Top Crop Manager

Top Crop Manager
A profitable increase

A profitable increase

Too many variables often make it difficult to recreate the same effective strategy year after year in agriculture.

Crop nutrition problems can become pest problems

Crop nutrition problems can become pest problems

Deficiency of a single nutrient can impair healthy plant growth.

Variable-rate planting

Variable-rate planting

As corn hybrids are being developed to respond better to higher seed populations, interest is growing in variable-rate seeding.

Field management to reduce blackleg risk

Field management to reduce blackleg risk

For many years, blackleg disease on the Prairies was managed fairly successfully through the use of disease resistant varieties and an extended rotation.

Cold temperatures hamper soybean nodulation

Cold temperatures hamper soybean nodulation

The 2014 growing season was the worst year in recent memory for poor root nodulation and nitrogen (N) fixation in soybeans.

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Agronomy

Spring application tended to be better than fall, with higher yields and greater nitrogen use. Optimizing ESN and urea management

 Through a major study, Alberta researchers are developing improved tools to help crop growers optimize their nitrogen fertilizer management for yield, quality, profitability and sustainability. The researchers have already completed five years of intensive data collection, from 2008 to 2013, at sites across Alberta. And they’ve learned a lot from their preliminary analysis of the data. Now they are working on an in-depth analysis so they can update provincial nitrogen fertilizer recommendations and enhance AFFIRM, a fertilizer decision support tool. “It’s been a long time since we have done this kind of research in the province. But as we get new crops, new varieties, new input products, new types of equipment, there is a need to re-visit or re-do these studies to make sure our fertilizer recommendations are up to date,” explains Len Kryzanowski of Alberta Agriculture and Rural Development (AARD). He is leading the study, which is a joint effort of AARD, Agriculture and Agri-Food Canada, Agrium and the Alberta Crop Industry Development Fund. AFFIRM – Alberta Farm Fertilizer Information and Recommendation Manager – is available on the AARD website. It is mainly based on Alberta conditions so it’s targeted to Alberta users, but people in Manitoba and Saskatchewan have downloaded AFFIRM too. “AFFIRM is popular with producers who want to identify economically appropriate rates of fertilizer application,” says Kryzanowski. “The current version came out in 2005. We want to update it with our research results and bring it up to a 4R Nutrient Stewardship level, to take into account some of the placement and timing aspects of fertilizer management.” He explains: “The 4R Nutrient Stewardship – ‘Right Source @ Right Rate, Right Time, Right Place’ – has become the industry motto to promote responsible, sustainable fertilizer use.” The Canadian Fertilizer Institute is leading a national initiative to help farmers use the 4R approach to increase their production and profitability, while enhancing environmental protection and improving sustainability. The Alberta study was initially prompted by the need for more information on Environmentally Smart Nitrogen (ESN) under Alberta conditions. ESN consists of coated urea granules. Moisture can move through the coating and dissolve the urea. As the soil warms, the dissolved urea moves out faster through the coating and into the soil. Since soil moisture and rising soil temperatures also promote crop growth, ESN could potentially improve yields by better synchronizing nitrogen availability with the crop’s need, while also reducing nitrogen loss to the environment. “Nitrogen losses are obviously going to impact crop yield, economics and productivity,” says Kryzanowski. “But nitrogen losses can also be quite significant from an environmental perspective.” Fertilizer nitrogen can be lost from a field by runoff, leaching and gaseous losses. Runoff and leaching losses can harm water quality. One of the gaseous losses is nitrous oxide, a potent greenhouse gas. Kryzanowski says, “Fertilizer management has come under a microscope as a source of nitrous oxide emissions.” He notes that nitrogen losses could also have value chain implications. For example, Walmart recently stated that it would like farmers in its food supply chains to optimize their fertilizer use, yield and productivity, including minimizing fertilizer losses to the environment. Intensive and extensive field studyThe Alberta study is comparing ESN, urea and a blend (75 per cent ESN and 25 per cent urea) under a range of application options and conditions to assess the agronomic, economic and environmental performance of the treatments and to provide recommendations about when to use which