Chapter 2 Aquaponics: Closing the Cycle on Limited Water, Land and Nutrient Resources
2.8 Summary
As the human population continues to increase, there is increasing demand for highquality protein worldwide. Compared to meat sources, fish are widely recognized as being a particularly healthy source of protein. In relation to the world food supply, aquaculture now provides more fish protein than capture fisheries (FAO 2016). Globally, human per capita fish consumption continues to rise at an annual average rate of 3.2% (1961—2013), which is double the rate of population growth.
· Aquaponics Food Production Systems2.7 Energy Resources
2.7.1 Predictions As mechanization spreads globally, open-field intensive agriculture increasingly relies heavily on fossil fuels to power farm machinery and for transportation of fertilizers as well as farm products, as well as to run the equipment for processing, packaging and storage. In 2010, the OECD International Energy Agency predicted that global energy consumption would grow by up to 50% by 2035; the FAO has also estimated that 30% of global energy consumption is devoted to food production and its supply chain (FAO 2011).
· Aquaponics Food Production Systems2.6 Land Utilization
2.6.1 Predictions Globally, land-based crops and pasture occupy approximately 33% of total available land, and expansion for agricultural uses between 2000 and 2050 is estimated to increase by 7—31% (350—1500 Mha, depending on source and underlying assumptions), most often at the expense of forests and wetlands (Bringezu et al. 2014). While there is currently still land classed as ‘good’ or ‘marginal’ that is available for rain-fed agriculture, significant portions of it are far from markets, lack infrastructure or have endemic diseases, unsuitable terrain or other conditions that limit development potential.
· Aquaponics Food Production Systems2.5 Water Resources
2.5.1 Predictions Fig. 2.1 Water footprint (L per kg). Fish in RAS systems use the least water of any food production system In addition to requiring fertilizer applications, modern intensive agricultural practices also place high demands on water resources. Among biochemical flows (Fig. 2.1), water scarcity is now believed to be one of the most important factors constraining food production (Hoekstra et al. 2012; Porkka et al. 2016). Projected global population increases and shifts in terrestrial water availability due to climate change, demand more efficient use of water in agriculture.
· Aquaponics Food Production Systems2.4 Pest, Weed and Disease Control
2.4.1 Predictions It is generally recognized that control of diseases, pests and weeds is a critical component of curbing production losses that threaten food security (Keating et al. 2014). In fact, increasing the use of antibiotics, insecticides, herbicides and fungicides to cut losses and enhance productivity has allowed dramatic increases in agricultural output in the latter half of the twentieth century. However, these practices are also linked to a host of problems: pollution from persistent organic compounds in soils and irrigation water, changes in rhizobacterial and mycorrhizal activity in soils, contamination of crops and livestock, development of resistant strains, detrimental effects on pollinators and a wide range of human health risks (Bringezu et al.
· Aquaponics Food Production Systems2.3 Arable Land and Nutrients
2.3.1 Predictions Even as more food needs to be produced, usable land for agricultural practices is inherently limited to roughly 20—30% of the world’s land surface. The availability of agricultural land is decreasing, and there is a shortage of suitable land where it is most needed, i.e. particularly near population centres. Soil degradation is a major contributor to this decline and can generally be categorized in two ways: displacement (wind and water erosion) and internal soil chemical and physical deterioration (loss of nutrients and/or organic matter, salinization, acidification, pollution, compaction and waterlogging).
· Aquaponics Food Production Systems2.2 Food Supply and Demand
2.2.1 Predictions Over the last 50 years, total food supply has increased almost threefold, whereas the world’s population has only increased twofold, a shift that has been accompanied by significant changes in diet related to economic prosperity (Keating et al. 2014). Over the last 25 years, the world’s population increased by 90% and is expected to reach the 7.6 billion mark in the first half of 2018 (Worldometers). Estimates of increased world food demand in 2050 relative to 2010 vary between 45% and 71% depending on assumptions around biofuels and waste, but clearly there is a production gap that needs to be filled.
· Aquaponics Food Production Systems2.1 Introduction
The term ’tipping point’ is currently being used to describe natural systems that are on the brink of significant and potentially catastrophic change (Barnosky et al. 2012). Agricultural food production systems are considered one of the key ecological services that are approaching a tipping point, as climate change increasingly generates new pest and disease risks, extreme weather phenomena and higher global temperatures. Poor land management and soil conservation practices, depletion of soil nutrients and risk of pandemics also threaten world food supplies.
· Aquaponics Food Production Systems