Back to basics - Organic Farming

As we have seen, the modernization of agriculture has come with many environmental implications in the quest to feed our growing population throughout the anthropocene. Many argue that we should revert back to old-fashioned agricultural practices to reduce the environmental damage. This would involve a change from intensive monoculture systems, which are heavily reliant on inputs of natural resources, to smaller scale organic agriculture with less external inputs to supply local demands, using more natural forms of energy inputs.

         In organic agriculture, chemical fertilizers and pesticides are not used. Complex crop rotations are used to protect against pests and animal manure is used as a natural fertilizer, legumes are planted to fix nitrogen rather than using chemical fertilizers. The Soil Association state ‘Organic farming offers the best, currently available, practical model for addressing climate-friendly food production. This is because it sequesters higher levels of carbon in the soil, is less dependent on oil-based fertilisers and pesticides and confers resilience in the face of climatic extremes.’

Pimentel et al (2005) report on a Rodale Institute farming trial, which compared organic and conventional farming over 22 years. The main conclusions from the trial reveal that:

–           Fossil fuel energy inputs were 30% lower in organic practices.

–           Soil organic matter was higher in organic systems, this helped conserve soil and water resources, which were beneficial in drought years, this is important for the future with climate change.

–           Nitrogen was higher in organic systems which highlights the success of legume cover crops over chemical fertlisers.

–           Crop rotations and over cropping successfully reduced soil erosion, pest problems and pesticide use in organic practices.

–           Use of livestock waste as fertilizer reduced pollution as well as the use of chemicals.

–           Organic plots had higher biodiversity, which contributes to a healthy ecosystem and reduces the need for chemical fertilizers and pesticides.

         Through the successes seen in the organic plots throughout the study, Pimentel et al (2005) suggest that in order to make our food production more sustainable we should incorporate some organic practices into our conventional systems.

         Organic agriculture wont stop our reliance on natural resources but it is using them in a more sustainable way. Organic farming technology can help make farming more sustainable and ecologically sound, but it is heavily debated whether organic agriculture can produce high enough yields at affordable prices to feed the world.

Can Genetic Modification Save the World?

            Genetic modification (GM) is often marketed as the solution to our global food crisis. GM crops are sold on the basis of their economic and environmental benefits through increasing yields and greater food production with lower production costs, compared with conventional crops.

            A Royal Society report ‘Reaping the Benefits’ (2009), supports the use of GM crops. The report confirms that GM can provide control of pests and weeds through use of disease-resistant crops that can minimize the use of chemical pesticides and herbicides. They also suggest that GM crops enable no-till agriculture, which can reduce soil erosion and fossil fuel use and drought tolerant seeds can be used to provide resilience to climate change. Thus the report states that ‘Britain's future food sustainability depends on employing some form of GM to increase yields’.

            The Royal Society fully support the notion that technological advances have provided us with the potential to use scientific solutions to feed the world. The report indicates that the problem of food security for our growing population is so serious that we should try anything we can, to solve the problem, and that this will not be possible without the use of GM.

            Alternatively, a group of NGOs, coordinated by environmentalist Vandana Shiva, produced a report on the role of genetically modified organisms (GMO) in increasing food production (Global Citizens' Report on the State of GMOs, 2011). The report reveals that the way that genetic modification is marketed as the solution to the world’s food crisis is highly misleading. Shiva boldly states that genetic engineering has failed to increase the yields of a single food crop but instead, it has increased the growth of superweeds.

            The NGO report indicates that weeds are becoming resistance to herbicides and pesticides, through the transfer of herbicide resistance to weeds, resulting in the development of super weeds and super pests. Shiva (2011) gives examples of this in India, China, the US, Argentina and Brazil and describes it as failed technology, as GM crops have not increased the control of pests and weeds, they have actually reduced it. This has resulted in an increase in the requirement of pesticides.

            Evidence suggests that some GM crops actually have reduced yields when herbicides are not applied therefore GM crops can increase our reliance on herbicides. Some believe, that the biotech industry is forcing us into a more chemical dependent agricultural system. Shiva (2011)  states that any benefits of GM crops are outweighed by the negative impacts associated with increased use of pesticides.

