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NUTRIDATE

Volume 31, Issue 3 2020

NUTRIDATE

Volume 31, Issue 3 2020

SUSTAINABLE AGRICULTURE

Manuela Callari, PhD, Science and Medical Writer

Over the past few decades, agriculture has changed dramatically. New technologies, mechanisation and increased use of fertilisers and pesticides have made food more abundant and affordable. But what is the cost of such efficiency?

Intensive agriculture has a high ecological, economic and social impact. It leads to topsoil depletion, groundwater contamination, air pollution, greenhouse gas emissions and animal exploitation. It has also caused a decline in family farms in favour of big corporations, and has profound impacts on the living and working conditions of farm labourers. Added to that, intensive agriculture represents a threat to human health and safety, contributing to the spread of new pathogens such as the recent coronavirus outbreak.

Figure 1: Modern, intensive agricultural practices are damaging and unsustainable.

Sustainable agriculture, therefore, integrates three main goals – environmental health, economic profitability, and social equity. It means to meet the needs of the present without compromising future generations’ ability to meet their own needs.

What is sustainable agriculture?

The word “sustain” comes from the Latin sustinere: sus- means “from below” and tenere means “to hold”. It means to keep in existence or maintain. It implies long-term support or permanence. When talking about sustainable agriculture, we refer to farming systems that can maintain their productivity and usefulness to society indefinitely. Such systems must be resource-conserving, socially supportive, commercially competitive and environmentally sound.

The common thread among sustainable agriculture methods is to mimic natural ecological processes. In a sustainable agricultural practice, farmers minimise tilling and water use, encourage healthy soil by planting fields with different crops year after year and integrate croplands with livestock grazing. They avoid pesticide use by nurturing the presence of organisms that control pests.

Beyond growing food, the philosophy of sustainability supports fair treatment of farmworkers and food pricing that provides farmers with a liveable income.

Figure 2: Crop diversification helps mitigate environmental impacts of agriculture.

Our resources aren’t unlimited

Figure 3: Agriculture uses 90% of the world’s increasingly precious water resources.

Agriculture uses 90% of the world’s water. In many parts of the world, including Australia, water is a scarce resource, and its quality is deteriorating.

Increasing salinisation, nutrient overloads and pesticide contamination are degrading water quality. To tackle this problem, scientists are selecting and breeding crop species that better tolerate droughts and saline water and studying ways to improve the soil to reduce water loss.

Loss of water supplies not only disrupts the environment, but it also threatens future irrigation capacity. In a recent study, researchers from the University of California found that half of the irrigated land that provides food for 1.3 billion people globally is unsustainable and depletes groundwater. But they also found that by using sustainable irrigation practices, we could feed 800 million more people without the need for deforestation and cropland expansion into pristine habitats.

Modern agriculture also heavily depends on non-renewable energy sources, especially petroleum. But the use of non-renewable sources is not sustainable in the long run. A shift to sustainable agriculture implies a conversion from non-renewable energy to renewable sources such as hydraulic, solar and wind power, biofuels from agricultural waste and animal labour.

Also, modern agriculture relies heavily on chemical fertilisers such as phosphates. These minerals are currently mined, but global reserves can only sustain food production for another 50 to 100 years. Unless new reserves are discovered, and innovations in the recovery of phosphates from waste are developed, they will soon be too scarce to sustain the current agriculture systems.

Alternatively, sustainable agriculture practices aim to reconnect the agrosystem to the natural cycle of nature to reuse nutrients. Nutrient recycling is facilitated by diversified agriculture that integrates livestock and crop production. Rotating crops with legumes, for instance, enriches soil with nitrogen, avoiding the need for environmentally harmful fertilisers.

Agriculture uses 90% of the world’s water. In many parts of the world, including Australia, water is a scarce resource, and its quality is deteriorating.

Increasing salinisation, nutrient overloads and pesticide contamination are degrading water quality. To tackle this problem, scientists are selecting and breeding crop species that better tolerate droughts and saline water and studying ways to improve the soil to reduce water loss.

Loss of water supplies not only disrupts the environment, but it also threatens future irrigation capacity. In a recent study, researchers from the University of California found that half of the irrigated land that provides food for 1.3 billion people globally is unsustainable and depletes groundwater. But they also found that by using sustainable irrigation practices, we could feed 800 million more people without the need for deforestation and cropland expansion into pristine habitats. Modern agriculture also heavily depends on non-renewable energy sources, especially petroleum. But the use of non-renewable sources is not sustainable in the long run. A shift to sustainable agriculture implies a conversion from non-renewable energy to renewable sources such as hydraulic, solar and wind power, biofuels from agricultural waste and animal labour.

