Natural Resources and Environmental Impacts of Food Systems - Minerals and Biodiversity PDF

Minerals (Nutrients) Romy Chammas, MSc. Summer 2024  Nutrients and Food Systems Nutrients such as phosphorus, nitrogen, potassium, calcium, and magnesium are not only essential for crop and livestock production, but are also essential for humans...

Minerals (Nutrients) Romy Chammas, MSc. Summer 2024  Nutrients and Food Systems Nutrients such as phosphorus, nitrogen, potassium, calcium, and magnesium are not only essential for crop and livestock production, but are also essential for humans. The terms ‘minerals’ and ‘nutrients’ are partially overlapping. When it refers to their origin (mainly from mines) or chemical state, the term minerals is commonly used. The term nutrients is more related to their use and function in plant production Limited availability of one or more minerals in agricultural soils leads to lower crop yields or lower livestock production. In the case of some nutrients (iodine, selenium, and zinc), limited availability in soils can also lead to low concentrations in food, leading to negative consequences for human health.  Nutrients and Food Systems Globally, soils vary largely in terms of the quantity of minerals they naturally contain. Weathered tropical soils are generally poor in minerals, while recent sediments (from rivers, seas, or volcanic) are typically rich. For crop production, the bioavailability of nutrients is the key characteristic, not the total nutrient content of soils. For example: Some soils are phosphate fixating, thus limiting the availability for plants. Certain microorganisms can enhance the bioavailability and absorption of nutrients, such as in the case of fungi in mycorrhiza. Also the soil pH has a large influence on the availability of nutrients.  Nutrients and Food Systems When there is limited supply of minerals, they can be added in food systems via: Fertilizer Feed or food additive Directly consumed by humans (such as iron)  Nutrients and Food Systems In crop production, the attention is usually focused on nitrogen and phosphorus. However, there are actually around 18 essential minerals for plants and humans combined (Table 6). Except for nitrogen, all minerals are mined. Nitrogen is not a ‘mineral’. It can be fixed from the air, either by biological nitrogen fixation (BNF) or by means of chemical fixation, which requires the input of fossil fuels. It is estimated that in 2005, globally about 120 Tg of nitrogen were fixed in the form of synthetic fertilizers.  Nutrients and Food Systems The global share of minerals used by food systems varies significantly from one nutrient to another (Table 6). Food systems, notably agriculture (production stage), are the dominant user of a number of macronutrients (P, K, S). It is hard to assess whether and when certain minerals will become ‘scarce’ in the future. Based on current known reserves and current consumption, reserves seem to be adequate for 50-500 years, but this will also depend on future consumption and potential new reserves.  Nutrients and Food Systems Deficiencies of macro- and micro-nutrients in human nutrition can have severe effects on human health. For some elements, such as iron and protein (source of amino acids, phosphorus, and sulphur), deficiencies are largely related to dietary composition, such as low intake of meat and vegetables. For other elements (zinc and selenium), concentrations in food products can vary significantly depending on concentrations in the soil.  Nutrients and Food Systems Figure 22 shows the flow of minerals in food systems, including the various issues concerning resource efficiency and environmental impacts. Many situations and issues are combined in this diagram; they do not occur for all minerals in all food systems. In many food systems, the flow starts with the input of minerals through fertilizers, which are taken up by crops and then processed or used as feed. Livestock typically only retain 10-30% of the minerals consumed; the rest are excreted in the form of manure and urine. A part of these minerals in the manure is reused, while another part is lost. The amount depends on the manure management. Crop and livestock products are transported from the farm and usually undergo one or more processing steps.  Nutrients and Food Systems In the case of meat production, a large quantity of nutrients is retained in offal and bones. These minerals are consumed by humans and excreted. The largest part of these minerals end up in sewage systems or landfills and are transported to rivers and seas, often causing pollution issues. (Bouwman et al., 2013b, Morée et al., 2013, Seitzinger et al., 2010, Sutton et al., 2013)  Flow of Minerals from Rural to Urban Areas Most food systems are characterized by a linear flow of minerals from rural areas to urban areas. Globally, only around 4% of urban nitrogen and phosphorous flows were recycled back to agriculture in 2000 (Morée et al., 2013), whereas most of the minerals ended up in sewage systems (and finally rivers and coastal waters) or landfills. Significant amounts of minerals are lost between fertilization and human consumption. For example, in some processes, nutrient-rich proteins are separated from carbohydrates and only the latter used (for example in beer brewing and sugar production).  Use of Fertilizers Use of fertilizers is projected to increase. The issues concerning minerals are expected to aggravate due to population increase, urbanization (meaning larger flows of minerals to cities), and increased livestock production. (Bouwman et al., 2009, Bouwman et al., 2013b, Neset & Cordell, 2012, Sutton et al., 2013) According to most projections, global fertilizer consumption will increase (Figure 23) in order to facilitate a growing crop production. The increased fertilizer use and manure production (related to the larger livestock production) is expected to lead to larger nitrogen and phosphorus surpluses and thus to higher losses to the environment. (Bouwman et al., 2009)  Consequences of an Inefficient Use of Minerals The current inefficient use of minerals (nutrients), as well as nutrient deficiencies in soils, lead to a number of serious issues: 1. A low nutrient status in soils generally leads to low crop yields. Due to an ongoing flow of minerals from rural areas to cities, this issue is expected to aggravate. 2. For some minerals (zinc, selenium), insufficient concentrations also lead to quality deficiencies in crops, which can lead to health problems for animals and humans. An estimated 17.3% of the world’s population is at risk of inadequate zinc intake.  Consequences of an Inefficient Use of Minerals 3. The low efficiency in most food systems implies that ‘fresh’ minerals are constantly needed as fertilizer to maintain current levels of crop production. This leads to a rapid depletion of current stocks of minerals. Moreover, in the case of nitrogen, it means that significant amounts of fossil fuels are needed to produce fertilizer. 