Craig Drury, a soil biochemist at the AAFC Harrow Research and Development Centre, is analyzing the effectiveness of nitrogen inhibitors and nitrogen placement strategies. Photo courtesy of Craig Drury.
Nitrogen inhibitors can dramatically improve productivity and injection is by far the best way to incorporate nitrogen into the soil while minimizing nitrogen loss.
These were key messages in a presentation by Craig Drury, a soil biochemist at Agriculture and Agri-Food Canada’s (AAFC) Harrow Research and Development Centre, at an Innovative Farmers Association of Ontario meeting in December 2015.
Drury is in the second phase of field studies funded by AAFC’s Agro-Ecosystems Productivity and Health Science Strategy and the 4R Nutrient Research Network (Fertilizer Canada), analyzing the effectiveness of nitrogen inhibitors and nitrogen placement strategies. The study, which is a continuation of a previous two-year study, began in 2015 and will continue until 2017.
The goals of the study are threefold – Drury’s team, which includes Dan Reynolds, Xueming Yang and Wayne Calder, first aims to analyze how much nitrogen is lost from the soil as ammonia through volatilization or as nitrous oxide through the denitrification process. Second, they are assessing the effectiveness of different fertilizer application methods and how these could reduce losses and increase nitrogen uptake by corn.
They are also examining the effectiveness of nitrogen inhibitors – Agrotain, a urease inhibitor, and Agrotain Plus or SuperU, both urease and nitrification inhibitors.
Drury says the landscape has changed in terms of nitrogen fertilizer trends in Canada. “From 1980 to 2010, nitrogen fertilizer sales in Canada increased by a factor of 2.4. The amount of nitrogen fertilizer sold and used is increasing for many reasons.”
But that’s not all that’s changed. Drury says urea and UAN together account for 74 per cent of nitrogen sales in Canada, and that figure is increasing. “Right now, about 52 per cent of the nitrogen fertilizer sold in Canada is urea and 22 per cent is UAN,” he says. “The point is that we have seen over time a greater and greater percentage of nitrogen fertilizer being applied contains urea, whether it’s all granular urea or it’s 50 per cent urea in liquid UAN.”
The problem? Much of the fertilizer added to soils in Eastern Canada is lost to the environment – a problem both for the environment and the grower’s bottom line.
Drury says that when nitrogen is added to the soil as a fertilizer, as manure, through natural atmospheric deposition or nitrogen fixation via legume plants, it undergoes natural biological and chemical conversions. To be used by the plant, nitrogen has to be converted to ammonium and/or nitrate; but ammonium can easily volatilize and be lost to the atmosphere.
Under very wet conditions, negatively charged nitrate can leach out of the root zone through tile drains or it can be converted to nitrous oxide, which is lost to the air, where ultimately it contributes to the greenhouse gas effect.
“That is a problem on many levels – your nitrogen is going into the air or out of your tiles instead of the soil or the plant, so it’s a costly loss of the applied fertilizer,” he says.
Nitrogen inhibitors can help diminish this effect by slowing the conversion of urea into ammonium, which allows more time for the nutrient to move into the soil.
Findings Drury’s study analyzed broadcast urea, UAN streaming and UAN injection, and used, in total, three separate fertilizer nitrogen sources: urea or UAN, urea or UAN plus a urease inhibitor and urea or UAN plus a urease and nitrification inhibitor.
The team used wind tunnels and air sampling instrumentation to measure ammonia losses.
The findings, so far, have been dramatic. Drury’s team found that 54 pounds per acre (lbs/ac), or roughly $3,200 for 100 acres of broadcast urea, was lost to volatilization, versus 23 lbs/ac or $1,500 for 100 acres of injected UAN.
Urease inhibitors decreased ammonia losses by 57 per cent (from 54 to 22 lbs/ac) for broadcast urea – $1,900 worth of savings for 100 acres. But even more notably, the use of urease inhibitors resulted in a whopping 97 per cent decrease in ammonia losses with the injection of UAN.
In total, Drury says, the combination of urease and a nitrification inhibitor also decreased nitrous oxide emissions by 21 per cent.
“If you have the opportunity to incorporate nitrogen into the soil through injection or immediate broadcast incorporation that’s certainly worth doing, and will get the nitrogen into the soil fast and efficiently,” he says.