option. Kryzanowski explains the blend was included in the treatments as a way to try to capture benefits of both ESN and urea. “There was a concern that the release of the nitrogen from the ESN pellet was a little bit too slow for the crop utilization, so a blend would provide some fast release and some slow release nitrogen. We also thought a blend might reduce seedling damage in comparison to urea alone. And a blend is less expensive than ESN alone.” The study had nine field sites – eight dryland and one irrigated – ranging from the Peace Region to the Lethbridge area, with soil and weather data collected for each site. At each site, the researchers compared ESN, urea and the blend applied at 0, 30, 60, 90, and 120 kilograms per hectare. The ESN and urea treatments were fall-banded, spring-banded and spring seed-placed; the blend was spring seed-placed. The researchers evaluated the effects of the treatments on crop growth, yield, quality, seedling damage and economics for hard red spring wheat, two-row barley and Roundup Ready canola. The study’s environmental component examined nitrous oxide emissions, which were measured at two dryland sites and the irrigated site. Along with determining how the different treatments affected nitrous oxide emissions, the researchers gathered measurements to help support the new Nitrous Oxide Emission Reduction Protocol. This protocol is one of the opportunities for producers in Alberta’s carbon offset market. By following the protocol’s practices, which are based on the 4R approach, Alberta crop growers can create credits that can be sold on this market. Yield, protein and seedling damage resultsAlthough yield responses to nitrogen fertilizer rate, form, timing and placement were significant for many sites and crops, the nature of the response differed greatly from site to site. “In terms of yield response, probably the most consistent thing we saw was the inconsistency in the responses. So we didn’t always get a better yield response with ESN versus urea, and we didn’t always get a better yield response with banding versus seed-placed. The responses varied quite dramatically from site to site. We suspect that relates to the moisture conditions,” explains Kryzanowski. ESN was usually the best option for sites with higher moisture conditions. For example, he notes, “Under irrigation, it was clear that ESN is a very good performer in terms of productivity.” The study also found a significant protein response to the nitrogen rate at all the southern sites, with protein content increasing as the nitrogen rate increased. Agronomically, spring application tended to be better than fall, with higher yields and greater nitrogen use. As expected, seed-placed urea resulted in the poorest growth and greatest seedling damage. In comparison, the seed-placed blend allowed higher nitrogen rates without seedling injury, and the seed-placed ESN allowed even higher rates. “If you want to use urea, then banding is a much better option,” says Kryzanowski. “If you want to seed-place your nitrogen fertilizer, then ESN is the best choice because it results in less seedling damage, more yield and greater productivity.” Canola suffered the greatest seedling injury from seed-placed urea, followed by wheat and then barley. “However, we found canola was able to recover from the seedling damage, as long as the plant population didn’t get too low,” he notes. Economically, the blend looks bestTo evaluate the economics, the researchers examined whether or not the value of the crop’s additional yield with ESN or the blend was large enough to offset the higher fertilizer costs compared to urea, using a partial budget approach. This analysis helps growers decide whether they should pay the extra for ESN, rather than use urea alone. Tables 1 and 2 present the analysis for canola using 2013 and 2014 prices. They show the percentage of ESN and blend treatments across the five years that provided a positive economic response, compared to urea. The highlighted numbers show those treatments with a higher probability of economic benefits (yellow = 51 to 74 per cent of the treatments were worth the extra ESN cost; green = 75 to 100 per cent of the treatments were worth the extra cost).   