Intensive Crop Culture for High Population
is Unsustainable

PETER SALONIUS / Culture Change 10feb2008

Editor's note: The following essay by soil scientist Peter Salonius is Part One of his two-part series for Culture Change that bursts the delusion of agriculture's providing for a large human population long-term. If after reading it you have doubt, read the scientific basis for it: the second part in the series, "Unsustainable soil mining, past, present and future." (A version of the second part was published in the May/June,2007 issue of The Forestry Chronicle.) The author lives in New Brunswick, and he published in Culture Change in 2003 "Energy tax made easy: Modifying human excess with international non-renewable energy taxation" (see link at bottom). - JL

A growing number of media commentators, such as Allen Greer in The Australian, John Gray in the Guardian’s Observer and Alan Weisman in his book "The World Without Us," have begun to suggest that a world with fewer people would be far better placed to deal with climate change and the exhaustion of the dirty fuels of the industrial past. Many of them appear to think that high technologies such as nuclear energy and Genetically Modified crops in combination with curbs on population would begin dampen the environmental disruption that is becoming increasingly obvious.

However, the problem, as I have come to understand it, is even more serious than that visualized by these thoughtful individuals who are convinced that the neoclassical economic model of open-ended expansion and "so-called sustainable growth" is a recipe for disaster.

As we run up against all of the renewable and non-renewable resource depletions (Peak Oil, Peak Soil, Peak Minerals, etc.) that will characterize the foreseeable future, we require an entire rethink as to how we do business, due to the fact that the human enterprise has been living on borrowed time for millennia.

After 44 years of research and thinking about agricultural cultivation and silviculture, I have reluctantly been forced (I am a passionate farmer/gardener) to conclude that:

INTENSIVE CROP CULTURE IS UNSUSTAINABLE

Humanity has been in overshoot of the Earth's carrying capacity since it abandoned hunting and gathering in favor of crop cultivation (~ 8,000 BC) and it has been running up its ecological debt since then.

William Rees and Mathis Wackernagel originated the idea of the Ecological Footprint and they appear to believe (lots of publications) that the global human family overshot global carrying capacity sometime in the 20th century. Trying to get a perfect measure of overshoot is tantamount to "fiddling as Rome burns." We know we are in serious overshoot and we know that the total human footprint (whatever enormity it is) must get smaller.

I am convinced that we begin unsustainable resource depletion (overshoot) as soon as we use (and become dependent upon) the first unit of any non-renewable resource or renewable resource used unsustainably whose further use becomes essential to the functioning of society, such as:

THE FIRST TONNE OF COAL
THE FIRST LITRE OF OIL
THE FIRST KILOGRAM OF FISSIONABLE URANIUM
THE FIRST BARREL OF FOSSIL WATER FOR IRRIGATION -- and
THE FIRST HECTARE OF FORMERLY NUTRIENT CONSERVATIVE NATIVE FOREST or
GRASSLAND/PRAIRIE PLOWED

This last category of unsustainable renewable resource depletion (excessive leaching/export of plant nutrients from arable soils associated with most agricultural practice, and more recently also with harvesting of nutrient-rich forest biomass) has been looming over us, unseen, for 10,000 years. We can expect that it will catch up with us shortly because most of us are dependent on foodstuffs produced by unsustainable farming, and fiber produced by unsustainable forestry. Recent visions, such as that put forward by the Post Carbon Institute's Relocalization program, of a fabric of local food and biofuel systems, revitalization of local industry, and community cooperation are good first steps that recognize global trade will wane as fossil fuel depletion gains momentum. They are also an attempt to wean humanity off industrial food production that treats soil as a medium for fertilizer-dependent hydroponic agriculture, and simply a substrate to stand plants up in. These are people who are interested in popularizing organic agriculture, solar powered tractors etc. that will make local economies more self-sufficient.

HOWEVER, these alterations are still tied to AGRICULTURE as a food production system -- as they must be in the short term.

All agriculture depends on the replacement of complex, species diverse, self-managing, nutrient conservative, natural grassland/prairie and forest ecosystems with monocultures or "near monocultures" of food crop plants that rely on intensive management. The simple shallow rooting habit of food crops and the requirement for bare soil cultivation produces soil erosion and plant nutrient loss far above the levels that can be replaced by microbial nitrogen fixation, accumulation of volcanic dust, and the weathering of minerals (rocks and course fragments) into active soils and plant-available soluble nutrients such as potassium, phosphorus, calcium, and magnesium.

