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EAP Publication - 16

An Introduction to Sustainable Agriculture

prepared by Ecological Agriculture Projects Macdonald College of McGill University June, 1989


Sustainable agriculture is both a philosophy and a system of farming. It has its roots in a set of values that reflects an awareness of both ecological and social realities. It involves design and management procedures that work with natural processes to conserve all resources, minimize waste and environmental damage, while maintaining or improving farm profitability. Working with natural soil processes is of particular importance. Sustainable agriculture systems are designed to take maximize advantage of existing soil nutrient and water cycles, energy flows, and soil organisms for food production. As well, such systems aim to produce food that is nutritious, without being contaminated with products that might harm human health.

In practice such systems have tended to avoid~ the use of synthetically compounded fertilizers, pesticides, growth regulators, and livestock feed additives. These substances are rejected on the basis of their dependence on non-renewable resources, disruption potential within the environment, and their potential impacts on wildlife, livestock and human health. For example, synthetically compounded fertilizers and pesticides generally suppress biological activity in the soil. Some growth regulators and feed additives are implicated in retarding the decomposition of manure and are potential human health hazards. Instead, sustainable agriculture systems rely on crop rotations crop residues, animal manures, legumes, green manures, off-farm organic wastes, appropriate mechanical cultivation, and mineral bearing rocks to maximize soil biological activity, and to maintain soil fertility and productivity. Natural, biological, and cultural controls are used to manage pests, weeds and diseases.

An evolving approach to agriculture

Sustainable agriculture has been practiced for many decades and encompasses a tremendous number of different approaches described by many different names. To this point, most of these approaches have largely been limited to the substitution of environmentally

More significant advances can be expected, however, as a result of developments in the science and art of agroecosystem design and management. The names of the major schools of thought in sustainable agriculture are outlined in Figure 1, and are classified according to whether their operating principles are based on concepts of "efficiency", "substition", or "redesign".

Many of the approaches in conventional agriculture (minimum tillage, chemical banding) would fall into the "efficiency" category. They demonstrate a reduction in resource use and associated negative environmental impact, and in many cases a reduction in input expenses for the farmer. They represent, however, only an initial step towards a truly sustainable system.

Efforts to substitute safe products and practices (botanical pesticides, biocontrol agents, imported manures, rock powders and mechanical weed control) are also gaining popularity. Despite the reduced negative environmental damage associated with them, they remain problematic. Botanical pesticides also kill beneficial organisms, the release of biocontrols does not address the question of why pest outbreaks occur, dependence on imported fertilizer materials makes the system vulnerable to supply disruptions and excessive cultivation to control weeds is detrimental to the soil.

The systems that focus on redesign of the farm are the most sophisticated and generally the most environmentally and economically sustainable, especially over the long term. These farm systems recycle resources to the greatest extent possible, meaning that little is wasted, few pollutants are generated, and input costs are reduced substantially. For example, chicken and orchard operations have been successfully integrated. The manure is used as a fertilizer, the chickens eat pests that attack the fruit, the feed bill for the chickens is greatly reduced, and the eggs and/or meat can be consumed or sold. Three to seven year crop rotations can be designed that minimize tillage, use legumes and green manures to maintain soil fertility, prevent pest and disease outbreaks, and provide a diverse diet for livestock.

Pigs and goats can be used to renovate wooded lands in preparation for sheep pasture. The pigs and goats replace the petrochemical energy that would be consumed in machines, herbicides and fertilizers. All these practices involve redesigning the farm (as well as the institutional supports, which will be discussed later).

As in conventional agricultural systems, the success of sustainable approaches is very dependent on the skills and attitudes of the producers. The degree to which different models of such farms are sustainable is very variable, and is dependent on the physical resources of the farmer, and the degree deficiencies in support farm, the talents and commitment of the of support available. The current from government, universities, and agricultural professionals means that farmers must often rely on their own talents and commitment.

The economics of sustainable agriculture

Once a farm has passed through the transition period, it is likely to be at least as profitable, if not more so, than under conventional practices. The principal reason for this is the decline in input costs, to, on average, 1/3 below conventional costs. Yields commonly decline in some crops (e.g., corn, potatoes) but increase in others (e.g., hay, soybeans, oats, barley), especially during dry years, when the better water holding capacity of the sustainably managed soil translates into a production advantage. Existing literature suggests that, when yields of commonly grown crops are averaged, there is an overall 10` yield decline compared to yields in conventional production systems. Total yield of all products on any individual farm, however,

that takes place, and the addition of complementary animal and crop production systems. If a premium price can be obtained for the products, then the profitability of the operation may exceed that under conventional operation. Returns to labour are often lower, either because yields are somewhat lower or because labour requirements increase. However, labour needs are usually more spread out over the year. Work may also be more rewarding as a result of diversification and reduced risks to health.

