What a desolate world ours would be without proper management of its resources! Humans have learned how to manipulate nature to get the best food and other resource outcomes. Is more progress for sustainability and agriculture still needed, though? Only good stewardship of the natural world and its resources will ensure that agroecosystems can function through climate change, war, and other global problems.
The definition of sustainability in agriculture
Sustainability is a term that is often used in agriculture. But what is its definition? What does it really mean?
Sustainability in agriculture refers to the ability of a farm or agricultural system to produce food, fibre, or other products indefinitely without damaging or depleting the resources on which it depends.
In other words, sustainability in agriculture is about:
Many factors contribute to sustainability in agriculture, including soil health, water conservation, and energy efficiency. By definition, sustainable agriculture must be economically viable, environmentally sound, and socially responsible.
Environmental sustainability in agriculture
Environmental sustainability in agriculture is tied to the practices, science and philosophies behind, naturally! Jokes aside, many current venues of pollution can be improved upon.
Pesticides, intensive land use and the danger of gene contamination are examples.
| Intensive agriculture staples | Alternatives |
| Nitrogen (N) fertilisers and monocultures | Cultures combined with nitrogen-fixing plants (which use bacteria to fixate nitrogen) such as legumes (beans, alfalfa, etc.) into polycultures. |
| Pesticides | Less toxic compounds such as capsaicin sprays, plant oils; natural predators (e.g. birds, bats); nets; crop protection technology (e.g. mounted, sensor-based sprayers), enhanced pesticide specificity. |
| Automated machinery | Fruit-collecting and picking machines equipped with sensors so that they don't destroy bird nests, branches, etc. |
| Selective breeding | Gene-editing |
| Water sprinkler irrigation | Drip irrigation (water slowly drips from specially-punctured pipes), rainwater storage tanks, soil moisture sensors, and on-site (decentralised, privately-owned) wastewater treatment. |
Pesticide specificity, or selectivity, refers to the chemical compounds of a substance that may specifically cause death in one selected genetic type of organism instead of affecting a broad range of organisms as casualties.
A downside of some of the more technologically advanced alternatives above is that they could be prohibitively expensive! Natural options, such as the rotation of crops and the encouragement of natural predators, are usually low-cost.
Crop rotation is the practice of planting different crops yearly or more often to improve soil health and combat weed pressure and even pest incidence.
Rotations are good because other crops extract or fixate different nutrients.
In sustainable agriculture, we also have permacultures: a system of perennial crops (as opposed to annual) and livestock farming, which intends to use resource recycling, integrated pest management, and agroforestry. Furthermore, mycorrhizae fungi are usually encouraged in soils.
Mycorrhizae are fungi which generally form symbiotic relationships with plants, helping them absorb nutrients, among others. They are traditionally sensitive to tillage and to the fungicides used in agroecosystems.
The genes category deserves a little more in-depth explanation.
Gene editing for agricultural sustainability
Advanced gene editing technologies can enhance the nutritional qualities of the existing crops and the vitamins, minerals and other essential elements they can synthesise. They can also make crops more resistant to drought, rain, pests, or other environmental factors.
The main concerns of gene editing are gene contamination events. The occurrence of gene contamination in the wild can lead to extinction events further down the food chain if the "escaped" edited genes provide resistance or immunity against an organism's regular predators.
Numerous varieties of genetically modified (GM) salmon grow faster and larger during periods of food abundance. In the wild, their size makes individuals more attractive for mating. In this event, most adult salmon ending up reproducing would be the genetically altered ones. However, when food reserves fall short, they can't slow down growth like regular salmon do due to the edited genes. This may cause their population to go hungry faster and collapse sooner.
Further, gene-edited varieties of plants may have already established themselves in and outside agricultural fields worldwide, including in the UK. The protection of plants from the unknown effects of gene contamination events is paramount.
Genetically modified corn, rapeseed and creeping bentgrass have been identified growing in the wild in the USA.2
Selective breeding crosses individuals with pre-existing desirable characteristics and hopes for natural mutations to occur down the line, whereas gene editing directly steps in, replacing a gene with another.