Under regimes dominated by complex, species-diverse, self-managing, nutrient-conservative, natural grassland/prairie and forest ecosystems, erosion rates of soil mass are minimal, and the diverse and deep structure of the below-ground rooting community, and its microbial associates, makes the escape of plant nutrients entrained in downward-moving drainage (leaching) water to the ocean very difficult.

Our ultimate goal, as we attempt to achieve a sustainable human culture on Earth, must be to move toward the sustainable exploitation of complex, species-diverse, self-managing, nutrient-conservative, natural grassland/prairie and forest ecosystems at rates that do not cause the loss of physical soil mass or plant nutrient capital any faster than they can be replaced by biological and weathering processes.

Obviously, as we move back toward a solar-energy dependent natural economy, we will no longer be able to run the massive ecological deficits that temporary fossil and nuclear fuel availability have allowed.

Just as obviously the "solar-energy dependent economy" will not support the human numbers that have been able to exponentially increase slowly as a result of agricultural mining of soil nutrient stores for the last 10,000 years, and rapidly because of the availability of non-renewable fossil and nuclear energy subsidies during the last 250 years.

In order to lower the human population to levels supportable by sustainable exploitation of complex, species-diverse, self-managing, nutrient-conservative, natural grassland/prairie and forest ecosystems we must begin to reestablish these natural ecosystems on lands that have historically been increasingly devoted to intensive cultivation during our agricultural past.

The best suggestion so far to produce Rapid population Decline (RPD) is for the collective global human family to adopt a One Child Per Family (OCPF) "modus operandi/philosophy." Even with general acceptance of RPD and OCPF, the human population decrease that is necessary to achieve a sustainable solar energy-dependent culture, will take several centuries.

As human numbers are contracting/shrinking under a OCPF/RPD scenario, the extant population will insist on being properly nourished -- and the only way we can produce enough food for them is by agricultural means that will further deplete the arable soils on the planet.

During the centuries of transition, as we move toward a solar-dependent culture that again sustainably exploits complex, species-diverse, self-managing, nutrient-conservative, natural grassland/prairie and forest ecosystems, we should be exercising as responsible an agriculture as possible on the shrinking arable land-base upon which it is still practiced. During this transition, the growing portion of the arable land base that is abandoned will rapidly revert toward natural grassland/prairie and forest ecosystems as soon as we cease cultivating it.

February 10, 2008

Read Peter Salonius's idea for cutting back on fossil energy consumption, using what he calls a market alternative to rationing Energy tax made easy: "Energy tax made easy: Modifying human excess with international non-renewable energy taxation" culturechange.org/energy_tax.html

source: 11feb2008

Part Two

ABSTRACT

Human settlement has increased food production by progressively converting complex, self-managing natural ecosystems with tight nutrient cycles into simplified, intensively managed agricultural ecosystems that are subject to nutrient leaching. (Most agriculture is unsustainable in the long term.)

Conventional stem wood forest harvesting is now poised to be replaced by intensive harvesting of biomass to substitute for increasingly scarce non-renewable fossil fuels. Removal of nutrient-rich forest biomass (harvesting of slash) can not be sustained in the long term.

[Key Words: soil nutrient depletion, biomass harvesting, site productivity]

Introduction

A general discussion of the concept of sustainability was presented by Gatto (1995), who suggested that notions of sustainability "reflect different priorities and optimization criteria, which are notoriously subjective"; however, the goal of maintaining soil-productive capacity is not a subjective notion. In this paper I will show that long term sustainable terrestrial carrying capacity depends on the maintenance of self-managing, nutrient-conservative plant communities.

The dynamic cyclical stability of complex ecosystems has been shown, for most animal populations, to depend on the ability of predators to dampen overshoot and runaway consumption dynamics of prey species (Rooney et al, 2006).

Predators, parasites and diseases deplete very high herbivore populations, that have already encountered Malthusian constraints (Royama 1992), before they produce extreme devastation of the plant ecosystems upon which they depend. In the absence of top predators, very high animal populations can degrade the biological diversity, carrying capacity and biological productivity of their environments (Terborgh et al. 2001).

