Chapter 11 Review Questions

F (see “Introduction”)

F (see “The Green Revolution”)

T (see “Agriculture and Climate Change”)

T (see “Agriculture and Climate Change”)

F (see “The Green Revolution”)

F (see “The Green Revolution”)

T (see “The Biofuel Revolution”)

T (see “Resistance”)

T (see “Implications”, Box 11.7)

F (see “Soil Compaction”)

During the mid-twentieth century, an increase in intensification of agricultural productivity was associated with the Green Revolution. The Green Revolution refers to technological advances designed to increase the productivity of agricultural lands, including use of chemical pesticides, use of auxiliary energy flows in the form of fertilizers, hybridization, higher-yield seeds (e.g., shorter maturation, drought resistance), genetic engineering, more complex irrigation systems, and modern farming equipment (e.g., tractors for plowing and seed sowing, mechanized food processing). Were it not for these developments, no doubt many more people in the world would be suffering chronic food shortages. However, the Green Revolution also carries with it significant long-term negative impacts that will ultimately lead to long-term productivity losses.

(see “The Green Revolution”)

For many people, lack of food is a day-to-day reality. Agriculture provides approximately 94 per cent of the protein and 99 per cent of the calories consumed by humans. Conversely, over 1 billion adults are classified as chronically hungry. Over 3 billion people, about 40 per cent of the world’s population, suffer from some form of micronutrient deficiency. The effects of malnutrition cross generations as well. Infants of malnourished, underweight women are likely to be small at birth and more susceptible to disease and death.

While some progress has been made in reducing hunger around the world, since 2014, the number of undernourished people in the world has increased. Rates of severe food insecurity, defined as having no food for a day or more throughout the year, also increased between 2014 and 2017 in all parts of the world except for North America and Europe, with almost 30 per cent of the population in Africa experiencing severe food insecurity in 2017, up from 22 per cent in 2014. More than half of the undernourished people (63 per cent) live in Asia, while sub-Saharan Africa accounts for almost a third (31 per cent). Every year, more than 3 million children die as a result of starvation, with half of all deaths of children under the age of five attributable to undernutrition.

In stark contrast, more than 300 million people are clinically classified as obese, and about half a million people die from obesity-related diseases every year; rates of childhood obesity are also increasing. The gross inequity between starvation and obesity rates suggests that hunger is a problem of distribution. In fact, enough food is produced to feed all people on the planet. Regardless of increasing global production levels, rising food prices and heavy agriculture subsidies result in food remaining inaccessible to many of the world’s poorest people. Furthermore, hunger is most pronounced where there are natural disasters, adverse climate conditions, and ongoing warfare. No single solution can address the challenge of increasing the quantity and quality of affordable foods. The solution will involve various approaches, including exploration of new marine and terrestrial food sources; continued research to increase yields of existing crops; improvements in the efficiency of natural resource use; family planning programs aimed at reducing population growth rates; elimination of global agricultural tariffs; more efficient food distribution systems to address chronic hunger; and a moderation in demand on the part of the already overfed countries.

(see Box 11.2)

Agriculture links to the SDGs in many ways, from the connections among health, education, and appropriate nutrition (SDGs 3 and 4), to how ending hunger can promote peace and justice (SDG 16). Important connections discussed in this chapter include:

• SDG 2: Zero hunger. Although we currently produce enough food to feed all people on the planet, millions are still going hungry. Meeting this goal will require an integrated approach to address issues associated with malnutrition, productivity levels, enhancing resilience and adaptability of food systems, and sustainable use of resources.
• SDG 12: Responsible consumption and production. Approximately one-third of all food produced goes to waste. Ensuring more efficient production, distribution and use of food products can help meet this goal.
• SDG 13: Climate action. As a significant source of greenhouse gas emissions, the agricultural sector must be considered when responding to issues of climate change and determining how to build more resilient and adaptable agricultural systems.

(see “Introduction”)

The amount of arable land is limited by weather and soil conditions. Less than 5 per cent of land in Canada can be viably farmed. Much of this land is in southern Canada, where most Canadians live. This juxtaposition of prime agricultural land and the main urban centres has meant that suburban expansion invariably leads to losses in agricultural land. Although much of this urban expansion has been in Ontario, other areas have also been greatly affected. Urbanization of agricultural land often affects specialty crops that have a limited ability to flourish in Canada. These crops often represent an important resource to local economies (e.g., the fruit belts in the Niagara and Okanagan regions). Cities also affect the use of surrounding lands in indirect ways—golf courses, gravel pits, and recreational areas are often located on agricultural land in areas adjacent to urban areas, and as a result, the effects of urban areas extend beyond their physical boundaries. In an effort to slow the rates of conversion, several provinces have enacted legislation regarding the protection of agricultural lands. However, these programs do create problems. Often, farmers whose lands fall within the program cannot compete with cheap agricultural imports from elsewhere.

