Since the dawn of agriculture, somewhere around 10,000BCE, humanity has grappled with the vitally important challenge of making food cultivation sustainable. The question has always been whether the key resources of soil, water and soil nutrients are being replenished as fast as they are being depleted or whether they are becoming increasingly scarce.
With a few exceptions, such as terrace farming in Asia, the report card from around the world has been fairly poor. Unsustainable agriculture practices over the long term may have significantly contributed to the decline of major civilisations including the Egyptians, Romans and Mayans.
During the last century, Western countries abandoned traditional growing techniques in favour of a mechanised, chemical-centred approach involving inorganic fertilisers and toxic pesticides. Dominated by such broadscale systems, modern agriculture has been unfavourably described by the ecological economist Paul Hawken as the most environmentally damaging human activity taking place on the planet. Its impacts are ubiquitous due to the vast scale at which it is practised.
However, with increasing awareness of the shortcomings within the mainstream model, the world is seeing an upsurge in biologically orientated organic farming. Even more common in Australia is the introduction of more sustainable practices to farms, often as a reaction to the drought.
It is widely accepted that the European style of agriculture transplanted into Australia is not ideally suited to the unique conditions of the world’s driest inhabited continent. Largely export-driven, Australian agriculture is fundamentally at odds with the constraints of the landscape, particularly its limited water resources. Soils are older and less fertile and the land is relatively flat, creating a challenge for successful drainage that avoids the problem of soil waterlogging and consequent salinity.
Identifying the issues
The wide spectrum of interlocking challenges associated with agriculture in Australia and New Zealand include:
- A long-term trend towards depopulation of rural farming areas. The merger of family farms into larger properties, with the corporate sector assuming a growing role.
- The risk of threats to future food production levels from rising fuel prices and the prospect of world oil production peaking by the end of the decade.
- Continuing drought conditions, a huge drop in rice and wheat production and the drying up of the Murray Darling Basin. In response, crops can be selected to reflect water availability, with hemp an environmentally sound alternative to water-thirsty cotton. As alternatives to older-style wasteful surface irrigation, far more water-efficient drip, microjet or sprinkler irrigation techniques are available.
- Grazing animals in arid areas during drought and the challenge of managing stocking densities.
- Large-scale monocultures, which often lead to a loss of biodiversity among fauna and flora and tend to attract pest attack.
- Pesticide use, which has been associated with biodiversity loss, human health impacts and groundwater contamination in certain areas. Alternatives include biological pest control (attracting beneficial insects), crop rotation and integrated pest management (IPM) which employs a diverse armoury of pest-reduction strategies.
- Chemical fertilisers that emit the greenhouse gas nitrous oxide are linked to nutrient runoff into waterways.
- The widespread cultivation of genetically modified cotton, recently joined by some GM canola in New South Wales and Victoria.
- Soil erosion via wind and water, worsened by excessive tillage, leading to the silting of waterways and estuaries. It is minimised through retaining native vegetation, not cultivating in areas vulnerable to erosion, reducing grazing pressure and employing low-till techniques.
- Dryland salinity. Occurring on land not subject to irrigation, this is caused by the clearing of trees and other deep-rooted native vegetation in favour of short-rooted crops, leading to the upward movement of salt-laden groundwater. It can be countered by the planting of salt-resistant tree species.
Searching for solutions
Whereas in the past, farming was treated as a reductionist activity in which each element was dealt with separately, there is a new trend towards regarding an entire farm as a holistic system. Under this model, attention is paid to the relationships between all the diverse elements. By maximising the recycling of nutrients on site, the requirement for outside inputs can be significantly reduced.
Agroforestry is a way of incorporating trees and shrubs into farming and may involve shelterbelts to reduce the effects of cold and heat stress on crops. Providing shade trees for animals is known to increase yields of both meat and milk by around 15—30 per cent. Following such an approach, biodiversity is enhanced, salinity can be reversed and mature farm trees harvested for their timber.
