Sustainable Agriculture Notes

Global Diets and Sustainability

• A study highlights the link between global diets, environmental sustainability, and human health.
• Rising incomes and urbanization are driving a shift from traditional diets to those high in refined sugars, fats, oils, and meats.
• If unchecked, these trends could lead to an 80% increase in agricultural greenhouse gas emissions and global land clearing by 2050.
• These dietary shifts contribute to increased incidence of type II diabetes, coronary heart disease, and other chronic diseases.
• Adopting healthier diets could reduce greenhouse gas emissions, land clearing, species extinctions, and diet-related chronic diseases.
• Agriculture significantly impacts the environment and human health, driven by dietary changes.
• Global agriculture releases over 25% of greenhouse gases, pollutes water, and uses about half of the Earth's ice-free land.
• Despite this, almost a billion people suffer from inadequate diets.
• A transition towards processed foods, sugars, fats, oils, and meats has led to 2.1 billion people becoming overweight or obese.
• Increased BMI is associated with chronic non-communicable diseases.
• In China, increased incomes and dietary changes led to a rise in type II diabetes from <1% in 1980 to 10% in 2008.
• Increased food demand and population growth are causing deforestation, threatening species with extinction.
• The global dietary transition poses a significant challenge due to its negative effects on human and environmental health.
• Solutions require analyzing the links between diets, the environment, and health, involving nutritionists, agriculturists, public health professionals, educators, policymakers, and food industries.
• The study compiles and analyzes global data to quantify relationships among diet, environmental sustainability, and human health.
• It evaluates potential future environmental impacts of dietary trends and explores solutions to the diet-environment-health trilemma.
• Lifecycle analyses (LCAs) of greenhouse gas (GHG) emissions from food production systems were examined. Emissions are expressed as $CO<em>2$ warming equivalents, in grams (g) or gigatonnes (Gt) of $CO</em>2$-Ceq.
• Plant-based foods have lower GHG emissions than animal-based foods.
• Ruminant meats (beef and lamb) have about 250 times the emissions per gram of protein compared to legumes.
• Eggs, dairy, seafood (excluding trawling), traditional aquaculture, poultry, and pork have lower emissions than ruminant meats.
• Sustainable grazing on unsuitable lands and feeding crop residues can increase food security, dietary quality, and provide environmental benefits via nutrient cycling.
• Seafood caught by trawling has about 3 times the emissions per gram of protein compared to non-trawling seafood.

Changing Diets in USA and China (1961-2013)

• USA diet changes:
  • 1961: 2602 cal/day
  • 2013: 3403 cal/day
• China diet changes:
  • 1961: 1268 cal/day
  • 2013: 2845 cal/day
• Overlap of global diets:
  • In 1961, the USA and China shared some dietary staples but also had distinct differences. Common foods included wheat, sugar, and milk.
  • By 2013, diets in both countries had converged further with increased consumption of items such as soyabean oil and poultry meat.

Consequences of Agricultural Intensification

• GHG emissions contribute to extreme weather events and global crop production losses
• Biodiversity loss, such as pollinator declines, threatens yields of pollination-dependent crops.
• Soil degradation, erosion, and reduced water quality lead to declines in crop productivity.
• Food production per capita is more environmentally efficient but unsustainable due to population increases.

Unsustainable Agriculture and Biodiversity Conservation

• The current agricultural path is inherently unsustainable for both agriculture and biodiversity conservation.
• Biodiversity declines are accelerating globally, with one-fifth of terrestrial vertebrates threatened with extinction.
• Habitat loss due to agricultural expansion is the greatest threat to terrestrial vertebrates.
• If current agricultural trends continue, 2–10 million $km^2$ of new agricultural land will be needed by projections based on population growth and dietary transitions.
• Conventional conservation approaches may be insufficient; proactive policies are needed to reduce threats to biodiversity, such as agricultural expansion.
• Responding to the biodiversity crisis requires detailed assessments to identify at-risk species and landscapes.
• A high-resolution analytical framework is developed to analyze the impacts of agricultural expansion on a large number of species.
• The model accounts for differences in how species are affected by land-use change and analyzes how food-system transitions might mitigate biodiversity declines.
• The approach identifies the species and landscapes most at risk and suggests alternative agricultural policies.
• A flexible and high-resolution model was developed to simulate agricultural land-cover change based on observed empirical relationships.
• This model differs from global food system models that rely on economic theory and expert opinion.
• The model can incorporate factors not accounted for in economic theory, such as enforcement of protected areas.
• The model is spatially explicit, with a resolution of 1.5x1.5 km.
• Projections indicate that 87.7% of species will lose habitat to agricultural expansion by 2050, with 1,280 species projected to lose ≥25% of their habitat.

