Monday, August 04, 2014

Soil Erosion, Climate Change and Global Food Security: Challenges and Strategies. Part 9.

This is the ninth (and final) part of a much longer article published in the journal Science Progress, and which may be found here:

24. How many people can the Earth support?

It is claimed78 that “a population density of 6─10 people per acre might be supported through permaculture, and in excess of the number that our current cereal-based food economy can sustain”. Since our ability to grow cereals, in the quantity we do, depends on industrialised agriculture, with its considerable inputs of oil- and gas-based fuels, fertilizers and pesticides, the practice is not sustainable and so the comparison is not strictly valid. We are then left with the question of how many people might be supported by the earth, if permaculture methods were widely introduced. If we assume the lower limit, this means that 15 people can be fed per hectare. Thus, to feed the human population of 7 billion, we would need 467 million hectares of land, or 4.7 million km2. Since we have 150 million km2 of dry land, and around 14 million km2 of arable land, it would appear there is no problem in sustaining the present global population, and that supporting even 9 billion by 2050, or 12 billion by 2100, is feasible. Toby Hemenway, regarded as one of the gurus of permaculture, is less optimistic, and believes that the maximum carrying capacity of the Earth is nearer 2 billion.79 [This is also the number arrived at by Pimentel et al.80, on the basis of the limited resources of energy, water and food available to us, and it seems most likely that it is failing supplies of these key inputs, particularly freshwater, that will reduce and finally limit our population. One is reminded of the “four horsemen of the apocalypse”: pestilence, war, famine and death, each rider being perceivable in a guise of resource shortages. Since the consequence of consumption is pollution, this too must prove a determinant to the numbers of humans that can live sustainably on “Spaceship Earth”, as the visionary Buckminster Fuller termed81 our existence].

Other permaculturists are far more sanguine than Hemenway about what might be achieved, in terms of sustaining the global population, and point out that predictions of food shortages are based on limits of the resources that are necessary for modern agriculture, whereas permaculture is based on the interacting and holistic mechanisms of nature, where nothing is wasted and everything is recycled, all elements being returned to the ecosystem, by death, and from which new life can flourish. David Blume claims to have fed up to 450 people on two acres (0.8 ha) of land for 9 years, by the end of which the soil contained 22% SOM, with a CEC of >25 (a measure of its humus content). This amounts to ca 18 m2/person, which might be understood to imply that the current world population of 7 billion could be fed on just 120,000 km2 of land. The key to this success is polyculture, which benefits from the growth of mycorrhizal fungi and less solar saturation82. Blume has described this technique as “restorative agriculture”, and he believes that there is, correspondingly, no immediate limit to the number that can be fed on Planet Earth, and that ethanol fuel, produced on the local scale could meet all our energy needs – including electricity production – and obviate the need for crude oil. Hemenway has spoken83 on the subject of: “How Permaculture Can Save Humanity and the Earth, but Not Civilization,” which may initially sound like an oxymoron. It is in fact a rather more subtle proposition, to the effect that while permaculture cannot sustain the present global economy and global civilization with a population of 7 billion people, it might support a lesser number of up to 2 billion, but, of necessity, its practices mean living in small communities. Thus, the civilization that permaculture could sustain is a globe of villages, not the global village. The principles of permaculture are central to the growing community-based Transition Towns movement59.


As we have seen, the subject of land degradation is complex. A significant part of this complexity lies in establishing a clear link between the degree of degradation – principally from soil erosion – and declining crop yields, since the latter can be masked by the application of fertilizers to improve soil productivity, even in cases where the soil has been significantly degraded. Irrigation is a key factor too. Most determinations of the extent of land degradation (e.g. GLASOD) have been made on the basis of “expert judgement” and perceptions, as opposed to direct measurements of this multifactorial phenomenon. More recently, satellite-based remote sensing measurements have been used to provide some overview of the global situation. Globally, the amount of biomass was measured to increase by 3.8% during the years 1981─2003, which is thought due to the fertilization effect of rising atmospheric CO2 concentration. However, 24% of the global land area suffered some degree of degradation over the same period. Hence, there are regions of “greening” while elsewhere, “browning” has occurred. It appears that while long-term trends in NDVI derivatives are only broad indicators of land degradation, taken as a proxy, the NDVI/NPP trend is able to yield a benchmark that is globally consistent and to illuminate regions in which biologically significant changes are occurring. Thus attention may be directed to where investigation and action at the ground level is required, i.e. to potential “hot spots” of land degradation and/or erosion.

The term “sustainable agriculture” has been described as an oxymoron, on the basis that by its very nature, agriculture is ultimately unsustainable84. It is not simply the degradation of the soil, or the loss of biodiversity that are at issue, but that the external energy inputs amount to perhaps ten times that actually consumed in the food itself. In the absence of a cheap and plentiful supply of crude oil (and the fuels, pesticides and herbicides that are derived from it), cheap natural gas (from which nitrogen fertilizers are made), and mined phosphate rock (used to make phosphorus fertilizers and mined using machinery powered by fuels refined from crude oil), the present industrialized global agricultural mechanism would be impossible, and it is only through the latter that the global human population has risen to its present number. Projections about future population numbers tacitly assume that these inputs will prevail into the future, when all evidence is that the age of cheap oil and gas is drawing to a close. It is very likely that the present system of large-scale industrialized agriculture will not survive, and humans will return to growing food on smaller areas, including the adoption of urban permaculture, as happened in Cuba when its bestowals of cheap fuels, and other agricultural inputs (pesticides, herbicides, fertilizers) from the Former Soviet Union were curtailed by the collapse of Communism2.While in principle, a permaculture approach can be applied on all scales (from the small plot to the full field), it cannot be adopted as a substitute for industrialized modern monoculture crop production since it is implicitly holistic. Accordingly it is not possible to separate our growing of food from other aspects of community, and so to adopt the design principles of permaculture for our food production, we must adapt all other lifestyle elements as an underpinning and simultaneous part of the process.

