Environment
Across most of south-central and southeastern Ontario, there’s been 50 to 100 per cent more rain than normal,” says Scott Banks, a cropping systems specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA). “It’s certainly been a challenging year. There isn’t really a silver lining to all this rain: no crops like being so wet. But growers have experienced tough years before. Outside of controlling the weather, there isn’t a whole lot they can do other than trying to minimize the issues and crossing their fingers for a warm, open fall.”
Published in Seeding/Planting
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.
Published in Soil
Precision mapping technology is increasingly user-friendly. In fact, Aaron Breimer, general manager of precision agriculture consulting firm Veritas Farm Business Management, says some precision map-writing software is so simple a producer can segment zones or draw a boundary around a field with little more than the click of a mouse. The challenge is that the maps are only as accurate as the information used to create them.
Published in Precision Ag
The U.S. environmental agency is considering banning sprayings of the agricultural herbicide dicamba after a set deadline next year, according to state officials advising the agency on its response to crop damage linked to the weed killer.

Setting a cut-off date, possibly sometime in the first half of 2018, would aim to protect plants vulnerable to dicamba, after growers across the U.S. farm belt reported the chemical drifted from where it was sprayed this summer, damaging millions of acres of soybeans and other crops.

A ban could hurt sales by Monsanto Co (MON.N) and DuPont which sell dicamba weed killers and soybean seeds with Monsanto’s dicamba-tolerant Xtend trait. BASF (BASFn.DE) also sells a dicamba herbicide.

It is not yet known how damage attributed to the herbicides, used on Xtend soybeans and cotton, will affect yields of soybeans unable to withstand dicamba because the crops have not been harvested.

The Environmental Protection Agency (EPA) discussed a deadline for next year’s sprayings on a call with state officials last month that addressed steps the agency could take to prevent a repeat of the damage, four participants on the call told Reuters.

It was the latest of at least three conference calls the EPA has held with state regulators and experts since late July dedicated to dicamba-related crop damage and the first to focus on how to respond to the problem, participants said.

A cut-off date for usage in spring or early summer could protect vulnerable plants by only allowing farmers to spray fields before soybeans emerge from the ground, according to weed and pesticide specialists.

Monsanto spokeswoman Christi Dixon told Reuters on Aug. 23, the day of the last EPA call, that the agency had not indicated it planned to prohibit sprayings of dicamba herbicides on soybeans that had emerged. That action “would not be warranted,” she said.

The EPA had no immediate comment.

EPA officials on the last call made clear that it would be unacceptable to see the same extent of crop damage again next year, according to Andrew Thostenson, a pesticide specialist for North Dakota State University who participated in the call.

They said “there needed to be some significant changes for the use rules if we’re going to maintain it in 2018,” he said about dicamba usage.

State regulators and university specialists from Arkansas, Missouri, Illinois, Iowa and North Dakota are pressuring the EPA to decide soon on rules guiding usage because farmers will make planting decisions for next spring over the next several months.

Tighter usage limits could discourage cash-strapped growers from buying Monsanto’s more expensive dicamba-resistant Xtend soybean seeds. Dicamba-tolerant soybeans cost about $64 a bag, compared with about $28 a bag for Monsanto’s Roundup Ready soybeans and about $50 a bag for soybeans resistant to Bayer’s Liberty herbicide.

Already, a task force in Arkansas has advised the state to bar dicamba sprayings after April 15 next year, which would prevent most farmers there from using dicamba on Xtend soybeans after they emerge.

Arkansas previously blocked sales of Monsanto’s dicamba herbicide, XtendiMax with VaporGrip, in the state.

“If the EPA imposed a April 15 cut-off date for dicamba spraying, that would be catastrophic for Xtend - it invalidates the entire point of planting it,” said Jonas Oxgaard, analyst for investment management firm Bernstein.

Monsanto has projected its Xtend crop system would return a $5 to $10 premium per acre over soybeans with glyphosate resistance alone, creating a $400-$800 million opportunity for the company once the seeds are planted on an expected 80 million acres in the United States, according to Oxgaard.