Several transgenic agricultural plants exist, such as herbicide-tolerant soybeans.
Transgenic means genes were taken from another organism, such as a bacterium, and introduced into the plant's genome!
Sustainability issues in agriculture
Agriculture is designed to control and manipulate the food web to provide enough resources to form complex communities and societies. As a result of this environmental engineering that humans are capable of, sustainability issues arise.
Reasons, why sustainability issues arise include the generation of by-products and waste.
Manure can alternatively be used in house-building and insulation, as well as in biodigesters. Farmers can make at-home biodigesters: tanks filled with bacteria that feed on decaying biological matter in the absence of oxygen (O2).
We may also not have enough access to quality information and general plant or animal reproduction knowledge to select the nutritionally densest foods (high-energy and nutrient content per gram).
The way we have used space for agriculture means that many natural habitats have been destroyed to make space for plantations and animal rearing.
Due to the effects of industrial and agricultural development (including habitat destruction, dams, and historic overfishing), most salmon populations native to New England were eradicated.3
Habitat conversion further contributes to soil degradation or loss of soil biota.
Introducing the European-native earthworm Lumbricus terrestris into the USA to enhance soil fertility has negatively affected forests because they evolved with denser, less aerated soils.
In the UK, harlequin ladybirds introduced from Asia to predate on crop pests are displacing native ladybird species that fill the same niche.
Specific issues arise with the unsustainable/excessive administration or introduction of certain chemical agents. Unsustainable use can mean, for instance, that a chemical agent is applied during the less effective times of the day (right before the rain) or seasons.
Types of chemical agents | Uses and sustainability risks |
Antibiotics | Treat or prevent infections → pathogens risk acquiring resistance E-coli gut bacteria are susceptible to building antibiotic resistance in farmed pigs. |
Hormones | Cause rapid growth in animals → hormones also enter the human bloodstream via ingestion. It can be used both to aid growth or to cause premature death. Diethylstilbestrol (a compound of the hormone oestrogen) injected in cows and ending up in human diets promoted cancer growth before it was banned.4 |
Pesticides | Help relieve pest/disease pressures in plants → harmful chemicals persist in the environment. Neonicotinoids, the most common pesticides in the USA but banned in the EU, are extremely toxic insecticides (neurotoxins) that act against the nervous system of a wide range of invertebrates.5 |
Weather control | Changes in the local temperatures or precipitation levels The silver iodide used in cloud seeding is considered hazardous to the health of animals and humans, as it accumulates in soils where it is used routinely (mountainous western United States)6. |
The ability to modify weather can alter local ecosystems. It is used to help certain patches of agricultural farmland.
Cloud seeding involves dispersing cloud-forming materials by plane, rockets, etc. Alternatively, cloud dispersal rockets can also be used to discourage the formation of hailstorm clouds that could negatively affect crops.
Climate change and agricultural sustainability
Issues in agriculture also derive from climate change. Changing precipitation patterns and increased temperatures globally significantly affect drought-sensitive species of plants, such as rice, and animals, such as waterfowl (ducks, geese). Warm waters also slow down the maturation of cold-water fish.
Agriculture contributes to climate change, releasing vast amounts of gases with the greenhouse effect into the atmosphere. These gases include methane (CH4) and nitrous oxides (NOx), especially from manures and fertilisers and from enteric fermentation (digestive gases).
The tillage and conversion of soils into agricultural lands also reduced the soils' capacity to retain CO2 (carbon dioxide), another greenhouse gas otherwise released in significant quantities by burning residues and vegetal waste.
Agriculture can be used to slow down climate change by growing crops that develop rapidly, sequestering carbon dioxide in their cells!
Further, intensive water use and eutrophication (a phenomenon generated by a nutrient surplus from farms, in which algae grow excessively and use up light and oxygen) contribute to environmental decline.
Rural communities are especially at risk from climate change due to their dependence on the land, ecosystem services, and resources. Their social life depends on harvests and natural cyclicality, which climate change disrupts.
Dancing, music, unique dishes and reunions are frequent during the autumn equinox in China when rural communities organise Harvest Festivals across the country.