            These two reports from different reputable actors puts great uncertainty in the fate of GM crops as a solution to sustainable food production for the future. For some, it seems like the ideal solution for increased yields and resistance to pests and weeds, whereas others see the problems of the uncertainty associated with the use of new technology and ideas. As the Global Citizens' Report on the State of GMOs reveals, technology and nature do not always interact as expected and as a result, GM crops could create a food production system ever more reliant on natural resources. 

            Whether we go ahead with GM food production or not is a highly important decision, as co-existence between GM and conventional crops is not possible due to genetic pollution and contamination of conventional crops which is impossible to control (Shiva, 2011). Therefore the Royal society report admits that we need a lot more investment in research into sustainable agriculture before we go ahead and fully implement GM practices. 

This is a obviously a very brief overview of the debates associated with Genetic Modification, so check out the two reports in more detail if you're interested.

I quite like this cartoon I found on another blog.

Modern Agriculture: The Cause? Or the Solution?

This video clearly states that technology has a large role to play in the solution and that old fashioned methods wont produce enough to feed the world. However, I am skeptical, as technology has not helped to reduce the environmental impact so far, it has in fact worsened it. Therefore I don't see how this simplistic video can state that 'with careful stewardship of the earth' modern agriculture is the solution.... its just not that simple! However, it does nicely highlight the issues associated with government policy and how these need to change in order to produce enough food sustainably. 

Global food systems must be transformed ‘on industrial revolution scale’

The existing food production system clearly isn’t working as millions of people are still malnourished and the environmental impact of food production is not sustainable – as this blog has shown.

‘1 billion are going hungry, 1 billion are lacking crucial vitamins and minerals from their diet and another billion are "substantially overconsuming”’ (Guardian, 2011).

This Guardian article 2011 highlights the need for a change in agricultural practices as shown in the Global Food and Farming Futures report, from the Government office for science. The article nicely sums up how, with our current practices, the world cannot feed itself without destroying the environment, therefore we have no option but to make a change.

We have three main issues – an expanding population to feed, which requires  a change in the unsustainable nature of the exploitation of our natural resources as well as consideration for the impacts associated with climate change – as agriculture is a large contributor of green house gasses. These issues highlight the urgency of the problem.

            The main conclusion is that farmers need to grow more food at a smaller cost to the environment – but unfortunately this is easier said than done and as a result, the report comes to the conclusion that no single solution exists.

            The report states that the solution must involve reducing food waste and spreading our existing knowledge to developing countries. As well as the incorporation of organic agriculture, although the report states that this shouldn’t be the main strategy, as they don’t believe that organic agriculture can meet future demands without huge changes in peoples diets (I will address this in a later post). The report also states that technological advances should be considered such as genetically modified crops and cloned livestock and that they shouldn’t be excluded on ethical or moral grounds. They also highlight that government policy has a large role to play in changing global food systems as the government have been criticized for suggesting that technology holds the solution, many believe it will take a lot more than that!

Have a read of the Guardian article and let me know what you think… should we put our faith in technology and go for GM or should we go back to the small scale organic production of the past, after all, it was a technological revolution that got us into this mess in the first place. Can technology get us out of it again?

Why are we using up our natural resources feeding livestock?

A 2006 United Nations, Food and Agricultural Organization report has brought to light many of the problems associated with the production of meat. Increased wealth has lead to changes in food preferences, which has resulted in increased consumption of meat. During the past 40 years global per capita meat production has increased more than 60% (Tilman et al 2002). Livestock products now provide one third of humanity’s protein intake and global production of meat is projected to more than double from 1999 to 2050 with our growing population (UN, 2006). The report states that the livestock sector emerges as one of the most significant contributors to the most serious environmental problems, on a local and global scale. The meat industry contributes heavily to problems of land degradation, climate change, air pollution, water shortage and pollution and loss of biodiversity.

5 reasons why you should become a vegetarian!         