Ecological Intensification

• Rising demands for agricultural products will increase pressure to further intensify crop production, while negative environmental impacts have to be minimized.
• Ecological intensification: entails the environmentally friendly replacement of anthropogenic inputs and/or enhancement of crop productivity, by including regulating and supporting ecosystem services management in agricultural practices.
• Effective ecological intensification requires an understanding of the relations between land use at different scales and the community composition of ecosystem service-providing organisms above and below ground, and the flow, stability, contribution to yield, and management costs of the multiple services delivered by these organisms.

Agriculture Changes

• Cropping system: includes crop (cultivar), crop rotation, and crop management.
• Pest Control: Chemical, genetic, and cultural control methods are used.
• Yield: Affected by the above factors.

Fall Armyworm

• Prior to 2016, confined to native range.
• 2016: detected in west Africa.
• 2020: detected in North Queensland.

Pest Management Research

• From the earliest origins of farming, agri-food production has undergone transformational changes.
• Crop domestication and breeding, agricultural mechanization, agronomy, irrigation and chemically synthesized fertilizers and pesticides have all progressively lifted productivity levels.
• Since the mid-1900s, substantial yield gain has been achieved by deploying improved crop varieties under input-intensive management schemes, for example, during the so-called “Green Revolution.”
• Although such packaged “seed × chemical” technologies became hallmark features of global agriculture, depressed food prices and thereby alleviated poverty, they also induced undesirable social- environmental externalities .
• In the world’s bread baskets, yields of prime food staples are now stagnating while total factor productivity drops.
• Overreliance upon petroleum-derived inputs is broadening the environmental footprint of global agriculture, triggering biodiversity loss, undermining resilience and promoting resistance to pesticides, while crops are increasingly under pressure from pests and diseases, weather anomalies and a fast-degrading natural resource base.
• Globally, food production relies on synthetic pesticides to tackle crop pests, diseases, and weeds. The manufacture, distribution and application of these compounds is highly energy-intensive, generating up to 6% of the greenhouse gas emissions from the world’s cropland.
• Since the 1940s, pesticide mass, usage intensity and toxicity loading have progressively increased and these patterns are currently exacerbated in the Global South .
• Pesticide-intensive agriculture is characterized by weakened trophic interactions and ecosystem function and consequently it is vulnerable to climatic disruptions and pest shocks.
• Meanwhile, climate change deepens biotic losses by facilitating the expansion of pest distributions, increasing pest survival and fostering pesticide resistance, thereby constraining the efficacy of the crop protection tool most favored by farmers .
• Since the late 1980s, scientists and world leaders have stressed the importance of implementing sustainable practices to secure current food production without compromising natural capital.
• In 1996, a conceptual framework was designed to analyse and implement a global transition toward the adoption of agroecological practices.

Key Agroecological Practices

• Organic farming:
  • Systems that ban the use of synthetic inputs.
  • Often emphasize diversified crop rotations and mechanical weeding.
  • Contrast with conventional farming, which relies on mineral fertilizers and synthetic herbicides, fungicides, and insecticides.
• Conservation tillage:
  • Systems that reduce the frequency or intensity of tillage operations.
  • Intensity reduced (alternative machinery, e.g., chisel, harrow disks).
  • Reduced tillage: tillage superficial/less frequent.
  • No-till: no tillage operations are conducted.
  • Contrast with inversion tillage (conventional).
• Crop diversification:
  • The number of crops grown at the field level is increased in space or time.
  • Intercropping: several crop species/varieties sown together in the field (in strips or as a blend).
  • Crop rotation: different crop species cultivated in a field over successive seasons.
• Adjacent non-crop habitat:
  • Off-crop habitats adjacent to the crop to promote natural enemies or disrupt the movements of pests.
  • Trap crop: plants grown with a specific crop plant to attract pests away from the crops (might reduce insecticide use).
  • Banker plants: seeded with and support natural enemies of key pests.

Definition of Organic Agriculture

• Organic agriculture is a production system that sustains the health of soils, ecosystems, and people.
• It relies on ecological processes, biodiversity, and cycles adapted to local conditions, rather than the use of inputs with adverse effects.
• Organic agriculture combines tradition, innovation, and science to benefit the shared environment and promote fair relationships and a good quality of life for all involved.
• Relies on certification for compliance to a standard endorsed by national and/or international bodies (IFOAM).
• Synthetic inputs (pesticides, fertilizers, etc.) are not permitted.

