Are You Conducting On-Farm Trials On Your Farm This Season?

Scenario

If you conduct on farm trials on your farm, especially with cereals or solid seeded soybeans, are you getting reliable information from them? The last thing anybody wants is to do a whole lot of work without getting anything for it.

Important Information You Should Consider!

If you are putting your inputs for the whole trial area on in the same directions that your treatments are laid out, you may be creating problems (not that putting inputs on perpendicular to the crop rows doesn't pose problems of its own). This is especially true for inputs that are put

on after the crop has been planted, including fertilizer, fungicide and weed control but still applies to preplant inputs if there is overlaps or misses in the application.

Impacts of Wheel Tracks, Spraying Overlaps & Misses

Consider the following diagram of a winter wheat plot layout in a field. The treatments are 30 feet wide and you have a 25 foot combine header that you will use to harvest the plots (1 pass down the plot). If your sprayer has a 60 or 90 foot wide boom, and you spray Folicur or post herbicides over the plot area, you will only be putting wheel tracks (A) in every second to third plot. Depending on how long your plots are, the impact of the lost yield in the wheel track area could ruin your chance to see the real effect of the treatment differences you set out to investigate. In addition, if the driver is not 100% accurate, you can have spray overlaps or misses (B) that can cause treatment effects due to crop damage or reduced yield from weeds not controlled in the missed area. All these contribute to a yield impact in the plots that is not due to the intended treatments you started out to compare.

Considering the above scenario, the impact on crop yields within plots due to wheel traffic and overlaps/misses can be significant.

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So, if you have this potential loss of yield in every 2^nd or 3^rd plot, do you think you can see the true treatment effects if you are comparing tillage systems, starter fertilizer differences, etc. I think we would be hard pressed to see a 20% difference between such treatments, but by applying overall plot inputs parallel to the crop planting and harvesting direction, the tramping alone in some treatments can be reducing harvestable yield by up to 20%. What differences do you want to see? Notice that increasing the plot length did not reduce the impact of the wheel tracks.

Inputs Perpendicular To Treatments

This clearly demonstrates that we have to seriously consider setting up our on farm trials so that application of whole plot inputs can be made perpendicular to the direction of our treatments (which are usually the direction of planting).

Wheel Tracks In Every Plot

If you are comparing treatments in an on-farm trial that need to be applied after the crop has emerged (ie herbicide treatment comparison), then you need to ensure that you have wheel tracks down the plot including the untreated check plot. In this case you run down the plot with the sprayer turned off. In this way the track tramping effect will be consistent in every plot. This still requires that the operator drive straight since weaving down the field can cause a wider tramping pattern than driving straight. Alternatively, you can have your plot setup wide enough that the combine can harvest an area within each plot where no wheel tracks exist.

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Impact of Wheel Tracks on Plot Results

Setup Plots To Minimize In-Field Variation

This issue of plot setup also applies to inherent in-field variation such as tile line direction, slope, change in soil type, removal of old fence bottoms etc. Anything we can do to minimize the variability in the trial area, or make it so that it impacts all plots equally, will go along way to allowing the trial to give us reliable and accurate results.

For more information, refer to OMAFRA Publication 811, "Agronomy Guide for Field Crops", Chapter 1, or resources on the OMAFRA Crop Website.

Related Links

• Agronomy Guide for Field Crops, OMAFRA Publication 811
• OMAFRA Crops Website

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