Enter the site with the plan of your trial layout in one hand and a tape measure in the other. Check that it all fits OK. If you’re short on space either reduce plot size or straddle the trial over a greater number of paddocks or years. Under no circumstances should you reduce the total number of head-to-head comparisons (replicates) to make a trial fit. Replication is much more important than plot size in determining the reliability of trial results.

Look for areas that might cause trouble, mark them on your trial map, watch them carefully over the season or to avoid making measurements on them entirely. Remember that when you’re making measurements you don’t have to harvest the whole plot – it’s better to avoid ‘funny bits’ than to let them affect your results.

Find out where your paddock is on the nutrient deficiency-sufficiency scale by conducting a soil test. Immediately after marking out the plots is the best time to do it.

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Remember that replication is much more important than plot size in determining the reliability of trial results. So if it looks like a tight fit, cut down on plot size rather than dropping replicates.

If you’re OK so far, fill in the trial space by marking out the individual blocks and plots in accordance with your trial plan.

Once the basic trial layout has been marked with pegs or flags it’s time to re-consider whether the design matches the site. Have the blocks been arranged to minimise variability within them? Do they form a path along the site variability? Have the plots been arranged to minimise variability between them? Do they form a path across the site variability? Are there any plots that are likely to cause problems in future due to weeds, obstructions or other irregularities?

If the match between site and layout isn’t quite right, now is the time to change it. Screwing up a piece of paper and re-planning the layout will cost you a lot less than establishing a problematic trial.

You may be able to re-arrange the trial to better match the site.

Measurements on the site

Once you’re happy with the general layout of the trial in the paddock or paddocks, it’s time for a more detailed examination of each plot.

Double check the plot dimensions, especially if you’re measuring yield from a weigh wagon. Without an accurate measure of plot area you won’t get an accurate measure of yield. Use a tape measure to get plot length.

If measurements of ‘initial conditions’ are required to achieve your aims you should make these now. If you’re doing fertiliser trials, a knowledge of soil fertility is required because the response to a given fertiliser is highly dependent on the availability of that (and possibly other) nutrients in the soil.

Make soil tests on a plot-by-plot basis if you can afford it. This gives you replication of starting values which, depending on what you want to know, can be just as important as replication of yield or other ‘final’ results. You needn’t get a complete soil test done on each plot sample. If you’re doing a nitrogen fertiliser trial, it might be a good idea to get a plot-by-plot analysis of nitrogen and a complete soil test done for the whole site.

If you’re not interested in the expense of plot-by-plot soil tests it’s still a very good idea to get a soil test for the whole site. This can be done using approved methods (a minimum of 20 samples taken from a zig-zag profile across the site) or by taking a minimum of 5 samples from each plot, bulking and sub-sampling.

Ideally, soil tests should be done at least a month before planting. This gives you time to get the results back before action is required. You can then decide whether or not the site is still suitable for the type of trial that you have planned.

Summary:

Understanding the starting characteristics of your trial site is essential if you are to (1) avoid problem areas, (2) track changes in site conditions and (3) meaningfully interpret your trial results. Plot-by-plot measurements of relevant variables made before the trial has started are the key to understanding your trial site.

Gathering all of the information outlined above will be of use to you only if you can find and understand it when you need it.

Record keeping is a really important part of conducting on-farm trials. In addition to helping you interpret your current trial, good records can be referred to for years to come. In this way, they can save effort on trials in the future.

It’s a good idea to have a special book devoted to your on-farm trial work. Make it the place where you keep every piece of information related to the trial – aims, treatments, design, measurements, everything. A book is probably better than a computer file, because you can cart it round with you in the paddock and enter any measurements or observations on the spot.

Making sure

If you’ve followed all of the guidelines to date, you should now be the proud owner of:

• A clear statement of what you want to find out from your trial, and why.
• A pair of treatments that you’ll compare in order to generate that information.
• Equipment that has been calibrated to accurately apply those treatments.
• A calendarised list of the measurements that you’ll make in order to gather trial results.
• A trial layout for a relevant site that has been replicated, randomised and arranged to give each treatment a fair chance of success.
• A paddock or paddocks loaded with pegs and holes. The pegs show you where the plots are. The holes are a reminder of your completed before-trial measurements.
• A book containing records of the above.

You’re now almost ready to establish the treatments in your trial.

Before you hit the paddock, cast an eye over Steps 1-5 to make sure that you haven’t missed anything.

End of section critical decision point

You’re just about ready to put your treatments in. Have you made measurements on the important characteristics of your site? If you’re asked ‘what was the trial site like’, will you be able to provide data on the conditions or just general impressions? Both are important if you are to get the most from your trial.

Have you quickly double-checked that you’ve done all the planning necessary for the future of your trial? The relevant On-FarmTrial Guide trial template will help.

It is important that you can satisfy these questions if you are to get the best from the next section – Getting the trial underway.