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Variable Seed Rates 'Deliver Biggest Yield Responses’ – Anglia Farmer – Mike Young, Nick Strelczuk

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Drilling The highest yield responses from precision agronomy are likely to come from variable seed rates in combinable crops, suggests new research.

Growers should consider new technology to calculate accurate seed rates for variable rate drilling this autumn, says Farmacy chairman Mike Young. Farmacy trials across the country this year achieved big yield increases in both winter and spring combinable crops, he adds.

Mr Young's advice is to take the time now to consider how best to optimise variable rate inputs for this autumn, with new technology such as TerraMap offering a genuine opportunity to enhance the benefits of precision agronomy.

“We know that the yield potential for crops is set at the time of drilling and if the variable rate plans are not created from the most accurate soil type maps, the yield potential of a crop is already compromised before it is established.”

Soil properties

Current GPS soil mapping systems use grid sampling, electro magnetic (EMI) or conductivity scanners to assess soil properties into zones of similar character. Samples are then drawn from each zone, explains Mr Young.

“These systems are definitely a step forward from whole field crop management, however they are by definition based upon averages and assumptions, which means information going into variable rate plans is not as accurate as it can now be.

“These soil scanning techniques can be influenced by compaction and soil moisture so the picture that you get of your soil in the autumn is likely to be very different from a scan taken in the spring.

"However, with the launch of the ground-breaking TerraMap soil scanning service earlier this spring, soil scanning and nutrient mapping can be carried out at far, higher resolutions and are consistent regardless of time of year and moisture status of the soil."

Leap forward

Farmacy claims TerraMap is a great leap forward in terms of accuracy. The company says it is 800 times more accurate than any other current system – so variable rate plans are much more likely to enable crops to realise their full yield potential.

This is because TerraMap uses completely different technology to assess soil properties, says Mr Young. It measures naturally emitted isotopes, such as caesium and potassium, that are very stable due to their extremely long half-lives.

TerraMap uses passive, gamma-ray detection technology to take more than 800 readings per hectare, providing higher definition mapping of all common macro and micro nutrients, acidity, soil texture, organic matter and CEC as well as elevation and plant available water.

There are very few limitations to when TerraMap can be used – offering a much wider operating window, says Mr Young. “It is not affected by soil moisture, compaction, crop cover or cultivation state – unlike scanning or satellite systems.”

The information from TerraMap can be used to create maps within Omnia. It can then be overlaid with yield potential, biomass and weed maps to create more meaningful data, which will result in much more accurate and consistent variable rate plans.

Significantly, Mr Young adds that TerraMap is costed at comparable levels to other soil sampling and mapping systems.

Trials prove benefits of more accurate approach

Using Omnia, it is possible to input all TerraMap information into the system to create the most accurate variable rate map possible – bringing about a more even establishment, says precision technology specialist Nick Strelczuk.

Maps can be created within Omnia for all of the necessary field and crop data and then matched to a target plant population for that variety, creating a detailed variable drilling plan.

"In our validation trials last year, we proved the benefits of variable drilling by comparing variably drilled wheat alongside a farm standard rate on spilt fields and taking them to yield,” says Mr Strelczuk.

The statistically-valid work proved that using Omnia Precision Agronomy can increase yields by an average of 0.6t/ha, worth £99/ha (based on wheat at £165/t). Similar results are anticipated from 20 winter wheat and spring barley validation trials in the ground this year.

“The variably drilled plots are much more uniform and even in terms of tiller and ear numbers. If we work on the Yield Enhancement Network (YEN) premise of more biomass and ear numbers leading to higher yields, it's certainly looking hopeful for a good harvest result.”