Principles of Organic Agriculture

• Principle of health: Organic Agriculture should sustain and enhance the health of soil, plant, animal, human and planet as one and these are indivisible.
• Principle of ecology: Organic Agriculture should be based on living ecological systems and cycles, work with them, emulate them and help sustain them. Ecological balance achieved through the design of farming systems, establishment of habitats and maintenance of genetic and agricultural diversity.
• Principle of fairness: Organic Agriculture should build on relationships that ensure fairness with regard to the common environment and life opportunities
• Principle of care: Organic Agriculture should be managed in a precautionary and responsible manner to protect the health and well-being of current and future generations and the environment.

Organic Farming Approaches

• Diversity of approaches:
  • Large scale: substitution-based organic tomato farm in California.
  • Smaller scale: holistic approach in greens, California.
  • Traditional knowledge-based system (Burkino Faso/Solomon Islands).
  • Large and small-scale organic farms (California).

Organic Agriculture: Landscape Importance

• Landscape context affects the sustainability of organic farming systems.
• Assessing how landscape context affects sustainability may aid in targeting organic production to landscapes that promote high biodiversity, crop yields, and profitability.
• Organic sites had greater biodiversity (34%) and profits (50%) than conventional sites, despite lower yields (18%).
• Biodiversity gains increased as average crop field size in the landscape increased, suggesting organic farms provide a "refuge" in intensive landscapes.
• In contrast, as crop field size increased, yield gaps between organic and conventional farms increased, and profitability benefits of organic farming decreased.
• Profitability of organic systems varied across landscapes in conjunction with production costs and price premiums, suggesting socioeconomic factors mediated profitability.
• Ecological sustainability benefits of organic agriculture are most pronounced in more intensive agricultural landscapes.

Organic Agriculture: Impacts

• Organic systems generally show higher biotic abundance and richness compared to conventional systems.
• Yields tend to be lower in organic systems.
• Profits tend to be higher in organic systems.

Organic Agriculture: Economic Implications

• Organic farming can enhance biodiversity, water quality, and animal welfare.
• Organic farming can improve soil quality.
• Agricultural systems and landscapes can be classified along a continuum from high-input intensive to agroecological.

Organic Agriculture: Holistic Assessments

• Life cycle assessment considers environmental impacts of a system based on resource use, emissions, and land use.
• Ecosystem services assess provisioning, regulating and maintenance, and cultural services provided by the system.
• Van de Werf et al., (2020) Nature Sustainability 3: 419-425

Organic Farming: Global and Regional Statistics

• 76.4 million ha managed organically
• Approximately 3.0 million organic producers
• Organic food products worth >US$100 billion
• 1.6% of world’s agricultural land is organic
• Oceania 47% of the world’s organic land (99% of this is in Australia)
• Organic foods NOT nutritionally superior to conventionally grown food (Dangour et al. 2009. Am J. Clin. Nutr. 90:680–85)

Organic Land Distribution

• Most organic agricultural land is located in Oceania and Europe.
• Africa: 2.7 million ha (3.5%)
• Asia: 6.5 million ha (8.5%)
• Europe: 17.8 million ha (23.4%)
• Latin America: 9.9 million ha (12.9%)
• Northern America: 3.5 million ha (4.6%)
• Oceania: 36.0 million ha (47.1%)

Organic Producers and Consumers

• India has the most organic producers, followed by Uganda and Ethiopia.
• The USA has the largest market for organic food, followed by Germany and France.

Largest Organic Agricultural Croplands

• Cereals:
  • 5'480'988 ha (0.74% of global total)
• Green fodder:
  • 3'218'742 (0.77% of global total)
• Oilseeds:
  • 2'098'555 ha

Problems with Insecticides

• Environmental/health impacts like non-target effects
• Evolution of insecticide resistance
• Pest resurgence
• Secondary pests
• These issues lead to the "insecticide treadmill".

Insecticide Resistance

• Documented cases of insecticide resistance worldwide vary among species.
• Lepidoptera, Homoptera, and Diptera are the orders with the most resistance cases.
• Most insecticides are nerve poisons that act on conserved parts of animal nervous systems.