• The livestock sector is responsible for 18% of greenhouse gas emissions measured in CO2 equivalent (this is a higher share than transport). The largest share of this comes from land use change, especially deforestation (UN 2006).
• Overgrazing by cattle for meat degrades land and reduces soil productivity. Livestock production accounts for 70% of all agricultural land and 30% of the land surface of the planet. This includes the vast amount of land required to grow feedcrops for cattle which has resulted in huge amounts of deforestation (UN 2006).
• The livestock sector accounts for over 8% of human water use, mostly for the irrigation of feedcrops (UN 2006).
• The production of 1kg of meat requires between 3 and 10kg of grain, which requires vast amounts of land and many natural resources for growth (Tillman et al 2002). Therefore for the same input of resources you get a much smaller output compared to eating the grain directly, making the system less efficient.
• Meat eating adds a trophic level to the food chain and energy is lost with each trophic level, meaning that meat eating is less energy efficient than vegetarianism. Therefore meat eating increases depletion of earths natural resources (Tillman et al 2002).

Therefore increased meat consumption is not helping in the quest to feed the world’s growing population within the world’s environmental limits. 

Coastal Eutrophication – The impact of Agriculture in Chesapeake Bay

Over the past 300 years, Chesapeake estuary in mid-Atlantic USA has been converted from natural forests and wetlands into agricultural fields and urban development. Brush (2009) took sediment cores from the estuary, dating back 14,000 years ago, to look at the effects of these changes.

Sediment, nitrogen, pollen, diatom, and seed profiles from sediment cores suggest that prior to disturbance, the nitrogen cycle of this area consisted of a balance between biological nitrogen fixation and denitrification (Brush, 2009). This balance was maintained while small agricultural settlements were developed. However as land use changed to incorporate more intensive farming to support a growing population, this balance was disturbed. As agriculture grew and became more intensive, wetlands were drained, land was deforested and streams were channelized to reduce flooding of agricultural land and chemically produced nitrogen fertilizers were used to farm less fertile, marginal land. Changes to the landscape vegetation, hydrology and geochemistry resulted in a reduced denitrifying capacity of the area. This resulted in increased nitrogen loadings into the estuary, which lead to coastal eutrophication.

This diagram was produced to highlight the changes in the area over time. It is evident that many changes occurred as the population increased and with the onset of intensive agriculture (Brush, 2009).

The diagram shows how pollen types reflect the changes in land use. Sedimentation rates also increase as land was cleared for agriculture. These changes led to a shift from a benthic dominated system to planktonic dominated system, due to lack of light in the water column, which was further reduced by continued Planktonic algal growth. The increase in fertilizer purchases was mirrored by nitrogen fluxes in the sediment column. Through the process of eutrophication, this eventually led to the deep waters becoming anoxic and productivity declined (Brush, 2009).

Brush (2009) highlights how coastal eutrophication in Chesapeake Bay has significantly reduced coastal shellfish and fishery resources (especially oyster farming as shown in the diagram), which are important food sources for humans. Therefore in an attempt to feed the growing population of Chesapeake Bay through intensive agriculture, other valuable natural food resources were destroyed, and so far, all efforts to return Chesapeake Bay to its natural state have failed.

Ecosystem services as natural resources

Defra defines ecosystem services as ‘what nature gives us - Nature provides us with the very essentials of life. It gives us clean air and water; enables us to produce and gather food, fuel and raw materials from the land and sea; regulates our climate; stems flood waters and it filters pollution’. Ecosystem services provide us with natural resources. However, intensive agriculture can put many of these at risk (Tilman et al., 2002).

SOIL - plays vital roles in biogeochemical cycles and the water cycle. They provide nutrients, which enables plant growth and they play a part in flood control, and water filtration among many other processes. ‘Since 1945 approximately 17% of vegetated land has undergone human-induced soil degradation and loss of productivity’ (Tilman et al., 2002). Monocultures and continuous cropping remove nutrients from the soils and reduce soil organic matter, which reduces the stability and fertility of the soil. The reduction of this ecosystem service then results in larger fertilizer and irrigation requirements.

