Making the introduction of variable rate pay

To most farmers, the adoption of precision farming strategies relies on a rather dogged question – does it pay? In many cases the answer remains elusive.

This reality has been cited as a major factor in the slower-than-hoped precision tech adoption rates among farmers worldwide. When it comes to variable rate technology, however, some farmers in Ontario, Canada, definitely have found significant, well-identified value. Coming largely in the form of input-cost savings, they say higher profitability is very possible – if one takes time to do the math.

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Jeff Vermeersch with the sprayer – variable rate also plays an important role in their farm’s crop protection regiment. – Foto: Photo: Ann Vermeersch

Record keeping essential

Chris Boersma, a precision agriculture specialist and grain, pea, and white beet farmer from Southwestern Ontario, says proper documentation is critical in determining whether a precision technology is providing a good return. This can be done either manually or through a data management programme, though modern tech has made record keeping and availability much easier.

“The equipment doesn’t give you the refund. It’s the work you put behind it”, says Mr Boersma. “It’s really more of a system… everything adds up. You have to do the analytics behind it to make it pay.”

Variable rate nitrogen applications

Years of record keeping have proven vital in determining the effectiveness of, for example, variable rate nitrogen applications. By documenting applied nitrogen specific to individual coordinates within a field, and overlaying that data with harvest maps – as well as running non-variable rate test strips for comparison – Mr Boersma says they can reverse calculate what rates work best, and where their savings are.

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The equipment doesn’t give you the refund. It’s the work you put behind it

He adds good records can’t be generated in a single year. Developing good data and deriving useful information from it, is a multi-year process. “If you fill everything in, do it all, you have all your records in one place where they’re easy to access”, says Mr Boersma. “It doesn’t matter whether it’s on a phone, or iPad, wherever, but you can go back to the field, see where a certain variety or application is. That is invaluable.”

Knowledge of varying growing conditions

Like Mr Boersma, agronomist and cash crop farmer Ann Vermeersch says determining the profitability of variable rate starts with calculating the impact of input redistribution. On her and her husband Jeff’s farm in Southern Ontario, variable rate lime application has proven particularly cost-effective for the past 7 years. Because of differing growing conditions – which she describes as “highly variable” in terms of soil type, drainage, elevation, and so on – Ms Vermeersch says uniform lime prescriptions are rarely appropriate.

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Ann Vermeersch: “We live in a world of imagery. I’m still trying to make imagery work.” – Photo: Ann Vermeersch

Soybean planting

Combined with the high volumes and costly nature of the input, she says the savings are both clear and consistent. Similar benefits have been found with variable rate potassium and phosphorous. They also began using the technology in soybean planting 3 years ago. Reducing the number of soybeans planted in good areas of the field – soybeans fill out well, making seed density less of a concern – has brought both a reduction in white mould issues and savings of $ 10 to $ 15 per acre in seed costs.

Ms Vermeersch does think it’s less likely variable rate would pay in more uniform field conditions. In her highly varying circumstances, however, it’s proven to be a very useful tool.

Supporting profitability with predictive mapping

For Dan Breckon, soil type management zone specialist for Woodrill Farms (a full-service crop input supply company, grain elevator, and grain farm in central Ontario) generating value from understanding growing conditions – specifically differences in soil type – can be taken a step further. His company employs predictive mapping technologies (GIS, spatial, and statistical mapping) to generate high-resolution soil type management zone maps, as well as fertility information.

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You need to use a sensor to tell you how the soil is, before a yield map makes sense

They combined these with soil landscape information gathered through RTK elevation, satellite and landscape other imagery, as well as soil sampling and monitoring and crop yield data.

Yield limiting pH levels

The use of “multiple perspectives” to assess field conditions, says Mr Breckon, lets him and his colleagues identify yield-limiting factors that explain some of the spatial variation in their yields. In multiple scenarios, for example, they found yield limiting pH levels caused by low magnesium and calcium.

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Woodrill Farms performs soil probe tests to measure soil characteristics through multiple layers. – Photo: Woodrill Farms

To correct this, the recommendation would be to apply dolomitic limestone to the low pH areas. Such an approach supports better yields on underperforming areas, and saves input costs everywhere else.

“In most cases the area that needs to be corrected is less than 50% of the farm field,” says Mr Breckon. “You need to use a sensor to tell you how the soil is, before a yield map makes sense.”

LiDAR tech image (r), old provincial maps (l). LiDAR can measure many geographical aspects, inclusing soil carbon content. – Image: Ontario MInistry of Agriculture, Food and Rural Affairs