Soil
Much of our Prairie landscape has gently rolling to hummocky topography. The parent geological material on which these soils formed is often glacial till that remained after the glaciers retreated 10,000 to 12,000 years ago.
Organic matter (OM) in soil is the result of hundreds to several thousand years of microbial, plant and animal residue additions to the soil. Soil organic residues are constantly breaking down and are in various stages of decomposition.
While the benefits of cover crops for soil health have long been touted by extension staff, it’s been difficult for researchers to determine how exactly cover crops affect the soil. But last year, an elaborate soil health monitoring system ­– the first of its kind in North America – was installed at the Elora Research Station, near Guelph, Ont.

Prior to installation, 18 soil columns were outfitted with multiple sensors at multiple depths for sampling soil water, nutrients and greenhouse gases. The measuring devices, called lysimeters, will be used to compare the environmental impact of two different long-term cropping systems. A conventional (non-diverse) corn-soybean rotation will be compared to a diverse rotation where cover crops and intercrops are included in a corn-soybean-wheat rotation.

In addition to evaluating how cropping systems impact soil health, the project will also measure the impact of crops on soil ecosystem services.

These are the benefits to society, such as increased carbon sequestration, reduced nutrient leaching and reduced greenhouse gas emissions....

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Recent rounds of wet weather over the past several years may contribute to an increase in salinity appearing in some areas of the Prairies. An increase in surface and subsurface soil water may bring dissolved salts into the rooting zone in concentrations high enough to impede crop establishment and growth. Traditionally, growers have planted salt-tolerant forages on the worst of their saline lands and barley on moderately saline soils.

“Growers are looking for a salt-resistant, non-cereal grain option as an alternative to barley, which is not that economically attractive compared to a crop like canola,” says Bryan Nybo, manager of the Wheatland Conservation Area (WCA) at Swift Current, Sask.

Growers concerned with soil degradation established WCA in 1983 with a special focus on salinity. It is now one of eight Agri-Arm research sites in Saskatchewan. Over the past several years, Nybo has been speaking to growers about research and completing demonstrations on using alternative crops on saline soils. One such demonstration was a 2012 Agricultural Demonstration of Practices and Technologies (ADOPT) trial conducted by Nybo. He demonstrated the option of growing canola in saline conditions.

“This demonstration of newer canola varieties attempted to emulate in the field what has been shown in the AAFC’s Salt Testing Facility by Dr. Harold Steppuhn, where canola has shown tolerance similar to barley,” Nybo says.

The Salt Lab opened at Agriculture and Agri-Food Canada (AAFC) Swift Current in 1988, and has provided practical solutions for Prairie farmers, ranging from the development of salt-tolerant crops and varieties, to assessing crop tolerances to salinity. Steppuhn worked at the Salt Lab for almost 30 years alongside technician Ken Wall, both who are now retired from AAFC. The Salt Lab has since been converted to a service facility, accommodating the research needs and projects of scientists across AAFC’s science and technology branch as well as private industry.

Steppuhn originally found hybrid canola had similar tolerance to saline soils as barley in controlled laboratory situations. He compared Harrington barley to Hyola 401 and InVigor 2573 canola. Emergence, stand density and plant maturity all decreased as saline levels increased, but at a similar rate for all varieties. In terms of relative grain yield, the two hybrid canola varieties actually performed slightly better compared to Harrington.

Relative grain yield of hybrid canola and barley at different saline concentrations
WTCM14 steppuhnSource: Harold Steppuhn, AAFC

Researchers use arbitrary ratings set up at the U.S. Salinity Laboratory to rate soil salinity. They classified soils with electrical conductivity (ECe) (a measure used by soil test labs) between zero and two deci-Siemens per metre (dS/m) as non-saline, between two and four dS/m as slightly saline, four to eight dS/m as moderately saline and above eight dS/m as severely saline. This corresponds to an approximate rule of thumb where a grower can observe the occurrence of white surface salts that equate to the field’s ECe rating: rarely if ever seen (zero to two dS/m); infrequently seen (two to five dS/m); frequently seen (five to eight dS/m); and almost always seen (greater than eight dS/m).

Recognizing that salinity is much more variable in the field, Nybo tried to replicate the Salt Lab trial with his ADOPT program. He developed a salinity contour map of the demo area using an EM 38 ground conductivity metre to measure soil conductivity. Two InVigor hybrids (5440 LL; L150), three Roundup Ready hybrids (45H29RR; DK73-75RR; VT 500), two Clearfield hybrids (BY5525 CL; 45H75 CL), a canola quality mustard (XCEED Oasis CL) and Harrington barley were seeded in strips down the saline gradient from non-saline to relatively high saline areas.

