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Historically, farmers have determined their fertilizer needs by analyzing previous yields, soil analysis from samples taken across the field and current soil moisture reserves. Today, with the increasing value of crops and fertilizers, farmers are interested in how they can improve the efficiency of their fertilizer inputs.

One of the ways they are looking at improving the efficiency of their fertilizer inputs is by using variable rate technologies that allocates fertilizers across the field according to specific needs in different areas or management zones. New variable rate seeding systems have made variable rate technologies more cost effective and easier to use. With these improvements, companies have entered the industry providing technical services and technology expertise to producers at reasonable prices. These reasons have made variable rate technology or VRT commonplace on many farm operations.

What is variable rate technology?

Variable rate technology (VRT) is a method of applying varying rates of crop inputs to specific management zones across a specific field.

The goal of VRT is to optimize crop yields and crop quality while creating efficiencies in input application. The program will help producers make strategic use of fertilizers to optimize yields.

How does VRT work?

In western Canada, the process normally begins by dividing the field into a number of management zones using satellite imagery. Intensive soil tests are taken from each of the management zones and analyzed. After yield targets are established in consultation with farmers, a prescription application plan is made. Variable rate technologies that tie GPS information and application equipment together are then used to vary the rate of fertilizer applied to the field, resulting in the strategic placement of nutrients.

Advice

Agronomists work with farmers to develop yield goals across management zones within a field. The goal setting process incorporates agronomic tools and information, including: soil test results, soil moisture, fertilizer and commodity prices—in addition to producers’ knowledge of their fields. The prescription plan is fully customized and compatible with any type of variable rate equipment.

Opportunities

Because soil characteristics change across a field, all fields have variability. Because of soil variations, different areas in the field will have different yield potential. Managing nutrient application to specific zones allows farmers to optimize their nutrient inputs by applying targeted rates at each zone.

Whether the goal is to maximize crop yield, to balance nutrient application to reduce lodging and promote more even ripening, or to maximize production while working within a set fertilizer budget, companies can customize variable rate fertility prescriptions for producers.

VRT costs

One of the largest constraints for many producers has been the cost related to variable rate technology. This has severely limited the use of grid sampling in western Canada. This is due to the fact that in order to get a good field assessment based on grid sampling, research has indicated that grid samples should be taken on a sub-two-acre grid and under variable land, possibly one-acre grids. This required a high number of samples and can be very expensive. In a zone-sampling scenario, the cost of sampling all zones every year is also expensive.

To lower the cost to growers, Farmers Edge has introduced a program called Precision Solutions Ultra. Under this program fields are zoned and sampled in Year one. In the following three years, one third of the acres are sampled and managed in the traditional VR manner. The prescriptions for the other two thirds of the fields are created utilizing a complex modeling program that will eliminate the need for soil testing. This program eliminates the need for the costs of soil sampling and analysis – thus lowering the cost to producers. Utilizing soil characteristics, weather and yield, this modelling program provides accurate information on plant available nutrients for the following crop.

VRT and sustainability

The Best Management Practices (BMP’s) for applying fertilizer are summarized as the four Rs:

• Right product  Choosing the right product is important in ensuring that the fertilizer used is environmentally best suited for the specific use intended. For example, urea is ideally suited for fall and spring banding but may not be the best product for use in the seed row or for broadcast applications.
• Right place – This refers to the application. The practice of banding fertilizer was pioneered in Western Canada. The increase in fertilizer efficiencies show that the proper placement of fertilizer may improve a crop’s utilization and reduce losses into the environment.
• Right time – Proper applications of fertilizer in the fall, during seeding in the spring, or in crop all have specific advantages under certain conditions.
• Right rate – Not only does applying the proper rate optimize crop production, it also helps the environment by reducing the excessive application of nitrogen to areas of the field where it may be lost via leaching or denitrification. By using variable rate technology, rates are matched to anticipated crop use.

Environmental sustainability

Variable rate nitrogen applications are recognized by the Nitrous Oxide Emission Reduction Protocol (NERP). The NERP is intended to reduce on-farm emissions of nitrous oxide (N2O) in a quantifiable, credible and verifiable way. In addition to NERP, producers can also increase their Carbon Credit returns in provinces where Carbon Credit payments are made. It is hoped that Saskatchewan will have a Carbon Credit program in the near future that will recognize the benefits of VRT fertilizer in reducing the emissions of nitrous oxide.

Things to look for in a VRT Program:

-An outline of fertility management zones based on satellite imagery such as NDVI.
-Fertilizer recommendations based on nutrient response curves that are calibrated to western Canadian production conditions.
-Reliable soil sampling and analysis at an accredited lab
-Agronomic recommendations and prescription maps based on producers’ needs and goals.
-Flexibility for producers to choose the type of variable rate equipment they use.
-Access to mapping and record keeping capabilities.
-An economic check that allows you to calculate the return from your investment.