All activities undertaken by humans and animals generate greenhouse gases (GHG). GHGs maintain the earth at a temperature that can support life, and elevated GHG concentrations due to human activities, including agriculture, are expected to bring about unpredictable climatic variation.¹ 

The main GHGs emitted from crop production are carbon dioxide (CO₂) and nitrous oxide (N₂O).  CO₂ can be emitted from fuel combustion, burning of crop residues, regular plant respiration, natural plant decay and decomposition or through soil carbon loss. CO₂ can be absorbed by plants through photosynthesis, which can then be sequestered in the soil. N₂O emissions originate primarily from volitization after application of commercial fertilizers and manure¹ and denitrification from soil bacteria. Nitrogen can be taken up by nitrogen-fixing bacteria in plants such as legumes.

Methane (CH₄) from agricultural activities also contributes to GHG, mainly through livestock and their manure. However, in the internationally-recognized GHG calculation methodology, CH₄ from livestock production is attributed to livestock, and not crop production even though manure may be used by crop producers as a fertilizer. A small amount of methane is emitted from land managed but not farmed by crop producers, through anaerobic decomposition in ponds and wetlands that may be on their land.

Particulate matter (PM) impacts air quality. PM suspended in the atmosphere reduces visibility and can reduce the amount of solar radiation reaching the earth, potentially impacting climate. PM can also contribute to ozone depletion, acid rain and smog, and inhalation of PM is associated with adverse health impacts.  PM generated by crop production activities includes dust from soil and plant material, bacteria, and particles or droplets from agro-chemicals.  Particulate emissions can also occur from equipment exhaust, burning of crop residue and backyard burning barrels.

Soil quality depends on physical, chemical and biological parameters. Practices such as residue management, crop rotation, tillage, and use of nitrogen-fixing plants and green manures all have direct impacts on soil quality.

Soil organic matter (SOM) is a key component of soil health, and strongly influences many aspects of soil quality. It stabilizes soil structure, making the soil less susceptible to erosion, and improving its ability to store and transfer air and water. Soil organic matter stores and supplies many nutrients, and binds potentially harmful substances such as heavy metals and pesticides. Soil organic matter also stores carbon dioxide (CO₂₎ captured from the atmosphere.

Soil erosion can pose a threat to the sustainability of crop production. Erosion primarily affects the surface layer of the soil, which is rich in organic material, and consequently reduces soil fertility. Productivity can be lost, and severely-eroded land could be permanently unsuitable for agriculture.

For the purpose of this report, pest management refers to all actions that a grain farmer may take to manage the impact of weeds, harmful insects and plant diseases on the yield and quality of the crop. Some of these actions may be preventative, such as using disease resistant varieties of crops, rotating crops (the successive planting of different crops on the same land) and the identification and monitoring of insects that are beneficial to the crop production.  Some practices may be for remediation, such as regular field scouting to assess weed, disease and insect problems and applying agrochemicals when appropriate to manage the identified problems.

Agrochemicals (agricultural pesticides) help crop producers reduce crop damage due to pests, primarily weeds, insects and fungi. Agricultural pesticides include:

• Herbicides to control unwanted plants. Selective herbicides control specific weed species, while leaving the actual crop relatively unharmed.
• Insecticides to control insects.
• Fungicides , which are chemical compounds or biological organisms,  to control fungi.
• Rodenticides to control rodents.

At the farm level, agrochemical stewardship includes a lifecycle approach to ensure that agrochemicals are responsibly managed through each step of the lifecycle, including the safe transportation, storage,  responsible use of pest management products, adoption of integrated pest management techniques, appropriate recycling/disposal of empty containers and safe disposal of obsolete agrochemicals.

Plants require nutrients for growth, specifically nitrogen (N), phosphorus (P), potassium (K), and sulphur (S). To maximize crop productivity, it is often necessary to supplement soils by adding nutrients through application of mineral fertilizers or livestock manure. Two different sources of nutrients are used in the production of Canadian grains: mineral fertilizer (referred to here as “commercial fertilizer”) and livestock manure (referred to here as “manure”).

The appropriate rate of application, proper timing, and proper placement of fertilizer and manure can optimize the use of the nutrients, as well as prevent the accumulation of excess nutrients in the soil and subsequent loss of nutrients into the environment.

Agriculture-related land use changes occur on various levels, as producers adapt to new technology, growth in the size of family farms, productivity increases and changes in market demands. Some of these changes may have impacts on environmental sustainability. Globally, the loss of forests and other ecosystems to expanding crop production may be critical, both for reasons of loss of environmental services, and the GHG emissions resulting from such land conversion.

Biodiversity refers to the variety of life on the planet, at genetic, species and ecosystem levels. Human conversion of landscapes from natural vegetation to other uses, including agriculture, could result in wildlife plant and animal habitat loss, degradation and fragmentation. How land is managed therefore impacts the extent and health of available habitat for plant and animal populations.

Water is a limited resource that is essential for people, animals and plants.   Crops take up water through precipitation events, including rain and water movement from spring snow melt, as well as through the below ground water tables, and utilize it for plant production.

Water quality can be adversely affected by human, animal, and plant activity.  Specific to crop production, excess plant nutrients such as nitrogen and phosphorus; improper or unfortunate timing of weather events or environmental conditions around applications of pesticides; and pathogens potentially in animal manure can cause unintended harm if they enter ecosystems surrounding agricultural operations.

Most nitrogen left in the soil is in the form of nitrate, which is water soluble, and can leach into ground water and surface water bodies when the environmental conditions are favourable to this. High nitrate levels in surface water can contribute to the growth of algae and eutrophication (where nutrient enrichment induces growth of plants and algae, and the increased biomass results in depletion of oxygen in the water body). Phosphorus can be transported in dissolved form, or on soil particles. Excessive phosphorus in surface water can contribute to eutrophication of rivers and lakes, and to algal blooms which reduce water quality and lead to restrictions on water use.

If pesticides are improperly applied, and/or unfavourable weather occurs, pesticides could enter the environment and eventually contaminate ground water and surface water. Similarly, pathogens from manure, such as bacteria, viruses and protozoa, could contaminate water.

In addition to the natural cycling of water throughout the cropping systems, there are some regions and crop types that utilize irrigation.  Worldwide, agriculture is a major source of withdrawals of fresh water from the environment. Although only 1% of Canadian crop land is irrigated³, management strategies are important to maximize agricultural water use efficiency, so that water can be conserved while optimal crop production and yield are maintained.  

The reduction of waste and pollution is recognized globally as one of the most important elements to sustainability. The mismanagement of waste can have negative impacts on both human health and ecosystems, such as soil and water contamination, the creation of air pollution and the reduction of productive land and habitats. For these reasons, most countries, including Canada,  have numerous regulations and programs to manage waste and pollution.

As in all human activities, wastes are generated in the course of normal farm operations. Examples of farm wastes that require careful handling are waste building materials, pesticides and fertilizers. The agricultural industry and various government agencies are working together to optimize recycling and reuse and to limit any unintended consequences that may arise from farming.