Nybo used EM 38 measurements to provide ECe readings rated from non-saline to relatively high salinity:

<80 EC non-saline
80 to 100 low salinity
100 to 130 low to moderate
130 to 160 moderate to high
>160 relatively high salinity

“We found that hybrid canola was able to perform quite well against Harrington barley, especially the hybrid varieties DK73-75RR and BY 5525 CL,” Nybo says. “EXCEED juncea canola didn’t perform as well as barley.”

Canola establishment at increasing levels of salinity (EM 38)
WTCM14
Source: Wheatland Conservation Area. 2012

While the ADOPT demonstration was able to show similar results as the Salt Lab in this trial, Nybo admits conducting agronomic work on salinity in the field is difficult because of soil and environmental variability. Salinity can vary from slight to severe within a short distance, making replicated trials difficult. That’s why the Salt Lab is so valuable to growers.

Steppuhn also studied salinity tolerance of camelina compared to InVigor 9590 canola at the Salt Lab as part of the Canola Agronomic Research Program (CARP) project. He found camelina did not have the same tolerance to saline soils as the hybrid canola. His May 2012 final report indicated: “Overall, root-zone salinity affected both camelina and canola grain yields more than it affected seedling emergence, plant survival, seed-oil content, and oil composition. However, as salinity levels increased, the camelina was more affected than the canola in seedling emergence and early survival, plant heights, relative grain yield and oil percentages. The primary impact of this research shows a need for caution when selecting camelina for saline fields that previously produced adequate canola crops.”

Nybo says the results of these demonstrations and research trials show hybrid canola may be an option where barley has traditionally been grown on moderately saline soils. He says because canola may be harder to establish, canola seeding rates may need to be increased. However, on soils higher in salinity, he cautions against growing an annual crop.

“On high salinity soils, you would still want to grow a salt-tolerant perennial forage as the best option,” Nybo says.

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It is more important now than ever before to educate youth on how to feed a population of nine billion by 2050. Fertilizer Canada has partnered with the Canada Agriculture and Food Museum to create a new Soil Lab Discovery Zone. The lab aims to educate Ottawa's youth about the overlooked foundation of agriculture: soil. Launched on Earth Day on April 22, the Soil Lab has already been met with positive response from schools and museum visitors.

The Canada Agriculture and Food Museum receives over 170,000 visitors annually – teaching them, with real soil science instruments, about the 13 essential nutrients found in soil, including the three most important to soil health and food production: nitrogen, phosphorus and potassium. The Soil Lab also highlights the chemical, physical and biological properties of soil and explains how farmers manage their cropland through sustainable fertilizer use.

Fertilizer is the primary source for replenishing essential plant nutrients like nitrogen, phosphorus and potassium in soil in order to keep fields sustainable and food on our tables. Plants absorb these nutrients as they grow, and therefore farmers must replenish the soil to keep it viable and avoid depleted fields for the future.
In parts of northeastern Saskatchewan, excess moisture and high water tables have prevented some growers from seeding certain fields in the Melfort area over the past few years. Water table levels have been monitored in the area since an observation well was installed in 1967, with the highest levels ever recorded in 2014. Water levels declined consistently from the mid-1970s until 2004, when they began to rise significantly through 2014. With the high cost of cropland, growers can't afford to not crop all of their acres.

“In 2014, a local area grower with land adjacent to the Melfort Research Farm contacted us to look into the potential of tile drainage,” explains Stewart Brandt, research manager with the Northeast Agriculture Research Foundation (NARF). “This 40-acre parcel, affected by excess water and salinity, had the Melfort Creek running through the quarter section. With grower investment and some additional funding (supported by the Agricultural Demonstration of Practices and Technologies [ADOPT] initiative under the Canada-Saskatchewan Growing Forward 2 bi-lateral agreement), we initiated a three-year project in the fall of 2014.”

As the first step before undertaking a tile drainage project, the landowner must contact the Saskatchewan Water Security Agency for approval. One of the most important factors is having a plan of where the water discharge from the tile drainage will be released, and to confirm that there is a viable outlet or point of adequate discharge, which means the amount of water being contributed from the tile drainage is insignificant compared with the amount of water flowing in the creek. For this project, the Melfort Creek provided the point of adequate discharge.

