Peak Phosphorus and the Threat to Our Food Security
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A rock and a hard place Peak phosphorus and the threat to our food security 2 soil association a rock and a hard place 3 executive summary the approaching ‘perfect storm’ of climate change, resource depletion, diet-related ill health and population growth is forcing us all to think again about how we produce and consume food Yet, there is one critical issue in securing our production without reliance on mined phosphate, Eating organic food can reduce our dependence diverting toilets, high-tech vacuum systems, and future food security that is missing from the is crucial for ensuring our future food supplies. on mined phosphate as organic farmers cannot use composting toilets. global policy agenda: we are facing the end of In this report we set out the actions we need to soluble phosphorus fertiliser, use little or no mined cheap and readily-available phosphate fertiliser take to close the loop on the phosphorus cycle phosphates, and make use of practices to improve on which intensive agriculture is totally dependent. to address future shortages and prevent further the efficiency of the use of phosphorus available in UK policy recommendAtions The supply of phosphorus from mined phosphate environmental damage from phosphate pollution. the soil, and its re-cycling within the farming system. rock could ‘peak’ as soon as 2033, after which this Amendments should be made to EU regulation non-renewable resource will become increasingly Changing how we deal with human excreta No. 889/2008 to permit the use of sewage sludge scarce and expensive. whAt Action is needed? A significant proportion of phosphorus is lost from on organic certified land subject to certain quality We are completely unprepared to deal with human excreta. It is estimated that only 10% of the criteria and appropriate restrictions, including the shortages in phosphorus inputs, the drop in Changing how we farm three million tonnes of phosphorus excreted by the maximum concentrations of heavy metal and production and the hike in food prices that will Farming systems vary as to the extent of their global human population each year are returned organic contaminants. follow. Without fertilization from phosphorus it reliance on mined phosphate inputs for producing to agricultural soils. Support for research and development for organic has been estimated that wheat yields could fall artificial fertilisers for use on grazing land and crops, In the UK, the majority of treated sewage sludge and agro-ecological systems, as recommended by from nine tonnes a hectare in 2000 to four tonnes and as additives in animal feed. (biosolids) is returned to land. At the present time, the IAASTD (2008) report, to include improving a hectare in 2100. The current price of phosphate Organic farming systems already make use EU organic regulations prohibit the use of such the efficiency of phosphorus use. rock is approximately twice that of 2006. When of many practices to reduce the need for mineral biosolids on organic farmland due to historical A shift towards ecological sanitation (ES) in the demand for phosphate fertiliser outstripped supply phosphate, including managing nutrient loss; using concerns about the toxic effects of heavy metals, UK is clearly a long-term goal involving significant in 2007/08, the price of rock phosphate rose 800%. farmyard manure, crop residues and green waste caused by combining human excreta with industrial infrastructure development in urban areas that are This may well be a taste of things to come. composts as fertilisers; increasing the availability effluent, domestic grey-water, and surface run-off. largely dependent on centralised sewage systems. In Europe we are dependent on imports of rock of phosphorus to plants by encouraging micro- Heavy metal levels have declined in recent years, However, there are many areas where infrastructure phosphate, having no deposits of our own, but the organisms and mycorrizal funghi; and using and are now low enough for the organic movement changes would be more straightforward: geographical concentration of reserves adds further crops with high uptake efficiency. to re-consider allowing treated sewage sludge to uncertainty to the future security of our sources. be used where it meets strict standards. ES could be made mandatory for all new In 2009, 158 million metric tonnes of phosphate Changing what we eat In the longer term on a global scale, the majority housing developments. rock were mined worldwide. 