There have not been top predators able to keep humans from overshoot of carrying capacity. Before the advent of agriculture, human populations used culturally mediated behavior like extended infant suckling, abortifactants and infanticide to limit their fertility, to keep their numbers far below carrying capacity, and to avoid Malthusian constraints like starvation (Read and LeBlanc 2003). Warfare between groups competing for the same resources, before the evolution of states, also appears have been a significant constraint on the growth of human numbers (Keeley 1996).

After the advent of agriculture, mortality rates, caused by conflict, decreased somewhat as local raiding by chiefdoms evolved into long-distance territorial conquest by states that developed complex patterns of authority delegation (Spencer 2003). These cultural and conflict behaviors, that limited human population growth, served to maintain balance between humans and other species during most of the historical record. Read and Leblanc (2003) suggest that hunter-gatherers, in areas of low resource density, tend to maintain generally stable populations, while high resource density, such as that produced by agriculture, decreases the spacing of births more rapidly than the increase in resource density which results in repeating cycles of carrying capacity overshoot and population collapse. While Boserup (2005), maintained that agricultural production was necessitated by the pressure of population increase, others suggest that the advent of agriculture allowed human carrying capacity to increase by increasing the access to and consistency of food supplies (Younquist 1999, Hopfenberg and Pimentel 2001, Abernethy 2002). However, as most agriculture is a soil-nutrient-depleting practice, this carrying capacity increase is unsustainable in the absence of exogenous (imported) nutrient supplies.

Carrying capacity of terrestrial ecosystems is hinged, in the long term, on the supply of nutrients for plant growth. Only the hunter-gatherer culture appears to have been sustainable because human numbers were controlled by the productivity limits of self-managed, nutrient-conserving forest and grassland (prairie) ecosystems (Manning 2004).

Intensive forest clearing begins in Europe

Human numbers increased slowly until massive forest clearing and plowing for agriculture, in Western Europe 1,000 years ago, increased food production enough to fuel much more rapid population growth; this assault on forests spread as European empires colonized the rest of the globe (Williams 2006). The exponential increase of human numbers during the last millennium has been relentless, although the elimination of one third of the people between India and Iceland in the 1300s, as a result of Bubonic Plague, did produce a very small dip in the growth curve before its inexorable increase resumed within a century (Stanton 2003).

The scarcity of forest land for agricultural clearing and the nutrient depletion of farmed soils have produced brakes on local population growth at various times during the last 10,000 years. When soil productivity was seriously diminished by agriculture in a particular area and/or population numbers exceeded local carrying capacity, the propensity of humans to migrate came into play as new forest lands were cleared and cultivated (Manning 2004, Williams 2006). Agriculture has mined soil carbon and available soil nutrients (by export and leaching, as well as by physical soil mass by erosion) to produce increasing amounts of foodstuffs and the growing number of people who depend on them.

Recent population growth

Just at the time that most of the earth had been submitted to human patch disturbance, forest depletion and the unsustainable practice of farming, finite fossil fuels allowed geological energy to replace wood fuel, draft animal power and to facilitate the mining, chemical synthesis and long distance transport of fertilizer nutrients to replace those removed by soil depleting agriculture. Albert Bartlett (1978) has said that "modern agriculture is the use of land to convert petroleum into food."

The six-fold population growth, from 1750 to the present, was facilitated by augmenting limited solar energy with massive amounts of temporarily available, geologically stored non-renewable fossil and nuclear fuels. As these fuel sources are exhausted during the next century, we can anticipate the replacement of population growth with energy-depletion-orchestrated economic and population shrinkage (Campbell 2002, Salonius 2005). Humans have far outstripped any equilibrium levels as they have usurped the living space of almost all other species on earth, and completely eliminated many of them. Humans have degraded the productive capacity of most of the ecosystems on the planet and are now proceeding to make more alterations to the atmosphere than have been experienced naturally in the last 600,000 years (Brook 2005) by burning fossil fuels and clearing forests.

Unsustainable exploitation

Among natural resource exploitative industries, forest harvesting and ocean fisheries offered the best possibility for long-term sustainability. Currently, as the the marine food chain has been fished down and the ability of the oceans to absorb pollutants has been compromised, marine productivity of food that is useful to humans has been, at least temporarily, diminished.