As fuel prices rise, and actual shortages of fuel ensue, long-distance mass transportation of food will no longer be economic or feasible, further driving food production at the local level, as a means to achieve food security and community resilience. The loss of soil organic matter (SOM) is a critical factor both in soil erosion and in the loss of soil productivity, the latter from the loss of soil (depth) per se, and a decline in the structure, level of nutrients and hence the innate fertility of the soil. Thus, by increasing the SOC, the structure of the soil is improved, which increases its holding capacity for water, and allows better drainage, hence there is more groundwater and less flooding, while droughts are mitigated. The agricultural productivity of the soil is heightened, enlarging crop yields, and soil erosion is attenuated, especially if the ground is also covered by mulching or with cover crops. Degraded lands may be restored in their production through increasing their SOC content, giving better soil, and water quality. The improved soil structure leads to a better retention of water and nutrients, and smaller inputs onto the farm of oil-based fuels, fertilizers, pesticides and herbicides, while biodiversity is enhanced. The term “biodiversity” does not only refer to what is visible above the ground, but also to the roots systems of plants, and their accompanying fungal rhizosphere which is an essential part of the soil food web. The importance of rebuilding the soil food web2 – the ecosystem of microbes, and visible creatures that dwell in soil – is central to maintaining food production in perpetuity, i.e. achieving a system that is truly sustainable.

The Chikukwa project shows that by using low tech methods, even highly degraded land, with severely eroded soil can be brought back to life - and with very little money, but a good design. This is not a quick-fix strategy, and has taken over two decades to come to achieve; however, it is a sustainable landscape, which is the more important element. In part it may appear that the case for catastrophic land degradation through soil erosion, and an according threat to the survival of humanity has been overstated, although the rising human population will increase demand inexorably for what the soil can provide. It must be stressed, that the productivity of much agricultural land is maintained only through those inputs, of oil and natural gas (from which fuels, pesticides, herbicides and fertilizers are sourced), and irrigation water, which are vital organs of current industrial food production. Therefore, on grounds of stabilising the climate, preserving the environment, and ensuring the robustness of the global food supply, maintaining and building good soil, in particular improving its SOM content and hence its structure, is highly desirable. In particular, those regions of the world that are significantly degraded are unlikely to support an appreciable population increase (e.g. Africa, whose population is predicted70 to grow from its present1.1 billion to 4.2 billion by 2100) in which case a die-off or mass migration might be expected, if population limitations are not included in future plans to achieve sustainability and food security.

The latter figure should be placed in the context of a total70 world population of almost 11 billion by 2100, nearly 40% of which would therefore be African. It is more likely, however, that a constraint on the size of future populations will be imposed by an insufficiency of oil, gas and therefore food, to sustain the growing multitude. Indeed, rather than the number of humans on Earth increasing throughout the present century and probably beyond, there are various analyses which indicate instead that the population will peak at some stage before 2100. It is probable that industrial populations will soon peak85, with the developing nations following suit around 40 years later as they try to emulate their current industrial counterparts. The population of Europe has been estimated85 to peak in 2025, with the world population peaking at around 8.5 billion around the year 2050. However, a critical loss in the global oil (and hence, food) supply could precipitate a more immediate and rapid decline in human numbers.



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Captions to figures.

Figure 1. Vertical structure of a typical soil. Mediterranean red soil. A, represents soil; B, represents laterite, a regolith; C, represents saprolite, a less-weathered regolith; the bottom-most layer represents bedrock. Credit Carlosblh.

Figure 2. A soil texture diagram- soil types according to their clay, silt and sand composition, as used by the USDA, redrawn from the USDA webpage: Credit Mikenorton.

Figure 3. Iron rich red soil near Paint Pots mineral springs in Kootenay National Park, British Columbia, Canada. Credit Marek Ślusarczyk.

Figure 4. The soil food web. Credit USDA.

Figure 5. A hillside covered in rills and gullies due to erosion processes caused by rainfall. Credit: Ivar Leidus.

Figure 6. Normalized Difference Vegetation Index (NDVI) from November 1, 2007, to December 1, 2007, during autumn in the Northern Hemisphere. Food, fuel, and shelter: vegetation is one of the most important requirements for human populations around the world. Satellites monitor how “green” different parts of the planet are and how that greenness changes over time. These observations can help scientists understand the influence of natural cycles, such as drought and pest outbreaks, on vegetation, as well as human influences, such as land-clearing and global warming. Credit: NASA.

Figure 7. Global soil regions. Source: U.S. Department of Agriculture.

Figure 8. Fertility of world’s soils.

Figure 9. Left - a nutrient-poor oxisol; right - an oxisol transformed into fertile terra preta. Credit: Bruno Glaser.

Figure 10. Subsurface waters. Source U.S.G.S.

Figure 11. Replenishment of aquifers by infiltration. Source: U.S.G.S.

Figure 12. Natural and artificial recharge of groundwater. Source: U.S.G.S.

Figure 13. A browse image of the water-level-change contours data set for the High Plains aquifer, 1980 to 1995. Credit: McGuire, Virginia L. and Sharpe, Jennifer B. '''Source''': United States Geological Survey[

Figure 14. This shot shows how the Chikukwa lands looked in the early nineties,
bare hillsides and soil erosion, with the consequence in poor nutrition. Credit: Terry Leahy

Figure 15. This picture shows a small section of the Chikukwa clan lands as they are now. The houses nestled among orchards, the bunds with vetiver grass in the
cropping fields and the extensive woodlots are all typical of this design strategy. Credit: Terry Leahy

Sunday, August 03, 2014

Soil Erosion, Climate Change and Global Food Security: Challenges and Strategies. Part 8.