“Tile drainage is a long-term investment and requires careful planning and consideration,” Brandt says. “Getting professional design and installation support is recommended and for this project we worked with Northern Plains Drainage Systems Ltd. from Manitoba, who provided the design, engineering and installation. In late October 2014, we held a half-day workshop followed by a half day in the field learning about tile drainage installation.”

The costs for tile drainage vary depending on soil texture, design and installation requirements. On coarse textured soils, the tiles can be placed quite far apart, reducing costs, but in clay soils, the tiles need to be placed closer together at about 40 feet apart, which requires a lot more tile drainage material. For large areas or entire fields, usually the most efficient and cost-effective design is a parallel installation. In some situations, a targeted design can be installed for smaller problem areas where other parts of the field do not require drainage.

One of the most important components of the installation is developing the initial field elevation map. “Recent advancements in GPS technology have reduced the costs of generating an elevation map substantially,” Brandt says. “Instead of having to have a survey crew out to develop the elevation map, good elevation maps are easily generated with GPS technology, which also improves the efficiency and accuracy at installation. The major cost of the project is actually for the amount of tile drainage materials required and the installation. Typically the materials have had to be imported from the U.S., but more recently, a Canadian supplier is offering the materials.”

Regular monitoring of the tile drainage installation is part of the project and began as soon as the installation was completed in the fall of 2014. The water began to flow as soon as the tiles were installed and continued until freeze-up. It then started again in the spring of 2015. Except for a brief dry spell at the end of June 2015, the tile drain continued to run through the year. A large rainfall event at the end of July 2015 was successfully drained off the field and also reduced some of the salinity impacts at the same time. The rainwater flushed the salts down and out of the drain rather than allowing the salts to be pushed up through capillary action in the soil with excess water. “We monitored electrical conductivity [ECe] levels on the water coming out of the tiles in the fall of 2014, as well as the water in the creek. The initial ECe was 8,000 at the outlet and 9,000 in the creek, meaning the creek was more saline than the tile drains, which was a bit surprising. However, most of the creek flow in the fall is due to subsoil seep into the creek.”

In 2015, half of the field was seeded to canola and the other half, which was badly affected by salinity, was left in the permanent forage stand. Although there isn't previous yield map data for comparison, the canola yields in 2015 appeared to show a good response to the tile drainage. The grower was pleased with the results and removed the remaining permanent forage in the fall of 2015. The entire 40 acres was seeded to barley in the spring of 2016.

“By the end of June 2016, a fairly decent barley crop had been established and the productivity appears to be very good,” Brandt says. “We also have a reference area with two previous years of yield data outside the tile drained project that is badly affected by both salinity and excess moisture for comparison. The grower is very pleased with the results so far and is considering tile drainage installation on another 2,000 acres of cropland as time and investment allow.”

Similar to previous findings in Manitoba, this project is showing several benefits to tile drainage, although some are difficult to quantify in terms of economics. “Removing the excess water not only improves the water use by the crop but it also creates temporary storage for water from rains and spring runoff in the field,” Brandt explains. “It doesn't decrease the total amount of water going into the stream, but it delays peak stream flow after a rain. Other benefits include more timely field operations, earlier start to seeding, less crop drowning out, less compaction and better access, timing and utilization of fertilizers and pesticides. All of these factors have a big impact in particular in areas like northeastern Saskatchewan where we tend to have a very narrow window for seeding and harvest and timeliness of operations is critical.”

Brandt has received a lot of calls about this project and believes it has probably generated the most interest he has ever had on a project. There is lots of interest in tile drainage projects in the area and all along the east side of the province. Planning ahead, getting necessary approvals and being able to plan for installation after harvest if conditions allow are the key.

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Aggregates (or peds) are those crumbly bits of soil that we find in woodlands and native prairies.

Well-aggregated soil is highly productive even under adverse weather conditions. It has strength that resists water and wind erosion and compaction. It allows water infiltration and internal drainage. It has high levels of organic matter that contribute to moisture retention. Space between aggregates allows air for healthy root systems that can feed from a large volume of soil.