FORESTS- ecosystem services include - minimizing flooding, moderating regional climate, removing atmospheric carbon dioxide and aiding regeneration of fertile soils (Tilman et al., 2002). Greater food demands has led to deforestation to increase land available for agriculture. With continued population growth this will continue, with most deforestation in developing countries, which will have a major impact on the extent of tropical forests and the ecosystem services they provide (Eickhout et al 2006).

BIODIVERSITY – is vital to the maintenance of all ecosystem services. One of the main services provided by biodiversity is disease and pest resistance (Tilman et al., 2002). As previously explained, monocultures remove these protective ecosystem services. Pesticides are therefore used to reduce this problem. However, they have many adverse affects. Rachel Carson’s book silent spring explains the problems associated with increased use of chemical pesticides including the problems associated with non target species ingesting pesticides. Especially the toxic side effects of organochloride insecticides (DDT), which fueled the green revolution. The high persistence of DDT means it moves up the food chain causing more severe effects at successive trophic levels (Krebs et al. 1999). Pesticides can therefore lead to reduction of biodiversity by affecting non-target species and therefore further reduction in ecosystem services. Pollination and seed dispersal by insects and birds are vital ecosystem services that are vulnerable to destruction due to the use of pesticides. These losses would have direct adverse affects to agriculture.

FRESHWATER – has many obvious ecosystem services including water for human consumption, irrigation, power and transport. However, the use of fertilizers and pesticides in agriculture jeopardizes these ecosystem services by causing eutrophication (Eickhout et al., 2006). As shown in this very simplistic but informative video…

In turn eutrophication will reduce the availability of freshwater and the ecosystem services it provides for agriculture.

It is clear that maintaining ecosystem services is crucial for sustainable agricultural production and this is vital if we are to meet the demands of food production in the future. Some ecosystem services such as pollination or control of pests are of direct benefit to the farmer but others may be beneficial to people in general, therefore less care is taken over their preservation. Tilman et al. (2002) state that ‘Agriculturalists are the principle managers of global ‘usable’ lands’. This highlights the great control farmers have over our ecosystem services and therefore our natural resources. 

The role of Nitrogen

This video highlights how nitrogen is a natural resource that we don’t worry enough about. Nitrogen is essential for plant growth and therefore a vital agricultural input. However we are wasting it through inefficient use of fertilizers (Eickhout, 2006).

In the early 20th century the Haber-Bosch process was discovered for synthesizing ammonium nitrate (converting Nitrogen into a reactive form). This increased availability of this limiting resource enabled huge increase in food production and therefore population growth (Steffen et al., 2007).

This has dramatically altered the natural nitrogen cycle, as worldwide, more nitrogen fertilizer is now used per year than can be supplied through natural sources as agricultural inputs currently exceed inputs from natural N fixation. More nitrogen is now converted from the atmosphere into reactive forms than by all the natural processes in terrestrial ecosystems put together (Steffen et al., 2007).

This diagram shows how the flow of nitrogen has been altered by human interruption.

Figure 1. Global terrestrial nitrogen buged for a) 1890 and b) 1990 in Tg N yr^-1. (Steffen et al., 2007)

The emissions from NOy reflect those from fossil fuel combustion. Those from the vegetation include agricultural and natural soil emissions and combustion of biofuel biomass and agricultural waste. The NH_x emissions from the cow and feediot reflect emissions from animal wastes. The transfers to the fish box represent the lateral flow of dissolved inorganic nitrogen from terrestrial systems to the coastal seas.

The enormous amount of N₂ converted to NH₃ in the 1990 panel compared to 1890 represents human fixation of nitrogen through the Haber-bosch process, made possible by the development of fossil-fuel based energy systems (Steffen et al., 2007).

Artificial inputs of nitrogen mean the nitrogen cycle is no longer a closed loop, which has led to huge losses of Nitrogen from agroecosystems (Eickhout et al., 2006). This is generally due to over-application of fertilizers and the inefficient use by crops. ‘The recovery of fertilizer N in global crop production is about 50%’ (Eickhout et al., 2006). The fertilizer that is not recovered by the crop ends up in our environment, mostly in surface water or in ground water. This can then contribute to eutrophication and pollution of aquifers and can also contribute to emission of the greenhouse gas nitrous oxide (Tilman et al., 2002).