This is the eighth part of a much longer article published in the journal Science Progress, and which may be found here:

19. Grain Yields Starting to Plateau?

There is evidence that the world’s grain yields are beginning to plateau73. In 1950, the average grain yield was 1.1 tonnes per hectare, but this had climbed 3.3 tonnes per hectare in 2011, while the U.S. and China were able to quadruple their grain yield over that same period. From the inherently fertile soils in the U.S. Midwest is produced 40% of the world’s corn crop and 35 % of its soybean crop. In Iowa, more grain is grown than in Canada and more soybeans than in China. The land to the west of the Alps, which extends across France to the English Channel is also very productive, meaning that Western Europe is able to export a surplus of wheat, in addition to feeding its own dense population. In the U.S., wheat is principally grown in the semiarid Great Plains, whereas in Europe it is produced on the fields of France, Germany, and the United Kingdom, which receive ample rainfall. The European wheat yields are typically in the range 6─8 tons per hectare, whereas in the U.S. 3 tonnes/hectare is good. In China, India, and other tropical/subtropical countries in Asia, it is common to employ double- or triple-cropping for rice, and so the annual yield is much greater, despite the yield per harvest being less.

The new dwarf wheats and rices that were introduced in the 1960s were selected genetically to be enhanced in their growth by both good irrigation and the application of fertilizers. More recently, farmers have worked on developing hybrid varieties of corn that can tolerate crowding, to improve yields, and whereas 50 years ago probably 25,000 corn plants were grown per hectare, when there is sufficient soil-moisture perhaps 70,000 plants per hectare can be raised. Between them, China, India, and the United States use 58% of the world’s fertilizers, as the major grain producing nations. China and the United States produce roughly 400 million tonnes of grain each, and the amount of grain produced per tonne of fertilizer in the United States is in excess of twice that of China. This is partly a consequence of the U.S. being the world’s main producer of soybeans (soya beans), since being a legume, this plant can fix nitrogen in the soil, which can in turn fertilize crops planted later on, e.g. corn, in a rotation of the two crops, thus requiring a smaller application of nitrogen fertilizer. During the period 1950─1990, the world grain yield increased by an average of 2.2% per year, but during 1990─2011, this fell to just 1.3% per year. In Japan and in South Korea, the rice yield has plateaued, having achieved the limit that can be met according to the prevailing day length, solar intensity, and ultimately that of photosynthetic efficiency.

Japan and South Korea together produce 12 million tonnes of rice annually, or 3% of the world rice harvest. Wheat yields in Europe achieved their limit more than a decade ago, with 8 tonnes per hectare as the maximum in the United Kingdom and in Germany. It appears that the yield of rice in China, the world’s most populous country, may also be about to plateau73. Since China uses twice the amount of fertilizer that the U.S. does, probably the application of it at a greater density will do little to improve yields. Chinese wheat yield too may be close to the maximum level, meaning that, along with those in Western Europe, practically 30% of the world’s wheat harvest would be grown in countries that probably cannot increase their production. Rising global temperatures are likely to place further limits on agricultural production.

20. Possible remedial actions for land degradation.

Soil erosion is most effectively prevented by covering the land with vegetation, a strategy which helps prevent erosion by both wind and water, in addition to ameliorating runoff and consequent flooding while allowing natural groundwater, and in some case aquifers, to recharge thus securing freshwater supplies. Terracing too has been practiced across the world since time immemorial, and is an extremely effective way to control erosion. Rows of trees and shrubs planted along the edges of agricultural fields provide windbreaks, which serve to protect the fields against the action of winds, and confer a number of additional positive features, e.g. providing microclimates for crops (by sheltering them from the drying and other damaging effects of wind), making a habitat for beneficial bird species, contributing to carbon sequestration, and enhancing the agricultural landscape from an aesthetic viewpoint. Traditional planting methods, such as mixed-cropping (rather than monocropping) and crop rotation are also known to reduce erosion rates appreciably. Some sustainable soil management principles have been outlined74 and are summarised in the following list:

· Soil livestock (microbes, earthworms etc.) cycle nutrients and provide many other benefits.

· Organic matter is the food for the soil livestock herd (soil food web).

· The soil should be covered to protect it from erosion.

· Tillage accelerates the decomposition of organic matter.

· Excess nitrogen urges the decomposition of organic matter.

· Moldboard ploughing speeds the decomposition of organic matter, destroys earthworm habitat, and increases erosion.

· To build soil organic matter, the production or addition of organic matter must exceed the decomposition of organic matter.

· Soil fertility levels need to be within acceptable ranges before starting a soil building programme.

The following techniques are proposed in order to build soil:

• To apply manure as a soil amendment. Typical rates for dairy manure would be 10 to 30 tonnes per acre or 4,000 to 11,000 gallons (15,000 to 42,000 litres) of liquid for corn. This provides organic matter and nutrients, and avoids the loss of SOM. Crop residues grown from manured soil would further contribute organic matter to the soil.

• Farm manure and other organic materials should be composted in order to stabilize their nutrient content.

• Cover crops and green manures: rye, buckwheat, hairy vetch, crimson clover, subterranean clover, red clover, sweet clover, cowpeas, millet, and forage sorghums can be grown as cover crops. If they are allowed to grow long enough to produce sufficient herbage, cover crops can contribute SOM to the soil.