By 2019, Monsanto predicts U.S. farmers will plant Xtend soybeans on 55 million acres, or more than 60 percent of the total planted this year. READ MORE 
Published in Herbicides
With a later than normal planting window and a summer growing season seemingly short on summer weather, some growers have been monitoring their corn growth stages and asking about gauging the risks associated with corn maturity and frost, particularly those who planted very late or have longer maturity hybrids. While there are still several weeks left to the growing season, a few things growers trying to gauge their crop stage for frost risk may want to consider include:

Crop Staging

Clearly, the closer to maturity (black layer) the crop is, the less impact a frost event will have on the crop. For quick review:

The emergence of silks is the R1 stage. As a rough guideline, once pollination occurs, it takes about 60 more days for the crop to reach physiological maturity. Thus, silk timing can give a bit of an indication of when maturity of the corn crop may be expected – a crop that pollinated around July 25th may be expected to reach maturity or black layer sometime around September 25th. While there can be some small differences across hybrid maturities, hybrid maturity ratings have a much more significant impact on the length of time in vegetative stages than reproductive stages.

The R2 blister stage occurs following pollination when fertilized kernels are just beginning to develop, while the R3 milk stage occurs when kernels are turning yellow and are beginning to fill with an opaque milky fluid. Grain fill is rapid by the R3 stage, and maturity under normal conditions would be 5-6 weeks away.

The R4 dough stage occurs when the milk solution turns pasty as starch continues to form, with some kernels beginning to dent as dough begins to turn to hard starch at the dent ends of kernels. Under normal conditions, the dough stage may be generally 3-5 weeks from maturity.

The R5 dent stage occurs when the majority of kernels have dented, and the milk line, which separates the hard starch phase from the soft dough phase, progresses from the dent end towards the cob. The dent stage may last approximately 3 weeks.

The R6 maturity or black layer stage marks physiological maturity. This occurs when a small layer of cells at the base of the kernel near where the kernel connects to the cob die and turn black, which marks the end of grain fill from the cob into the developing kernel. Maximum dry matter accumulation has occurred, so any frost or stress event after this stage will have little impact on yield unless harvestability is compromised. Black layer normally forms once milk line has reach the base of the kernel, although significant stress events (extended period of very cool average temperatures, significant defoliation) can result in black layer formation before the milk line has reached the base of the kernel.

Frost Severity

In regards to frost severity, a light frost (ie. 0°C) may damage or kill leaves, but not be cold enough, or last long enough to actually penetrate into the stem and kill the plant. While premature leaf death limits further grain fill from photosynthesis, a living stem can still translocate dry matter to the developing grain to continue to provide some grain fill after a light frost event.

In the event where temperatures are low enough (ie. -2°C), or last long enough to penetrate and kill the entire plant, there is no ability of the plant to continue filling grain, and yield at that point has been fixed.

Any frost event during the blister or milk stage would result in significant grain yield losses as significant grain fill is still yet to occur at these stages.

A light frost event at the dough stage may reduce yields by 35% while a killing frost may reduce yields by 55% (Lauer, 2004).

Yield loss in the dent stage depends on the relative time left to mature. A light frost at the beginning of dent stage may reduce yields by 25% while a killing frost may reduce yields by 40%. During the mid-dent stage, significant dry matter accumulation has occurred, and light and killing frosts may reduce yields around 5% and 10% respectively.

Estimating Time to Maturity

Time required to reach maturity can be estimated by knowing the approximate Crop Heat Units (CHU) required for each reproductive corn stage. A general approximation of CHU required to complete the various R growth stages in corn is presented in Table 1. Scouting corn for the crop stages described above and referring to Table 1 will give an indication of how many CHU are required for the corn crop to reach maturity.



