECH (\(-0.0028\)) is lower than the total effect of urbanization (\(-0.003\)). Therefore, the mediating effect of ATECH weakens \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Variables} & \multicolumn{2}{c}{**Total Effect**} & \multicolumn{2}{c}{**Impact of Urbanization on M**} & \multicolumn{2}{c}{**Impact of Urbanization, M on the GPCI**} \\ \cline{2-7}  & **InGPP** & **MCI** & **PS** & **ATECH** & **InGPP** & **InGPP** & **InGPP** \\ \cline{2-7}  & **Model 7** & **Model 8** & **Model 9** & **Model 10** & **Model 11** & **Model 12** & **Model 13** \\ \hline \hline \multirow{2}{*}{L.InGPP} & 0.820 & & & & 0.794 & 0.809 *** & 0.810 *** \\  & ***(32.17) & & & & ***(31.69) & (32.66) & (30.89) \\ \multirow{2}{*}{W*InGPP} & 0.304 *** & & & & 0.320 *** & 0.269 *** & 0.315 *** \\  & (8.38) & & & & (9.20) & (7.49) & (8.57) \\ \multirow{2}{*}{M} & & & & & 0.001 *** & 0.417 *** & \(-0.018\) ** \\  & & & & & (4.37) & (4.91) & (\(-2.30\)) \\ \multirow{2}{*}{L.M} & & 0.677 *** & 0.945 *** & 0.841 *** & & & \\  & & (22.16) & (48.36) & (48.37) & & & \\ \multirow{2}{*}{W*M} & & 0.500 *** & 0.276 *** & 0.172 *** & & & \\  & & (13.77) & (8.96) & (7.31) & & & \\  & \(-0.003\) *** & \(-0.219\) ** & \(-0.001\) *** & \(0.009\) *** & \(-0.0029\) *** & \(-0.0027\) ** & \(-0.0028\) ** \\ \multirow{2}{*}{urban} & \((-3.04)\) & \((-1.98)\) & \((-5.71)\) & (7.41) & (\(-3.57\)) & (\(-2.10\)) & (\(-3.11\)) \\ \multirow{2}{*}{Control} & YES & YES & YES & YES & YES & YES & YES & YES \\ \multirow{2}{*}{AR (1) P} & 0.00 & 0.03 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 \\ \multirow{2}{*}{AR (2) P} & 0.51 & 0.92 & 0.46 & 0.16 & 0.57 & 0.33 & 0.52 \\ \multirow{2}{*}{Sargan P} & 1.00 & 1.00 & 0.00 & 1.00 & 1.00 & 1.00 & 1.00 \\ \multirow{2}{*}{Wald P} & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 \\ \hline \hline \end{tabular} Note: ***\(p<0.01\), **\(p<0.05\). Round brackets show \(t\)-values. M is a collective term for mediating variables.  
\end{table} 
Table 6: Mediating effect of urbanization on GPP. the negative effect of urbanization on the GPCI. The mediating effect of ATECH is 0.009 \(\times\)\(-\)0.018 = \(-\)0.000162, accounting for 5.40% in the total effect, which makes it a partial mediating role. The mediating effect of ATECH significantly alleviates the decrease in the GPCI due to urbanization, exhibiting a transmission path of \"urbanization \(\rightarrow\) ATECH \(\rightarrow\) GPP\". H4 is verified.