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the dirt on dirt…

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We focus a lot of our attention on what grows out of the ground and what we build on top of it, but often, little attention to the ground itself.  The overall health of our soils is important in supporting the growth of all of our foods and fibres, whether directly or indirectly, but also plays a global role with many other functions.

“Soil acts as a filter, cleaning air and water. It exchanges gases with the atmosphere and thus influences global climate. Soil receives organic wastes and recycles their nutrients back to plants; it also holds and breaks down some toxic wastes. Because soil plays such a key role in world health, economies, and environmental stability, we must conserve it and use it in a sustainable manner. (The Health of Our Soils, 1995)

What are the problems with our soils?

Our ecosystems are interrelated and, in order to produce healthy food year after year, care must be put back into the soil to maintain its integrity and ability to support new growth.  Often, the pressure to produce more foods causes the focus to shift to crop yields rather than soil health.  When the soil health starts to decline, increased amounts of chemical fertilizers and pesticides will be used to maintain a certain level of production in poorer soils.  Unhealthy soils are less able to utilize these chemicals and increased application results in chemicals running into water systems (The Health of Our Soils, 1995).

The key soil degradation processes include: erosion, salinization and water logging, compaction and hard setting, acidification, loss of soil organic matter, soil nutrient depletion, biological degradation, and soil pollution. Agricultural activities influence all these processes (Agriculture at a Crossroads, 2009).

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The 2012 World Bank Report on Climate Change

Climate change is also likely to have adverse affects on our soils and the amount of arable land that can be used for agriculture. “Given the competition for land that may be used for other human activities (for example, urbanization and biofuel production), which can be expected to increase as climate change places pressure on scarce resources, it is likely that the main increase in production will have to be managed by an intensification of agriculture on the same—or possibly even reduced—amount of land. Declines in nutrient availability (for example, phosphorus), as well as the spread in pests and weeds, could further limit the increase of agricultural productivity. (Turn Down the Heat, 2012)” Global crop production may increase with some increase in world temperatures (predicted from 1°C – 3°C) but beyond a certain level will decline substantially.  Increased drought and desertification will put incredible pressure on food production systems to feed more in less space.  Interestingly, with increased CO2 levels in the atmosphere, there will actually be a fertilization effect to a certain extent for many crops.  The World Bank Report on Climate Change indicates that this effect will be washed out by the negative impacts like drought, however.

The Global Assessment of Human-induced Soil Degradation (GLASOD) showed that soil degradation in one form or an- other occurs in virtually all countries of the world. About 2,000 million hectares (23% of all used land) are affected by soil degradation. Water and wind erosion accounted for 84% of these damages, most of which were the result of inappropriate land management in various agricultural systems, both subsistence and mechanized (Agriculture at a Crossroads, 2009).

Conventionally, adding fertilizers to our soils has drastically improved the yields from our farm.  In fact, the development and burgeoning use of fertilizers in the 1970’s was a part of what was dubbed the “Green Revolution” because of the significant improvement to crop yields of cereal grains.  It was an important part of food strategy for increasing production and feeding our exploding populations worldwide.

There are some troubles with the widespread application of fertilizers – increased greenhouse gas emissions, the amount of energy that goes into producing the fertilizer chemicals and the eventual effect that it has on soil health and sustainability.  Nitrogen fertilizer use has lead to the increase of nitrous oxide emissions (N2O  – the same stuff that makes you giggle at the dentist) which is a much more potent greenhouse gas than carbon dioxide or methane.  Ammonia-based fertilizers result in large methane emissions.  In terms of energy use, approximate 5% of our world’s natural gas supplies go toward the production of ammonia for fertilizer – almost 2% of our total world’s energy supply! (Wikipedia – Fertilizer) – and results in the corresponding greenhouse gas emissions from fuel use. If we endeavour to move to a carbon-free future in any respect, we will have to figure out a way to ease our dependency on chemical fertilizers.

From IAASTD’s Global Report on Agriculture, “The impact of nitrates from fertilizers and livestock production on soil and water resources is a related issue. This impact can be described in general terms as the nitrification of the global ecosystem from inorganic fertilizers and alteration of the global nitrogen cycle. Eutrophication as a consequence of nutrient runoff from agriculture poses problems both for human health and the environment. Impacts of eutrophication have been easily discernible in some areas such as the Mediterranean Sea and northwestern Gulf of Mexico.”

So how can we improve our soils?

Support alternative agricultural practices

Organic, urban and peri-urban, and conservation agriculture are all practices that can help to ensure that soil health is maintained.  Organic agriculture helps to ensure that less chemicals are being applied to the soils and enter the ecosystems (though a reliance on manure fertilizers have negative environmental implications).  Urban and peri-urban practices can make use of limited spaces and encourage biodiversity, but there can be environmental impacts from pesticides and pollution from agricultural activities in densely populated areas.  It could have very positive implications for food supply however, “For example in Hanoi, Vietnam, urban and peri-urban agriculture supplies about one-half of the food demand and engages more than 10% of the urban labor force in process- ing, marketing, retailing, input supply, and seed and seedling production (Agriculture at a Crossroads, 2009)“.

Conservation agriculture puts an emphasis on zero-tillage, crop rotations, use of cover crops and maintenance of plant cover through the year.  It promotes minimal soil disturbance with no plowing or harrowing, maintenance of permanent vegetative soil cover, direct sowing and sound crop rotation (Agriculture at a Crossroads, 2009).  “Broader adoption of conservation agriculture practices would result in numerous environmental benefits such as decreased soil erosion and water loss due to runoff, decreased carbon dioxide emissions and higher carbon sequestration, reduced fuel consumption, increased water productivity, less flooding, and recharging of underground aquifers” (Agriculture at a Crossroads, 2009).