Comparing the estimated CHU required from Table 2 to an estimated number of CHU available until typical first frost date gives an idea of how much CHU would be available in an “average” year, and how close to maturity the crop may be for the average expected first frost date. Typical first killing frost dates based on 30 year climate normal across a selection of locations in the Province are presented in Table 2, while CHU values can be estimated through calculation tables in the Field Scouting chapter of Pub 811 Agronomy Guide for Field Crops, or through other weather information providers such as Farmzone.com or WeatherCentral.ca.

This Report includes data from WIN and Environment Canada
Published in Corn
Though often abused and neglected, mixed forage stands can respond to fertilization. Still, some growers are hesitant to apply fertilizer to meet fertility needs, perhaps because forage yields tend to decline over time or because lack of spring rainfall can limit yield responses.
Published in Other Crops
Farmers in Alberta are being given the tools to take charge against climate change by adopting on-farm best management practices that are scientifically proven to limit the impacts of agriculture on natural resources like air, water and soil.

Fertilizer Canada is proud to announce the signing of a Memorandum of Understanding with the Agricultural Research & Extension Council of Alberta (ARECA) that includes integration of 4R Nutrient Stewardship (Right Source @ Right Rate, Right Time, Right Place®) into the province's Environmental Farm Plan (EFP). This agreement marks a significant milestone on Fertilizer Canada's journey to create truly sustainable and climate-smart agriculture in Canada.

"We are pleased that ARECA has officially recognized 4R Nutrient Stewardship as a best practice for nutrient management on Alberta farms," said Garth Whyte, President and CEO of Fertilizer Canada. "By encouraging farmers across the province to use fertilizer effectively, Alberta is joining the front lines in the fight against climate change and ensuring their place among the world's leaders in sustainable agriculture."

"ARECA is a long-time supporter and promoter of 4R Nutrient Stewardship," said Janette McDonald, Executive Director. "There is no doubt this formalized partnership with Fertilizer Canada will aid us in expanding awareness of the program as a best practice for nutrient management planning."

4R Nutrient Stewardship is a science-based nutrient management system that is universally applicable yet locally focused. By applying the right source of fertilizer at the right rate, the right time and the right place, farmers can ensure nutrients are efficiently taken up by their crops and are not lost to air, water or soil. This increases crop productivity and reduces unwanted environmental impacts.

Managed by ARECA, the province's EFP self-assessment process encourages producers to assess and identify environmental risks on their farms and take action to improve their practices.

"While Alberta's EFPs already include a section on nutrient risks, adding information about the positive long-term benefits of 4R Nutrient Stewardship will expand awareness among the province's farmers," said Paul Watson, EFP Director at ARECA.

As growers in Alberta adopt 4R Nutrient Stewardship under the Alberta EFP, the acres they manage will be counted under Fertilizer Canada's 4R Designation program, which tracks the amount of Canadian farmland using 4R Nutrient Stewardship to boost productivity and conserve resources. Fertilizer Canada aims to capture 20 million 4R acres by 2020 – representing 25 per cent of Canadian farmland – to demonstrate to the world the commitment Canada's agriculture sector has made to adopt climate-smart and sustainable farm practices.

To learn more about 4R Nutrient Stewardship and the benefits it offers, visit www.fertilizercanada.ca

Learn more about the Alberta Environmental Farm Plan and the benefits it offers by visiting www.AlbertaEFP.com
Published in Corporate News
When is the “right” time to put soybeans into the ground? Research in Manitoba is moving beyond the recommendations borrowed from Ontario and south of the border to develop Prairie-specific guidelines.  
Published in Seeding/Planting
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.
Published in Soil
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....

Don't forget to sign up to our E-newsletters (for free!) and subscribe to the Western edition of Top Crop Manager (print and digital) for the full story. The more you know, the better you grow.
Published in Soil
Farm Credit Canada (FCC) is offering support to customers in parts of eastern Ontario and western Quebec facing financial hardship as a result of excessive moisture during this year’s growing season.

Many producers in that area are facing a cash shortfall since they were unable to seed or were forced to replant due to extreme rainfall, while others face additional costs from having to purchase feed as a result of reduced yields of corn, soybeans and hay.