• Reduce tillage: the effects of tillage on the soil may be adverse. Tillage reduces the natural aggregation of soil and the number of earthworm channels, while porosity and water infiltration are often decreased. Soils that have been tilled are more prone to erosion than soils left covered with crop residue.

•Minimise application of synthetic nitrogen fertilizers: ideally carbon and nitrogen sources should be added in combination: animal manure is a good source of both. If nitrogen fertilizer is used, it is best to apply it along with a heavy crop residue to the soil, e.g., a rotation of corn, beans, and wheat would thrive if nitrogen fertilizers were added after the corn residue was rolled down or just lightly tilled in.

21. Seed-saving and climate change.

In many primitive societies, to save and preserve seeds was considered as an almost sacred duty. While the practice has lapsed in the past several decades, it may prove necessary to embrace it once more. This is the message from a recent report by the Ecumenical Advocacy Alliance, The Gaia Foundation & The African Biodiversity Network, "Seeds for Life: scaling up agrobiodiversity.”, in which it is argued that adapting agriculture to cope with climate change cannot be done without preserving seed diversity. Thus, in the absence of a wide gene pool of crops, it will not be possible for farmers to spread their risk, or breed new varieties to adapt to changing weather patterns. The blame for a profound loss of global diversity is placed on the fact that modern agricultural methods and the marketing of agribusiness corporations rely on relatively few varieties and crops.

The report proposes that to remedy this situation, farmers must be supported in a revival of their traditional seed saving practices and the accompanying knowledge, such that this diversity is maintained and made accessible both for farming today and into the future. Many farmers grow from just one or two varieties of purchased seed, but the entire crop may fail if the rains arrive too late or too early, are too heavy or there is no rain. Climate change is expected to cause irregularities of this kind, and yet it is those seed varieties that were harvested traditionally and saved, but were then abandoned decades ago, that may serve best in the future. The Green Revolution has changed the face of farming since the 1960s. Before then, it was the practice to plant dozens of different crops, from which the seeds were routinely saved, in a process of developing and adapting new varieties such that the many and various challenges of soil, pests, disease, nutrition and flavour could be coped with. Since the Green Revolution came about, there has been an enormous loss both in the diversity itself and the associated knowledge of how to tend and nurture it, particularly on farms in North America and Europe. There is currently a rising pressure on farmers to adopt corporate seed varieties at the expense of their locally-adapted versions, in Africa, Asia and Latin America.

22. Permaculture.

As a working and practical definition, permaculture2,75,76 may be described as a low impact method which uses perennial cultivation methods to produce food crops, working through principles that are in harmony with nature. This might sound slightly "new age", but since much of the energy used in mechanised agriculture is employed to forge processes that restrain the land from returning to its natural wilderness, if productive agriculture can be had at a minimum of this energy input, then we have the essence of a significantly more efficient and "natural" way forward. Certainly in developed nations, food is not grown locally but must be brought in from surrounding regions, and much of it is imported globally. The monoculture system that is typical of modern farms drains nutrients from the land, which is fed with artificial fertilizers, and many of the natural flora and fauna (soil food web) no longer exist. Such single crops are vulnerable to pests and diseases: for example, the Irish potato famine was a result of Blight disease which rapidly devastated the single species of potato which was being grown at the time, and was the staple food for the poor. Previous generations grew cereal crops but since the potato was more robust to changes in the weather and produced about four times as much food per hectare, it became the crop of choice. Production of 'biofuels' is diverting more land to the growth of monoculture crops, and along with the eradication of vast swathes of rainforest (e.g. to grow palm for palm-oil), it is far less 'green' as a fossil-fuel alternative than is frequently claimed. The necessary competition between growing crops to feed humans and animals or cars has also driven up the price of staple foods like wheat and corn.

The term Permaculture75,76 (a portmanteau word derived from permanent agriculture, or culture) was coined by Bill Mollison and David Holmgren in the mid-1970s, to describe an “integrated, evolving system of perennial or self-perpetuating plant and animal species useful to man.” According to Holmgren, “A more current definition of permaculture76, is ‘Consciously designed landscapes which mimic the patterns and relationships found in nature, while yielding an abundance of food, fibre and energy for provision of local needs.” People and their buildings, and the ways they organise themselves, are central to permaculture. Thus the permaculture vision of permanent (sustainable) agriculture has evolved to one of permanent (sustainable) culture.” Broadly, permaculture may be classified (insofar as such an holistic entity may be) as a branch of ecological design and ecological engineering which aims to develop sustainable human settlements and self-maintained agricultural systems modelled from natural ecosystems. One major change incurred by converting to permaculture is that cereals cannot be produced at the scale of industrialized agriculture, and amendments in our diet would be necessary, to consume more vegetables, fruit, nuts, berries etc., which can be produced effectively by its means.

The core tenets of permaculture are:

· Take Care of the Earth (“Earth Care”): Provision for all life systems to continue and multiply. This is the first principle, because without a healthy earth, humans cannot flourish.

· Work with nature.

· Act to oppose destruction and damage.

· Consider the choices we make.

· Aim for minimal environmental impact.

· Design healthy systems to meet our needs.

· Take Care of the People (“People Care”): Provision for people to access those resources necessary for their existence.

· Look after ourselves and others.

· Working together.

· Assist those still without access to food and clean water.

· Develop environmentally friendly lifestyles.

· Design sustainable systems.

· Share the Surplus (“Fair Shares”): Healthy natural systems use outputs from each element to nourish others. Humans can do the same; by taking control of our own needs, we can set resources aside to further the above principles.

· Resources are limited and only by curbing our consumption and population will there be enough for all, now and in the future.

· Build economic lifeboats.

· Develop a common unity.

· Modify our way of life now - don’t wait: become part of the solution not part of the problem.

· Need to become reconnected with the natural world: shift in thinking and being.

