The Saskatchewan VRT Project is performing field-scale investigations in Northeast Saskatchewan to assist producers in the adoption of variable rate nitrogen applications. Currently, farmers apply constant rates of nitrogen and this results in over application in some areas, which harms the environment, and under application in others, which reduces profitability. The VRT Project has found that variable rate fertilization reduces production risks and improves profitability. Project leaders Dr. Dan Pennock, Dennis McIntosh, and Cory Willness have teamed up to develop a practical method to implement variable rate fertilization on Saskatchewan farms.
The Northeast Agricultural Research Foundation (NARF) is a non-profit organization established to encourage and direct the development of agriculture research for producers in Northeast Saskatchewan. Work completed to date has focused on using yield mapping systems to evaluate on-farm research trials. Examples of field-scale research that the producers have tested includes fungicides, micronutrients, weather station disease modeling, soil sampling systems, and alternative crops. Recently NARF has decided to support the Saskatchewan VRT Project as its top priority.
Dennis McIntosh is a long-standing NARF board member that was determined to find the solutions to make site-specific management of N fertilizer work on his farm. He has been farming for 25 years a few miles north and west of Melfort. His drive to reduce crop lodging, increase uniform maturity and use fertilizer efficiently may have been sparked by his education in chemistry. Dennis also has the computer and technological expertise to put the various hardware components, and the software in the system together and make it work. In his quest to make this work on his farm he has traveled and networked with experts across North America who are attempting to find the same answers he is.
In 1998 Dennis began some field scale research trials on his farm with NARF. Dennis hoped to be able to use aerial photography and topographic based soil testing to establish nitrogen management zones. He started out with 2 fields establishing small management zones using grey-scale photography. As he applied the anhydrous Dennis felt he should be overriding the rates that the prescription map was feeding to his applicator. The results that cropping season were evaluated against fixed rate strip trials also laid out in these fields. During the growing season the lodging indicated to him that there were problems with the zones that had been laid out. These observations were also confirmed with remote sensing techniques. The yield maps used to quantify the results of the management zones against the strip trials showed that the procedure was working on a large portion of the field. However in the remaining areas there were serious enough errors that when these numbers were converted to financial returns there had been no benefit to this management zone approach.
Dennis decided to use his "intuition" or gut feel for the rates of N he felt should be applied based on the observations and data which he had collected in the 25 years he had farmed these 9 quarters. He felt his intuitive interpretation of soil N status was probably more reliable than the guidelines obtained from an extensive site-specific soil testing program. All the technology was already in place on his equipment to capture and record these rates. If this approach proved profitable maybe one could work backward or reverse-engineer to come up with a predictive analysis that could be standardized for others to use.
The term Dennis uses to describe this method is the "seat of the pants" method. It is based on the familiarity that farm operators acquire with their land over a number of cropping years. It is based on observations throughout the seasons, grain yield and crop residue produced, soil characteristics, and even past histories that only the human mind can manage. Dennis refers to these as virtual images or maps the human mind has created. He is in a sense capturing and converting these images into a digital format that our GIS software can handle thorough the seat of the pants N application method.
To get started at this procedure Dennis toured the field by ATV bringing to mind the field characteristics that he thought would impact how much N he should apply. For the startup passes he placed pin flags of different colors at various field locations to help jog his memory when he was actually in the tractor seat adjusting the N application rate. He says, "Given some experience, the rate patterns soon imprint and it's possible to develop a high level of consistency between different passes across the field."
One of the problems Dennis encountered with the term "management zone" was that others seemed to be trying to develop application parameters based on only 1 or 2 factors that vary across a field. He prefers to view each field as a collection of many small management squares arranged in a grid. Each square or grid location in a field can be as complex as a mini-ecosystem and may respond differently to specific management practices than neighboring grid cells. He calls each of these grid locations a logical management unit (LMU).
