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Fire Up the Injector -- It's Calibration Time!

Thu, Feb 6th, 2020, created by Nick Flax
As we get closer to the beginning of bedding plant season, growers all over are dusting off their sprayers, checking heaters, and performing early-season maintenance on different systems and pieces of equipment in their greenhouse operations. The question for this week is: have you checked on your injectors yet?

Last week, one of my e-GRO colleagues (Rosa Raudales) posted an excellent resource that growers can use to interpret water test results. If you didnít catch her post when last weekís Alerts went out, check it out here. In case you didnít take Rosaís post as a reminder that you should get a fresh irrigation water test done soon (hint, hint), take a few minutes to collect a water sample and send it in to your favorite analytical lab! If you need a refresher on best practices for collecting water samples, check out Roberto Lopezís e-GRO alert from our very first season, back in 2012 (e-GRO Alert 1.13). With those test results in mind, does anything need to change in your greenhouse this year?

If you are a grower with very stable water quality from year to year -- kudos to you! Most growers who utilize well- and other non-municipal water sources, however, will likely see some differences in their test results. Significant changes in pH, alkalinity, and mineral nutrients present in irrigation water often necessitate changes in fertilizer formulations in order to hit the same targeted nutrient concentrations applied to crops in previous years. But the target EC of 15-5-15 at 200 ppm N is the same as 21-7-7 at 200 ppm N, right? Wrong!

Different water-soluble fertilizer formulations can have very different target ECs, even when mixed to the same ppm N. Though the magnitude of differences can vary from one formulation to the next, it is not safe to assume that you can carry on without recalibrating injectors when you switch to a new feed program. Especially if you are using a new fertilizer formulation this spring, grab your pH/EC meter and set aside an hour or so to spend some quality time with your injector(s) in order to get that calibration dialed in. Calibration tips can be found in another of our earliest e-GRO Alerts back in 2012 (e-GRO Alert 1.05).

Either way, whether you are using a new fertilizer or the same stuff as last year, remember that injectors are pieces of equipment that endure heavy use and near-constant service in springtime. They have moving parts, get knocked into, can get repaired or rebuilt without your knowledge, and just fall out of calibration over time. Spare yourself some major headaches and moments of panic during bedding plant season this year by spending a little time checking and re-calibrating your injectors now!

About the Author:

Nick Flax

Commercial Horticulture Educator, Penn State Extension

Nick Flax is a Commercial Horticulture Educator with Penn State Extension, based in Doylestown, PA. His background is in greenhouse crop physiology, with an emphasis on plug production, annual bedding-plant production, seasonal potted crops, and container-crop production using biocontainers. Nick has industry experience in wholesale young- and finished-plant production, retail floriculture, and has a strong background in pest and disease management, biological IPM, and controlled-environment crop research.

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