On a regional or national level, it appears that more widespread adoption of sustainable agriculture can meet many of the government's stated policy objectives for agriculture. Studies done to date indicate that total net farm income would increase, government subsidy payments could decline, environmental damage would decline, food quality would improve, and rural employment possibilities rise. Potential problems that could develop include a decline in export of major commodities such as wheat (due to diversification of production), dislocations in the farm input supply sector, and a shortage of skilled labour, manure and sources of potassium.

The role of certified organic food and farming

Some producers have chosen to employ sustainable production practices that will permit them to market their produce as "certified organic". There are no national estimates yet of what percentage of production from sustainable practices is marketed in this way,.but in Québec, the figure is estimated at about 30%.

Use of the label "certified organic" developed as a way to assure consumers that the food they are eating is, in fast, grown according to the practices that are commonly associated with the word "organic". Those involved in promoting "organic" food have seen what happened to the "natural" food market. Because "natural" was not clearly described it was easy for the work to be coopted and to be used to describe almost any kind of food product or process. The term "organic", first used extensively in the USA by J.I. Rodale. founder of Rodale Press, has continued to be used because it is the term most understood by consumers in the market place. Attempts to use other words that more accurately describe sustainable agriculture practices have failed to become established, principally because they had no meaning in the marketplace. Le Ministére de l'Agriculture, des Pecheries, et de l'Alimentation du Québec (MAPAQ) has agreed that this term is appropriate for this reason.

The certification process is useful in our food economy because consumers usually do not know the farmer whose products they are buying. Many organic growers are involved in interprovincial and international trade. In some countries, such as Japan, certification has not been as important a development. The Japanese sustainable agriculture movement has instead focussed on bringing consumers and producers closer together by creating consumer producer cooperatives and buying groups, thereby reducing the need for certification. In this kind of system, consumers may even be involved in farm management decisions. This approach is also being practiced in a few places in North America.

Certification standards have been developed for most provinces in Canada. Although they all have a common base, they often differ in details, depending on the ecological and economic conditions that exist in the region. Although based on "agroecological" principles, each set of standards is in fact a compromise between the ideal situation and the state of development of sustainable practices in each region. For example, in some standards, certain fertilizers and pesticides are permitted even though they may have detrimental effects on beneficial soil organisms, natural pest control agents and wildlife. In many cases, our understanding of the ecology of a pest or production system has not advanced to the point where we can assure a productive and profitable system without using such products over the short term. As described above, the sustainable agriculture movement is very diverse, so each set of standards is also a compromise between the different schools of thought.

Ecology as a tool to understand sustainable agriculture

It is common to hear a farmer say, "I don't grow my crops this way because it's organic, I do it because it makes good agronomic sense". What has become increasingly clear to a growing number of agricultural professionals in the last few years is that good agronomy is based on an understanding of ecology. An "agroecological" approach is used increasingly by agricultural professionals to analyze the success of sustainable farming systems, and to identify ways of improving the productivity profitability, and resource efficiency of them.

Agroecology is a relatively new scientific approach (dating from the 1940s) and has not yet attained the stature of other agricultural disciplines. As a result, most of today's agriculture: professionals have little formal training in this area, or' soil or even crop and livestock ecology. This situation : changing rapidly, particularly in the USA and Europe. Many schools now offer undergraduate and graduate programs in ecological agriculture. For example, the core undergraduate program o] the University of Maine is the Sustainable Agriculture Program. In Quebec, the greatest interest in providing training in this area is coming from the Commissions Scolaires, the ITAs and the CEGEPs (junior college-level institutions). Macdonald College will be offering a 24-course Minor in Ecological Agriculture starting in September 1989. Laval is beginning a program entitled Agriculture and Environment. Guelph is developing a course, and a number of community colleges across the country are also investigating possible offerings in this area. Some governments, including MAPAQ (the Québec department of agriculture), are preparing training programs for their agricultural professionals in order to be able to provide services to interested farmers.


Sustainable agriculture approaches are being adopted throughout North America at a rapidly increasing rate. Quebec's main farm organization, Union des producteurs agricoles, has estimated that 40% of Québec producers will be practicing sustainable agriculture within 20 years. Governments are introducing legislation and programs to support these initiatives. Agricultural professionals have been slow to respond to the needs of these producers, but many are now actively pursuing training and research in this area in order to contribute to this growing movement.


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