A Grower’s Guide to On-Farm Trials
This is a guest post written by Jessie deHaan (M.Sc.; Research Technician, Biological Crop Protection at Vineland Research and Innovation Centre).
Now that it’s halfway through spring bedding plant season, you may be considering changing some of your current IPM or production practices for next year that just aren’t working as well as they could. Conducting on-farm trials is an easy way to evaluate how well a new product, process or technology will work in your operation.
Before making any large-scale changes, it is important to test things on a small scale first. Read on to learn how you would go implementing a small on-farm trial to get you results that are meaningful.
The Basics of On-Farm Trials
Because this is a long post, we’ve put in this table of contents so you can quickly refer back to a section if you’re setting up your own trial in the future!
The basics to planning and running any trial are to 1) control as much as you can, 2) acknowledge what you can’t control, and 3) document the process. We’ll outline each of these, below.
Control as much as you can
When designing a trial, you’ll want to control as many variables as possible. This just means trying to keep things consistent between your treatments. For example, when testing dips (the variable you’re interested in) you want to keep as many other factors as possible the same. This includes factors such plant species and variety, growing media, light intensity and duration, irrigation and fertigation, temperature, and humidity.
Although it can be tempting to conduct your trials in a separate area of the greenhouse, or use old or leftover growing material, try to keep your trial as close to your normal production practices as possible. Prepare the plants according to your normal processes and place your trial alongside your normal production plants. Not only will this help you keep track of the trial better, but it will also give you a more accurate picture of what implementing changes at a larger scale would look like in your main growing area.
Don’t forget to compare the results of your test (i.e., treatment) plants to a group of plants set aside as your “control” treatment – or your normal/current practice. This control group should also be marked as part of your trial so those plants don’t get thrown out, shipped or moved around!
Acknowledge what you can’t control
It’s important to recognize that you can’t control everything, and that’s okay. There are some factors called unknown variables that can also contribute to the results of a trial. To capture a clear picture of the results and to reduce the effects of any unknown variables, you’ll need replication, randomization and blocking.
To make sure the changes you want to make are safe for your production, consider; the more replication, the better! Here, a “replicate” simply means a whole plant, or a bag of cuttings – whatever is the “whole unit” you would actually treat. Aim for 10-20 replicates when dealing with whole plants (i.e., pots/baskets) or at least four replicates when comparing batches (i.e, plug trays or bags of cuttings). Do what is feasible for you and your operation, but enough so that the trial isn’t pointless.
Randomization and blocking are other ways to limit unknown variables, or “noise” in the experiment. Randomization means to randomly assign each unit (i.e, pot/basket, plug tray) to a treatment group.
For example, ff you’ll be using different shipments of cuttings for your experiment, be sure to randomly assign a portion each of them to both the control group and your treatment groups. This way, if a shipment has been under stress (e.g., held too long before shipping, poor refrigeration on the truck, etc), it won’t accidentally look like effects from the treatment. Both the control (no dip) and the treatment (dip) will show signs of weakened cuttings, and you’ll know it wasn’t from the dip itself.
Blocking is used in larger trials and can help reduce the effect of a variable you cannot eliminate from your setup. For instance, if you have a corner of your main production that gets particularly hot, it would be a bad idea to place all of one of your treatment plants in that area. The temperature of that area may affect the result of the treatment.
Instead, break up your experiment into sets, called blocks, that contain at least one replicate from each treatment/control group. That way all of the groups experience the hot corner equally. See Fig.1 for a sample layout in this scenario.
Another example of blocking is repeating the trial one or more times throughout the year to make sure the observed effect is consistent over time.
Document the process
Trying to remember what you did a year ago can be difficult. So, do a bit of upfront work and get organized; make a separate folder on your computer for the trial. Inside it, write a protocol and a timeline, create a data sheet and a folder for all your photos.
Your protocol is a written guide on what you plan to do (or did, if you’re writing it afterwards); record the dates of major events like sticking or transplanting, greenhouse sections used, fertilizer ppm, soil pH, greenhouse temperature settings or graph, pot size, and plant variety/colour used. Include anything else that might be relevant. If you plan to use your normal production process, record it in detail here. If you make any changes to your protocol during your trial, be sure to record that information in your document. Writing a detailed protocol will help you make sense of the results.
The timeline is a schedule of events in your experiment. Plan out when the major events will occur, add in your data collection days, and try to stick to your timeline. Remember, if you deviate from your timeline, go back and record the changes you made and why.