4. The low efficiencies also imply that there are large losses of nutrients to the environment and an accumulation of certain minerals, leading to soil and food quality issues. Losses of nitrogen and phosphorus lead to the eutrophication of surface and coastal waters, which can lead to the large-scale disturbance of marine ecosystems, with consequences for food production from marine sources. Losses of ammonia (nitrogen) to the air lead to the disturbance of terrestrial ecosystems. Eutrophication Biodiversity and Ecosystem Services  Biodiversity and Ecosystem Services for Food Systems Biodiversity is generally defined as the variety of animals, plants and microorganisms at the genetic, species, and ecosystem levels. This variety is necessary to sustain key functions of ecosystems. Ecosystem services are defined as benefits people obtain from ecosystems. Biodiversity and ecosystem services are crucial natural resources for primary food production in all its forms: agriculture, aquaculture, fisheries, hunting, and gathering. Food systems also put major pressures on biodiversity and ecosystem services.  Biodiversity and Ecosystem Services for Food Systems As a consequence, food systems impact ecosystem services and biodiversity at large. It is estimated that around 60% of all global loss of terrestrial biodiversity is related to the food sector. (PBL, 2014a) The main driver of terrestrial biodiversity loss is the huge amount of land needed for food production. (PBL, 2010) Biodiversity is particularly low on intensively managed arable land due to removal of the original vegetation and introduction of monoculture practices. Terrestrial biodiversity is also negatively influenced by pesticide emissions, nitrogen accumulation, and climate change, and food production contributes to each of these factors! Food production also has a negative impact on aquatic ecosystems through the leaching of nutrients (minerals) and pesticides.  Is the Current and Projected Use of Biodiversity and Ecosystem Services Sustainable? A number of factors threaten the sustainability of biodiversity and ecosystem services: Overexploitation of services leads to the degradation of ecosystem services and production capacity, such as overgrazing and fish stock depletion. Ongoing deforestation, drainage of wetland, and removal of landscape elements will also impact certain ecosystem services such as pest control, water regulation, and pollination. The increasing share of monocultures, often based on crops with a narrow genetic base, will lead to biodiversity losses.  Is the Current and Projected Use of Biodiversity and Ecosystem Services Sustainable? A number of factors threaten the sustainability of biodiversity and ecosystem services (Cont’d): Use of pesticides and antibiotics may disturb current ecosystems and biodiversity. Nutrient losses may lead to large-scale changes in ecosystems, notably of wetlands, lakes, and coastal seas, affecting fish stocks for example. Climate change may impact the functioning of ecosystems.  Is the Current and Projected Use of Biodiversity and Ecosystem Services Sustainable? The pressure on biodiversity is expected to increase due to the projected increase in food production, which leads to, among other things, the expansion of crop areas and increased nutrient losses. (PBL, 2014a) As for efficiency, data to judge whether ecosystem services are currently used efficiently are lacking. However, farmers could in various ways rely much more on ecosystem services and less on external inputs such as fossil fuels, pesticides, and irrigation water, while simultaneously arriving at higher yields.  Consequences of Inefficient and Unsustainable Use There are many important consequences of the current largely inefficient and unsustainable use of biodiversity and ecosystem services: Loss of resilience of agro-ecosystems, which lowers the capacity of these systems to cope with shocks such as climatic events and certain pests and diseases, resulting in lower crop yields Lower delivery of certain ecosystem services For example, lower pollination results in lower crop yields. Higher need for certain inputs such as pesticides and nutrients, replacing ecosystem services Lower regeneration of fish stocks, leading to lower fish catches Food Categories, Resource Use, and Human Health  Food Categories, Resource Use, and Human Health Human diets vary largely across the globe, based on aspects such as food availability, food prices, culture, and personal preferences. Differences in diet may lead to large differences in resource use and environmental impacts as some food categories are less resource- efficient or lead to more environmental impacts than others. One of the main distinctions is between animal- and plant-based products. This difference is mainly due to the fact that animals consume more energy and protein than is embedded in the final products (meat, eggs, and dairy). The reason is that part of the energy, proteins, and minerals in the animal feed are used for the animals’ metabolism and another part ends up in inedible parts such as bones.  Food Categories, Resource Use, and Human Health Livestock products lead to higher greenhouse gas emissions than plant- based equivalents. In modern livestock production, feeds are used that would also be suitable for human consumption (grains and soybeans). Therefore, it would be more efficient if humans were to eat this food directly. Food Categories, Resource Use, and Human Health Figure 25 demonstrates the differences in resource use and environmental pressure expressed as land area and greenhouse gas emissions per kg of protein. Land area is the highest for beef production. Poultry meat, milk, and eggs require on average about two to three times more land per unit than vegetable types of protein, and pig meat even requires a factor of five more land. Similar differences have been found between the various protein sources and nitrogen emissions. (Leip et al., 2014)  Summary and Conclusions Natural resources such as land and soils, fresh water, biodiversity (including genetic resources), marine resources and minerals are in many cases not managed sustainably or efficiently (Table 9). This creates risks for future food production, and simultaneously leads to considerable environmental impacts outside the food system: about 24% of all anthropogenic global greenhouse gas emissions are related to food systems.  Summary and Conclusions Due to a combination of factors, the pressure on natural resources is expected to increase over the coming decades. Main factors are the increase in population, increased wealth, urbanization (leading to dietary shifts), and climate change. For example, due to the increased food demand, the cropland area is projected to continue to grow by 2050, mainly at the expense of ecologically vulnerable areas like forests.