Blazing a trail for a new soils mindset
March 13, 2008:
Thinking long-term is critical to support soil conservation practices and address modern issues such as greenhouse gas emissions.
Built over centuries. Changed in an instant.
These two facts about soils are arguably the most important to keep in mind as Canada aims to conserve its soils for the next century and beyond, says Dr. Brian Amiro, head of the department of soil science at the University of Manitoba.
"On the Canadian prairies, our soils are built up from the last glaciation, but with new farming approaches and other practices we can alter them very quickly," says Amiro. "These changes have wide-ranging effects, not only on the soils themselves but on the variety of ecosystems where soils play a central role."
Because soils take decades and even centuries to build, viewing soil management with a long-term perspective is as essential as it is challenging, says Amiro.
"We absolutely have to think long-term and look long-term," he says. "It's the only way to truly understand our soils and conserve them in a sustainable manner."
Producer backing critical
In agriculture, getting producers on side with this concept is critical, says team leader Peter Gamache of Alberta Reduced Tillage Linkages, a program that works with Alberta farmers to increase the adoption of sustainable production systems.
There are many agricultural producers who want to conserve soils, says Gamache. But in order to do that, they also need to survive economically. "Today we have the knowledge and tools to accomplish both."
Alberta Reduced Tillage Linkages
Short-term needs can't be ignored, but a strong focus on longer term impact can't be overlooked for farmers to keep soils productive and get the most overall value.
"Tillage practices are a good example," says Gamache. "From our experience, most farmers who switch to minimum tillage practices do see some changes in their soils in the first three, four, five years. But it's really in the seven-to-10 year range where the major benefits kick-in – you see a much healthier, much more productive and sustainable soil base."
It's not an immediate payoff strategy, but in the end it's a much bigger payoff strategy, he explains. "The key is to stick with it. The result is better production and less input requirements that can be sustained over a long career of farming."
Don't lose soil heritage
Long-term soil research plots are a key resource to get that message across, both to agricultural producers and society in general, say both Amiro and Gamache.
These plots are also a unique and irreplaceable tool for generating knowledge to strengthen soil management practices.
"These long-term plots provide a tremendous amount of value," says Amiro. "They're not something you can re-create. It's critical we keep them going."
Case in point are two historical long-term soil plots in Western Canada – the Breton and Lethbridge plots, which are nearly 80 years old and over 100 years old respectively.
University of Manitoba
The Breton plots, established in 1929 and managed today by the University of Alberta, were originally designed to identify farming systems suitable for the wooded soil belt. Today, they address a wide swath of questions and are the oldest soil research plots on gray luvisolic soils in Canada and possibly the world. The Lethbridge plots, set aside in 1902 and managed today by Agriculture and Agri-Food Canada, are a similarly rare global resource for brown soils, delivering unique knowledge on how soils change over time and, as a comparative example, on the impact of various agricultural practices.
Both long-term plot locations are used to assess the interaction among environment, crop productivity and soil quality, including specific studies to examine big picture aspects such as the long-term flux of soil carbon under different farm production systems.
"The long-term plots are really the only ones that can provide an appropriate baseline to look at these types of issues," says Gamache.
Protecting existing plots is essential to harvest the investment they represent and avoid losing decades of progress, says Amiro.
Manitoba once had multi-decades-old plots similar to Breton and Lethbridge, but those were lost to land development pressures. "That was a huge loss," he says. As a result, the longest term Manitoba soil plots are now just 14 years old. "We still learn a heck of a lot from these plots," says Amiro, "but it will take decades for them to provide the type of knowledge we could have gotten from our older plots."
Look at modern practices
A key priority for the establishment of new long-term plots is to more thoroughly examine the effects of modern practices, says the conservationists. For example, in agriculture, the effects of various crop rotations, tillage practices and manure applications.
"These are the elements we want to look at in new plots we're planning to establish near Glenlea (Man.)," says Amiro.
In agriculture, on a year-to-year scale, researchers have learned a lot about what nutrients and other components are needed to keep soils healthy and productive. But in the lifetime of the soil, knowing what happens over a three or five year period doesn't tell very much.
"Plots that examine the newer practices will help us gauge where these practices are taking us."
Think big picture
The reach of long-term plots goes far beyond just agriculture or even soil management, says Amiro. The Breton and Lethbridge plots help researchers understand issues that weren't even thought of at the time they were established, such as climate change related to greenhouse gas emissions.
"Long terms plots can show that stored soil carbon is lost very quickly with new practices that disturb soil or leave less organic matter," says Amiro. "And it takes decades to build them up again, once we change a practice."
Carbon in forest soils is also very important, he says. "At forested sites. Trees gather in the carbon dioxide and ultimately it is the soil that becomes the reservoir for the stored carbon."
Long-term studies of soil plots in forested areas have been slower to emerge than have agriculture related plots, but some key plots have been established for a decade or more and are now yielding important data, says Amiro. Plots near Thompson, Man., established in 1994 by Harvard University, and now operated by the University of Manitoba, are now the longest running studies of carbon exchange in boreal forests in the world.
"One of the main aspects we've studied at the Thompson plots is carbon fluctuations," says Amiro. "We've found there's quite a lot of variability. The forest lost carbon from about 1994 to 1998, then were neutral from 1998 to 2000, then since 2000 have been gaining again. This is another example that reinforces you really need long-term data to get past the year-to-year variability and see what the real trends are."
Get the complete story
From a broader environmental and societal perspective, it's important more emphasis is placed on understanding soil management issues not only in the context of industries such as agriculture or forestry, but from an ecological health viewpoint, notes Amiro.
Soil itself is very complex, containing a collection of air, water, organic matter and various living organisms. It plays a vital role in sustaining life on the planet and a unique connection role between the biosphere, atmosphere and hydrosphere.
"Soil really does make a huge difference to the whole ecosystem," says Amiro. "One of the real issues in appreciating this is that soil is a tremendous buffer. It is biologically rich and is a living medium, and every time we change a practice we affect how that critical living medium is operating. But because of its great buffering capacity, it takes much longer for either solutions or problems to show up in the soil environment."
The latest thinking in soil science is pushing for more studies of soils and related systems on a macro-level basis, to capture more of the true nature of soils and their broad impact, he says.
"When we view soils on a narrow basis, we're not really getting the complete story," says Amiro. "For example, there may be a practice that appears very good for a particular industry, but may have effects on water holding capacity or other aspects that won't show up for decades.
"We're realizing we need to ask different questions that what we've typically been asking, to get a better handle on those broader long-term implications. I think today we're on the edge of a much better understanding of what those questions should be."