Dr. Dan Pennock is a professor and researcher with the soil science department at the University of Saskatchewan. He reported at the recent Site Specific Management Conference in Edmonton that "Site-specific management has turned out to be a lot more site-specific than researchers originally assumed." This has made it difficult to develop recommendations for site specific management within a given region. It supports the need for on-farm research. Dan suggested that "producers need to work with researchers and professional agrologists to ensure that the on-farm research they conduct will answer the questions that the producer wants answered."
Cory Willness is an agrologist with the Co-op Agronomy Centre at Naicam and a member of the NARF management board as well. He also promotes on-farm research. Cory was the catalyst that lit the fire for the Saskatchewan VRT Project in the winter of 2001. He says, "Dennis' work is impressive because he has single handedly put together a working solution for variable rate fertilizer application using field scale machinery and equipment along with readily available GPS technology and software." "He already has a successful implementation of variable rate fertilization that farmers, researchers, and agrologists can learn and build on." Cory says that because the VRT Project has used field-scale machinery and equipment and on-farm research for evaluation, the transfer of information and techniques to other producers will be smooth.
One of the key issues that the VRT Project team has identified as a hindrance to the progress of variable rate fertilization is that there isn't a reliable method of determining how much nitrogen will be released from the soil throughout the growing season. This particularly applies to the northeast region of Saskatchewan that has many soils with high organic matter contents and generally higher moisture availability. Dr. Pennock confirms that the scientific literature indicates "variable rate fertilizer prescriptions based on measured values of plant available nutrients (using standard soil testing procedures) have generally been unsuccessful."
One of the focuses of the VRT project is to determine an accurate method of predicting mineralizable N. This is the amount of plant available N that will be released from the soil and taken up by the crop throughout the growing season. The project team is evaluating 3 different methods of measuring mineralizable N in soils at the Central Research Site of the VRT Project. They feel that this will be key in coming up with accurate N recommendations needed to write prescriptions for the LMUs. By including a zero N rate test strip in their trials the project team has found there are LMUs that are receiving too much N under the constant rate application methods we currently use.
The next phase of the project is to test and evaluate the seat of the pants method on other farms in Northeast Saskatchewan. This phase is set to begin in 2002. Other producers equipped with yield mapping systems to assess their results will be putting down trials on their farms. They will all be running fixed rate strip trials including a zero N rate strip. SSCA members Ed and Marguerite Beauchesne, Terry Gates and Al Moskal are among the producers that will be carrying out on-farm trials this year. This is the first step in taking the technology to Saskatchewan producers.
On his own farm Dennis will be going to a 1 pass seeding system this spring applying NH3 at seeding time. He has chosen a Morris Special Edition air drill with their new coulter-style fertilizer banding units. The seeding unit will be equipped with a custom version of variable rate application technology that is state of the art. Dennis says that after working for 6 years to develop prescription N applications he will be using this seeding and fertilizing system on his entire farm this coming spring.
Dennis has been seeding with a minimum tillage program until now. Usual operations included banding NH3 with knives before seeding with an air seeder. Sometimes he needed a tillage pass to manage residue. He expects to cut costs with 1 pass seeding and that should raise his profit margin. He is particularly excited about some of the new features of the Morris angle-disk fertilizer coulter. He has a mixture of soil characteristics and feels he needs a mid-row banding system that is more versatile and rugged than older coulter designs that are on the market. Dennis says "I think the combination of the rubber soil retaining wheel that improves NH3 capture and the tine option to reduce soil and straw buildup will give much better results over a wider range of soil types and moisture conditions".
Site specific management is at a turning point where economics and environmental sustainability are now driving the adoption of this technology. Successful implementations of SSM will carry an immense value to Saskatchewan producers in the next few years. Partnerships such as the Saskatchewan VRT Project may be one of the most effective ways to overcome the obstacles to SSM implementation so that we can become leaders in the adoption of this technology on our farms. The VRT Project began on a Saskatchewan farm and the project leaders and supporters are hopeful that the benefits of this work will soon impact many other Saskatchewan farms.