There have been episodes of forest foliage and litter collection to augment depleted fertility levels on agricultural lands, in the period before non-renewable- energy dependent mining, chemical synthesis and long-distance transport of fertilizers made such collections unnecessary. However, most forest harvesting, not associated with land clearing for agriculture, has been confined to the removal of tree stems. Nutrient-rich braches and foliage (slash) were not removed from harvesting sites. This appears to have been sustainable, if harvest openings were sized to approximate natural disturbance dynamics, at least as concerns the maintenance of soil nutrients for plant growth, even though biodiversity and forest ecosystem stability appear to have been compromised in many cases by unnaturally large harvest openings (Perera et al. 2004, Salonius, 2007).

Impending energy scarcity, exacerbated by continuing human population growth, is influencing the forest industry to consider high-nutrient slash (foliage, and fine branches with large bark/wood ratios from forest-harvesting operations as a source of biomass energy. Removal of this material will deplete the nutrient capital of forest soils and degrade their productive capacity (Sterba 1988, Rolff and Agren 1999, Dzwonko and Gawronski 2002, Jandl et al. 2002, Merganicova et al. 2005).

Policy implications for forestry

Whole tree harvesting, with delimbing at roadside, has been found to lower harvesting costs in comparison to methods that remove only stem wood (Meek and Cormier 2004). Land managers have allowed this wasteful practice, which previously necessitated burning (disposal of) piled harvesting (slash) at roadside to reduce the fire hazard caused by it. The value of this (roadside) waste material is increasing in concert with developing markets for biomass energy. A return to harvesting methods that remove only stem wood will not occur without regulations designed to conserve plant nutrients and maintain long-term site productivity.

Crown land managers in several Canadian provinces are presently attempting to assess the proportion of harvesting slash that can be safely removed according to the nutrient status of individual forest sites. As the pressure to make very large harvest openings and remove smaller tree parts (nutrient rich branches and foliage) increases in response to the demand for forest biomass energy, even forest harvesting is becoming an unsustainable soil nutrient mining practice similar to agriculture because of the depletion of soil nutrients and the consequent erosion of long-term productivity.

Scarcity of conventional energy sources will develop during the next forest rotation (Salonius 2005), and pulp and paper production is shifting to countries with lower production costs. Decisions must be made as to what proportions of the stem wood harvest are to be used for pulp and paper, lumber or biomass energy and as a source of industrial chemicals. Wood is becoming the new petroleum and a source of carbon-carbon bonds previously obtained exclusively from fossil fuels. Wood can be a renewable resource if harvested responsibly, however each unit of wood can only be used once. Decisions are required as to whether to produce wealth by the sale of forest products to distant markets or whether some of the harvest, that historically has been directed to commodity markets, is to be used locally for the production of organic chemicals, liquid biofuels and cogeneration of heat and electricity.

Long-term constraints on growth are necessary

Malthus predicted that agricultural production increases would not be able to meet the requirements of a steadily growing human population. However he was not aware that the depletion of soils by the agriculture, that was feeding less than one billion humans in the 1700s, was already unsustainable in the long term. Malthus could not have conceived of the temporary increase of carrying capacity and food production that would be made possible by the use of non-renewable fossil and nuclear fuels during period after his death. The abandonment of the effective controls on human birth rates exercised by pre-agricultural societies and the decrease in mortality by warfare that followed the evolution of states have allowed the exponential expansion of human numbers to be fueled by increased availability of food. This expanded human population now sees nutrient-rich forest biomass as a partial substitute for declining supplies of geologically stored fossil fuels.

The long-term solution to the natural resource demand/supply mismatch requires a gradual, planned shrinkage of human numbers [Alpert 2007] as opposed to continually attempting to meet the nutritional and energy needs of an expanding population.

Summary and conclusions

Humanity must understand that, in the absence of effective natural or cultural controls on its numbers, population limits should be established by mutual social consent to avoid the overshoot of long-term carrying capacity. Homo sapiens, the species with the large brain, and the capacity to foresee future consequences, has not collectively understood the need for the control of its fecundity.

* * * * *

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source: 11feb2008