# Promoting Urban Farming for Creating Sustainable Cities in Nepal
## 2 Theory of Urban Farming  
The first settlements on the earth started in areas with fertile plains. Such settlements later emerged as urban centers, where people from peri-urban areas and remote villages used to have farmers' markets organized on a regular basis. However, those traditions were not enough to meet the requirements of a large urban population. After the harvest,many agricultural products quickly perished, and they needed to be transported to the consumption sites quickly. Since there were no good transportation networks, many of the products decayed during their long transit. To solve this problem, a German economist and agriculture planner, [PERSON] (1783-1850), in 1826, using the example of Chicago, argued that city farming should be located centrally within an \"Isolated State\" (Figure 1). The [PERSON] model developed a theory of marginal productivity by assuming a uniform land surface without any undulation. Land may be rented to grow crops and transported to different households on an oxart. The cost of any agricultural products would involve the land rent and transportation cost, as given by Equation (1):  
\[L=Y\;(p-c)-Yfm \tag{1}\]  
where \(L=\) location rent or land value, \(Y=\) yield per unit of land, \(c=\) cost of production per unit of commodity, \(p=\) market price per unit of the produce, \(f=\) transport cost of the farm produce to the market (cost per agricultural unit, per unit distance), and \(m=\) distance of the farm from the market. Since the typical isolated state was surrounded by \"unoccupied wilderness\", especially in a place of food desert, farmers needed to grow agricultural crops and dairy products in the nearby urban areas because agricultural products would perish while being ferried from the production site to the distant urban centers. This was before refrigerated trucks were developed. Farmers largely grew their own food, such as dairy products, fruits, vegetables, eggs, and meat, and consumed it fresh. However, the situation has changed in the last several decades with the development of trucks with refrigerated containers. The long-distance hauling facilities offered by such trucks have made it possible to transport perishable food products over long distances, with less damage to the food. However, the long-distance food transportation process can cause several environmental problems. First, transporting food increases emissions of various toxic and greenhouse gases. Additionally, the packing and unpacking of food have increased the use of plastic, tin, metal, and paper. The production of these materials contributes 14 to 17% of global anthropogenic emissions [10]. The production, packaging, storage, and transportation of agricultural farm products contribute additional greenhouse gas emission (GHG), which, at present, accounts for 3 to 6% of the total emissions globally [11]. Second, when food is transported over long distances, a significant portion of that food is still wasted. Globally, one-third of all the food produced is wasted, with almost 1.6 billion tons of food being spoiled on the way to the market or date-expired during storage and simply thrown away [12]. Every year, over 600 million people get sick from eating contaminated food [13]. Additionally, long hauling also increases the cost of food. The supply chain can be disrupted for many reasons, such as labor issues, road  
Figure 1: [PERSON] model of land use. (Adapted and modified from [9]). conditions, inclement weather, the availability of fuel, political unrest, and pandemics, such as COVID-19. It is useful to capture atmospheric carbon by using carbon sequestration in urban areas too, i.e., trapping carbon by plants to convert it into plant food, biomass, and fruits. Plants can sequester carbon and increase net primary productivity (NPP) per unit area, eventually increasing the gross primary productivity (GPP) [14] of an urban area. Atmospheric carbon can be stored on plant bodies that contribute to plant growth.