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Health of our Soils | Index

Summary

L.J. Gregorich and D.F. Acton

Introduction

Soil health is indisputably a major factor in our ability to sustain agricultural activities in Canada and to safeguard the environment. This report defines soil health in terms of agriculture and presents key results of research undertaken in the past decade to increase our understanding of the factors affecting soil health, to monitor indicators of soil health, and to identify and refine farming practices that help to maintain and improve soil health. It also gives a picture, although an incomplete one, of the health of Canada's agricultural soils today.

Apart from small areas of agricultural expansion, Canada has reached the limit of land suitable for crop production. Thus, agricultural productivity will be maintained mainly through wise use of present resources preserving the area and the quality of land currently in agricultural use.

Current and future trends in soil health

The use of conservation farming methods has increased over the past 10 years. As a result, some agricultural soils are improving in quality and becoming less susceptible to erosion and other damaging forces. For example, levels of soil organic matter have increased in some areas, the risk of erosion has decreased nearly everywhere in the country, and the risk of salinization has decreased in the Prairie Provinces. However, this general improvement is a small one overall, and does not apply to all soils. On the other hand, it provides proof that the health of our agricultural soils can indeed be maintained and even improved with the right care.

Three general trends emerge from this assessment of soil health:

• Soil health will continue to decline in areas of intensive cropping and marginal land where conservation farming methods are not used.
• Soil health is holding steady or improving in regions where conservation practices have been tailored to local problems of soil degradation.
• Declines in soil health occur rapidly, often most dramatically in the first 10 years following conversion of virgin land to agriculture; improvements in soil health take place slowly and at greater cost than maintenance.

Because of the wide diversity of landscape, inherent soil quality, and farming systems in Canada, more specific trends in soil health are best observed and interpreted at the regional level.

Obviously, agriculture involves the rearranging of nature to bring it more in line with human desires, but it does not require exploiting, mining, or destroying the natural world.

Don Worster
Good Faming and the Public Good in Meeting the Expectations of the Land

British Columbia

Mild climate and adequate rainfall permit a long growing season in southern British Columbia. Deteriorating soil quality in this region is mainly related to cropping intensity, particularly of high-value specially crops, and the associated machinery traffic and use of agrochemicals. Agrochemical entry into groundwater is a serious problem where farmland overlies shallow aquifers. Table S-1 presents important findings on soil health in this region.

Prairie Provinces

In the Prairie Provinces a large area of soils are inherently of good quality, and this region has generally suffered comparatively less soil degradation that other regions of the country. Many agricultural soils are subject to the stresses of a dry climate and are susceptible to certain degradative process, particularly wind erosion and salinization. The reduced risk of wind erosion over the past 10 years is attributed to reduced use of summerfallow and increased use of conservation tillage and other erosion controls, such as permanent cover and shelterbelts. The risk of salinity attributed to agricultural practices has decreased in some areas, apparently because of the use of salinity controls (permanent cover, extended rotations). Conservation practices have resulted in stabilized levels of soil organic matter in some areas. Further improvements in soil quality are expected as more farmers adopt these methods. Important aspects of soil health in this region are presented in Table S-2.

Central Canada

Many soils in central Canada are under the stress of intense cultivation; cropping intensity (defined as cultivation of more than 70% of total farmland) has increased by 3% in southern Ontario over the past 10 years. Large areas have low levels of soil organic matter, and soil health is expected to decline further if conservation practices are not adopted. Areas of intensive cropping, row-cropping, and monocultures are particularly vulnerable to continuing degradation. Extended crop rotations, conservation tillage, and organic matter added to the soil have all resulted in improved soil health in some areas. The large livestock industry in this region creates the need for manure disposal; manure is a beneficial soil amendment, but future management of this resource must consider its potential to contaminate groundwater with nitrate and bacteria. Aspects of soil health in this region are highlighted in Table S-3.

The energy contained in nature in the earth and its waters, in the atom, in sunshine will not avail us if we fail to activate the most precious vital energy; the moral-spiritual energy inherent in man; in the inner recesses of his being; in his mysterious, uncompromising, unfathomable, and divinely inspired soul.