(see “Urbanization of Agricultural Land”)

Various impacts are associated with the development of agriculture and, more specifically, with the development and spread of modern farming systems:

• Humans, rather than natural selection, have become the primary influence on the number and distribution of species.
• Energy flows are increasingly directed into agricultural as opposed to natural systems.
• Biogeochemical cycles are interrupted as natural vegetation is replaced by domesticates that are harvested on a regular basis.
• Auxiliary energy flows used in modern agricultural systems to supplement the natural energy flow from the sun are often in excess of those derived from natural sources.
• In many areas, agriculture involves supplementing rainfall with irrigation to provide adequate water supplies. This has led to large-scale water diversions and to changes in groundwater, soil characteristics, precipitation patterns, and water quality.
• Soils are altered not only chemically through fertilizer and biocide inputs but also physically through plowing. There is no natural process that mimics the disturbance created by plowing.
• Natural food chains are truncated as humans destroy and replace natural consumers and predators at higher trophic levels.
• Natural successional processes are altered to keep agricultural systems in an early seral stage.
• The stocking densities of domesticated herbivores are often much higher than that of natural herbivores, leading to a reduction in standing biomass and changes in the structure and composition of the primary production system.
• The industrial system of livestock production acts directly on land, water, air, and biodiversity through the emission of animal waste, use of fossil fuels, and substitution of animal genetic resources. It also affects the global land base indirectly through its effect on the arable land needed to satisfy its feed concentrate requirements. The industrial system requires the use of uniform animals of similar genetic composition, contributing to within-breed erosion of domestic animal diversity.

(see Box 11.3)

Soil erosion occurs naturally through gravitational, water, and wind processes. It is minimal under natural conditions because vegetation binds soil together, keeping it in place. Agricultural activities often remove this natural plant cover, replacing it with intermittent crops plantings, which exposes the soil to erosive processes. Land kept under vegetative cover for grazing can also be subject to increased erosion due to animal movement.

(see “Soil Erosion”)

Acidity in soils can occur naturally but can also be augmented by fallout from acid precipitation and the use of fertilizers. Nitrogen fertilizers undergo chemical changes in the soil that result in production of H+ ions, causing greater acidity. Often the contribution to soils acidification is much greater than that from acid rain. This is particularly a problem in naturally acidic soils. Excess acidity reduces crop yields and leads to nutrient deficiencies and export of soluble elements such as iron and aluminum into waterways. Liming is a common agricultural practice to combat the effects of acidity.

Salinization is the deposition of salts in irrigated soils. Soil salinization is a major problem in many areas of the world where irrigation is common as it leaves soil unfit for growing most crops. As water evaporates, it leaves behind dissolved salts. Over time, these salts can accumulate in sufficient quantities to render the land unusable. Estimates suggest that 50–65 per cent of irrigated croplands worldwide are now less productive due to salinization. Alkaline soils occur naturally in areas of western Canada that have high sodium content and shallow water tables.

(see “Soil Acidification and Salinization”)

Cultivation involves a continuous process of removing plant matter from a field. In so doing, both the organic and nutrient content of the soil are reduced. Organic matter is critical for maintaining the structure of the soil, influencing water filtration, facilitating aeration, and providing the capacity to support machinery. It also helps to maintain water and nutrient levels. On the Prairies, current organic matter levels are estimated to be 50 to 60 per cent of original levels, representing a probable annual loss of about 112,000 tonnes of nitrogen. This nitrogen is replaced by the addition of synthetic fertilizers, which in turn contribute to the problem of acidification.

(see “Organic Matter and Nutrient Losses”)

Livestock manure can be a valuable fertilizer for crop production but can also become a source of pollution if not managed properly. Manure consists of various substances, including nitrogen, phosphorus, potassium, calcium, sodium, sulphur, lead, chloride, and carbon. Manure also contains countless micro-organisms, including bacteria, viruses, and parasites.

Many microorganisms in manure are pathogenic and if introduced into drinking water can lead to outbreaks of illnesses such as those caused by E. coli in Walkerton, Ontario, or spread of diseases such as “mad cow disease” (bovine spongiform encephalopathy).

Odour and air pollution are identified as serious environmental and human health concerns related to intensive livestock operations (ILOs). High concentrations of noxious gases such as CH₄, hydrogen sulphide, CO₂, and ammonia are often found in manure pits and confinement barns.