But even with injection, the team still noted ammonium volatilization losses through the injection slot. “So with both broadcast urea as well as injection, it was still beneficial to include the urease inhibitor to decrease volatilization and have the nitrogen go into the crop,” Drury says.
These findings are not just about losses – Drury’s team also measured gains in yield. He says use of urease inhibitors increased yields by 5.5 bushels per acre with broadcast urea, and by 12.5 bushels per acre with the combination injected UAN. The benefit totaled $1,700 per 100 acres for broadcast urea, or $54 per acre, or $5,400 per 100 acres in the injected fields when urease inhibitors were also used.
“In all cases, it was very profitable, even when you consider the cost of the inhibitors. The revenue from the yield increase was far greater than the cost of the inhibitors,” he says.
“Clearly, there are ways of managing our fertilizers and our soils to reduce environmental losses and losses of expensive nutrients and have more of that nitrogen going to the crops and increasing yields.”
Developed by plant breeders in Saskatchewan and Manitoba during the 1960s and 1970s to meet a growing demand for edible oil production in Canada, canola has become a major cash crop in Western Canada. It has been less attractive economically for eastern producers, primarily because so few crushing facilities are located within a reasonable distance from the major growing areas in Eastern Canada.
However, that is changing. Between 2006 and 2011, canola production in Eastern Canada increased 305 per cent to more than 141,000 acres, increasing farm-gate cash receipts almost 700 per cent to $46.3 million. And the 2010 operationalization of a canola and soybean crushing plant and oil refinery in Becancour, Que., by Twin River Technologies – Enterprise de Transformation de Graines Oléagineuses (TRT-ETGO) further significantly brightens the prospects of canola production in Eastern Canada.
This growth created an urgent need for the industry to develop sound agronomic practices for canola production in Eastern Canada, particularly with respect to nitrogen fertilizer application and improved nitrogen-use efficiency, for the environmental and economic sustainability of canola production.
To address that need, Agriculture and Agri-Food Canada (AAFC) scientist Dr. Bao-Luo Ma is leading a project at the Eastern Cereal and Oilseed Research Centre (ECORC) in Ottawa, with the assistance of university professors Dr. Donald Smith and Joann Whalen from McGill University, Dr. Anne Vanasse from Laval University, Dr. Claude Caldwell from Dalhousie University and Dr. Hugh Earl from the University of Guelph, as well as Peter Scott, the provincial forage specialist for New Brunswick’s Department of Agriculture, Aquaculture and Fisheries.
Since 2011, the group has conducted experiments during the growing seasons at various sites in Eastern Canada to investigate the growth, yield and yield components of canola in response to various combinations of pre-plant and side-dressed nitrogen with soil-applied sulfur and soil and foliar-applied boron. Sites are located in Ottawa and Elora, Ont.; Ste. Anne de Bellevue and St-Augustin-de-Desmaures, Que.; Fredericton, N.B. and Canning, N.S.
At these sites, the researchers are investigating the responses of different canola cultivars (hybrids) to the timing and rate of nitrogen application, the combination of nitrogen and sulphur, nitrogen and boron, yield, nitrogen use efficiency and carbon footprints of different rotation systems – canola following wheat, soybean or corn. And, they are identifying the traits and tools for the development of nutrient cycling knowledge, implementing site-specific best management practices and adapting canola to existing cropping systems.
“Our preliminary results indicate that canola yields increased by 9.7 kilograms per hectare (kg/ha) for pre-plant nitrogen application and by 13.7 kg/ha for side-dress nitrogen application, for every kilogram of nitrogen per hectare applied, in six of the 10 site-years,” Ma says. “The challenge remains to develop site-specific fertilizer applications that deliver ample nitrogen, sulfur and boron for canola production considering that unfavourable weather conditions may cause nutrient losses and constrain canola growth at key development stages in Eastern Canada.”
Because agriculture production is a complex system, modifying one nutrient in the cropping system could have cascading effects on other nutrients and other crops as well. Developing efficient nutrient management regimes is a prerequisite for promoting canola as a viable cash crop in Eastern Canada.
“Canola is a non-legume crop and requires large amounts of nitrogen fertilizer for production,” Ma says. “Inefficient use of this nutrient not only reduces farmers’ profits, but may also put the environment at risk with nitrate nitrogen leaching, ammonia volatilization, nitrous oxide emissions, etc. affecting the air we breathe, water we drink and daily environment.”
