# Modeling the Impact of Atmospheric Warming on Staple Crop Growth in China in the 1960s and 2000s
## 2 Methods
### Data Sources  
The details of the input data and data sources used in the study are shown in Table 3. The research period mainly included two parts, namely the period from 1961 to 1969 (1960s) and the period of 2000-2009 (2000s). The data analyzed for the 1960s and 2000s in this study were the ten-year average value over the two periods. The observed meteorological \begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Crop**} & \(\mathbf{T_{L}}\) & \(\mathbf{T_{O}}\) & \(\mathbf{T_{U}}\) & **Range of \(\mathbf{T_{O}}\) (\(\mathbf{f(T)\geq 0.95}\))** \\  & (\({}^{\circ}\)C) & (\({}^{\circ}\)C) & (\({}^{\circ}\)C) & (\({}^{\circ}\)C) \\ \hline Rice & 12 & 29 & 40 & 27–33 \\ Winter wheat & 3 & 18 & 35 & 16–25 \\ Maize & 9 & 30 & 42 & 26–33 \\ \hline \end{tabular}
\end{table} 
Table 2: Base (\(T_{L}\)), optimum (\(T_{O}\)) and maximum (\(T_{U}\)) temperatures for crop photosynthesis [31]. data of the five sites were obtained from the China Meteorological Administration, including the observed daily maximum and minimum temperature, daily solar radiation and precipitation of the 1960s and 2000s. To fill the data gap in observed solar radiation data, a method by [PERSON] et al. (2000) [PERSON] et al. (2000) was adopted to estimate daily solar radiation. The method was calibrated beforehand with historical observations from 11 meteorological sites in China to ensure its validity in [PERSON] et al. (2007) [PERSON] et al. (2007). For more details about the method, the reader is referred to [PERSON] et al. (2000) [PERSON] et al. (2000) and [PERSON] et al. (2007) [PERSON] et al. (2007). The atmospheric CO\({}_{2}\) concentration data between 2000 and 2009 were obtained from the World Meteorological Organization (Table 3). The soil, crop and field management data between 2000 and 2009 were obtained from the Chinese Ecosystem Research Network (CERN), which contained 21 sites under different crop rotation systems. The rice sites included the main rice areas in Northeast China, North China, East China, Central China and South China, covering the main rice planting areas in China from north to south, namely, a single rice cropping system in Northeast China, a rice-wheat rotation system in East China and a double rice cropping system in Central and South China. The wheat sites included the spring wheat in Northeast and Northwest China, winter wheat in Southwest China, North China and East China. The maize sites included the summer maize in North China and spring maize in Northeast and Northwest China. These sites almost covered the typical rotation systems of rice, wheat and maize. The observations included crop calendar (sowing, heading, harvesting, etc. ), LAI, leaf weight and aboveground and belowground biomass. The methods of irrigation and synthetic fertilizer application and the amounts of organic manure and residue retention were also recorded. The soil properties relevant to crop growth, i.e., the total soil nitrogen and organic carbon, bulk density, pH and sand/clay fractions, were site-specific. Each observation site consisted of 4-6 observation quadrates. During simulation, except for the temperature data, the other input data for the two periods were based on input data for the 2000s and only considered the influence of temperature differences in the 1960s and 2000s on crop photosynthetic production to better reflect effects of temperature changes on crop photosynthetic production.