Daniel Hillel
Out of the Earth:
Civilization and the Life of the Soil

Atlantic Provinces

In the Atlantic Provinces, poor inherent soil quality combined with intensive agricultural activity has resulted in severe soil degradation in many areas. Row-cropping and short rotations have contributed to this condition. On the other hand, soil organic matter levels have increased in areas where rotations have been extended and forage crops have been plowed into the soil. As producers adopt these methods along with practices that control erosion, soil health should continue to improve. Important findings on soil health in this region are given in Table S-4.

Current and future trends in water quality

The chief effect of agriculture on water quality is the entry of nitrate into groundwater and surface waters. Nitrate is found in virtually all groundwaters in the agricultural regions of Canada. Its main sources, apart from naturally occurring nitrate, are fertilizers and manure. Regions that currently have significant problems with nitrate entering groundwater are southwestern British Columbia and scattered locations throughout southern Ontario, Quebec, and the Maritime Provinces. The future of water quality as it relates to nitrate contamination is mainly a matter of controlling the amount of nitrate applied to soil. Trends in water quality will be determined by producers' willingness and ability to match the rate and timing of manure and fertilizer application to crop needs, as well as by the ability of soils to retain nutrients (determined by levels of soil organic matter). Contamination of water by bacteria derived from manure is expected to decrease as producers use refined methods of storing and applying this soil amendment.

Water contamination by pesticides is less serious now than 10-20 years ago, because the pesticides in current use are generally less persistent and more specialized. However, pesticides are present in waters of some areas of the country (aquifers in southern British Columbia and domestic wells in southern Ontario, Quebec, and the Maritime Provinces), and the long-term effects of these substances are usually unknown. Public concern about the potential health hazards of water contamination is expected to encourage the trend toward decreased use of agricultural pesticides and increased use of non-chemical pest controls.

Methods for improving soil quality

Although soil degradation has taken place since cultivation first began, the problem became urgent in the prairies during the 1930s and seriously affected the rest of the country by the 1970s. The high value placed on maximum crop yields created pressures on producers to increase production by using more mechanization, fossil fuels, and agrochemicals. High crop yields often came at the expense of soil health.

In the past decade, the problem of soil degradation has received considerable attention and is now better understood. Research and regular monitoring continue to improve our understanding of the processes that degrade soil. But soil health will not be maintained or improved unless corrective action is taken. This corrective action must involve both stopping practices that degrade soil health and starting practices that enhance it.

Conventional tillage pulverizes soil, breaking down soil structure and increasing the risk of wind and water erosion. Tillage machinery causes tillage erosion and compaction of the soil. Some traditional cultivation practices also result in deteriorating soil health, because they promote erosion and the loss of soil organic matter. These include:

• up- and down-slope cultivation
• intensive row-cropping
• monoculture
• fallowing.

Practices that enhance soil health do so by building up and protecting soil organic matter and soil structure. These practices include:

• conservation tillage, including no-till
• residue management
• contour cultivation on hilly land
• application of organic amendments, such as manure, compost, and sewage sludge
• reducing fallow by extending crop rotations or cropping continuously
• including legumes and forages in crop rotations
• water management
• erosion controls, including growing forages in rotation, interseeding, planting shelterbelts, strip-cropping, and restructuring the landscape (such as with terraces, grassed waterways, diversions).

Trends in management practices

Most agricultural soil degradation is the result of inappropriate farming techniques. It stands to reason then that soil degradation can be abated by changing these techniques. The management practices needed to improve soil health not only exist but are already being used in many parts of Canada. Future trends in soil quality will depend on how quickly these practices are adopted by producers who are still using conventional farming methods.

In 1991 the Census of Agriculture required producers to report on land management practices for the first time. Agriculture and Agri-Food Canada staff used this information to assess the use of these practices at the national and regional levels. This assessment can be used as a baseline for determining changes in land management practices in the future.

Conservation tillage generally improves soil health by reducing the mechanical disturbance of soil, protecting the soil surface with residue cover, and adding more organic matter to the soil. In 1991, conservation tillage (including no-till) was used on one-third of Canada's cultivated land. This type of tillage is increasing in popularity, especially in the Prairie Provinces, where there is a great need to reduce the effects of wind erosion, and in Ontario (Table S-5). Conservation tillage is used mainly on large farms that grow cereal crops and grain corn. It is used least in the Atlantic Provinces. Conventional tillage continues to be used in areas where manure must be tilled into the soil.