“Agriculture is the only industry we serve, so we have a deep understanding of the challenges that come with the business,” said Michael Hoffort, FCC president and CEO, in announcing the Customer Support Program.

“Excessive rainfall has certainly impacted the growing season in parts of Eastern Canada and, in some cases, caused financial challenges for farm operations, as well as personal hardship and stress,” he said. “We want our customers to know we stand by them and will show flexibility to help them through challenging times.”

FCC will work with customers to come up with solutions for their operation to reduce the financial pressure caused by excessive moisture.

Although FCC customer support is being offered in specific locations, Canada’s leading agriculture lender offers flexibility to all customers through challenging business cycles and unpredictable circumstances on a case-by-case basis.

Customers in Ontario and western Quebec are encouraged to contact their FCC relationship manager or the FCC Customer Service Centre at 1-888-332-3301 to discuss their individual situation and options.
Published in Corporate News
“Across most of south-central and southeastern Ontario, there’s been 50 to 100 per cent more rain than normal,” says Scott Banks, a cropping systems specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA).
Published in Corporate News
Jeff Schoenau, a soil scientist with the University of Saskatchewan was involved in a research study conducted in the mid-2000s that compared four tillage treatments that were imposed on no-till fields (longer than 10 years) at Rosthern (Black soil), Tisdale (Gray soil) and Central Butte (Brown soil), Sask.
Published in Tillage
After the Prairie Farm Rehabilitation Centre kicked off its shelterbelt program in 1903, the Indian Head Research Station sent out more than one billion free trees to western Canadian producers.
Published in Corporate News
What if we could design a landscape that would provide a variety of nutritious foods, high-quality habitat, and ecosystem services, while also delivering a healthy profit to the landowner? According to University of Illinois researchers, it is not only possible, it should be adopted more widely, now.

“We need to be on the road to figuring things out before we get to tipping points on climate change or food security, or we could be left way behind. In future environments, people might get paid for ecosystem services or carbon credits, or food might become more valuable. If so, these systems become much more attractive for landowners,” says Sarah Taylor Lovell, an agroecologist in the Department of Crop Sciences at U of I.

Lovell believes multifunctional woody polyculture is the way forward. She and several co-authors introduce the concept and discuss their experimental design in a recent paper published in Agroforestry Systems.

Essentially, the idea is to incorporate berry- and nut-bearing shrubs and trees in an alley cropping system with hay or other row crops. The combination is meant to mimic the habitat features, carbon storage, and nutrient-holding capacities of a natural system. “We wanted to capture that aspect, but we also wanted it to be commercially viable,” Lovell says. “The trees and shrubs need to fit in perfect linear rows 30 feet apart, so you can fit equipment. That was a much more practical agronomic consideration.”

Lovell and her colleagues are three years into what they hope will be a long-term experiment on the U of I campus. Their trial consists of seven combinations of species in commercial-scale plots, from simple combinations of two tree species to highly diverse combinations including multiple species of trees, shrubs, and forage crops. “We added increasingly diverse systems so we can get a sense of how much is too much diversity in terms of trying to manage everything in a feasible way,” she says.

The researchers will measure crop productivity, management strategies, and economic potential as the experiment gets established. “We’re keeping track of all the person-hours that go into each of these different combinations, so we’ll capture the labor involved and figure out whether it’s economically viable,” Lovell says.

Farmers accustomed to traditional row crops may be daunted by the long wait associated with nut crops. Lovell says chestnuts and hazelnuts don’t produce worthwhile harvests until 7 to 12 years after planting. But, she says, the other species can bring in profits while farmers wait. Hay or vegetable crops can be harvested from the alleys in year one. And shrubs could start bearing high-value fruit crops, such as currants or aronia berries, within a couple of years.

Lovell points out that the market for some nuts is growing. For example, Nutella lovers may recall headlines about an international hazelnut shortage a couple of years ago. “It would take a while to saturate that market,” she says. But she also points out that some nuts could be used more generically for their starchy or oily products.

