How to Design Useful Test Plots
The goal of all agronomic trials is to gain knowledge that can be used to guide future management decisions. On-farm test plots can provide valuable information about the performance of a product or practice in your specific field environment. When designing and conducting an on-farm trial, make sure to consider the following items.
- Know the goals of the trial. Whether doing a simple side-by-side comparison or a complex agronomic trial, it is an experiment. The design and placement of the trial should be based on the question you are trying to answer.
- Avoid confounding factors. Make sure all factors except the one being tested are uniform across all entries. Using different agronomic practices among entries, such as seeding or fertilizer rate, can make it impossible to determine what is really contributing to yield results.
- Test in fields that reflect local conditions and are appropriate for your trial goals. This does not necessarily mean testing in the highest yielding field. In some cases, targeting a specific stress environment may provide more valuable insight. If the goal is to understand performance of a product like Optimum® AQUAmax®* hybrids, place the experiment in a field that's likely to experience water limitations.
Minimize variability between the factors (products or agronomic treatments) being tested during the experiment. All fields have some degree of variability. The key is to set up the trial in a way that reduces variability between test factors or products so each gets a fair shot.
- Orient row direction across potential sources of variability such as soil type changes.
- Limit the number of entries to increase precision and save time in planting and harvest.
- Use wider and longer harvest areas where practical. Shoot for high plot length-to-width ratios.
- Be aware of the influence of plant height or adjacent agronomic treatments on the yield of an entry and try to minimize these. Wider entries or buffer strips can help minimize border effects. Differences in plant height of several inches can influence yield levels of adjacent products by 5% to 10% or more in narrow (4 rows or less) strip trials versus a solid field.
- Don't let results from 1 or just a few local plots influence your learning too much. Next year the weather will be different, different management practices could be in place and the results might change. Look at results from more plots over wider geographies and years whenever possible.
*Product performance in water-limited environments is variable and depends on many factors such as the severity and timing of moisture deficiency, heat stress, soil type, management practices and environmental stress, as well as disease and pest pressures. All hybrids may exhibit reduced yield under water and heat stress. Individual results may vary.