Soil resilience refers to the ability of a

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...

to resist or recover their healthy state in response to destabilising influences. This is a subset of a notion of '' environmental resilience''.

Overview

Soil resilience should first be looked at in terms of soil formation and development ( pedogenesis), a continuous process taking thousands of years – this puts into context the short time that humans have so extensively utilised, changed and depended directly on soil. Pedogenesis is the result of five factors: the first two are parent material and topography, which are passive and contribute to soil mass and position; the next two are

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologic ...

and the biosphere, which are active and supply the energy in soil formation. Finally, there is time. It is the active factors in soil formation that vary so as to constitute an environmental change or shock. Over time, variations have been significant: *Over millions of years the soil has endured varying atmospheric conditions including a complete absence of

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

and associated behaviour of soil elements in a reducing environment, and the establishment of life – particularly of terrestrial vegetation 420 million years ago. *Over ten thousand years and following the last

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...

, though average climate has remained relatively stable, the soil has faced periods of extended wet, dry and fire. If soil were not resilient, then in the face of past influences it would not be in any condition to support the natural and commercial services that we expect of it currently. So what do we expect of soil resilience? *Constant or evolving state? – Do we expect that the soil to remain constant – to continue to provide the same

environmental A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...

and commercial services as at present, or; that it will establish a new equilibrium? *How long will it take? – How long do we expect soils to ‘hold out’ or adjust, and are we realistic about pedological time?

Australian context

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, the above questions are relevant given the strong dependence on the soil, yet the significant degradation of soils over little more than 200 years due to adoption of European styled

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to ...

. This is in the context of the real prospect of

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

, cyclical drought and other degrading affects. It is in the interest of humans to sustain soils as this is the essence of our existence: the maintenance of fertile soil is "one of the most vital ecological services the living world performs"; the "mineral and organic contents of soil must be replenished constantly as plants consume soil elements and pass them up the food chain". It is claimed by Watson (1992) that the

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

s of Australia, which have evolved over millennia, have been decimated over the last 200 years. Our expectation has been one of ongoing environmental and commercial service, yet the practices applied have been unsustainable and have led to such soil related problems as salinity, acidity, nutrient decline, erosion and structure decline. Barrow (1991) claims that despite decades of humans talking of an impending environmental crisis, including the breaking point of our soils' fertility, threats to the environment have continued to grow faster than the willingness to control them. Even with good intentions and best

farming Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to ...

practices, still we are caught out by drought and wet periods, which cause unsustainable degradation.Barrow, CJ 1991, Land Degradation, Cambridge University Press, Cambridge The pressure that we impose on the soil in terms of biosphere (direct human impacts included) and climate constitute environmental change – the rate of this change compared to other changes over pedological time constitutes a shock. The resilience of the soil is limited by the rate and extent of change we impose compared with the time that soil requires to recover.

Conclusion

Soils are resilient to environmental changes and shocks – that is, they will recover from or adjust to change if sufficient 'pedological' time is allowed. The soil management practices that have been applied by humans in a short time frame are unsustainable – a declining soil health threatens human livelihood. The resilience of the soil in terms of human expectations and time frames will depend on its ability to recover to an equilibrium state once improved practices have been extensively applied.

References

{{Natural resources Land management Resilience Soil science

Overview

Australian context

Conclusion

See also

References