Soil aggregates form when organic matter is bound to soil minerals by glomalin – a sticky exudate primarily from mycorrhizal fungi. These fungi are a type of microbe that thrive in native undisturbed soil. Glomalin accounts for nearly 30 per cent of the carbon found in healthy soil. These fungi form as nearly invisible threads that penetrate plant roots and extend, often several meters out into the soil where they collect nutrients, particularly phosphorus, and also some water, and bring this back to the plant in exchange for sugars and starches taken from the plant. Most of these fungi do not survive soil disturbance. As a result, tillage quickly results in lost soil structure (aggregation) that leads to increased water and wind erosion, slaking, compaction and water loss.

The cropland manager can maintain or improve soil aggregation by eliminating full-surface tillage and planting in narrow strips of disturbed soil. When this is done continuously, mycorrhizal fungi and other soil biota can survive between these strips. Soil aggregation is enhanced when we further mimic nature by adding organic matter – by keeping crop residue on the land, by using carefully managed cover crops, and by applying manure and compost. This provides food for biota, including microbes (bacteria and fungi), earthworms and other soil life that in turn break down plant residue and improve aggregation. Soil microbes are most active in the top five centimeters of soil and populations rapidly decrease at greater depths. Even shallow and intermittent full-surface tillage practices are devastating for aggregate contributors.

Many bacteria thrive when oxygen is introduced to the soil through tillage. This contributes to nutrient release from organic matter and results in increased crop growth. However, tillage-based crop production use-up organic matter and reduces water holding capacity unless large amounts of organic matter are added to the soil. Because tillage destroys mycorrhizal fungi, soil aggregates and stability are lost, regardless of organic matter levels. Thus, tillage-based crop production is not sustainable.

On all landscapes, the development and maintenance of aggregates is critical to minimize soil degradation, particularly by very large storm events. On our flat clay plains, compaction, loss of organic matter and water runoff that carries phosphorus-laden sediment can only be overcome or decreased by using practices that increase and maintain soil aggregation. On complex topography, sheet and rill erosion by water can be controlled by practices that maintain aggregation but must be combined with check dams to manage concentrated water flow. While practices like direct seeding on the Canadian Prairie have maintained crop residue for soil surface protection from wind, if a high percentage of the soil surface under the residue is disturbed, then soil aggregate destruction and tillage erosion are serious issues.

Precision crop production that uses full-surface tillage on complex topography causes eroded areas to constantly increase in size. Alternatively, soil care leaders are using precision yield and soil information to support landscape restoration – the movement of excess topsoil from depositional areas back to eroded upper slope positions. The result is less yield variability and higher average yield. The reported payback time is remarkably short – as little as two years in some cases. To keep soil in place and retain yield it is necessary to use management that maintains soil aggregation.

We can easily see the benefits of soil aggregation when:

·       We see clean water flowing off well-aggregated soil into a stream or drainage ditch that carries silt-laden water from tilled cropland.

·       We crop over what has been undisturbed soil, such as an old fence row. This well aggregated soil produces dramatic crop growth and yield improvement compared to adjacent tilled soil.

We do have good farmland managers who are improving and maintaining the aggregation of their soils. They are profiting from their good management and hard work.

Aggregates are the ultimate measure of a healthy soil that will produce in a reliable, sustainable and environmentally friendly way. They are our lifeline to the future.
There was a time on the Prairies when heat and lack of moisture stress were more common than excess moisture and cool temperatures. Indeed, the movement to direct seeding and no-till was in response to droughts in the 1980s and early 2000s. Even though the last decade has seen more challenges with excess moisture than lack of moisture, for some growers the start of the growing season in 2016 was a reminder that dry conditions are never far off. With that in mind, a review of several research studies reinforces the value of surface residue on root heat stress and crop yield.
Send five soil test samples to five different labs and you’ll likely get five different recommendations. Understanding why will help you get the most out of your fertilizer dollars and optimize yields over the long term.
Scientists at the University of North Carolina at Chapel Hill have pinpointed a key genetic switch that helps soil bacteria living on and inside a plant’s roots harvest a vital nutrient with limited global supply. The nutrient, phosphate, makes it to the plant’s roots, helping the plant increase its yield.

The work, published in the March 15 issue of Nature, raises the possibility of probiotic, microbe treatments for plants to increase their efficient use of phosphate. The form of phosphate plants can use is in danger of reaching its peak – when supply fails to keep up with demand – in just 30 years, potentially decreasing the rate of crop yield as the world population continues to climb and global warming stresses crop yields, which could have damaging effects on the global food supply.