From their research, Ma’s team have determined a number of best practices for successfully growing canola in Eastern Canada, including applying a small portion of nitrogen fertilizer at pre-sowing and the majority of the nitrogen nutrition at the five to six leaf, or bolting, stage. “This would increase canola seed yield and/or increase nitrogen use efficiency,” Ma says. “This may also give farmers the option to reduce the amount of nitrogen application when drought or other stresses are expected during the growing season.”
Other best practices are to plant the crop in narrow row spacing – seven inches – at a seeding rate of five kg/ha and, based on the long-term trend of average minimum air temperature in April and May, to determine the optimum seeding date. Optimum seeding dates usually occur the last week of April to the first week of May for Ottawa, Guelph and Montreal regions; May 11 or after for Sainte-Foy and northern Quebec region; and late May for Harrington, P.E.I.
Ma says they will continue to create and advance the knowledge and technology required to broaden canola production in Eastern Canada to meet the demand of the industry, improve producers’ competitiveness on the global market, provide consumers with healthy and environmentally friendly food and fuel and provide the general public with a continued high quality environment.
“As new cultivars are being developed, research activities are required to develop/implement site-specific and matching strategies to obtain the true potential of new cultivars in farmers’ fields,” says Ma, narrowing the gap between cultivars’ potential yield and realized yield under field conditions as an example.
Oct. 29, 2015 - In their first year of large field-scale trials in Western Canada, nitrogen stabilizers N-Serve and eNtrench proved to secure more available nitrogen for plants and in many cases, contribute positively to yield.
N-Serve and eNtrench, used with anhydrous ammonia and liquid fertilizer respectively, prevent the loss of soil-applied nitrogen to leaching or denitrification by keeping nitrogen bonded to the soil in its positive form.
Fall-applied N-Serve trial results
In 18 trials across Western Canada where N-Serve was applied with anhydrous ammonia in the fall, soil tests taken two weeks after emergence found those fields to have 81 per cent more positive ammonium available, compared to adjacent trials where only anhydrous ammonia was applied.
Why apply nitrogen with a nitrogen stabilizer in the fall?
"Two big advantages: save time and save money," says Jason Smith, market development specialist with Dow AgroSciences Canada. "You have the opportunity to get that field work done in the fall rather than spring, and take advantage of lower fall fertilizer prices.
"Many growers apply nitrogen at higher rates in the fall, understanding that they were going to lose some of that nitrogen. A product like N-Serve eNtrench is going to significantly reduce the potential for those losses and therefore keep all that nitrogen available to your plant for the next spring."
Spring-applied N-Serve and eNtrench trial results
When N-Serve and eNtrench were applied in the spring in 30 different trials across Western Canada, soil tests taken four weeks after emergence showed those fields to have 44 per cent more positive ammonia available, compared to fields with only either anhydrous ammonia or liquid fertilizer.
"Overall the field trial results have been very positive and very encouraging," Smith says. "In areas where we had good rainfall and in some cases excessive rainfall, we're seeing some fairly significant differences in yield as well."
"So overall, anecdotal results, we're seeing about 3-5 bushel yield bump where nitrogen loss is a significant factor, and in the wheat we're seeing yield bumps in that range of 5-10 bushels."
Growers interested in learning more about N-Serve and eNtrench nitrogen stabilizers and product availability should speak with their retailer, or contact their Dow AgroSciences representative. More information is also available at www.protectyournitrogen.ca.
September 30, 2015 - Ontario is working to improve and maintain water quality in the Great Lakes by supporting the development and implementation of a nutrient stewardship program for farmers.
As part of a recently signed Memorandum of Cooperation, Ontario will provide $50,000 to Fertilizer Canada and the Ontario Agri Business Association to develop educational programs for farmers about nutrient management based on the internationally-recognized 4R Nutrient Stewardship system, which promotes efficient fertilizer application to improve profitability while reducing nutrient losses.
"Canada’s fertilizer industry is encouraged by the Government of Ontario’s endorsement for 4R Nutrient Stewardship as an important tool to meet the province’s environmental stewardship goals," says Garth Whyte, president and CEO of Fertilizer Canada. "We look forward to working with the Ontario government and agri-retailers to improve practices that will ensure the sustainability of the agriculture industry while enriching the health of the Great Lakes."