Examples of sustainability in agriculture
Sustainability in agriculture may be brought by closed-loop systems designed to use human or animal and vegetal by-products. The following are examples of sustainability in agriculture.
Hydroponics and Aquaponics
In aquaponics, fish excrements and the waste of other water organisms provide nutrients for the plants, and the plants help to purify the water for the fish (biofilters). Lettuce and other leafy greens can be grown in small aquaponics systems, while larger systems accommodate fruiting plants like tomatoes and cucumbers.
Off-grid hydroponics farms are popular in warmer parts of the country, such as South Devon, UK.
Hydroponics refers to the science of growing plants in water instead of soil!
Aquaponics is a type of sustainable agriculture that combines raising fish, shellfish, or algae, with growing crops in a soil-free environment, usually in multi-storey facilities that aim to maximise space use.
Aquaponics is also suitable for producing ornamental plants like flowers and herbs.
Agroforestry
Agroforestry systems can increase production, protect and improve soil and water quality, provide wildlife habitat for a broader range of organisms than farmland alone, and sequester carbon, all while delivering new food resources such as nuts, fungi, fruits, leaf fodder (e.g. birch, beech), etc.
Agroforestry, also known as 'silvopasture' or 'agrisilviculture', is a type of land use management that integrates trees and shrubs into traditional farming and ranching systems.
Grazed oak and larch woodlands in Italy, Spain ("Dehesa" forest management) and Greece.
Indicators of sustainability in agriculture
Sustainability can be understood as responsible resource use and durable socio-economical policies that do not cause unrest or lead to nutritional deficiencies within a population. To calculate the sustainability rating of a farm, the following may be taken into account:
- Greenhouse gas emissions: estimated from the amount of soil aerated and cultivated, quantity and types of fertilisers used, number of animals present and the gases they release, decaying matter burned, any fuel used for transportation or equipment, or water usage.
- Wildlife biodiversity: the biodiversity of farmland and its components can be assessed by ecologists carrying out field observations and trapping.
- Soil biodiversity indicators: high soil biodiversity rates or a good soil health index on agricultural farmlands are typically desirable.
- Species resilience: when organisms that appear healthy and thriving are observed over an established period or through lab analyses of samples, the agricultural practices can also be considered beneficial from an ethical standpoint.
PMSG, or pregnant mare serum gonadotrophin, is a hormone extracted from pregnant mares' urine and widely used in Europe and the USA on animals such as pigs to aid breeding. However, the PMSG industry does not have official international guidelines, despite the serum being shipped or imported worldwide from pregnant mares kept in unstandardised conditions. This has raised ethical questions among consumers.
In conclusion, several sustainability indicators need careful management. Farmers can ensure that their agricultural practices will continue to be productive long-term by implementing sustainable practices on their land.
Sustainability in Agriculture - Key takeaways
Soil health, water conservation, chemical use and energy efficiency are four broad categories contributing to agricultural sustainability.
Introduced species, lack of diversity within crops and farmland habitats, gene contamination and the elimination of wildlife species further contribute to sustainability problems in agriculture.
There are also ethical and socio-economic aspects to agriculture that significantly affect consumption behaviours.
Empirical observations can be drawn more easily from visual phenomena associated with agricultural landscapes, such as water eutrophication, deforestation, low soil biodiversity indexes, and invertebrate scarcity.
Greenhouse gas emissions, incremental loss of habitats, water and soil pollution, and health problems derived from chemical use have all historically been harder to observe and quantify in due time.
References
- Adam Vaughan, Breeding with farmed fish is changing the life cycle of wild salmon, 2021
- Doug Gurian-Sherman, Transgene Escape! – But No One Has Called Out the Guards, 2007
- NOAA Fisheries, Atlantic salmon, 2022.
- A. P. Raun et al., History of diethylstilbestrol use in cattle, 2002
- Wildlifetrusts.org, Bad news for bees: Government reverses ban on bee-killing neonicotinoids, 2021
- Britannica, Methods of modifying atmospheric phenomena, 2022.
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