67% of this resource The benefits of reducing the amount of meat of human excreta will need to be returned to a large incentives and support could be provided was mined in just three countries - China (35%), the in our diets in terms of health benefits and reducing proportion of agricultural soils to close the phosphorus for retro-fitting with ES where appropriate, USA (17%) and Morocco and Western Sahara (15%). greenhouse gas emissions are commonly known, but loop. It will all need to be of a high quality to protect for example in rural areas where houses are not China has now restricted, and the USA has stopped, switching to a diet with less meat can also reduce human health and avoid environmental damage. connected to centralised sewage systems and exports of phosphate. demand for mined phosphate. This is because the This will require more fundamental changes to access to agricultural land would be easiest. There are serious environmental impacts of efficiency with which phosphorus inputs are our sanitation systems. We need to start thinking This would be particularly useful on small- phosphate fertiliser production and use including the converted to dietary phosphorus is much higher in of human excreta as a resource, not a waste. holdings and farms. production of toxic and radioactive waste, cadmium vegetable-based products than livestock products. Ecological sanitation (ES) systems collect and installing ES in public toilets and public pollution to soils, greenhouse gas emissions, and Of course different types of meat have different treat wastewater flows separately, optimising their buildings would also be excellent steps forward. the eutrophication of rivers. levels of mined phosphate demand depending on potential for re-use in agriculture, whilst minimising In the UK, and internationally, there has been the farming system used to produce them. Meat hygienic risk. They can reduce the risk from potential Support for public health policies that promote no serious discussion of, or action on, what peak from livestock grazed on grassland that has not been contamination from heavy metals and organic diets that are both healthy and climate-friendly, phosphorus means for food security. A radical fertilised with artificial fertilisers, will perform much contaminants and can also reduce the high water and reduce demand for phosphate – much less meat rethink of how we farm, what we eat and how better than meat from livestock grazed on fields and energy use of, and pollution caused by, the and dairy products (but proportionally more from we deal with human excreta, so that adequate that have been, or livestock fed on grain grown current “flush-and-forget” system that dominates grass-reared livestock) and more seasonal fruit and phosphorus levels can be maintained for crop using artificial fertilisers. in the developed world. Examples include urine- vegetables, starchy carbohydrates and whole grains. 4 soil association a rock and a hard place 5 why is phosphorus so vital for our food security? phosphorus is an essential nutrient for all plants and animals. it forms part of genetic material, and is used for energy transfer, within the cells of living things1 – and our supply of phosphorus from mined phosphate rock could ‘peak’ as soon as 20332 An adequate supply of phosphorus to plants is rich in phosphate.6 In parallel, as Lady Eve Balfour Figure 1 essential for seed formation, root development and alludes to,7 the introduction into urban areas historicAl globAl soUrces of fertilisers (1800–2000)14 the maturing of crops.3 It is second only to nitrogen of flush toilets meant that human excreta was as the most limiting element for plant growth4 and no longer returned to the soil, but washed out phosphorus 22 it cannot be substituted in food production. into water systems. (Mt/year) The amount of phosphorus that is found phosphorus rock 20 naturally in soils varies greatly and can range “…When water-borne sewage was introduced from around 500 to 2500kg per hectare. However, into our cities, the capital of the soil – its fertility guano 18 only a small proportion of this phosphorus will be – which is removed from it year by year in the form in the right form (soluble organophosphates in the of crops and livestock, no longer found its way back human excreta 16 soil solution) for it to be available for plants to take to the land in the form of the waste products of up, indeed this is often less than 10g per hectare. the community, but was poured into the sea or manure 14 The majority of the phosphorus is stored in the otherwise destroyed.” soil in insoluble forms (mineral and organic) that The Living Soil, lady eve Balfour, 1943 12 are not readily available to plants. As they grown, plants take up the available phosphorus and deplete By the late nineteenth century, processed mineral 10 the soluble pool. This can be replenished by the phosphorus fertiliser from phosphate rock was conversion of the insoluble phosphorus through routinely used in Europe and its use grew substantially 8 chemical transformations in the soil and microbial in the twentieth century.8 Figures from the US activity5 – if there is enough stored in the soils. geological survey show that production of phosphate 6 Under natural conditions the phosphorus taken rock increased from approximately three million up by growing plants is returned to soils in plant tonnes in 1900, to 41 million by 1960 and reaching 4 residues, and from the urine, excrement and current levels of around 150 million by 1980.9 carcasses of the animals that have grazed the Today, non-organic agriculture is dependent 2 vegetation.