Table 1: Canola - percentage of treatments with a positive economic response, 2008-13, compared to urea, based on 2013 prices* *Canola price in 2013 = $605/tonne. Fertilizer cost differences in 2013: ESN - urea = $0.36/kg of nitrogen; blend - urea = $0.27/kg of nitrogen Yellow highlights = 51 to 74 per cent of the treatments were worth the extra ESN cost. Green highlights = 75 to 100 per cent of the treatments were worth the extra cost. Source: Len Kryzanowski, AARD. For instance, consider the results for Lacombe, calculated with the 2013 prices. In only 37.5 per cent of the fall-banded ESN treatments was the added canola yield high enough to offset the extra cost of ESN. In contrast, the added cost was worth it 87.5 per cent of the time when ESN was seed-placed. The higher canola prices and lower fertilizer cost differences in 2013, compared to 2014, make a big difference to the results. The tables also show that when nitrogen is banded, ESN would not likely be worth the extra cost most of the time, particularly if it’s fall-banded – at most sites, there’s less than a 50-50 chance that the extra cost would pay off when fall-banded. Urea would usually be a better economic choice when banding. When nitrogen is seed-placed with canola, the blend would have the best chance of being worth the extra cost. And seed-placed ESN would have a good chance of being worth the extra cost, at most sites, when canola prices are high. The greatest economic benefits from using ESN or the blend were for canola, followed by wheat and then barley. For all three crops, the economic results varied greatly within sites, between sites and between years. Kryzanowski says there were indications of regional differences. “Some sites were highly economical. For instance, under irrigation, it was easy to get higher yield productivity using ESN or the blend and the economic benefits from those higher yields. But when you started getting into drier conditions, the results became much more variable.”   Table 2: Canola - percentage of treatments with a positive economic response, 2008-13, compared to urea, based on 2014 prices* * Canola price in 2014 = $425/tonne. Fertilizer cost differences in 2014: ESN - urea = $0.38/kg of nitrogen; blend - urea = $0.29/kg of nitrogen Yellow highlights = 51 to 74 per cent of the treatments were worth the extra ESN cost. Green highlights = 75 to 100 per cent of the treatments were worth the extra cost. Source: Len Kryzanowski, AARD. Reducing nitrogen lossCompared to the agronomic and economic results, nitrous oxide emission results were more consistent from site to site. Spring application was clearly the most effective way to reduce emissions. “We typically saw between 17 and 25 per cent reduction in nitrous oxide emissions by going from fall-applied to spring-applied nitrogen. Spring application avoids that most critical time for nitrogen loss, the thawing period,” says Kryzanowski. ESN resulted in somewhat lower emissions than urea. “Switching from fall-applied urea to fall-applied ESN resulted in about 6 per cent reduction in emissions. And going from a spring-applied urea to a spring-applied ESN resulted in a 5 per cent reduction.” Emissions tended to increase as the fertilizer rate increased. Regional differences in emissions were related to moisture, with the highest emissions at the irrigated site. In-depth analysis coming soonIn the coming months, the researchers will be working on in-depth analyses of some key considerations. They are analyzing the data from this and other recent Alberta studies to develop improved fertilizer recommendations and update AFFIRM. For example, they are evaluating nitrogen mineralization from soil organic matter and its contribution to yield. “We’ve had a measurement of nitrogen mineralization in AFFIRM, but we now want to get a better link between the total nitrogen available for the crop, how it is utilized by the crop, and how that affects how much fertilizer needs to be applied,” explains Kryzanowski. The researchers are also mining the data for more information on nitrogen use efficiency, especially in terms of how much of the applied nitrogen is being captured by the crop under different conditions. As well, they are examining the effects of regional climatic conditions, especially moisture, to determine when a producer should choose ESN versus a blend versus urea. “The challenge is to reliably predict where, when and for which crop the economic benefits of using ESN over urea [are evident],” says Kryzanowski. They will also be increasing the flexibility available in AFFIRM regarding precipitation probabilities, to further enhance AFFIRM’s applicability across Alberta and into Saskatchewan and Manitoba. And they are in the process of supporting the scientific basis of the Nitrous Oxide Emission Reduction Protocol, so crop growers can earn extra income by reducing their nitrogen losses. The results from all this work will help crop growers make optimal nitrogen fertilizer choices for their own situation. For now, Kryzanowski suggests growers consider using seed-placed ESN if seedling damage is a concern, if the economics are right (for example when growing a high value crop), and in higher moisture areas. If you are banding your nitrogen, then urea tends to be the best option economically. And a seed-placed blend could be a better choice than either ESN alone or urea alone. “From our preliminary analysis, the seed-placed blend probably has the greatest potential for providing agronomic and economic benefits, as well as an environmental benefit, and minimizing seedling damage.”   