Ontario's farmers have already made significant contributions as stewards of the land, completing more than 23,500 on-farm environmental improvement projects since 2005, including grass buffer strips, wind breaks, cover crops, nutrient storage and structures to prevent soil erosion. The Memorandum of Cooperation will further support the province's farmers as well as protect watershed areas and prevent algae blooms.
"Agri-retailers are well positioned to work with Ontario farmers to implement the 4R Nutrient Stewardship Program as a practical tool for enhanced environmental sustainability," states Dave Buttenham, CEO of the Ontario Agri Business Association. "The financial support and commitment by OMAFRA demonstrates the recognition within government that 4R can play a key role in achieving both environmental and farm sustainability."
The 4R Nutrient Stewardship system uses four key pillars for fertilizer application: Right Source, Right Rate, Right Time, Right Place.
On December 19, 2014, Ontario approved the new Canada-Ontario Agreement on Great Lakes Water Quality. In that agreement, both Canada and Ontario commit to creating action plans to reduce the impact of excess nutrients on the water quality of Lake Erie.
Oat is a competitive crop that is suited to central and northern Alberta growing conditions, but oat agronomic research has been lacking in Alberta in recent years.
“When I found out about the high yield potential of oat, I was fascinated by its potential to be a high-value crop for growers,” says Linda Hall, a weed scientist and agronomist at the University of Alberta.
Her excitement about oat’s potential inspired Hall to initiate a three-year project on optimizing production of food-grade (milling) oats in Alberta. She is working with Sheri Strydhorst, an agronomy research scientist at Alberta Agriculture and Forestry; Bill May, a crop management agronomist with Agriculture in Agri-Food Canada in Indian Head, Sask.; and Joseph Aidoo, a graduate student at the University of Alberta.
Based on Statistics Canada data, the average oat yield for Alberta for the past five years was 82.7 bushels per acre (3120 kilograms per hectare). This low average yield may be due in part because oat is often grown for hay and forage, rather than for grain, but also because oat is sometimes planted as a default grain crop when it’s too late to seed crops like wheat or canola. Results from variety trials and other sources show oat grain yields on the Prairies can be around 120 to 155 bushels. According to Hall, oat’s yield potential could be over 200 bushels under the cool, moist growing conditions preferred by the crop and using agronomic practices aimed at high yields.
“Although oat can be high yielding, the common variety grown in Alberta is not the best for high-value milling oats,” Hall notes. “So one objective of our project is to compare the yield of some newer high beta-glucan oat varieties. This may provide a new marketing opportunity for Alberta growers.” Food processors are interested in beta-glucan because this dietary fibre has important health benefits, such as lowering cholesterol.
“The most reasonable way to increase oat yield is to plant early and increase nitrogen fertilizer. Unfortunately, higher nitrogen tends to result in thinner seeds, which is not as good for the milling market, which prefers plump seeds with a high test weight,” she says. “So we need to find a balance – how do we maximize yield and yet still retain quality?”
Another effect of high nitrogen rates is a greater risk of lodging. Hall says, “Particularly in northern Alberta where moisture levels are usually good, when growers use higher rates of nitrogen, the crop tends to lodge, which causes harvesting problems and reduces yields. So our second objective is to determine if new plant growth regulators can improve the harvestability and standability of oat varieties.”
Plant growth regulators are synthetic compounds that modify plant growth; their effects on cereals may include shorter, stronger stems, reduced lodging and/or higher yields. Little research has been done on the use of growth regulators on oat in Canada, so Hall’s project could provide valuable insights.
The project, which started in 2014, involves two field experiments. Experiment 1 aims to evaluate the effects of nitrogen rate and oat variety on yield, lodging and beta-glucan content. In this experiment, nitrogen in the form of urea is banded at seeding. The treatments are 5, 50, 100 and 150 kg N/ha, with the amounts of the urea applications adjusted for the soil type and the amount of soil nitrogen. The experiment compares five oat varieties: AC Morgan (four to five per cent beta-glucan); OT3066 (four to five per cent beta-glucan); Stride (5.5 to six per cent beta-glucan); CDC Seabiscuit (5.5 to six per cent beta-glucan); and CDC Morrison (six to 6.5 per cent beta-glucan). In 2014, Experiment 1 was conducted at Edmonton and Barrhead, which are both in Alberta’s prime oat growing region.
