Your Reading List

Variable rate can be used for more than fertilizer

Reading Time: 2 minutes

With more producers interested in the benefits of precision agriculture, the concept of variable rate technology isn’t just limited to fertilizer application rates, says a specialist with Agri-Trend Agrology Ltd.

Variable-rate technology – the concept of making more efficient use of a crop input – can be used with fungicides and even manure, says Warren Bills, an Agri-Trend coach specializing in precision farming technology. Agri-Trend is an Alberta-based consulting and crop management company, offering services across Canada.

“For the past few years, farmers have been hearing more about variable rate technology, as it relates to fertilizer application rates,” says Bills during an interview at the 2008 Agri-Trade farm show in Red Deer. “But the technology can also be used with other inputs as well.”

Warren Bills of Agri-Trend says the concept of variable-rate technology can be applied to most crop inputs. Determining the proper rate of a fungicide, for example, requires a slight change in intelligence gathering, he says. In determining a prescription for variable fertilizer application rates, specialists use yield data from combine yield monitors, soil test analysis, and often satellite imagery to assess the yield potential of various sites over a field.

“But a satellite image of your 2007 crop isn’t going to help you determine whether a fungicide or what rate of fungicide is needed on the 2008 canola crop,” says Bills. “To determine that we need in-season imagery.”

An important tool in the process is an aerial photo or “real shot imagery” taken of the particular crop about two weeks before a fungicide application may be needed. The real shot image is taken from an airplane flying at elevation of about 10,000 feet, capturing infrared images of a field at one metre resolution.

“The process still requires ground truthing – to look at the crop on the ground – to determine the density of the crop canopy and the risk for disease development,” says Bills. “But, if the decision is to treat the crop, the real shot imagery can be used to determine which areas of the field need the required treatment.

“It may be that part of the field can benefit from a fungicide treatment and while another part doesn’t need the treatment. Or the individual crop advisor may determine, for example, part of the field can benefit from a full rate application, while another only needs a three-quarter or half-rate or less.

“Again the whole concept is to make the most efficient use of the crop input,” says Bills, “It doesn’t necessarily mean using less of the input, but more about applying the proper rate where it will do the most good.”

Along a similar line with manure application rates, Agri-Trend has worked with producers in Manitoba to determine variable manure application rates. This project involved dividing a field into five-acre grids and then soil sampling each of those grids.

From that data, the field could be divided into zones and then different rates of manure applied to those zones as indicated by soil test information. The objective was to apply the proper amount of manure where it was most needed to help even out crop yield.

About the author



Stories from our other publications