Another barrier to adoption may be the cost of specialized equipment needed to harvest tree nuts, berries, and row crops. “There’s a tradeoff in terms of how complex to get and still be able to manage it in a reasonable way,” Lovell says. But she suggests the potential of farming cooperatives with shared equipment as a way to defray costs.

It will be several years before Lovell will have results to share, but other trials have shown that multifunctional woody polyculture could be both economically viable and environmentally beneficial. Lovell’s article details the outcomes of long-standing experimental sites in France and Missouri, but she says those two sites are the only large-scale examples in the temperate region. “That really shows just how little research there is on this so far,” she says. “We need to invest in this research now because it’s going to take so long to get to the solutions.”

The research team is working with regional farmers to replicate small- and large-scale versions of their experimental setup on-farm. Lovell knows it might take some convincing, but points out that many farmers are willing to set aside portions of their land into the Conservation Reserve Program. “If we can provide the same benefits in terms of water quality, habitat, biodiversity, and nutrient cycling as CRP but then also have this harvestable product, why wouldn’t you consider that?”
Published in Seeding/Planting
Parts of southwestern Ontario remain dry, while eastern Ontario continues to have frequent rainfall and saturated soils in many areas. While yields have been good, making dry hay continues to be a struggle for many growers under the later conditions.

Winter wheat harvest has continued this past week in eastern Ontario. Most fields in the area have yielded between 70 to 80 bushels per acre. Quality has generally been better than expected. Spring cereal harvest has just begun on a small number of acres that were able to be planted early this spring.

Insects
Soybean Aphid numbers are generally low, but increasing in some areas in eastern Ontario. Soybean growers should be scouting. Apply foliar insecticide when threshold of 250 aphids per plant with increasing populations has been reached in the R1–R5 stage of soybeans. If aphid populations do not appear to be on the increase above 250 per plant, do not apply insecticide, as it will kill off the beneficial insects that are keeping the aphid population in check. Aphids are then likely to increase quickly in the absence of their predators and could easily reach threshold.

For further information on scouting techniques, thresholds and management options, see OMAFRA Publication 812, Field Crop Protection Guide.

Potato Leafhopper (PLH) continued to be a problem in many alfalfa stands particularly in eastern Ontario. Sweeps collected are showing at and above threshold numbers in many fields that have not been treated. Although PLH are rarely a problem in soybeans they can cause significant yield and quality losses in alfalfa and edible bean stands. New seedling alfalfa stands are particularly vulnerable as the PHL damage can weaken the new seedling alfalfa plant, making them more susceptible to stresses like winterkill.

Economic losses occur before plant symptoms develop, so it is important to identify the presence of large leafhopper populations before the damage occurs. Scouting with a sweep net will help you determine whether early harvest or spraying is needed. Scout at intervals of 5 to 7 days. To determine the number of leafhoppers, including adults and nymphs, take 10 sweeps and divide the number of insect captured by 10. Do this in 5 representative areas of the field and note the height of the alfalfa. Recommended action thresholds are listed in Table 1 below:

Table 1: Thresholds for Potato Leafhoppers in Alfalfa
Stem Height      # of PLH per sweep
9 cm (3.5 in.)     0.2 adults
15 cm (6 in.)      0.5 adults
25 cm (10 in.)    1.0 adults or nymph
36 cm (14 in.)    2.0 adults or nymph

It is important to make decisions to control PLH based on these threshold numbers as spraying insecticides on alfalfa will also kill beneficial insects, the natural enemies of PLH and alfalfa weevil.

Foliar insecticide options are available in Publication 812, Field Crop Protection Guide here.

Western Bean Cutworm (WBC) trap counts are still increasing in most counties north and east of Perth and into eastern Ontario. That means that WBC moth flight has not yet peaked in those areas. This is important because this also means that we have not reached peak egg laying in those areas and that there are a lot of moths flying around looking for somewhere to lay their eggs. Late planted corn fields that are still in the early pollination stages (i.e. silks have not dried down yet) and edible beans are still at risk.