Experiment 2’s objective is to assess the effects of four rates of a plant growth regulator on Stride, under the same four nitrogen treatments as in Experiment 1. The growth regulator is under
development and not yet registered for use on oat in Western Canada. The researchers chose Stride for this experiment because it showed lodging tendencies at higher nitrogen rates. In 2014, this experiment was carried out at Edmonton, Indian Head and Barrhead.
First year results
In Experiment 1 in 2014, oat yield increased as the nitrogen level increased, as expected. Hall says, “Our best yielding variety was AC Morgan, the variety used by most Alberta growers. But unfortunately Morgan had the lowest beta-glucan content of the varieties in our trial. CDC Morrison, the highest beta-glucan variety, was the lowest yielding.”
The optimal nitrogen rate for maximum oat yields varied depending on the oat variety and the location. For example, CDC Morrison’s yields were highest at the 150-kilogram rate at both locations, while AC Morgan’s yields were greatest at 50 kilograms at Edmonton and 100 kilograms at Barrhead. Higher nitrogen levels tended to decrease 1000-kernel weights and increase the percentage of thins. Also, plant height and lodging tended to increase as nitrogen increased, although there was minimal lodging at the sites in 2014. Height and lodging were variety dependent, with Stride lodging more than the other varieties.
In Experiment 2, at two of the three sites, the plant growth regulator reduced plant height and lodging. “As we increased the nitrogen, the height of Stride increased, and as we applied more plant growth regulator, we saw a reduction in height. So, by using a plant growth regulator, we were successful in counteracting the increase in height from the nitrogen,” Hall explains.
In 2014, the plant growth regulator did not affect oat yield. Hall notes, “Accurate timing is very critical for a plant growth regulator to be effective. In auxiliary experiments, we found that the growth regulator had to be applied at early stem elongation, after the herbicide application window and before fungicides are applied. To be effective, the plant growth regulator would have to be applied as a separate treatment.”
Once the project is completed, the researchers will be able to share up-to-date information on food-grade oat production with central and northern Alberta growers.
Sept. 17, 2015, Guelph, ON - The Government of Ontario, Fertilizer Canada, and the Ontario Agri Business Association formalized a commitment on agricultural sustainability and environmental action. With a combined industry investment of $300,000 over three years, the partners signed a Memorandum of Cooperation helping Ontario farmers maximize crop yields with minimal environmental impact using 4R Nutrient Stewardship.
4R Nutrient Stewardship is an internationally recognized best management practice system with four key pillars for fertilizer application: Right Source @ Right Rate, Right Time, Right Place. This science-based approach helps farmers understand how efficient fertilizer application improves profitability while reducing nutrient losses into the environment.
"The strength of this agreement lies in the shared-value partnership approach. Working together helps broaden our understanding of the challenges and the steps necessary to encourage agricultural growth in a sustainable manner," said Garth Whyte, President and CEO of Fertilizer Canada.
The Ministry of Agriculture, Food and Rural Affairs; Fertilizer Canada; and the Ontario Agri Business Association will work in partnership with Ontario farmers and conservation groups to support the adoption of sustainable 4R Nutrient Stewardship Systems.
"Sustainable agriculture is a priority for Ontario's five million acres of farmland," commented Anne Loeffler, representing Conservation Ontario. "Conservation Authorities are pleased to work with agricultural organizations and producers to manage healthy soil, water and landscapes supporting productive agricultural systems, rural communities and economies."
Sustainable water quality and land use is a priority for Ontarians. The agriculture industry understands the concerns regarding Great Lakes water quality and considers voluntary actions to be part of the solution. The Government of Ontario has embraced 4R Nutrient Stewardship as an important tool to meet the province's agricultural and environmental goals. This support is amplified by partners in the agriculture industry, who have undertaken efforts to adopt and promote 4R Nutrient Stewardship in Ontario.
"Farmers are excellent stewards of the land and understand how important healthy soils and clean water are for the sustainability of Ontario's agriculture sector" said Jeff Leal, Ontario's Minister of Agriculture, Food and Rural Affairs. "Ontario's agriculture industry has been a leading partner in identifying and adopting ways to reduce the sector's overall environmental impact. By working together, we have promoted initiatives, such as this, to ensure a healthy Great Lakes system positively benefits all Ontarians."