As our population continues to grow, our agricultural yields will also have to, therefore even more nitrogen fertilizer will be required. However, Tilman et al. (2002) state that increased application of nitrogen is unlikely to be as effective at increasing yields as it previously was due to diminishing returns. Figure 2 shows how efficiency declines with higher levels of addition. Therefore as more is applied to the land in the hope of increasing yields, the greater the losses and pollution of the environment will be.

Figure 2. trends in nitrogen-fertilisation efficiency of crop production (annual global cereal production divided by annual global application of nitrogen fertiliser). (Tilman et al., 2002)

Total reactive nitrogen loss will increase dramatically with the worlds increasingly intensive agricultural systems (Eickhout et al., 2006). Therefore we need to improve nutrient use efficiency so that less nitrogen is lost to the environment.

Reliance on Natural Resources

These graphs of agricultural trends over the past 40 years of a) global cereal production and b) total global use of nitrogen and phosphorous fertilizer (USSR not included). 

(Tilman et al. 2002) 

I think they show very clearly, how agricultural yields of cereal rely so heavily on natural resources - Water, Nitrogen and Phosphorous.

What a lot of water!

Intensive Irrigation

Wasting Water

Water is a renewable natural resource, yet limited access to freshwater renders it finite. Irrigation for agriculture is the largest consumptive use of water (Bouwer, 1994). The majority of our freshwater is stored in aquifers as groundwater and is abstracted for irrigation. However over-abstraction can result in aquifers becoming unproductive. Dams are often built to store water in irrigation reservoirs but these alter the natural hydrological cycle.

In 2000 agriculture accounted for ~ 75% of human water use (Wallace, 2000). Availability of fresh water is therefore a major limiting factor in population expansion. As the global population increases the demand for food increases and thus the demand for water increases. However, for the foreseeable future, ‘annual renewable freshwater resources are largely fixed’ therefore with population growth water scarcity becomes a huge concern (Wallace, 2000).

Irrigation is very inefficient, Wallace (2000) states that crops actually only use 10-30% or water put onto the land. Runoff losses and deep percolation are sources of inefficiency (Bouwer, 1994). Pimentel, et al. (1997) point out that controlling erosion can help to conserve water by reducing runoff and protecting forests and other biological resources can help maintain the hydrological cycle. As agriculture intensifies, soil erosion and deforestation are both likely to increase, therefore threatening long-term sustainability of water supplies.

Evapotranspiration is another major source of water loss from agriculture, which is likely to increase with climate change. Bouwer (1994) likens irrigated fields to evaporation pans where water is evaporated and salts are left in the soil, which can reduce the quality of the soil. The only way to reduce this water loss is to reduce the irrigated area while maintaining yields, by increasing crop yield per unit of water used (Bouwer, 1994). We need to increase the production of food for our growing population with the existing supplies of land and water (Wallace, 2000). This means agriculture must become even more intensive and even more reliant on fertilizers and pesticides. This in turn increases pollution of the limited freshwater supplies and can result in eutrophication.

            Water resource management will become increasingly complicated as the population continues to rise, especially as the areas with the largest populations to feed are often the most water scarce areas (Wallace, 2000). Wallace (2000) argues that this problem isn’t given enough attention by the scientific community. He believes that science can be used to develop the ability to grow more food with less water. Pimentel et al (1997) point out that most human activity has a negative effect on the quality of freshwater sources, as population continues to grow this effect will increase and the increased demand for water will become even more difficult to meet. 

Are corporations ruining food? – A lecture by Rob Lyons.

Last night (23/11/11) I attended a UCL Current Affairs Society lecture by Rob Lyons - deputy editor of spiked-online.com, writer on science and risk and author of Panic on a Plate: how society developed an eating disorder.