Getting to know some of your local food producers can be a way of learning how to support these various techniques.  For example, our Community Shared Agriculture program this summer provided us with a basket of veggies each week that we know are being grown with organic and conservation agriculture practices.

Trying to grow some veggies in your own backyard can be a great way to start appreciating how soil health can support plant life.  Planting nitrogen-fixing plants (the plants that take nitrogen out of the air and mineralize it into their roots, which is then transferred into the soil to fertilize other plants!) in rotation can keep the nutrient-levels of your soils up while letting you enjoy peas and beans!

Increase the organic matter in soils

Plants that grow from the soil take some of the nutrients from the soil to make the plant – when these plants are harvested, those nutrients are removed from the system entirely.  If you can help return organic matter to the soil, nutrients will be replaced.  “Commercial fertilizers can be added to replace nutrients removed from the soil but they do not directly build up soil organic matter. Rather, they promote plant growth, which in turn results in more residue being returned to the soil. Other materials, such as crop residues, animal manure, green manure (leguminous plants, such as alfalfa and red clover, and grasses), compost, peat, and wood chips must be added to maintain or increase soil organic matter. (The Health of Our Soils, 1995)

Whatever you can do to add organic matter to soils, will ultimately help preserve the quality of your soil as you use it.  When you harvest your haul of veggies, leave the roots and leaves and stalks and anything else that you aren’t actually eating on and in the ground to help put some organic matter back into the earth.  That pumpkin you carved for Hallowe’en? Toss it in the backyard before it snows and in the spring you’ll have a nice mushy lump of organic matter to turn in the soil.  Apples from your tree this year?  Shake them into the garden!

Ditch the chemicals

While pesticide residues in Canada are not seen as a pressing issue right now (we have only been practicing agriculture throughout the prairies for about 100 years) there is cause for concern about the accumulation of agro-chemicals in our ground and surface water.  “Although most of the Prairie ecozone is thought to be at low risk of contamination by agrochemicals, their entry into the subsoil and groundwater can be significant under certain conditions. For example, applying feedlot cattle manure on the land at the maximum recommended rates has resulted in substantial soil and groundwater contamination by nitrate at some locations in Alberta. (The Health of Our Soils, 1995)

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Green Calgary’s Pesticide Free signs

If you’re in the city, join the “Growing Movement” and go pesticide free.  Get out and enjoy the sun and the invigorating exercise of pulling weeds by hand.  We love dandelions because they provide the first food of the spring for our sleepy bees and all of our other native pollinators and can mean the difference between a starved hive and a thriving one.  We can appreciate, though, that not everyone shares a love for dandelions.  Staying on top of them and pulling them before they go to seed will eventually see the departure of that wonderful little weed from your yard.

It is illegal in Calgary to wash your car in the street because our run-off sewers go straight into the Bow River.  Chemicals applied to your yard that are washed away during rain will end up in the same place.

Change things up

Rotating your garden and companion planting to increase the diversity of plants growing in your soil is another way to improve its health.  Companion planting can also allow you to take advantage of some pest control techniques to avoid using chemicals, for example planting onions around your carrots can help keep bugs away from the carrots.

According to the UN Food and Agriculture Organization, “Crops should be mixed and their spatial-temporal distribution varied, to create a greater diversity of niches and resources that stimulate soil biodiversity. For example diverse habitats support complex mixes of soil organisms, and through crop rotation or inter-cropping, it is possible to encourage the presence of a wider variety of organisms, improve nutrient cycling and natural processes of pest and disease control” (Organic Agriculture and Soil Biodiversity).

Eat less meat

There are a couple of things that can help to improve soil from a global perspective.  World meat consumption is expected to increase 70% by 2030 and is one of the major causes of increased fertilizer use – which is expected to increase by 188 million tonnes in the same period!  “These systems can lead to concentration of manure; although manure is a valuable source of nutrients, concentrated spreading of manure leads to significant emissions, to air, soil and water. (Agriculture at a Crossroads, 2009)”  The demand on our agriculture system to produce more meat from smaller amounts of land will put an incredible amount of pressure on our farming systems.  By decreasing our own demands on the amount of meat that needs to be produced will allow our limited resources to produce more food and calories in, hopefully, more sustainable ways.

At the end of the day…

“Soil degradation is the most serious crisis facing the agricultural industry in the long term. This statement does not diminish the facts of the current economic crisis in some sectors of agriculture, but economic problems are cyclical in nature, and it is to be hoped that the present problems will be managed satisfactorily in the near future. On the other hand, soil degradation is with us today, and will be with us tomorrow, next year, and forever. Unless we take further action, we shall lose the competitiveness of our agricultural industry in the next few years. The health of the agricultural industry depends on both the quantity and the health of the soil.”  (The Health of Our Soils, 1995)

Even though these words came from a report written in Canada almost 20 years ago:, the message remains the same today.  If anything, the scope of the danger has only increased from agricultural competitiveness to the ability to feed our growing population in the future.  

How do you feel about the dirt beneath your feet?  Leave us a comment!

Resources

Agriculture and Agri-Food Canada. The Health of Our Soils: Toward sustainable agriculture in Canada.  1995. 

Report for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics. Turn Down the Heat: Why a 4°C Warmer World Must be Avoided. November, 2012.

IAASTD Global Report. Agriculture at a Crossroads. 2009.

http://en.wikipedia.org/wiki/Fertilizer

UN Food and Agriculture Organization. ORGANIC AGRICULTURE AND SOIL BIODIVERSITY http://www.fao.org/ORGANICAG/doc/soil_biodiversity.htm

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