Through this Memorandum of Cooperation, Certified Crop Advisors will help growers implement 4R Nutrient Stewardship on their farm. Once a grower has implemented these best management practices, their acres can be counted to demonstrate the commitment being made by the agricultural industry to the environment.
"Endorsement from agri-retailers helps farmers commit to the adoption of best management practices under 4R Nutrient Stewardship. Through this effort, sustainable crop nutrition can be achieved," says Matt Gardner, President of the Ontario Agri Business Association.
For more information about fertilizer best management practices and implementing 4R Nutrient Stewardship in Ontario, visit www.fertilizercanada.ca.
By Ken Panchuk, PAg, Provincial Specialist Soils
Early June is a good time to reassess your crop nitrogen needs. Generally, nutrient recommendations based on soil testing are adequate for most growing seasons but there are times when a top-up of nitrogen may be needed:
- If growing season conditions have improved since seeding and the crop is in need of more nitrogen to achieve the potential realistic target yield and/or protein level, then top-up nitrogen may be required.
- If higher than normal losses of nitrogen applied last fall or this spring are suspected, and/or the crop is starting to show symptoms of nitrogen deficiency, a top-up may be required.
Reviewing the soil test information, tissue testing, field scouting for nitrogen deficiency symptoms and a handheld Greenseeker may be used to compare areas within a field to aid in determining whether more nitrogen is needed. Also, get additional help, if needed, from your area agronomist or Agrologist.
The most common symptoms of nitrogen deficiency are the yellowing of the older leaves and/or pale green leaves, but keep in mind there are other causes of these symptoms.
Earlier application of top-up nitrogen helps recover yield better than applications made at later crop stages. The rate of nitrogen needs to be high enough to increase yield or protein. Also, keep an eye on the long-term weather forecast to help determine if top-up nitrogen will be effective.
Liquid nitrogen has the best fit for in-crop dribble banding using drop tubes or split nozzles. If rainfall is not expected shortly after application, then consider using a urease inhibitor that helps reduce volatilization loss while waiting for a rain to move the nitrogen into the soil.
If you are like most Ontario corn producers, you probably think applying a band of dry fertilizer at seeding is a completely outdated concept. And, unless your opinion strays far from that of your neighbours, you likely also believe reduced tillage is, if not an outright impossibility for your farm, at least an unnecessary inconvenience with downsides that outweigh the benefits.
But recent studies by the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) suggest you may want to change your mind on both fronts.
“We’ve spent several years looking at a number of agronomic possibilities to improve corn efficiency,” Greg Stewart, OMAFRA corn industry program lead says. “On the fertilizing side, there are people who would say what we are proposing is a step backwards. But it doesn’t take a whole lot to convince them that applying dry fertilizer at planting could be a reasonable thing to do. And in terms of reduced tillage, we’re suggesting an intermediate step that works in harmony with the dry fertilizer concept.”
The majority of corn farmers today opt exclusively for injectable, liquid forms of phosphorus (P) and potassium (K). This choice can make sense, so long as the cropping land’s soil starts off with fairly strong levels of nutrients and only requires a minimal top-up. On land testing in the moderate to low range for P and K, however, a product like a liquid 6-24-6 fertilizer applied at a typical five gallon per acre rate will only contribute about 3.5 pounds of K per acre: not enough to bump up a deficient soil’s capacity to meet a corn crop’s nutritional requirements. A much more cost-effective way to easily apply larger amounts of P and K is to band dry fertilizer.
“If you are deficient in K, you can put on 10 times as much potash, and at a price that is much more competitive per pound, if you use dry fertilizer over liquid,” Stewart says.
Stewart suggests a four-point checklist when evaluating the impact dry fertilizer might have on your operation. Those four points are: soil test levels, soil structure, intensity of tillage and land tenure.
“If a grower has high soil test levels for P and K, has excellent soil structure, does fairly intensive tillage and owns all his land, then it is most likely that dry fertilizer won’t pay,” Stewart says. “But at the other end of the spectrum is the grower with lower testing soils and soil structure that still needs some improvement, who would like to do less tillage and who rents much of his land. In that case, dry P and K could be a very important factor in boosting corn yields.”
Most producers will fall somewhere in-between the two extremes, and will need to evaluate how much potential dry fertilizer might offer.
To minimize extra passes, Stewart suggests one of two dry fertilizer application methods, both of which may raise your neighbour’s eyebrows.