Short but thought provoking, the lecture revealed Lyons’ views that modern agriculture has enabled us to achieve all that we need to, in terms of food production. He stated that “for most of human history, the politics surrounding food was simply 'will there be enough'. Now such fears are absent from the developed world, the politics of food now focuses on who produces it and how”. Lyons took a historical view from when food was local and organic but expensive and scarce, making the current food system look far more successful! Food is now cheaper and more varied (due to trade) therefore people in the developed world eat a better, more varied diet. – So far intensive agriculture is looking good.

When questioned about the environmental impacts of these practices in terms of soil erosion and eutrophication, Lyons stated that our rivers and lakes are much cleaner today than they have been in the past - ok fair enough. Regarding soil erosion, he compared the desertification occurring in developing countries, where small-scale subsistence farming methods deplete nutrients, with soil in developed countries where fertilizers and irrigation maintain soil quality- I see his point here too. Lyons seemed positive that there will always be ways to improve environmental conditions with advances in technology and understanding in the future, therefore we need not worry about damaging it now.

            However, when I questioned Lyons on the long-term sustainability of intensive farming in terms of fossil fuels and phosphorous depletion, required to maintain the agricultural inputs, he simply suggested that fossil fuels aren’t really running out. He named a couple of newly found fuel reserves and explained that the viability of the extraction of shale oil is increasing. Similarly with phosphorous, Lyons stated that new reserves have been found therefore availability of phosphorous is no longer a problem. He explained that as we get close to the depletion of a resource, the value of that resource will increase and therefore more effort will be made to find new reserves. Lyons seemed pretty sure that we wouldn’t run out of these vital resources for at least 100 years – so there’s no need to panic!

            I do agree that maybe the depletion of fossil fuels is often dramatized, however, I think that continuing our reliance on them even longer is just going to increase our vulnerability by enabling the population to grow even more. We will never produce fossil fuels as quickly as we are using them so we will inevitably run out at some point and we need to prepare for this. Similar to the green revolution – I believe that finding more resources to rely on is just ‘postponing the day of reckoning’.

I left the lecture feeling intrigued but frustrated. I felt like the environmental impact of modern agriculture had been dismissed, as if it didn’t really matter because Lyons wasn’t concerned about it.

Other issues raised in this lecture will be discussed in later posts.

Monoculture Wheat Crop

Monoculture Wheat Crop - Montana (National Geographic)

MONOCULTURES

A summary of Altieri's report (University of California) on the problems associated with monocultures. 

Monocultures are agricultural land areas ‘devoted to single crops and year-to-year production of the same crop species on the same land’ (Altieri, University of California). Development of monocultures was enabled by agricultural mechanization, the improvement of crop varieties, and the development and increased availability of pesticides and fertilizers. Governments have encouraged this as monocultures can contribute significantly to the ability of national agricultures to serve international markets.

Intensive farming has enabled farmers to become more integrated into international economies. As a result, monocultures are ‘rewarded by economies of scale’ (Altieri, University of California). Therefore farms today are ‘fewer, larger, more specialized and more capital intensive’. However, monocultures are highly vulnerable and dependent on many chemical inputs, as the lack of rotations and diversification has taken away key self-regulating mechanisms.

Problems

-       The move from crop rotation to harvesting the same crop type each year means the same nutrients are removed from soils year after year and nutrient depletion and soil degradation becomes a huge problem and is highly unsustainable.

-       Crop types have been selected for their high yields, ‘sacrificing natural resistance for productivity’; this makes them more susceptible to pests. This is overcome by increasing the use of pesticides, however, many argue that the negative impacts of pesticides, including the reduction of beneficial insects, outweigh the positives. (As shown in Rachel Carson’s, Silent Spring, which I will look into further at a later date)

-       Monocultures are also more vulnerable to disease, as populations of the same species will have the same resistance to certain diseases, therefore whole populations can be wiped out by one disease outbreak. Protecting monocultures and treatment of disease requires a further increase in inputs, occasionally to the extent that, ‘the amount of energy invested to produce a desired yield surpasses the energy harvested’ (Altieri, University of California).