Also, modern agriculture relies heavily on chemical fertilisers such as phosphates. These minerals are currently mined, but global reserves can only sustain food production for another 50 to 100 years. Unless new reserves are discovered, and innovations in the recovery of phosphates from waste are developed, they will soon be too scarce to sustain the current agriculture systems.

Alternatively, sustainable agriculture practices aim to reconnect the agrosystem to the natural cycle of nature to reuse nutrients. Nutrient recycling is facilitated by diversified agriculture that integrates livestock and crop production. Rotating crops with legumes, for instance, enriches soil with nitrogen, avoiding the need for environmentally harmful fertilisers.

Figure 3: Agriculture uses 90% of the world’s increasingly precious water resources.

Agriculture and the climate crisis.

Climate change and agriculture are very interconnected. Anthropogenic (human created) activities are causing global warming, extreme weather and harsher, longer droughts.. These conditions are unfavourable for agriculture and undermine the Earth’s capacity to produce enough food for a growing population.

Agriculture is a major contributor to global warming through the extensive use of fossil fuel and production of greenhouse gases such as carbon dioxide, methane and nitrous oxide. Most of the methane emissions result from the use of livestock for meat, in particular ruminants such as cattle and pigs.

Agriculture practices such as tillage, fertilisation and pesticides use release pollutants in the environment including ammonia, nitrate and phosphorus. These pollutants deteriorate the quality of the air, water and soil, affecting natural microbial activity and destroying biodiversity. It alters the Earth’s land cover, which can change its ability to absorb or reflect heat and light, thus further contributing to global warming.

The growing food demand increases deforestation to clear land for pasture and crops. Deforestation causes habitat loss for millions of plant and animal species. It also exacerbates climate change because fewer trees are left to absorb carbon dioxide out of the atmosphere.

Other consequences of land clearing are droughts and desertification. When forests are destroyed, the soils tend to dry out because there is no longer shade. If there are not enough trees to assist the water cycle, water vapour does not return back to the environment.

Figure 4: Intensive agriculture is accelerating deforestation and destruction of vital habitats.

Cultures with the most significant impact on the environment

We’ve seen that intensive agriculture is a major contributor to carbon dioxide, methane and nitrous oxide (greenhouse gasses) emission. It causes deforestation and desertification, destroying habitat for animal and plant species. So, which cultures have the most significant impacts on the environment?

  • Beef. Beef production requires a lot of land, water and energy, and generates considerable waste. A quarter of global land use is dedicated to beef production, and growing demand is causing increased deforestation.
  • Dairy. Global demand for dairy continues to increase in large part due to population growth, rising incomes and westernisation of diets in countries such as China and India. Milk production impacts the environment, produces a lot of waste and depletes natural resources, including freshwater and soil.
  • Sugarcane. Sugarcane is a water-intensive crop and significantly affects the environment and biodiversity. Sugar is prevalently used in western diets and increasingly used as a source for biofuels and bioplastics. The demand is constantly increasing, and as the price of petroleum rises, there is a growing market for ethanol from sugarcane.
  • Palm oil. Palm oil is primarily used for cooking in developing countries. It is also used in food products, detergents, cosmetics and as a biofuel. In the U.S., more than half of all packaged products contain palm oil. Global demand for palm oil is increasing rapidly, and plantations are spreading across Asia, Africa and Latin America. This leads to a dramatic loss of biodiverse, tropical forests that are habitats for many endangered species and some human communities.
  • Soy. Soybeans are not only used in food products, but they are also widely used as animal feed, and increasingly used for biodiesel production. The United States, Brazil, and Argentina together produce about 80% of the world’s soybeans.
  • Cotton. With approximately half of all textiles made of cotton, it is the most widespread profitable non-food crop in the world. Its production provides income for more than 250 million people worldwide and employs almost 7% of all labour in developing countries. Current cotton production methods are environmentally unsustainable because of the large amount of land and water used.

Figure 5: Livestock is one of the most environmentally damaging food source.

Ecological benefits of sustainable agriculture

Converting modern agrosystems into sustainable systems can help the environment by:

  • Saving limited precious resources like water
  • Preventing the pollution of water reservoirs like lakes, rivers and groundwater
  • Maintaining a healthy and fertile soil by recycling nutrients
  • Enhancing soil structure that prevents erosion
  • Enhancing carbon sequestration by the soil
  • Promoting the use of renewable energy sources
  • Decreasing emissions of air pollutants and greenhouse gases
  • Creating habitats for beneficial insects including bees, which pollinate two thirds of our food.
  • Ensuring the welfare of farm animals while providing space for respectful coexistence with native wildlife.