The first is to carry dry fertilizer on your planter. “People are spending huge amounts of money on corn planters that seem to be able to do anything: minutely control seed placement, adjust pressure, plant at 15 kilometers per hour, carry and switch back and forth between two seed varieties. And here some government guy gets up and says they should carry dry fertilizer on their planter. It’s kind of a 1970s concept: not very new, not very exciting ,” Stewart says. “But, based on the results from the studies we’ve done, in the realm of return on investment, it would be a mistake to completely ignore the concept of banding dry fertilizer beside the seedrow.”
Admittedly, there may be logistical hurdles to the concept, especially since today’s big planters often don’t have the capacity to carry dry fertilizer on board. In some cases, retrofitting a machine may only be a moderate investment, such as installing tubs across the front of the machine that each deliver dry fertilizer to just a couple rows. Alternatively, a planter without onboard capacity might require a separate pull-behind cart that blows fertilizer through tubes alongside seedrows.
“For some people, it’s just not going to be logistically possible to set up a workable system, even to tender the dry fertilizer to the planter. But, there are a large number of producers who shouldn’t dismiss this idea completely,” Stewart says.
A second option for applying dry fertilizer is to apply it prior to seeding (either in fall or spring) in an eight-inch tilled strip.
Conservation tillage for corn has had a difficult time gaining ground in Ontario. However, strip tillage solves the issue of residue and slow spring warming and drying, while still offering the soil health and environmental benefits of reduced tillage. And, when laid out on the contour (the strips cut horizontally across slope rather than vertically up slope), strip tillage can work as multiple mini dams to very effectively reduce erosion.
“Precision steering makes creating these eight-inch strips and then getting the corn rows on top of them suddenly quite possible,” Stewart says. “If you put your dry fertilizer on your strip tiller, when you come along with your planter the land can be exactly how you like it – absolutely naked. You just plant and go. There’s real harmony between the ideas.”
Initial trials last season, led by Stewart and the Innovative Farmers Association of Ontario (IFAO), showed some cost benefit from applying dry fertilizer during strip tillage. In the first year of trials, the results were not entirely consistent. The project will be continued in 2015 and updated results posted to the IFAO website.
“If we were careful, we could put all of our fertilizer into the strip zone in advance, which offered some cost savings. But, putting all of the N, P and K into that eight inch strip can make it too hot for seedlings, and softening the blow by switching to a polycoated urea added costs over and above conventional urea, which took away some of the cost benefit.”
Still, the environmental benefits, convenient timing of fertilizer application, and elimination of later season fertilizer broadcasting and knifing mean the system offers benefits beyond input dollars and cents.
“If we could get people to move to strip tillage, that would be a really good step forward, even if they are never going to switch all the way to zero tillage. It’s not necessary to move completely to no-till in order to see the benefits of reduced tillage. This is a new way of looking at field management,” Stewart says.
The fertilizer industry strongly promotes the 4R’s of Nutrient Stewardship – right source, right rate, right time and right place. Split application of nitrogen (N) fertilizer into two or three applications over the growing season is being promoted as a way to synchronize N application with the crop’s ability to utilize N and therefore increase fertilizer use efficiency. But does it work under Prairie conditions?
There are suggestions that split-applying N fertilizer is a way to avoid volatilization, leaching and denitrification losses. The thinking is that when all N is applied at a single application at or before seeding in spring, then much of the N is vulnerable to loss in late May and June before a crop is taking up much of the N fertilizer, leaving a window for potential loss. For this reason, some agronomists suggest postponing application of a portion of the N until the crop is better able to utilize the N and crops will take up the N more effectively. However, use critical thinking to decide if applying in-crop N is potentially beneficial for you.
For cereal and oilseed crops, many farmers in Western Canada either band their N before seeding or place all fertilizer N in a side- or mid-row band at the time of planting. After seeding, most of the N fertilizer will slowly convert to nitrate nitrogen (NO3-), the form of N that plants take up. As long as N losses from leaching and/or denitrification are minimal, efficiency of N uptake should be in the range of 60 to 70 per cent, which is very good.
It is very true that N fertilizer can be vulnerable to loss, depending on soil type and climatic conditions. For example, if you direct seed a wheat or canola field on May 15 and all N fertilizer is applied at planting, and if the soil is warm and moist, most of the applied N will convert to NO3- by early June. Then, if heavy precipitation occurs during the second and third week of June, NO3- leaching losses can be significant in sandy soils, and denitrification can be significant in medium and fine textured soils. This N loss often results in substantial yield loss.