Diamondback Moth

• Global problem (>US$5 billion per year).
• Africa: weekly prophylactic treatment is common.
• Asia: prophylactic treatment every 3-5 days is common.
• Queensland, Australia: 1.5 applications/week is common; IPM can reduce applications 5-10 fold.
• Cameron Highlands, Malaysia: 80% farmers treat weekly.
• Fiji: >70% farmers treat 2-3 times/week, increase application rate, mix compounds; typical crop receives 39 applications in a 12-week cycle.

Sustainable Insecticide Use

• Limited insecticides available in Sigatoka Valley: Deltamethrin, Chlorotraniliprole, Indoxacarb, Lufenuron, Bt-aizawi (experimental).
• DBM susceptibility to available insecticides in Sigatoka Valley shows varying levels of resistance.

Insecticide Resistance Management (IRM)

• 2014: National Awareness Campaign: insecticides and insecticide resistance.
• Bt-a launch, abamectin promoted.
• SPC, MoA Fiji, and UQ worked closely with local pesticide importer/reseller, AgChem Fiji Ltd.
• IRM strategy developed for stakeholders: farmers, extension officers, retailers.
• IRM strategy used available products adopted general principles advocated by IRAC.
• Insecticides used as a component of an IPM approach.
• Selective insecticides were used carefully to preserve natural enemies.
• Mode of Action classes were alternated in 18-day windows to avoid exposure of successive generations to compounds from a single MoA class.
• Frequent pest monitoring: insecticides applied only if needed.

Fiji - IRM Strategy Adoption

• Reduced insecticide use: affects natural enemy abundance (& efficacy)

Plant Health Clinic (PHC) Benefits

• Rapid response to farmers’ issues.
• Direct farmer communication.
• Accurate, up-to-date knowledge.
• Practical & long-term management advice, with follow-up.
• Help farmers reduce pesticide use: IRM strategy explained and promoted.
• Pest and disease database developed.
• Increased awareness through Plant Health Clinic program.

Non-Target Effects of Pesticides

• Bio-magnification
• Contamination of human food chain
• Broader unanticipated effects: implicated in worldwide bee decline

Changes in Insecticide Use

• In conventional agriculture, insecticide use has changed in recent decades.
• Types (mode of action) of insecticides and relative use have changed in recent decades.
• Neonicotinoids are implicated in bee decline.
• They are banned in Europe but still used in Australia.
• Quantities of newer neonicotinoid insecticides used has increased; soil persistence is much greater than anticipated.

Pesticides and the Environment

• Many routes of possible neonicotinoid transport and exposure in the environment exist.

Farming Practices and Bird Populations

• Agricultural intensification has resulted in reduced biodiversity.
• This includes a decline in bird populations across Europe.

Enlisting Nature for Crop Protection

• Comment: Carbon benefits of enlisting nature for crop protection.
• Pesticide-centred crop protection is highly carbon-intensive; product synthesis, distribution, and field application generate up to 136.6 $MtCO_2$ equivalent per year.
• Carbon financing offers an opportunity to bring more natural and sustainable alternatives to scale.
• To create accountability in sustainability commitments, GHG emissions need to be quantitatively assessed.
• Carbon and Environmental Benefits of Biological Control and Agroecology: deployment can attain 70-90% cuts in pesticide use, increased yields, and enhanced farm revenue, while restoring ecosystem functions and curbing GHG emissions.

Insect Pest Management on Organic Farms

• Organic farms emphasize multiple and varied tactics within cropping system design to prevent economically damaging pest populations.

Organic Crops

• Prioritized preventative strategies and direct measures considered where preventative strategies are insufficient.

Naturally Derived Insecticides

• Show greater promise in developing countries in tropics: source plants available, conventional insecticides are expensive & dangerous to poorly trained and ill-equipped users.

Natural Enemy Biodiversity and Pest Suppression

• Does increased natural enemy biodiversity (species richness) increase pest suppression?
• Generally assumed to do so based on one of two models:
  • Species complementarity model: pest mortality due to combined action of natural enemies ≥ summed mortality caused by each species of natural enemy on its own
  • Lottery model: as species richness increases probability of presence of effective natural enemy species increases
• Possible negative effects of natural enemy diversity on pest suppression:: Intraguild predation
• Possible reason for lack of effect of increased natural enemy diversity of pest suppression:: Functional redundancy: species share traits of how, where and when prey is attacked and belong to a single functional group in this respect

Yields on Organic Farms

• Are typically lower than on conventional farms (Seufert et al., 2012)
• Advantages of organic farming:
  • enhances the natural-resource base and environment
  • making farming financially viable (current subsidies/premium prices)
  • contributes to the well-being of farmers and their communities