## 4 Inventory and Analysis
### Analysis of Rooftop Agricultural Production Potential in Shibei District
#### 4.2.1 Determine the Annual Yield per Unit Area of Vegetables under Different Cultivation Methods
2.2 Select the Cultivation Methods for Different Building Types of Roofs and Calculate Their Annual Yield  
For residential building roofs, it is recommended to use soil cultivation as the main method, which can be combined with small arched sheds and some outdoor facilities for cultivation. The reasons are as follows: (1) There are requirements for sunlight time in residential buildings, and the height of the roof greenhouse will affect the lighting of the northern residential area, except for in new residential areas that have already considered designing a roof greenhouse in advance. (2) Proceeding from pragmatism, residents produce a large amount of organic waste in their daily life, and organic fertilizer can be obtained through composting treatment. Soil cultivation is conducive to the use of organic fertilizer for planting, thus realizing waste recycling. (3) According to relevant surveys, \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Examples of Facility** & **Area (m\({}^{2}\))** & **Vegetable Variety and** & **Annual Output per** & **Remarks** \\
**Cultivation** & & **Yield** & **Unit Area (kg/m\({}^{2}\))** & \\ \hline The Green Dot Roof & & Green leafy vegetables, & & Adopting a glass \\ Greenhouse in & & with an annual output of & 32.1 kg/m\({}^{2}\) & greenhouse with a \\ Brooklyn, New & & 45,000 kg & & higher yield \\ York [20] & 12,500 m\({}^{2}\) & Tomatoes 32.10 kg/m\({}^{2}\), & & \\  & 7500 m\({}^{2}\) & cherry tomato & & \\ Shanghai Ground & 7500 m\({}^{2}\) & 17.92 kg/m\({}^{2}\), & Average 23.8 kg/m\({}^{2}\) & Mostly high-yielding \\ Greenhouse Crops [21] & 5000 m\({}^{2}\) & cucumber 30.02 kg/m\({}^{2}\), & & vegetables \\  & 5000 m\({}^{2}\) & and sweet pepper & & \\  & 15.33 kg/m\({}^{2}\) & & & \\ Facility cultivation & & & & Average production \\ vegetables in China [19] & 58.721 million mu & 252 million tons & 6.44 kg/m\({}^{2}\) & capacity under existing \\  & & & & facility cultivation \\  & & & & techniques; \\ Annual yield per unit area of facility cultivation & & 15.04 kg/m\({}^{2}\) & see supplementary data \\ Examples of soil & & Area (m\({}^{2}\)) & Vegetable variety and yield & Annual output per & for details (1) \\   cultivation & & & unit area kg/m\({}^{2}\) & notes \\ Rooftop soil farms in & & Vegetables, chickens, bees; & & \\ Brooklyn, New & 10,000 m\({}^{2}\) & annual production of & 2.3 kg/m\({}^{2}\) & \\ York [20] & & 50,000 pounds, 22,680 kg & & \\ Li Bojun’s Roof & & Four roofs of 525.4 m\({}^{2}\), & Vegetables, tomatoes, & & High level of \\ Vegetable Cultivation & 593.3 m\({}^{2}\), 453.6 m\({}^{2}\), and & cucumbers, eggplants, & 12.69 kg/m\({}^{2}\) & technology, 4-year roof \\ Experiment [18] & 56 m\({}^{2}\) & radiishes, loofah, etc. & & cultivation experiment, \\  & & & & and 4 farming systems \\ Vegetable farming in & & & & \\ soil culture in & 276.279 million mu & 546 million tons & 2.97 kg/m\({}^{2}\) & \\ China [19] & & & & \\ Annual yield per unit area of soil culture & 4.78 kg/m\({}^{2}\) & See supplementary data for details (2) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Examples of facility cultivation and soil cultivation and analysis of annual yield per unit area of vegetables. citizens are more inclined to simple soil cultivation with labor. (4) Soil culture more easily creates a pastoral atmosphere, with a strong sense of life and affinity for working in the field. (5) The relatively small roof area of residential buildings is not conducive to building greenhouses and maximizing their economies of scale. For roofs of other types of buildings (public buildings, industrial buildings, etc. ), it is recommended to focus on facility cultivation combined with soil cultivation. The reasons are as follows: (1) From the perspective of production efficiency, urban agricultural planting should focus on facility cultivation. The roof area of public and industrial buildings is generally large, which is conducive to the development of greenhouse agriculture.