## 5 Food Security in the Face of Increasing Food Demands  
The global rise in demand for crop production is largely driven by (1) an increase in food demand, which, in turn, is strongly related to population growth; (2) predictable shifts in dietary patterns also referred to as 'nutrition transition' [68,69] and related increase in fodder use due to increase in meat consumption (e.g., it has been postulated that 38 kg of grain are required for the production of 1 kg pork protein; and 61.1 kg of grain for the production of 1 kg beef protein) [70]; and (3) by an increase in biofuel production. Estimates put the increase in crop production needed by 2050 between 60% and 110%, depending on whether they consider food demand alone or in conjunction with biofuel consumption. FAO's production estimates, for example, do not consider the increase of agricultural production for biofuels; consequently, their estimates project a 60% increase in crop production required by 2050 [71]. In regard to the land resource--food price nexus, [PERSON] et al. [29] outline its implications on the 17 SDGs and show that economic and growth pathways account for lesser impacts compared to resource-use and management policies. When focusing on four key crops that account for approximately 75% of global agricultural calories--maize, rice, wheat and soybean--big discrepancies between projected and needed yields are anticipated to exist by 2050 [72]. With the need to substantially increase agricultural production by 2050 (e.g., FAO estimates an increase by 60% [71]), annual expected growth rates of maize (1.6%), rice (1.0%), wheat (0.9%) and soybean (1.3%) lag far behind the needed growth rate of approximately 2.4%. The currently expected growth rates translate into a global growth of 67% in maize, 42% in rice, 38% in wheat and 55% in soybean; hence, business as usual will definitely lead to rising food insecurity worldwide. Furthermore, large regional differences in crop productivity exist, globally. As an example, in Africa, rates of maize yield are increasing in, for example, the Nigerian states of Yobe and Adamawa, in Ethiopia, Angola, South Africa and Madagascar but maize yield rates are decreasing in Morocco, Chad, Somalia Kenya, Zambia, Zimbabwe, Rwanda, Burundi and the Democratic Republic of Congo [72]. Figure 4: (**A**) Total Food supply since 1961 (y-axis: kcal/capita/day); (**B**) Food supply from vegetable products since 1961 (y-axis: kcal/capita/day); (**C**) Food supply from animal products since 1961 (y-axis: kcal/capita/day); (**D**) Urban and rural population developments since 1961 (y-axis: population in billions). Data derived from TED, FAO and IFA. All panels grouped by world regions as indicated in colour legend. The application of fertilizers is currently the only available anthropogenic measure to provide additional nutrients to the soil and to enhance its fertility, which helps to boost crop yields. Fertilization, either organic or mineral-based, has the purpose to supply soils with nitrogen, phosphorus and potash (potassium) as the three most important macronutrients for crop growth. According to the International Fertilizer Industry Association (IFA) [73], global fertilizer demand is expected to grow; it was 176 megatons in 2011-2013 and is expected to be around 179.5 megatons in 2013/14 and 184.3 megatons in 2014/15 [74]. The share of Nitrogen accounted for approximately 58 percent, phosphate for 24 percent and potash for the remaining 18 percent. Of note, inequalities for different stakeholders and regions relate to the global fertilizer value chain. For example, China, the United States and India are the top three fertilizer consumers, accounting for 58% of the world consumption in 2010 [75], whereas Sub-Saharan Africa--as one of the three key developing regions besides Latin America and South Asia--imports only small amounts of fertilizers [76].