When manure storage systems are inadequately built or sited too close to waterways, or when manure is spread on fields in amounts too great to be absorbed by soil and plants, nutrient contamination results. Excess nitrogen and phosphorus loading to streams, lakes, and wetlands accelerates eutrophication, loss of habitat and changes in biodiversity. High nitrate levels kill many amphibian larvae, and elevated ammonia kills fish.

(see “Intensive Livestock Operations”)

Integrated pest management (IPM) seeks to avoid or reduce yield losses caused by diseases, weeds, insects, mites, nematodes, and other pests while minimizing the negative impacts of pest control. The presence and density of pests and their predators and the degree of pest damage are monitored, and no action is taken as long as the level of pest population is expected to remain within specified limits. IPM considers the crop and pest as part of a wider agro-ecosystem, promoting biological, cultural, and physical pest management techniques over chemical solutions to pest control. Combinations of approaches are used, including the following: bacteria, viruses, and fungi (pathogens); insects such as predators and parasites (biological management); disease and insect-resistant plant varieties; synthetic hormones that inhibit the normal growth process and; behavior-modifying chemicals and chemical ecology products (such as pheromones, kairomones, and allomones). If pesticide use is deemed essential to pest control, only pesticides with the lowest toxicity to humans and non-target organisms are applied.

(see “Integrated Pest Management”)

The goal of integrated plant nutrient systems (IPNSs) is to maximize nutrient use efficiency by recycling all plant nutrient sources within the farm, using nitrogen fixation by legumes, and supplementing soil productivity through a balanced use of local and external nutrient sources, including manufactured fertilizers. IPNSs also seek to minimize the loss of nutrients through the judicious use of external fertilizers. IPNSs aim to optimize the productivity of the flows of nutrients passing through the farming system during a crop rotation. The quantities of nutrients applied are based on estimates of crop nutrient requirements.

(see “Integrated Plant Nutrient Systems”)

No-till/conservation agriculture (NT/CA) protects and stimulates the biological functioning of the soil while maintaining and improving crop yields. Essential features of NT/CA include the following: minimal soil disturbance restricted to planting and drilling, instead of plowing; direct sowing; maintenance of a permanent cover of live or dead plant material on the soil surface and; crop rotation, combining different plant families. Crops are seeded or planted through soil cover with special equipment or in narrow cleared strips. Soil cover inhibits the germination of many weed seeds (which minimizes weed competition and reduces reliance on herbicides), reduces soil mineralization, erosion, and water loss, builds up organic matter, and protects soil micro-organisms. Crop sequences are planned over several seasons to minimize the buildup of pests or diseases and to optimize plant nutrient use by synergy among different crop types, and alternating shallow-rooting crops with deep-rooting ones to utilize nutrients throughout various layers of the soil. These practices increase yields, reduce yield variability, reduce labour costs, and lower input costs.

In 2016, the areas worked in Canada with no-till techniques had increased significantly over the past three decades. The area worked with conventional tillage, which had historically been the most popular tillage method, represented 17 per cent of agricultural operations, an increase of 1.9 per cent since 2011; this was a reversal of trends seen since 1991, where the percentage of agricultural lands engaging in conventional tillage practices had been decreasing. The increased popularity of no-till and reduced areas of summer fallow have turned Canadian cropland into a GHG sink rather than a source.

(see “No-Till/Conservation Agriculture”)

Be sure to mention any five of the following:

• Enhance biological diversity within the whole system
• Increase soil biological activity
• Maintain long-term soil fertility
• Recycle wastes of plant and animal origin in order to return nutrients to the land, thus minimizing the use of non-renewable resources
• Rely on renewable resources in locally organized agricultural systems
• Promote healthy use of soil, water, and air as well as minimize all forms of pollution that may result from agricultural practices
• Handle agricultural products with emphasis on careful processing methods in order to maintain the organic integrity and vital qualities of the product at all stages
• Become established on any existing farm through a period of conversion, the appropriate length of which is determined by site-specific factors such as the history of the land and the type of crops and livestock to be produced.

(see “Organic Farming”)

Approaches to sustainable agriculture such as IPM, IPNS, and conservation tillage each consider only one aspect of the farming system components—pest ecology, plant ecology, and soil ecology, respectively. Organic agriculture, however, combines these and other management strategies into a single approach, focusing on food web relations and element cycling to maximize agro-ecosystem stability. Organic agriculture is a production management system that aims to promote and enhance ecosystem health. It is based on minimizing the use of external inputs and represents a deliberate attempt to make the best use of local natural resources while minimizing air, soil, and water pollution.