The 30% reduction in the area of fallowed land in the past 20 years (see Chapter 2, Table 2-1) has contributed to the decreasing risk of erosion. The shift toward continuous cropping and extended rotations on this land has resulted in greater returns of organic matter to the soil.

Growing legumes and forages in rotation with other crops helps to present erosion and builds up soil organic matter. In 1991, forages were grown on 42% of Canada's farms, mainly in the humid regions of the country (see Chapter 7, Table 7-1).

Ultimately, the fate of the soil system depends on society's willingness to intervene in the marketplace and to forego some of the short-term benefits that accrue from "mining" the soil so that soil quality and fertility can be maintained over the long term.

E. Odum
Ecology and Our Endangered Life Support Systems

Improving soil quality in the future

Promotion of conservation farming in the past 10 years has tended to focus on individual management practices, such as conservation tillage. However, because each area of land has its own unique characteristics, not all conservation practices are suitable for all areas. For example, conventional tillage is superior to conservation tillage in some areas where the soil benefits from being broken up occasionally. Furthermore, conservation practices are usually most beneficial when used in combination, such as conservation tillage plus continuous cropping with an extended rotation. This means that a soil management program must be site-specific, or tailored to the needs of a specific soil. This is best done at the farm level. (An integrated farm system plan)

Farming systems

Management practices should be combined in farming systems (overall plans to manage cropping and soils) that are aimed at keeping soils healthy and productive. These systems require the usual decisions about the variety, pattern, and sequence of crops; tillage methods; and levels of inputs, including agrochemicals and organic amendments. But these decisions are made with the understanding that they affect soil health and the broader environment, along with productivity. Systems also include a "producer factor," which assesses the level of skill, management ability, education, and commitment to conservation shown by the producer.

To hasten the adoption of conservation farming practices, policies and programs that encourage poor farming systems should be replaced by those that support beneficial ones. This shift in policy will require careful study of the factors that cause producers to select certain farming practices over others. It will also place an emphasis on finding better ways to transfer technology, ensuring that producers are knowledgeable about the factors that affect soil health, as well as about the farming methods that promote soil health.

Producers usually implement conservation farming only when they are convinced of its economic benefits. However, many of them are accustomed to evaluating farm economy only in the short term, based on markets and costs. Conversion to conservation farming is made more easily when producers realize that continued use of conventional methods will inevitably result in further soil degradation and declining profitability.

A carefully defined objective tells us where we are going, what the value is of getting there, and what is the probability of success. It is the measure of our achievement....Next we have to determine the cost, make the commitment to pay it, and then commit ourselves to keeping our commitment. Now we are ready to do battle.

Chris Maser
The Redefined Forest

New policy for sustainable agriculture

Agricultural policy has typically focussed on high production and has viewed agriculture as a closed system. The concept of sustainable agriculture creates a need for new policy that acknowledges the environmental effects of agriculture and promotes resource conservation along with productivity. This new policy should have the following objectives:

• to recognize agriculture as a human activity that affects both the local and the broader environment
• to maintain and improve agricultural soil health as an essential step in maintaining and improving environmental health and ensuring long-term farm profitability
• to maintain and improve soil health by promoting practices that build soil organic matter and otherwise protect soil structure
• to foster increased understanding of the factors affecting soil health and the means to maintain and improve it through continued research and monitoring programs
• to conserve agricultural lands and soils by curtailing their nonagricultural uses and by protecting against soil losses resulting from erosion
• to promote practices that conserve resources, including
  • recycling organic wastes (such as manure, compost, wood chips, and sewage sludge)
  • reducing the use of fossil fuels and agrochemicals and making their use more efficient
  • conserving water quality (mainly by minimizing off-farm movement of soil and agrochemicals)
• to support producers during their transition to conservation-farming systems.

Built on the foundation of these objectives, the goal of policy should be to diminish the degradation of agricultural soil and the broader environment and to maintain soil health by targeting programs to problem areas and problem farms. It is the task of policy-makers to use the findings of ongoing research and monitoring programs to design policy that reaches this goal effectively and quickly. (Sustainable land management)