Intensified chemical controls are required to overcome the limiting factors reducing the productivity of monocultures, such as high pest potential, limited soil moisture, or low-fertility soils. The efficiency of the many inputs required to maintain monocultures are decreasing and crop yields in most key crops are leveling off, making the whole practice highly unsustainable.

5 Food Facts

1.   As of 1990 we are using approximately 1,000 litres of oil to produce food from one hectare of land (Pfeifer, 2004).

2.   The US food system consumes ten times more energy than it produces in food energy (Pfeifer, 2004).

3.   There will be an estimated 2-2.5billion new mouths to feed by 2050 (Cordell et al, 2009).

4.   Global food production will need to increase by about 70% by 2050 to meet the global demand (Cordell et al, 2009).

5.   In 1970 it was believed that if the hungry world was to feed itself, it must increase its use of fertilizers by 100% and pesticides by 600% (Paddock, 1970) and the population has almost doubled since then, with the majority of the growth being in developing countries!

The Phosphorous Problem – “we are effectively addicted to phosphate rock”

In my previous post the Guardain blog entry brings to attention one of the limited natural resources that rarely gets a mention - Phosphorous! As we now know, modern agriculture is heavily reliant on fertilizers containing phosphorous, nitrogen and potassium. Phosphorous is derived from phosphate rock, which is a non renewable resource. Cordell et al. (2009) explain the phosphorous problem….

Historically crop production relied on natural levels of phosphorous in the soils. Old fashioned techniques such as crop rotation and use of manure maintained phosphorous levels for a while, however, human population soon outgrew the natural limits. Production of fertilizer moved from local, organic waste products to phosphorous material from distant sources such as guano (bird droppings deposited over previous millennia) and phosphate-rich rocks. Since the end of World War 2, global extraction of phosphate rock has tripled to meet industrial agricultures demand for NPK fertilizers.

The natural biochemical cycle recycles phosphorous back to the soil in situ via dead plant matter, whereas through modern agriculture, crops are harvested before they decompose, and transported all over the world to be consumed by humans. The phosphorous is therefore not returned to the soil directly, as human excrement is flushed into watercourses for treatment, rather than put straight back to the soils. Phosphorous is returned back to soils through annual applications of manufactured chemical fertilizers to ensure maximum yields are maintained.

Not only does our interruption of this natural cycle require copious amounts of fossil fuel-based energy, but the efficiency of the cycle is also severely reduced - 55% of phosphorous in food is lost between ‘farm and fork’ (Cordell et al 2007). Phosphorous is leached from the soil and can result in eutrophication of watercourses, this is often due to over-fertilization as chemical fertilizers contain far more phosphorous than manure.

Phosphorous flows through global food production and consumption system. (Losses and recovery are in millions of tonnes per year, Cordell et al. 2009)

Global demand for phosphorous is predicted to increase by around 3-4% annually. Reports estimate its depletion in 50-100 years. We are expected to reach peak phosphorous production in 2030 and production costs are already increasing. The quality of phosphate rock is declining therefore cheap fertilizers will soon become a thing of the past. Equally, the mining and manufacture of fertilizers is only possible when cheap fuels exist and these are rapidly running out.

90% of worldwide demand for rock phosphate is for food production. It is one of the most highly traded commodities on the international market. Only a few countries control phosphate reserves, with China having the largest. Export tariffs have recently been imposed to ensure China maintains enough phosphate to feed itself. 


There is no substitute for phosphorous in food production. One of the only viable solutions is the recovery of phosphorous, which would require a shift from importing phosphate rock to domestic production of renewable phosphorous fertilizer (potentially from human excreta). Not only would recovery of phosphorous reduce the extraction of the non-renewable resource, it would also increase countries self-sufficiency.

Cordell et al (2009) highlight “as we are learning from climate change and global water scarcity, a long time frame is required to address phosphate scarcity”. We need to take action now before peak phosphorous is reached and we have no alternative. Despite all this, phosphorous scarcity has not been addressed in the UN’s Food and Agricultural Organization official reports.

How green was the green revolution? By increasing our reliance on fertilizers, it made us addicted to phosphate rocks, which did enable many more people to survive – but for how long?