Polycultures, which are suited to smaller acreages, may involve the use of beneficial weeds or the growing of more than one crop in the same area via companion planting. Imitating natural ecosystems, polycultures are naturally more biodiverse and resilient to environmental stress. Yields are often boosted and far fewer pesticides required.
A range other sustainable strategies, some familiar and others less well known, are available to the farming community.
Organic and biodynamic
When the world shifted towards chemical-based farming in the first half of the 20th century, this move was not universally accepted. Some dissenting landholders adhered to a set of biological techniques that later came to be known as “organic”. Once dismissed by the mainstream as nonsense, they have become increasingly recognised as an important solution to the range of urgent environmental problems we now face.
Avoiding chemical fertiliser inputs and pesticide applications, coupled with a greater emphasis on manual labour in place of machinery, organic farming is significantly less energy intensive. Under organic regimes, an increased production of humus leads to increased fertility, improved yield and higher moisture retention. Soil erosion is minimised and tests have confirmed the nutritional quality of food is higher.
Biodynamic farming, which was developed by Rudolf Steiner shortly after the First World War and predates the organic movement, is seen by its adherents as a more sophisticated form of organics. Utilising a range of specific preparations that are often made on site, it is more in tune with lunar cycles and the influence of cosmic energies.
Healthy biodynamic soil is a rich, chocolaty-looking substance. Its dark colour indicates the presence of high nutrient concentrations. Home to an impressive range of biodiversity, it holds a large percentage of its own weight in water and is very drought resistant.
Natural sequence farming
Natural sequence farming (NSF) was developed 30 years ago by a farmer named Peter Andrews on an Upper Hunter racehorse-breeding property named Tarwyn Park. Running counter to existing wisdom, it was ignored for decades despite tenacious attempts to interest agricultural decision-makers.
Probably the most important feature of NSF is the slowing down of water movement, especially after rain events. This prevents nutrients from being lost off site via erosion and instead replenishes ground-water levels. To achieve this water retention, Andrews followed an unconventional approach involving the strategic placement of rocks, logs, reeds, willows and weeds.
On many farms, a combination of hooves and unsustainable farming techniques has turned waterways into gullies that allow the fast passage of water. Andrews has re-created the chains of ponds found on natural floodplains by rebuilding these eroded stream beds back up to their original height.
Relocating grazing animals at night from the valley floor to higher ground results in the transfer of fertility to the valley sides, from where it slowly migrates downhill. This encourages plant growth and, although some of these species are normally labelled as weeds, they can provide the important benefits of storing nutrients and preventing erosion. In turn, these weeds are slashed, later to be succeeded by useful grasses.
Tarwyn Park manages to function without either irrigation or chemical use. Andrews believes NSF, if applied on a huge scale, could reverse the degradation of Australia’s landscape, combating salinity, soil erosion and drought. Irrigation water extraction in the Murray Darling Basin could be minimised, thereby increasing natural flows.
Carbon farming
As debate around climate change has intensified, the issue of the soil’s carbon content has come to the fore. Soils hold an incredible 82 per cent of all terrestrial carbon and there is enormous scope for them to them to absorb carbon emissions currently in the atmosphere. This “carbon-negativity” would help reverse climate change.
Where feasible, absorbing these emissions into the environment (also known as biosequestration) is obviously a better outcome than unproven and expensive underground geosequestration of carbon from coal-fired power stations. In addition to its climate benefits, carbon farming would also improve soil health, reduce erosion and combat salinity.
Specific practices for maximising soil carbon levels include minimum tillage, regenerative grazing and revegetation using perennial grasses. Pasture has the advantage of sequestering more carbon than an equivalent area of forest, which will require around 10 years to reach its maximum carbon sequestration; in the opinion of many climate experts, this will be too late to decisively tackle climate change.
An Australian group called the Carbon Coalition against Global Warming is calling for a major shift in direction, whereby farmers switch to growing the perennial deep-rooted grass species which the Carbon Coalition sees as the most effective way to lock up carbon in the soil. Such a move would obviously require financial incentives.