Figure 6: Sustainable agriculture protects and provides habitats for bees, which are critical for pollinating food crops.

Converting modern agrosystems into sustainable systems can help the environment by:

  • Saving limited precious resources like water
  • Preventing the pollution of water reservoirs like lakes, rivers and groundwater
  • Maintaining a healthy and fertile soil by recycling nutrients
  • Enhancing soil structure that prevents erosion
  • Enhancing carbon sequestration by the soil
  • Promoting the use of renewable energy sources
  • Decreasing emissions of air pollutants and greenhouse gases
  • Creating habitats for beneficial insects including bees, which pollinate two thirds of our food.
  • Ensuring the welfare of farm animals while providing space for respectful coexistence with native wildlife.
Figure 6: Sustainable agriculture protects and provides habitats for bees, which are critical for pollinating food crops.

Economic benefits of sustainable agriculture

Increasing government involvement in the agricultural sector has led to an escalating concentration of agribusiness (industries that manufacture, process and distribute farm products) into fewer and fewer hands. Market competition is limited, and farmers have little control over prices, receiving a smaller and smaller portion of what consumers pay.

Economic pressure has led to a loss of farms, particularly small farms, during the past few decades. This contributes to the disintegration of rural communities and localised marketing systems. Economically, it is very challenging for potential farmers to enter the business today.

Social impact of sustainable agriculture

Sustainable agriculture has to take social equity into consideration. In most industrialised countries, wages for farm labour are so low that the agricultural sectors rely substantially on migrants from poorer nations. On the one hand, this leaves farmers vulnerable to changing immigration policies. On the other hand, the questionable legal status of many of these workers contributes to their low pay and poor living conditions, lack of job security, lack of opportunities to improve their situation, and exemptions from occupational safety protections considered standard in other industries.

In a sustainable agricultural system, farmers form cooperatives and share resources. Cooperatives represent an alternative way to increase labour equity and social justice. Farmers can share labour among farms with different seasonal crops. They can work together in mentoring workers and provide affordable health insurance and better housing.

Sustainable agriculture practices

Conservation agriculture. Conservation agriculture aims to reduce soil disturbance by reducing tillage, leaving crop residue in the soil after the harvest, and introducing crop rotation. It also aims to reduce soil erosion by covering the ground and minimising damage to soil structure to improve soil moisture and nutrient retention.

Controlled traffic farming. By minimising the use of machinery, it is possible to reduce the impact on soils, avoid soil compaction, and allow water to penetrate the soil more easily.

Rotating crops and embracing diversity. Planting a variety of crops can have many benefits, including healthier soil and improved pest control. Crop diversity practices include growing a mix of crops in the same area and crop rotations.

Planting of cover crops. Cover crops are planted during off-season times when soils might otherwise be left bare. These crops protect and build soil health by preventing erosion, replenishing soil nutrients, and keeping weeds in check, reducing the need for herbicides.

Integrating livestock and crops. Industrial agriculture tends to keep plant and animal production separate. Animals live far from the areas where their feed is produced, and crops are grown away from abundant manure fertilisers. Integrating crops and livestock can be more efficient and profitable.

Integrated pest management. Mechanical and biological methods can keep pest populations under control while minimising the use of toxic chemical pesticides.

Managing whole systems and landscapes. In sustainable farming, uncultivated land is valuable. It has an essential role in controlling erosion, reducing nutrient runoff, and supporting pollinators and biodiversity.

Student activities

1. How does modern agriculture impact Earth’s resources?

2. What are the three main goals of sustainable agriculture?

3. What does sustainable mean?

4. In pairs, discuss how current agricultural systems are interconnected with the climate crisis

5. Describe at least four cultures with the most significant impact on the environment

6. In pairs, discuss what changes you could make in your diet to have a smaller impact on the environment.

7. What are the ecological benefits of sustainable agriculture?

8. In groups, discuss examples of sustainable farming practices.

9. What are the economic benefits of sustainable agriculture?

10. What are the social benefits of sustainable agriculture?

References

Brodt, S., J. Six, G Feenstra, C Ingles, and D Campbell. 2011. “Sustainable Agriculture.” Nature Education Knowledge 3 (10). https://www.nature.com/scitable/knowledge/library/sustainable-agriculture-23562787/.

Parletta, N. 2020. “Smarter Irrigation Could Feed Millions More.” Cosmos Magazine, April 5, 2020. https://cosmosmagazine.com/earth/water/smarter-irrigation-could-feed-millions-more/.

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