Permaculture is about making an effective design, emphasizing patterns of landscape, function, and species assembly. It asks the questions: Where does this element go? How can it be placed with other elements for the maximum benefit of the system overall? The fundamental principle of permaculture is, therefore, to maximize useful connections between components to achieve their best synergy in the final, and optimal design. Permaculture does not focus on individual elements, in isolation, but rather on the relationships created among those elements in the way they are placed together; the whole becoming greater than the sum of its parts. Therefore, permaculture design aims to minimize waste, human labour, and inputs of energy and other resources, by building systems with maximal benefits between design elements to achieve a high level of holistic integrity and resilience. Permaculture designs are “organic” and evolve over time according to the interplay of these relationships and elements and can become extremely complex systems, able to produce a high density of food and materials with minimal input.

23. Turning problems into solutions: from erosion to accumulation.

The Chikukwa project77 in Zimbabwe is an edifying example of how a thoroughly degraded landscape can be brought back to verdancy using practical permaculture. As noted earlier, when land has become badly degraded, especially in developing countries, it is often considered too expensive to recover using engineering/technological approaches and is accordingly "written off". In contrast, the Chikukwa project shows that by using low tech methods, even highly degraded land, with severely eroded soil can be brought back to life - and with very little money, but a good design. This is not a quick-fix strategy, and has taken over two decades to achieve; however, it is a sustainable landscape, which is the more important element. The fruition of this project is immediately apparent from the “before and after” photographs77 such as those shown in Figures 14 and 15. There is a 50 minute video available which describes the project in its entirety: Chikukwa is on the edge of a mountainous region of Eastern Zimbabwe, on the border with Mozambique. The Chikukwa clan consists of 7000 members who live in 6 villages situated along a 15 km stretch of hills and valleys. Indeed, from Figure 15, it would be easy to think that they have simply continued to live a centuries-old life according to their traditions.

This is not so, and the Chikukwa project began in 1991 when the water supply that had provided for around 50 households in the village of Chitekete suddenly dried up. Attempts to dig for water were thwarted by further rains which caused the stream to become silted up again. At this time, the area was being increasingly deforested and most of the people were growing cash crops to earn their living. Along with cattle being let loose to graze, the denuding of the mountainsides of vegetation exacerbated soil erosion which further compounded the water problem. Those mountainsides, formerly lush and abundant had dried out, and soil erosion had impacted badly on the fertility of the land, which was steadily becoming desert. The lack of normal groundwater recharge as a result of deforestation had caused the springs to dry up, and when new water sources were tapped, they became blocked by silt from erosion. Beyond the practical aspects, the drying up of the springs had a spiritual dimension too, because according to traditional beliefs, water spirits live in wells and springs, who must be cared for by ensuring the health of the springs. In permaculture terminology, Chikukwa is well described as an edge, both in terms of ecology, culture and language, and the edge effect has undoubtedly yielded a rich and active vibrancy in all respects. Ironically, it is as though an interstitial industrialized phase has been bypassed, and a direct route to a sustainable community has been taken instead. The demand on external inputs is but minor, and the community can be described as being largely self sufficient. This, however, a way of life that is remote in all respects from that in the developed nations, and the majority live in mud huts and provide for themselves and their families by subsistence farming. Every family has access to running water, taken from mountain springs; communal land in the valley is used to grow wheat and maize flower, providing bread and maize meal. Along the mountainsides are grown fruit trees which everyone can help themselves to.

[Figs 14 and 15]

The Chikukwa project is built on the principles of permaculture and the testament of its success is that, in contrast to the majority of agriculture projects in Africa which fail very quickly, it remains in flourish. The “before” photos taken in the early 1990s show barren hillsides with a few trees spartanly surviving here and there, with massive erosion gullies in common sight. Around the springs the banks are bare and trampled by cattle, while the drying up of the springs made it necessary for villagers to walk five km and more to bring water from a more permanent stream further downhill. There was little feed for cattle during the dry season and wood for fuel was in short supply, while the harvest had become poor. During the wet season, there were floods as rainwater poured down the hills, inundating houses and bringing silt up to the window ledges. In the after” photos, we see households that are now small farms, surrounded by orchards and vegetable gardens. The hillsides are ringed by contour bunds (Figure 15) topped by vetiver grass, while abundant indigenous woodland is hosted by the gullies. Bunds are small barriers to runoff coming from external catchments, which slow down water sheet flow on the ground surface and encourage the build up of soil moisture and groundwater recharge (infiltration). Bunds are among the most common techniques used in agriculture to collect surface runoff, increase water infiltration and prevent soil erosion. Bunds are constructed using either stones or soil, and by building them along the contour lines of a hill or mountain, the flow of water is slowed down leading to a greater degree of infiltration and enhanced soil moisture. Bunds may be used on both even and uneven grounds (with a gentle slope of up to 5%), by adapting the exact design.

A dense woodland, planted on the slopes, provides firewood and timber. Water is harvested during the wet season by woodlots and swales which release it steadily, so that the springs run throughout the year. Accordingly, yields of cereals, vegetables, fruits and animal protein have been increased, making Chikukwa an exception in the wards of South and Eastern Africa where food shortages are typical. By establishing a fresh landscape, the Chikukwa project has established a fresh landscape, and its strategic components have been embraced in each of the region’s six villages, each of which has, as its water source, a spring about a third of the way down from the hilltops. In order to protect the indigenous woodland, deliberately planted and sown by the villagers, the gully is fenced off. One or more poly pipes leads down from the spring to a community water tank which supplies water to taps in household yards taps in household yards. Woodlots of fast growing trees are planted on the upper slopes and on some of the lower ridges, to maintain the health of the springs, and aid the storage and release of ground water, while preventing erosion and they also provide fuel and timber. While in principle, permaculture2,75,76 can be applied on all scales, it cannot be adopted as a substitute for industrialized modern monoculture crop production. It is not possible to separate our growing of food from other aspects of community, and so if we adopt the design principles of permaculture for our food production, we must adapt all other lifestyle elements as a necessary and simultaneous part of the process.