For late planted corn fields, most of what you need to know about scouting and management has already been posted in a previous post here.

For edible beans, it is not as straight forward. Unlike in corn, WBC are nearly impossible to find in dry bean fields until pod feeding begins. Pheromone traps can still help indicate which fields are at greater risk though. Traps at dry bean fields that capture an accumulation of 50 or more moths per trap are likely at greater risk and require scouting for pod feeding.

Pod feeding is expected to begin 10 to 20 days after peak moth flight has occurred, as indicated when trap counts begin to decline after weeks of steady increase. Prior to pods being present on the plants, scouting for egg masses in adjacent cornfields can also help determine what the local WBC populations are like. If any of the corn fields in the immediate area are past early tasseling, the dry bean fields will be more attractive for the moths. If an adjacent corn field reached the corn egg mass threshold and required spraying, the dry bean field is also likely at risk.

Once pods are present, scout 100 plants (10 plants in 10 areas of the field). Look for signs of early surface feeding or holes going directly into the pod. If pod feeding is easily found, a spray application is necessary. Control is still very effective when done as soon as pod feeding is found. WBC exit and enter new pods each night, so insecticides still work at controlling the larvae, as long as the pods are present during the application so that there is residue left on the pod surface.

Spraying too early when pods are not present on the plants will not protect the crop from damage. Spraying too late, when pod feeding has been taking place for some time will not reduce the risk of seed damage and pod disease incidence. The key is to protect the plants when the larvae are feeding on the pods.

Foliar insecticide options are available in Publication 812, Field Crop Protection Guide.
Published in Corporate News
Bumblebees are less able to start colonies when exposed to a common neonicotinoid pesticide, according to a new University of Guelph study.
Published in Insecticides
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.
Published in Soil
While driving through the Salaberry-de-Valleyfield region in southern Quebec in mid-June, John McCart, president of the Quebec Farmers’ Association, noticed farms in the area were sitting empty, void of the crops that should have been planted the month before. 
Published in Corporate News
Like it or not (and believe in climate change or not), Canada has committed to greenhouse gas emission (GHG) reductions, and the implementation will affect farmers. Part of GHG mitigation will certainly revolve around reducing nitrogen (N) fertilizer losses.

“Farmers already have production challenges with growing crops, and this will add another layer of complexity...We don’t know yet how it is going to impact at the farm level,” says Mario Tenuta, a soil scientist at the University of Manitoba.

Tenuta says agriculture is a significant contributor to greenhouse gas emissions, and nitrous oxide is the big one for agriculture. The increase in agricultural emissions in Canada is largely related to an increase in nitrogen (N) fertilizer use. In Canada, N fertilizer use has risen five-fold since 1970. In 2009, agriculture in Manitoba, for example, was responsible for 35 per cent of total GHG emissions (excluding fuel and fertilizer production). Fifty per cent of nitrous oxide emissions came from fertilizer and crop residue, and another 27 per cent came from indirect emissions from the soil.

In December 2015, the Manitoba government committed to reduce emissions from 2005 levels by one-third by 2030 and one-half by 2050. The province is committed to being emission neutral by 2080.

“Nobody likes to be a target, but we are. It is happening so what are we going to do about it?” Tenuta says.

4Rs and enhanced efficiency fertilizers
The “4R” nutrient stewardship program focuses on getting the best nutrient use efficiency by using the right source, rate, time of application, and placement of fertilizer. It aims to improve or maintain yield and profitability, while limiting fertilizer loss and providing water and air quality benefits. From a GHG emissions perspective, Tenuta says financial incentives could be used to encourage implementation of the 4Rs to reduce emissions. In 2015 at the Manitoba Agronomist Conference he reviewed current research and outlined how using the 4Rs could reduce GHG emissions.

Two research projects in Manitoba showed how increasing the N fertilizer rate also increased nitrous oxide emissions. In a Carberry, Man., potato crop, nitrous oxide emissions increased linearly as the N rate increased from zero to 240 pounds per acre. The economic rate was about 60 pounds per acre. In another trial in Glenlea, Man., a similar increase in emissions occurred as N rates increased.

