Variable rate fertilization makes big farms more efficient

One reality of modern agriculture and the trend toward larger farms is that efficiency often trumps agronomy.

This is especially true during seeding, when many managers, armed with data showing yield losses of more than one percent for every day that seeding is delayed, try to compress planting into fewer and fewer days.

Farmers who crop more than 5,000 acres have indicated in surveys that they plan to seed in 14 to 16 days the same amount of crop that they would have been planned to seed in 21 days 10 years ago.

At the same time, most of these large farming operations have adopted a one-pass system for their seeding and fertilizer operations.

They have also have moved to systems requiring no pre-planting operations in the spring, other than a herbicide application, and have streamlined their seeding and fertilizing operations, sometimes to the detriment of their agronomy.

The need for efficiency has resulted in farmers seeding fewer crops and simplifying their fertilizer practices.

Large farms often end up with one or two fertilizer blends, which were bought in fall or winter. They are often applied at a per crop rate rather than a per field rate.

For example, a producer may apply a 16-26-0-12 blend at 135 pounds per acre across all canola acres. This might be a good blend for the entire farm, but it will not reflect nutrient differences across fields or within a field.

The same practice is seen with nitrogen when growers don’t change the rates from field to field. It results in them losing the option of a tailored fertilizer blend or nutrient rate for a specific field.

Or has it?

Variable rate fertilization can maintain the nutrient needs of individual fields and even individual areas of a field without losing efficiencies enjoyed by using single blends. It also enables managers to not only vary the rate per field but also by zones within the field.

Modern monitors and memory cards allow mangers to install prescriptions for entire farms into each seeding unit. Managers are then guaranteed that the correct rate will be applied to the correct field, regardless of the operator.

Total amounts are calculated for each field so that it becomes easy to deliver correct amount of products to each field. The entire farm’s requirements are also calculated.

Such a system prevents rookies from seeding neighbours’ fields because the technology won’t allow seeding when the equipment is not within the borders of assigned fields.

Managers also receive an as-applied report.

Most managers using variable rate fertilization see an increase in productivity and profitability. Sometimes they also notice an overall reduction in the amount of fertilizer that is applied.

Variable rate fertilization is also an environmentally friendly farming practice because it uses one of the 4Rs of nutrient stewardship: the right rate.

As well, it is recognized as a best management practice under Alberta’s nitrous oxide reduction protocol. Used as prescribed, it allows farmers to sell carbon credits under Alberta’s Carbon Offset Program.

Variable rate fertilization allows managers of large farms to use their knowledge and experience on their farmland and incorporate it into inputs similar to what managers of smaller farms have done in the past. However, rather than increasing or decreasing the fertilizer rate from the tractor seat, the work is now done at the manager’s desk during the winter.


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