Friday, August 01, 2014

Soil Erosion, Climate Change and Global Food Security: Challenges and Strategies. Part 7.

This is the seventh part of a much longer article published in the journal Science Progress, and which may be found here:

17. “Peak Water”.

Water is a resource that will begin to run short within a few decades, as is espoused in the book65 entitled "Mirage", written by Cynthia Barnett, which focuses on water-use in the United States and in Florida particularly. It is well known that to the east of the longitudinal line along the 100th meridian, rainfall is plentiful, while to the west of it the climate is relatively arid. Indeed it was once believed that farmers in the "east" would never have to worry about watering their crops, but in recent years demand for water has surged with calamitous environmental consequences. She refers to a house falling into a "sinkhole", which is a collapse in the limestone rock that underlies Florida as a consequence of its natural dissolution by underground water. These can be opened-up as a result of human activities including well-drilling and moreover the excessive pumping of groundwater. She discusses the complex politics involved in "development", and the overpopulation of that southern tip of the Florida peninsular particularly by retirees ("seniors"), thus requiring an infrastructure - including very green and hence heavily watered lawns and golf-courses etc., – to a degree that surpasses even what can be provided by the greatly abundant rainfall there. Meeting the shortfall necessitates the extraction of groundwater on a huge scale with environmental, economic, political and social consequences, including at least one death as she describes in the chapter "Water Wars". Indeed the history of water supply in the United States is wryly inscribed in the quotation (attributed to Mark Twain), "whiskey's for drinkin' and water's for fightin'.”

A central theme in the book is that water is a commodity. Often the real costs of water provision are borne by states or municipalities rather than by corporations, who cash-in on a cheap resource for which no regard is consequently imbued, nor for environmental actions such as damming rivers as mighty as the Colorado for various "aquatic" projects. Bottled "spring" water is an immensely overpriced designer toy, costing around 10,000 times as much as tap water and often with much the same analytical composition. Indeed, not all spring-water does in fact come from a spring, and is to a large degree, pumped groundwater.

While the competition over the use of arable land to grow either food or fuel crops is a well established and critical factor in making biofuels at scale, there is less awareness about the water required to irrigate the land on which the crops are to be grown. It is unequivocal that China is the new industrial nation, in an unparalleled phase of its economic and social development. This might be expected to continue for as long as the West can afford to buy its cheap goods, but in the current recession, that duration is debatable. Underpinning Chinese industrial growth, as for all industrial growth, is energy, and in recognition of peak oil, emphasis is on biofuel (and all other kinds of energy resources in China, including coal-to-liquids, CTL conversion) as products need to be transported for sale. It is aimed that by 2020, 12 million metric tons of biofuels will be produced in China. To put this into context, this is equivalent to around one fifth of the petroleum-derived fuel used in the United Kingdom annually. The fuel is to be bioethanol, fermented from corn (maize) which is a relatively water-efficient starch crop.

According to one analysis66 in order to irrigate sufficient corn to produce 12 million tonnes of bioethanol, a quantity of water equivalent of the annual discharge of the Yellow River would be required. 64% of China's arable (crop-growing) land is in the northern part of the country, and is already under pressure since the existing use of water exceeds its reserves and water-tables are falling67. We have neither sufficient land nor water to maintain the illusion that we can continue as we are, certainly not in terms of liquid transportation fuel and thus transport itself, merely by substituting declining oil and natural gas supplies by biofuels. Massive water demand should be anticipated in consequence of expanding biofuel production in other countries too. For example, in India and in the western United States, water tables are falling. As already noted, agriculture in the U.S. Midwest is maintained by draining "fossil water" from the Ogallala aquifer, which underlies eight U.S. states. Once it is used up, this supply of water cannot be replenished. It is likely that climate change and the shifting of the temperate regions to the north may impact further on the American West. In Australia, another major producer of starch crops, water supplies are also under stress. It has been reckoned19 that some 5,000─6000 km3 of water would be needed to irrigate sufficient crop to supplant the world's petroleum based fuel by ethanol generated from corn. We may compare this number with the entire supply of fresh water available on Earth of 13,500 km3 - i.e. the crop would require about half of it. Other potential fuel crops, e.g. wheat, soybeans and rapeseed, have an even greater demand for water than does corn. This is a clear warning and additional expression of the limitations of crop-based biofuels.

The quantity of water that we use in our daily lives is deceptive. For example, an average Briton is said to use 150 litres of water a day, and yet the true total rises nearer 3,400 litres per day68, once the amount of “embedded (embodied) water” (hidden water) is included, which is the water used to grow and produce various products. 65% of the water we use is for our food, and the quantities of embedded water that are used to provide some very commonplace items are staggering. For example, it takes 3,000 litres of water to produce a beefburger, and in Britain some 10 billion burgers are consumed per year, therefore necessitating the consumption of 30 trillion litres, or 30 cubic kilometers (km3) of water. A tomato has about 13 litres of water embedded in it; an apple has about 70 litres; a pint of beer about 170 litres; a glass of milk about 200 litres.