If significant N loss occurs, or if you want to split-apply N fertilizer to avoid N losses, there is a range of application options, each with some risk:
In-crop broadcast application of urea (46-0-0):
Often soil and air temperatures are warm in mid to late June and hot in July, resulting in favourable conditions for N volatilization of broadcast urea. N losses could easily be in the range of 20 to 40 per cent. Coating the urea with a product such as Agrotain (urease inhibitor) or another slow N release product should reduce N volatilization loss. After N application, a 10 to 15 mm rain is needed to move the urea into the soil. Then, it will take two to three weeks for soil microbes to convert the majority of the urea to NO3- for plant uptake. The delay from the time of N fertilizer application, having rain to move the N into the soil, then to convert urea to NO3-, could be three to four weeks or more. By this time, it may be too late for the N fertilizer to be beneficial to wheat, but the canola field may benefit if the crop is still branching and flowering.
In-crop application of liquid 28-0-0:
This can be applied by dribble banding or using spray jet nozzles. Remember that 50 per cent of the N in 28-0-0 is in urea form and subject to volatilization, so a urease inhibitor should be used to minimize volatilization losses when applied in warm June conditions. One-quarter of the N in 28-0-0 is in plant available NO3 form when precipitation moves the fertilizer into the soil.
For both in-crop broadcast 46-0-0 and in-crop application of 28-0-0, the very best efficiency of uptake would be 35 to 40 per cent, and would occur if precipitation moved the fertilizer into the soil within a day or two after application and the product was applied in mid to late June. This means that if 30 lb N/ac was applied and efficiency of uptake was 40 per cent, only 12 lb N/ac would actually be taken up by the crop, in the best-case scenario.
Fertigation of liquid 28-0-0:
Application through a pivot system is a reasonably good option for irrigation farmers. Some volatilization of the urea in the 28-0-0 will occur on warm, windy days. Remember that after fertigation of 20 lb N/ac, a quarter of the N will be immediately available to the crop, but the remaining N will take two to three weeks to become available for crop uptake. Therefore, fertigation application must take place about two to three weeks before the crop will need the N fertilizer.
Foliar application of 28-0-0:
Maximum application rate using spray nozzles is about 20 lb N/ac to avoid leaf burn. Generally, less than five per cent of the applied N is taken up via the leaves in a best-case scenario, which means less than one lb of N/ac of a 20 lb N/ac application would be taken up by the foliage, which is almost insignificant to increase crop yield. The N fertilizer would have to be washed from the leaves by precipitation and moved into the soil, and converted to nitrate for plant uptake. Therefore, this method of application is not normally recommended.
Broadcast application of ammonium nitrate (34-0-0):
This is a very effective in-crop product with very little potential N loss. Half the N in the fertilizer is in the plant available form of NO3, which is immediately available to a crop after rain has moved the fertilizer into the soil. Unfortunately, only a couple of companies import 34-0-0 into Western Canada so availability is generally extremely limited.
For Western Canadian farmers, if leaching or denitrification is not normally a problem, banding all N fertilizer before or at seeding will result in the best uptake efficiency for cereal and oilseed crops. In wetter regions of the Prairies where leaching or denitrification is a more common problem, particularly in June, it may be beneficial to reduce N application in spring by 30 to 40 per cent and apply a second split application about mid-June for availability in early July. Rates of 40 to 50 lb N/ac will be necessary when application efficiency is 40 per cent or less. Although 34-0-0 is the best choice for in-crop use, for most farmers, availability will be restricted to 46-0-0 or 28-0-0. When using either product, keep in mind the best practices to minimize volatilization losses.
In wetter regions with increased concerns of N losses, another option at planting is to use a combination of urea and a slow release N fertilizer in a ratio such as 40:60 to reduce potential N losses. In studies by Alberta Agriculture and Rural Development (AARD) with wheat, barley and canola with urea versus ESN versus a blend of urea: ESN have shown clear benefits using ESN. Additional studies with ESN have also shown benefits with longer-season irrigated potatoes and dry bean.
So for efficient N management, consider the benefits of slow release N products applied at planting versus less efficient in-crop N application.
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