(see “Organic Farming”)

In the absence of governmental support for the expansion of organic production, farmers may be reluctant to convert to organic farming for several reasons. Conversion from conventional, intensive systems to organic production causes a loss in yields. Yields can be 10 to 30 per cent lower in organic systems, and it may take three to five years to restore the ecosystem to the point where organic production becomes economically viable, although more recent research suggests the yield gap may be reduced over time. In addition, production costs per unit of organic production (e.g., labour, certification, and inspection fees) and marketing expenses can be higher, but once produce qualifies as certified organic, some costs can be offset by price premiums. In some countries, including Canada, organic production is limited due to the presence of GM crops, which contaminate nearby organic crops. Finally, intensive, large-scale organic farms can sell organic foods for less, which discourages smaller farmers from trying to compete.

(see “Organic Farming”)

The grasshopper effect occurs via atmospheric transport and deposition of persistent and volatile chemical pollutants whereby the pollutants evaporate into the air in warmer climates and travel in the atmosphere towards cooler areas, condensing out again when the temperature drops. The cycle then repeats itself in a series of “hops” until the pollutants reach climates where they can no longer evaporate.

(see “Biomagnification”, Box 11.5)

Salinization can also be exacerbated through cropping practices that remove natural vegetation and increase the rate of surface evaporation, leading to greater salt concentration at the surface. Summer fallow has this effect. Summer fallow is a practice common on the Prairies in which selected land is kept bare to minimize moisture losses through evapotranspiration.

(see “Soil Acidification and Salinization”)

Various risks of biocides include:

• Resistance
  • If a biocide is effective, most of the pest population will be killed, but a small number of individuals likely will have a higher natural resistance and survive the chemical onslaught. This remnant resistant population may then grow rapidly in numbers, ultimately creating a population resistant to the biocide. This results in a continuous need to develop new biocide products (or pest-resistant plant varieties) to keep one step ahead of biological adaptation.
• Non-selection
  • Many biocides are popular because they are broad-spectrum poisons. Unfortunately, they tend to eliminate not only pest species but also other, valuable species, including some that may act to control the population of the pest.
• Mobility
  • The effects of the chemical application are often felt over a much wider area, sometimes spanning thousands of square kilometres, because of the mobility of the chemicals in the Earth’s natural cycles, particularly the hydrological cycle, and the manner in which chemicals are applied.
• Persistence
  • Not only do biocides spread over vast areas, they also continue to contaminate through time, as many are very persistent. They may also gradually accumulate in the tissues of organisms (bioaccumulation).
• Biomagnification
  • Concentrations of POPs multiply five- to tenfold with every step in the food chain. The relatively low concentrations at the lower end of the food chain are magnified many times by the time they reach top predators.
  • Together, biomagnification and bioaccumulation are often known as bioconcentration. Humans are exposed to the harmful effects of biocides through bioconcentration.
• Synergism
  • A single biocide may contain up to 2,000 chemicals, and as the chemicals break down, new ones are created that may again react with each other in unpredicted ways. The combined effects are often greater than the sum of their individual effects.
    (see “Biocides”)

In Canada, new chemicals cannot be introduced into the market without undergoing scientific tests regarding their capacity to cause cancer, birth defects, and mutations. The Pest Management Regulatory Agency (PMRA), a branch of Health Canada created in 1995, has the primary responsibility for regulating biocides. The federal government shares the responsibility for managing biocides with provincial, territorial, and in some cases municipal governments.

In 2015, the Commissioner of the Environment and Sustainable Development released a report, suggesting that the PMRA:

• had not made progress in limiting the duration of some conditional registrations (a key recommendation of the previous audit conducted in 2008), including those provided for a number of neonicotinoids;
• had not assessed cumulative health effects when required in re-evaluations of chemicals;
• had made insufficient progress in completing re-evaluations of older pesticides, as required every 15 years under the Pest Control Products Act; and
• did not promptly cancel the registrations of some pesticides whose risks it had deemed unacceptable.

Lack of compliance with the regulatory framework has also been an issue and is partly due to problems with pesticide labels. Some agricultural pesticides may have 30 or more pages of directions in fine print, while other label instructions are difficult to follow. For example, labels are often ambiguous, and application therefore depends on the applicator’s interpretation.

(see “Biocide Regulation”)

A report released by the World Resources Institute (2018) highlights key strategies to achieve this:

• Reduce growth in demand for food and agricultural products.
• Increase food production without expanding agricultural land
• Exploit reduced demand on agricultural land to protect and restore forests, savannas, and peatlands.
• Increase fish supply through improved wild fisheries management and aquaculture
• Reduce greenhouse gas emissions (GHG) from agricultural production.
  (see “Sustainable Food Production Systems”)