It takes 27,000 litres of water to produce one bar of chocolate, 100 litres of water are used to make one cup of coffee. It takes 4 litres of water to make one one-litre plastic bottle of water… that’s before the water is put into it. To make a cotton T-shirt needs 2,000 litres of water, 15,000 litres for either a pair of jeans, or one kilogram of steak. To make a car takes 400,000 litres68. The amount of water used to produce food and goods imported by developed countries is worsening water shortages in the developing world, and this raises moral questions, e.g. whether it is appropriate for developed (legacy) nations to import beans and flowers from water-stressed countries such as Kenya. If the world's population increases to 8 billion by 2030, 50% more food and energy will be needed, and the demand on fresh water will rise by 30%. This not only reflects the rise in population per se, but that more affluent people eat more food – particularly meat - and the consumer society is expected to expand within its number.

As a result of overpumping (extracting water faster than the natural rate of rainwater recharge) to meet food production demands, some nations have reached a state69 that has been described as “peak water”. To place our demand for water in perspective, although on average we drink around 4 litres of water daily, in various forms, to produce the food we eat requires more like 2,000 litres, and it is the latter which is struggling against available supplies. Almost half the calories we eat is provided by grain, 40% of world supply being grown on irrigated land. The world’s irrigated land area increased from around 250 million acres in 1950 to nearly 700 million acres by the year 2000. However, in the past decade, despite an increasing global population and demand for food, the area of irrigated land has increased by merely 10%, which may mean that we are approaching a maximum in the amount of water that can be provided. The process of irrigation began with the Sumerians some 6,000 years ago, who garnered river water by means of dams and reservoirs.

Gravity-fed tunnels allowed the water to flow onto fields where crops were grown. Once it was no longer possible to expand surface irrigation by this means, water was accessed by drilling boreholes into aquifers, the majority of which were refilled from rainwater. Some aquifers are not refilled, since they contain water that was laid down millions of years ago, sometimes termed “fossil water”. Thus a fossil aquifer is something like an oil well, in that once the water it contains has been withdrawn, it is not replaced, and can similarly be counted as a finite resource. Two of the most important of the latter kind, in terms of global agriculture, are the deep aquifer which lies under the North China Plain, and the Ogallala aquifer which lies under the Great Plains of the United States.

[Fig 13]

The Ogallala aquifer (Figure 13) flows for 174,000 square miles from South Dakota to the Texas panhandle65, and it is the main source of water for the collective national breadbasket, supplying as it does one third of all the groundwater used for irrigation in the entire U.S. Ogallala contains "fossil water", set in the ground from the melt of the last ice-age 10,000 years ago, and once it is used-up there is no more. Access to cheap electric pumps in the 1950's permitted farmers to draw this legacy upward at increasing rates with the result that the Ogallala has fallen by 100 feet in parts of New Mexico, Kansas, Oklahoma and Texas. It is inevitable and merely a matter of time that all wells sunk into this huge aquifer will run dry, with impacts on agriculture overall, including the vast corn crop grown to produce corn ethanol, as a replacement for those fuels currently refined from crude oil. The Aquifer Storage and Recovery (ASR) technology is given especial mention. The idea is that during wet-periods, when water is plentiful, water is pumped into gigantic underground aquifers set deep into Florida's limestone, and which can be pumped-up again during dry months. Some 36 million gallons a day are drawn from Peace River, which starts in Central Florida's Green Swamp and ends 105 miles further south in the Charlotte Harbour Estuary.

There are almost 1,700 ASR wells in the US altogether, most of them in the states of California, Nevada, Texas and Florida, and all of them particularly short of water. However, caution is urged, as the first well sunk at Peace River became seriously contaminated with arsenic, present naturally in the aquifer. Desalination is another technology often invoked as a solution to water shortages especially in near-coastal regions, even though it is very costly to set up a desalination plant in the first place, and running one requires considerable amounts of energy. Nor is the technology guaranteed: e.g. a plant at Tampa Bay built at a cost of $110 million suffered all kinds of difficulties and finally the high-tech membranes required to separate water from salt by reverse-osmosis clogged up. Groundwater pumping was actually reduced by one third in the region, without the need for desalinated water, purely through more conventional means of reservoir and surface water treatment combined with aggressive water-conservation measures65. The tapping of aquifers permitted a greater volume of water to be extracted than was possible from rivers, resulting in an artificial expansion of agriculture and the amount of food that could be grown. Rather as the situation for oil and gas, which fuel agriculture on a scale that would be impossible without them, so water from aquifers has contributed to an artificially maintained food bubble. The UN prediction70 that the global human population will reach nearly 11 billion by 2100, is tacitly underpinned by the assumption that supplies of oil and natural gas, and indeed water, will continue to grow to meet the according demand.

The three major grain producing nations, India, China and the U.S., are overpumping their aquifers, along with several other nations with large populations, e.g. Pakistan, Iran and Mexico. Saudi Arabia, Syria, Iraq and Yemen have each passed their peak in water production, with peak grain following closely behind. 1973 was the year of the first “oil shock”, in which as a show of strength to the West over its support of Israel in the Yom Kippur War, the OPEC countries in the Middle East reduced oil exports by 5%, causing the price of a barrel of oil to increase by 400%14. However, in the realisation that a counter-embargo on grain might be imposed, Saudi Arabia introduced a liberally subsidized agricultural programme underpinned by water pumped from fossil aquifers, becoming self sufficient in wheat. This situation prevailed until 2008 when the Saudis announced that they would cut their planting of wheat by 12.5%/year meaning that in 2016 production would cease.

It is planned that in 2016, food demand in this Kingdom of 30 million people will be met by importing 15 million tonnes of wheat, rice, corn and barley. Currently in the grip of civil war, Syria is becoming dependent on imported grain, since its own production has fallen by a third since the peak production year of 2001, while in Iraq production has plateaued during the past decade. Both Syria and Iraq are experiencing a diminished flow from the rivers Tigris and Euphrates, as more of the water is being taken upstream by Turkey. Thus the restrictive effect of aquifer decline on water supplies is further compounded. The water table in Yemen is falling by around 6 feet each year, meaning that one of the most rapidly growing populations in the world will be dependent on imported grain in only a few years.