“We show precisely how a key ‘switch protein’, PHR1, controls the response to low levels of phosphate, a big stress for the plant, and also controls the plant immune system,” said Jeff Dangl, John N. Couch Distinguished Professor and Howard Hughes Medical Institute Investigator. “When the plant is stressed for this important nutrient, it turns down its immune system so it can focus on harvesting phosphate from the soil. Essentially, the plant sets its priorities on the cellular level.”

Dangl, who worked with lead authors, postdoctoral researchers Gabriel Castrillo and Paulo José Pereira Lima Teixeira, graduate student Sur Herrera Paredes and research analyst Theresa F. Law, found evidence that soil bacteria can make use of this tradeoff between nutrient-seeking and immune defense, potentially to help establish symbiotic relationships with plants. Bacteria seem to enhance this phosphate stress response, in part simply by competing for phosphate but also by actively ‘telling’ the plant to turn on its phosphate stress response.

In recent plant biology studies, there have been hints of a relationship between plant phosphate levels and immune system activity – a relationship that some microbes can manipulate. In the new study, Dangl and colleagues delved more deeply into this relationship, using mutant versions of Arabidopsis thaliana, a weed that has long been the standard “lab rat” of plant biology research.

In one experiment, Dangl’s team found that Arabidopsis plants with mutant versions of the PHR1 gene not only had impaired phosphate stress responses, but also developed different communities of microbes in and around their roots when grown in a local native North Carolina soil. This was the case even in an environment of plentiful phosphate – where phosphate competition wouldn’t have been a factor – hinting that something else was happening in the plants to trigger the growth of different microbial communities. The researchers found similar results studying PHL1, a protein closely related to PHR1 with similar but weaker functions.

In another experiment, in lab-dish conditions, the researchers colonized roots of sterile-grown normal Arabidopsis plants with a set of 35 bacterial species isolated from roots of plants grown previously in the same native soil. In these re-colonized plants, the phosphate stress response increased when exposed to a low-phosphate condition.

Investigating further, the team showed that PHR1 – and probably to a lesser extent PHL1 – not only activates the phosphate stress response but also triggers a pattern of gene expression that reduces immune activity, and thus makes it easier for resident microbes to survive.

The findings suggest that soil-dwelling microbes have figured out how to get along with their plant hosts, at least in part by activating PHR1/PHL1 to suppress immune responses to them. Dangl’s team also thinks these microbes may even be necessary for plants to respond normally to low-phosphate conditions. It could be possible, then, to harness this relationship – via probiotic or related crop treatments – to enable plants to make do with less phosphate.

“Phosphate is a limited resource and we don’t use it very efficiently,” said Dangl, who is also an adjunct professor of microbiology and immunology at the UNC School of Medicine. “As part of fertilizer, phosphate runs off into waterways where it can adversely affect river and marine ecosystems. It would be better if we could use phosphate in a way that’s more efficient.”
Modern crop production has a lesson or two to learn from the ancient Amazonians, including the benefits of using biochar to enrich infertile agricultural soils.
Brenda Shanahan, Member of Parliament for Châteauguay—Lacolle, on behalf of Minister of Agriculture and Agri Food Lawrence MacAulay, has announced a repayable contribution of $470,000 to help a Quebec company, Logiag Inc., commercialize a laser-based soil analysis system that replaces the more traditional chemical analyses.

This funding will allow the company to introduce to the market laser-induced breakdown spectroscopy (LIBS), a technology that allows for faster and more accurate data at lower cost. The goal is to provide producers with the exact amount of fertilizer needed and thereby avoid the overuse of chemicals.

The technology was developed by Logiag in 2015, in collaboration with the National Research Council of Canada (NRC) and the support of its Industrial Research Assistance Program. This investment from the AgriInnovation program, a $698-million initiative under the policy framework, will help Logiag create 45 jobs over five years.
Soil microbes provide billions and billions of teeny helping hands to your crops. Those helping hands are key to sustainable, profitable crop production. Crop growers can choose practices that promote healthy soil microbial communities, and researchers like Bobbi Helgason are developing ways to further enhance agriculture’s ability to tap into the remarkable capacity contained in soil microbial life.
Conducting regular soil tests is one of the simplest, fastest and least expensive ways to optimize one’s fertilizer program and maximize crop yield. Yet many producers still underuse this vital tool.
Members of the Canadian 4R Research Network gathered in Ottawa on Dec. 1 to share important agronomic data that may assist the federal government in meeting sustainable development goals and greenhouse gas mitigation targets.
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