Machinery

A 120-foot boom equipped with six Greenseeker sensors moves through a wheat field. The system senses the colour and biomass of the crop and sends a signal to a rate controller to adjust product rates up or down.  Searching for solutions

Ontario crop researchers are putting the Greenseeker technology under the microscope to see if it can work for the wheat crop. They’re testing its ability to analyze the nitrogen (N) needs of the crop, which would help farmers apply the right amount of fertilizer. Peter Johnson, provincial cereal specialist with the Ontario Ministry of Agriculture and Food and Ministry of Rural Affairs, along with Dr. David Hooker of the University of Guelph, Ridgetown Campus, is leading trials to adapt the system to Ontario’s conditions. Johnson’s goal is to increase profits for farmers by applying higher N rates to areas where the crop will respond while reducing the rates where there’s a lower response. “At the end of the day, we’re trying to figure out how to have better-targeted nitrogen applications, more yield where possible, less environmental impact where the yield doesn’t have that potential, and more dollars in the grower’s pocket,” says Johnson. The Greenseeker system from Trimble Agriculture uses optical sensors with an integrated application system to measure crop status and variably apply the crop’s nitrogen requirements. The technology works in real time, allowing the operators to make variable rate app-lications on the go. The sensor uses light-emitting diodes to generate red and near-infrared (NIR) light. The light is reflected off of the crop and measured by a photodiode at the front of the sensor head. Red light is absorbed by plant chlorophyll and healthy plants absorb more red light and reflect larger amounts of NIR than those that are unhealthy. The reflectance values are used to calculate the Normalized  Difference Vegetation Index (NDVI), which is an indirect measurement of the crop’s above-ground growth. By comparing the NDVI of the crop being evaluated to that of an N-rich strip in the field, the technology can be used to respond to field variability. As the applicator moves across the field, a built-in microprocessor analyzes the NDVI readings and determines the N requirements that are needed to meet full yield potential. Pre-determined algorithms calculate the amount of N required. The information is relayed to the rate controller to provide variable rate N application in real time as the applicator moves across the field. Ontario researchers are working with an algorithm that was created at the University of Kentucky for soft red winter wheat. Johnson says the trials have been designed to evaluate the algorithm and adapt it to Ontario field conditions. According to previous research in Ontario’s fixed rate trials, the wheat crop shows a response to 150 pounds of nitrogen 60 per cent of the time. With the Greenseeker’s ability to vary the application rate, Johnson is hoping to apply less nitrogen but still match the yield response of a 150-pound application.In the first year of the trials in 2013, the system didn’t produce a positive economic response. Johnson suspects that they didn’t set the target rate high enough. “In many fields, a fixed rate with a higher rate than what a Greenseeker applied was our most economical rate,” he says. The target was set at a higher rate in 2014, but Johnson was not comfortable with the much higher amount of nitrogen that was applied, which reached 200 pounds in some areas. While it didn’t achieve the desired results, Johnson is still intrigued by the system. “I would look at the field, walk it and see a nice uniform field, and then you get the NDVI map and there were all kinds of differences,” says Johnson. “How real are those differences? We don’t know that.”Dr. Lloyd Murdock, a soil specialist at the University of Kentucky, had a similar experience when writing the algorithm. Murdock received a grant to run experiments with the Greenseeker, which was developed at Oklahoma State University. Murdock says farmers were generally doing a good job of estimating the amount of N needed for the crop by counting the tillers and looking at the colour. The method, however, is highly subjective and doesn’t address the variability in the field. “You have an instrument that could actually look at the crop and see what it is doing and make that assumption, not on a subjective factor, but on the factor on how it has grown and what it’s done,” says Murdock.He evaluated the technology using algorithms developed in Virginia and Oklahoma. Calling the initial results “OK,” he notes that they couldn’t beat the results of the old system. The researchers applied less N using the two algorithms, but the yields were lower. “When we did the economics, we were getting less money. So it became apparent to us that the algorithm has to be a regional thing,” says Murdock. In a process to regionalize the system for Kentucky (which took approximately four years), the researchers conducted several small plot trials with different rates of N applied at different times around the jointing stages of the crop. They used hand-held Greenseeker units to record the readings that were then used to develop the algorithm and realize the technology’s potential of applying N more effectively. The algorithm was then tested on farmers’ fields and was found to be better than the old method by raising the yields and economic returns. “Two years ago, when we had a lot of N carryover from a poor corn crop and lodging of the wheat plant . . . that year was terrible,” recalls Murdock. “But if you used the Greenseeker, it picked up that difference and didn’t put much N on. It’s based on the fact the technology is better than our eyes.” With a yield gain of about five to seven bushels per acre, Murdock notes that the $20,000 Greenseeker system isn’t for everyone. Farmers who have 1,000 or more acres and who plant wheat every year would be more likely to see a quick return on the investment. Johnson’s team is also seeking ways to regionalize the algorithm for Ontario. They’re using hand-held units to record NDVI readings from sites that have received various amounts of N, a method similar to the Kentucky algorithm. The results would then be correlated with the yields. “If we get enough of these sites, maybe we can actually find out what that curve should look like under Ontario conditions,” adds Johnson. Another important factor is to ensure that nutrients such as sulphur and manganese aren’t deficient. The Ontario researchers learned that the Greenseeker will read them as a nitrogen deficiency and apply N where it won’t help at all. “We need to make sure that we solve those issues before the Greenseeker technology is going to do what we want it to do,” says Johnson. In addition to the Greenseeker technology, they’re also flying unmanned aviation vehicles with multi-spectral cameras to see if that might be a more effective way of gauging the variability in the fields. “Putting a prescription map into an applicator might be just as effective, or even more effective than trying to read it on the go because there is always the challenge of the lag time between the sensor readings and when we change the rate,” says Johnson. “It’s quick, but is it quick enough? There are lots of questions we’re still trying to address.”