Iran has 77 million people (growing by one million per year), but suffered a 10% fall in home grain production during 2007-2012, in correlation with the fall in water production, and since a quarter of its grain depended on aquifer pumping, irrigation wells started to go dry. Thus the Middle East is a singular example where the antagonistic forces of rising populations, inadequate water supplies and policies and falling grain yields are in interplay. Pakistan (182 million) and Mexico are suffering severely from water shortages and aquifer decline. Between them, China, India and the U.S. produce around half the world’s grain, although the relative reliance on irrigation as opposed to other water supplies is quite disparate. China uses irrigation to grow around 80% of its grain, using surface water mostly from the Yellow and Yangtze river systems, while India irrigates some 60% of its grain crop, mostly using groundwater. The figure is nearer 20% in the U.S., since the majority of the grain crop is rain-fed, e.g. in the Midwestern corn belt.

Overpumping has largely depleted the shallow aquifer under the North China Plain, forcing well-drillers to turn to the region's deep aquifer, which is not recharged and is thus a one-off bestowal, which is falling by 10 feet per year. In India, over 21 million irrigation wells have been drilled from which enormous volumes of underground water are being extracted. The Indian population of 1.23 billion is growing by 15% annually, and there are no restrictions on drilling for water. In North Gujarat the water table is falling by 20 feet per year. Given that three fifths of its grain is produced on irrigated land, and a relatively small proportion of the water used for this purpose comes from rivers, it is India that is the most vulnerable to overpumping, since only a minor share of its irrigation water comes from rivers69. We are witnessing a duality, where water is in many regions the principal limiting factor in how much food can be grown, not land area per se. However, soil erosion is the limiting factor in other regions, such as Mongolia and Lesotho, where it has caused a reduction in the area of productive land.

In northwest China and in the Sahelian region of Africa, two enormous dust bowls are being formed, far greater in size that that of the 1930s U.S. Midwest. These conjoined twin forces, of constraining water supplies and soil erosion, are not only militating against an expansion in global food production, but may mean that current food levels will prove non-maintainable. The reliance of modern agriculture upon a cheap and plentiful supply of crude oil - to provide fuel for farm machinery, to transport food from farms and around nations and the world, to make herbicides and pesticides – may prove the weak link, however, should that supply fail for either economic or geo-technical reasons.

18. The relentless soil-water nexus.

In a recent United Nations report71it was stressed that an increasing demand for land and water, from both urban and industrial consumers, and by the farming industry to produce livestock, crops (both for food and other purposes) and also biofuels, is likely to prove unsustainable. It is developing nations that are likely to fare worst, since typically this is where land, soil nutrients and water are most under threat. The world’s cropland grew by only 12% during the period 1961─2009, and yet 150% more food was produced on it, as a result of markedly improved crop yields. However, in many regions, the rates of growth in agricultural production have been in decline and are now just about half of the amount at the zenith of the ‘Green Revolution’, which occurred during the Second World War and on through to the late 1970s. The latter was a consequence of the application of synthetic fertilizers on the large scale, irrigation and the selection of particular strains, e.g. of rice and wheat, that could thus be brought to high yields. The report concludes that of the Earth’s land surface, one quarter is highly degraded, 8% is “moderately” degraded, 36% is “stable” while 10% is “improving”. 18% of the Earth’s land surface is bare and 2% is covered by bodies of water. Worst affected regions are along the west coast of the Americas, across the Mediterranean region of Southern Europe and North Africa, the Sahel and the Horn of Africa, and throughout Asia. Loss of soil quality, loss of biodiversity and the depletion of water resources are all highlighted, hence a quite comprehensive problem needs to be addressed.

The impact on water resources is worsened by practices of continuous cropping72, and the amount of soil-water sets a maximum to crop productivity in rain-fed, semi-arid regions. To cope with limitations in the supply of water requires that particular management practices are employed during those stages of development that are crucial determinants of the eventual yield, e.g. floral and grain development. For example, in western Kansas following a fallow time of almost one year, even though drought conditions had prevailed, a sustained output of winter wheat was obtained, in contrast to wheat that had been grown in water-depleted soil, rather than leaving it fallow. The fallow period is often used to grow oilseed crops like canola (rapeseed). In a study by workers at Kansas State University, wheat was grown in sequences of three years, including: a wheat phase; corn or grain sorghum after wheat; then either a fallow period or a replacement crop of spring canola, soybean or sunflower. It was found that, relative to water use, continuous cropping resulted in a smaller crop yield by 18%, reduced the grain productivity by 31%; and reduced the net economic returns for the wheat crop by 56%. Reductions in these parameters were also observed when an oilseed crop was grown rather than having a fallow period.

Thus it is clear that deficits in soil-water deficits, when extreme, can have an adverse influence on grain yield formation, and more severely than on the overall biomass productivity. When such processes as floral development are impaired, the yield may be reduced by “sink strength” (the number of developing grains), in addition to “source strength” (canopy productivity). It is thought that these conclusions are general and should also pertain for crop productivity in those areas that are normally water-sufficient when they are subject to drought. It is further predicted that drought conditions will prevail more frequently and more severely, under the influence of climate change, which will amplify the oscillations of weather patterns. Research continues to identify crops, including wild varieties of the major species grown, that can maintain their yields under conditions of low water and higher temperatures, and that by introducing stress tolerance traits into productive crop cultivars, cropping systems may remain resilient to future climatic and environmental impacts.