“The simple way to reduce emissions was to match application rate to crop uptake,” Tenuta says.

Crop rotation also affected emissions. Nitrogen fixing legumes such as fababean, alfalfa or soybean had little to no nitrous oxide emissions and were fixing N into the cropping system instead of emitting N. Other rate considerations to potentially reduce emissions include using variable rate N, soil testing every year, and better understanding differences in variety and hybrid N requirements.

The second of the 4Rs, placement of fertilizer, also has an impact on emissions. Subsurface banding N fertilizer reduces nitrous oxide emissions, and when enhanced efficiency fertilizers such as environmentally smart nitrogen (ESN) or SuperU fertilizers are banded, reductions are even greater, at 26 per cent less than banded urea.

“Good band closure and coverage of the band is important. We are also looking into band depth, because we are banding more shallow with crops like canola, and we don’t know enough about losses from shallow bands,” Tenuta says.

Another key component of the 4Rs is application timing. Traditional yield estimates based on N application timing showed fall broadcast/incorporated to be 80 per cent of spring broadcast/incorporated, while fall banded was equal to spring broadcast/incorporated, and spring banded was 20 per cent better. However, Tenuta has found very late fall application just before freeze-up doesn’t increase nitrous oxide emissions when compared to spring banded N. Two years of his research comparing fall versus spring anhydrous ammonia application found the spring timing had much greater nitrous oxide emissions.

“Lower emissions from fall application goes contrary to what people thought might happen. Because the soil temperature was very cool, the timing used nature to stabilize the N and freeze it in,” Tenuta says.

Fertilizer source is the final of the 4Rs to take into consideration. With conventional sources of N fertilizer, scientists generally accept that anhydrous ammonia produces the highest emissions, followed by urea, ammonium and nitrate fertilizers. Nitrification – the conversion of ammonium to nitrates – is behind most nitrous oxide emissions from N fertilizer.

The other choices in sources of N fertilizer come from enhanced efficiency fertilizers (EEF). These include stabilized, controlled release, slow release and nutrient blend N products. The goal of these products is to slow the conversion of N fertilizer into forms that are more easily lost through ammonium volatilization, nitrification or denitrification, and to more closely match N availability with crop uptake.

WTCM13.5 EEF mechanismEnhanced efficiency fertilizer mechanism of action. Source: Tenuta, University of Manitoba.

“In the field, the research shows that these EEF products really do work. They tend to provide a larger benefit in wet years,” Tenuta says. “I recommend that you talk to the manufacturer representatives to make sure you are using the right product properly.”

Another source of N that reduces nitrous oxide emissions is legume plowdown as an enhanced efficiency N source. Current research at the U of M has found that, compared to conventional cropping systems with N fertilizer, a legume plowdown results in very little emission.

“You have to estimate if EEF are worth it for your system. For example, if you’re putting more N fertilizer on in the fall to compensate for winter losses, you might be able to put on a EEF in the fall at a reduced N rate and that might pay for the additional cost of the product,” Tenuta says.

He adds that uses of the 4Rs and EEF N products are currently focused on improving yield and N use efficiency for higher profitability. But they can also play a role in reducing nitrous oxide emissions and helping to meet emission reduction targets. Ultimately, if farmers are contributing to emissions reductions, the hope is that they will be compensated for those practices.

Best management practice recommendations to reduce nitrous oxide emissions
• Use the 4Rs – right rate, time, source and placement.
• Optimize N application rates through soil testing, understanding crop requirements and interactions with the other Rs.
• Consider using lower emitting sources of N fertilizer.
• Legume crops emit little nitrous oxide.
• Green manuring limits nitrous oxide emissions.
• Banding works.
• Investigate ways of making EEF products work through reduced N application rates and improved N use efficiency.
• Spring apply N fertilizer unless fall banding can be accomplished shortly before fall freeze-up.

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