Champions of soil carbon strongly favour its inclusion in Australia’s Carbon Pollution Reduction Scheme (CPRS), due to commence in 2010. Ross Garnaut, the government’s senior climate advisor, believes soil carbon needs to be incorporated into the scheme. However, it was recently revealed agriculture will not be included in the CPRS until 2015 at the earliest, with a decision to be made in 2013.
In New Zealand, agriculture is currently expected to join that country’s newly launched emissions trading scheme in 2013. An online calculator is already available that enables farmers to estimate their emissions.
One voluntary alternative is an offsetting-style carbon trading scheme known as Australian Farm Soil Credits, launched by the group Carbon Farmers of Australia. Under this program, soil carbon levels are indirectly estimated through changes in land management whose effects on soil carbon can be predicted with reasonable accuracy.
Biochar
Another rapidly emerging carbon-negative solution to the climate crisis is a fine-grained charcoal known as biochar, also known as agrichar or terra preta (Spanish for “dark earth”). Biochar is usually produced by pyrolysis, a low-temperature combustion in an oxygen-free environment that ensures no carbon is released. Pyrolysis byproducts include oils and methane gas, both of which can be sold as renewable fuels or fed back to power the whole process.
The presence of this soil carbon-rich material has been identified in large areas of the Amazon basin, totalling thousands of square kilometres and believed to have been deposited through the agricultural practices of early indigenous peoples. Terra preta is incredibly stable, remaining in the soil for hundreds or even thousands of years. In comparison, only a fraction of regular organic matter decomposing on the soil turns into soil carbon, and in a less permanent form.
Beyond greatly boosting soil fertility and minimising fertiliser requirements, the addition of biochar improves moisture retention and has been found to reduce soil emissions of the two greenhouse gases methane and nitrous oxide by 50—80 per cent. Being pH-neutral or alkaline, biochar is most beneficial when added to acid soils, especially if these are characterised by low organic matter and high aluminium levels.
For maximum sustainability, crop residues such as wheat straw make ideal biochar feedstock alternatives to timber. In tropical areas, slash-and-burn agriculture could be transformed into a carbon-friendly and fertility-enhancing practice of “slash and char”. Problem agricultural wastes such as dairy and chicken manure are another alternative and their conversion to biochar has the added benefit of preventing methane releases.
Encouragingly, in 2007 a couple of biochar research professorships were announced for Massey University in New Zealand. One of these will look at the behaviour of biochar in New Zealand soils while the other will focus on the production of biochar from biomass using pyrolysis.
Small is beautiful
In 2006, a remarkable and under-publicised study from Turkey showed that farms under one hectare in size are on average 20 times more productive per unit area than those of more than 10 hectares. This heretical observation, which overturns an edifice of received wisdom, has been confirmed by other studies from around the world.
While we are fed the message that larger acreages and increased mechanisation are the paths to agricultural efficiency, it seems that in fact the opposite is true: the best chance we have of feeding the world in a low-oil future is through more labour-intensive micro-size farms rather than by embracing genetic modification or other corporate cure-alls.
Last year, the intergovernmental agricultural survey group IAASTD put out a report calling for a major change in the world’s agricultural priorities. The report encourages a focus on small-scale farmers operating in diverse ecosystems and urges governments to adopt a more holistic attitude towards agriculture.
Such a view is shared by Australia’s CSIRO. It is calling for a major rethink, involving a shift away from large monocultures to a “mosaic” of different crops and animals, all suited to local conditions.
Garnaut’s verdict
In October 2008, Professor Ross Garnaut issued his final climate-change report, which contains some interesting agricultural proposals.
More than half of Australia’s agricultural greenhouse emissions come from sheep and cattle belching methane and for this reason Garnaut foresees the emissions trading scheme driving a shift away from the production of beef and lamb in favour of chicken and pork. Kangaroos produce almost zero emissions and he also anticipates a large increase in their population, farmed for their meat in place of cattle.
In Garnaut’s evaluation, the mulga (acacia savannah or shrubland) country of the outback is capable of absorbing at least half of Australia’s annual emissions through biosequestration. Furthermore, he expects landholders in this region will soon be earning vastly more from land restoration than from farming activities.