When collecting data, writing it in paper and pencil first will help you catch typos (fun fact: pencil is waterproof). Create an organized datasheet with clearly marked columns for the date and measurements taken and include an extra column for additional observations (anything else you notice, like outdoor weather or the presence of pests). These additional observations may help you interpret your results in the future. Use the same measuring equipment (i.e., rulers, pH meters, soil probes) and make sure to regularly check the calibration.
Lastly, take photographs of the progress of your experiment from repeatable heights and angles to document plant growth or product performance over time. Include plant identifiers like a tag or label to help keep your treatments organized digitally. Use high resolution when taking research photos with a smart phone and try to keep consistent lighting, angle and distance from the subject. If you’re feeling really fancy, use a tripod for stability and a neutral background to help show the plant’s colours.
Questions to Ask Before Starting (with Example)
To help keep on-farm trials simple and the results as clear as possible, it’s best to follow a set of steps known as the scientific method. We’ve simplified this process to 5 questions to ask yourself when starting a trial.
Here, we use whether or not to dip cuttings in reduced risk products to knock down incoming thrips numbers as an example.
What question do you want to answer?
In this scenario, our first question would be “Will new products harm my cuttings if incorporated into my biocontrol program as a dip?”
Formulating your research question will help you design the trial and get you the best information you need to make a decision. It’s best to answer only one question at a time. Looking for phytotoxicity is a good first step; but whether or not your dip reduces the pest you’re concerned about is a separate question!
What knowledge or resources already exist to help you answer it?
Check the product labels, consult with industry professionals and speak with other growers about their experiences. The Ontario Crop Protection Hub has a section dedicated to products that can be used as dips, which includes reports of phytotoxicity.
What do you think the answer will be?
One likely answer is: “using new products according to the label in a dip solution should not cause phytotoxicity in my main variety of cuttings”.
Even if you hope this is the answer, the point of testing is to prove this right or wrong, especially on the crops you are most concerned about. Also, every farm is different, so this will confirm that this technique will work for YOUR crops, with YOUR staff doing the dipping, and growing the cuttings under YOUR conditions.
How can you test this answer?
Select a plant variety that you propagate regularly (or a lot of) and use this variety to test all the dip treatments you are interested in. Have the same person dip and stick all the cuttings. Create an experimental timeline and checklist so each task is completed on schedule. Dip and stick one tray of each treatment (dipped versus undipped, or several kinds of dips versus undipped). Do this every week for 3 consecutive weeks,
Repeating the dips over consecutive weeks helps to make sure your results aren’t a fluke. For example, phytotoxicity caused by accidentally using too high of a dip rate, or a dip applied to weak cuttings. Keep all trays alongside normal production and flag the trays for regular follow up. Take photos to document the results.
What data do you need to collect to verify the answer?
Inspect each tray for phytotoxicity for several consecutive weeks after dipping and record the observations. Just before transplanting, record whether you would be comfortable incorporating the new products into your production practices (yes, no, more testing needed). This might include grading a subset of the rooted cuttings in each treatment, or looking for delayed rooting.
Phytotoxicity can look like burned leaves that appears rather quickly (week 1), but products could also affect rooting. This is why it’s important to assess the cuttings at several time points. We recommend assessing the rooting status of each tray at 3 and 6 weeks after dipping, as well.
Key Points to Success
Be Organized – lay out or prepare supplies in advance. Colour-code and label everything to make your trial as easy-to-follow as possible, just in case someone needs to step in and collect data for you. For example, use the same colour tags for all the trays or pots of a particular treatment, and mark that colour onto your data sheet with a matching tape colour. Have your data sheets and protocol printed out, and compile everything into a binder.
Be Thorough – take lots of photos and notes at every stage so you can look back on what you did and know what you’re looking at (and so you can share the results). You may not remember from year to year what you tried already and what the results were unless you record it.
On-farm trials are born out of curiosity, but they don’t have to be complicated; start with a simple production or growing practice change that tests a new idea against your tried-and-true methods, then plan, get organized, and document the process! The data you collect will help you make confident changes; because testing on a small scale first ensures that any major changes won’t have a major impact on your bottom line. Finally, remember to share your results; we can’t wait to see what you discover!
More Resources for Conducting On-Farm Trials
Websites
We’ve added a few sites that further guide you in conducting research on your farm:
https://www.nurserymag.com/news/grow-tech-trials-greenhouse
https://www.growertalks.com/Article/?articleid=19967
Vineland Guide to Dip Phytotoxicity Trials
We’ve also created a PDF outlining how to do dip trials yourself, in detail! This includes damage metrics and the kinds of treatments to include. You can download it below.
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