Author Archives: Goris Passchier

About Goris Passchier

Goris Passchier is a controlled release fertilizer formulator (fancy name for technical representative) at Northern Star Minerals - a division of Wilbur-Ellis Company ( You can eMail him at

Misconceptions With Controlled Release Fertilizers

Pilon: How do rates vary between incorporation and topdressing? Passchier: There are two factors involved when speaking about incorporation and topdressing the fertilizer. The first is the potential differences in nutrient availability for the plant when incorporating versus topdressing. The second is the amount of fertilizer that is used when incorporated compared to the topdressing

Q&A On Controlled-Release

Pilon: What are the methods controlled-release fertilizers (CRF) are applied? Passchier: The two most common methods of applying controlled-release fertilizers in greenhouses and nurseries is to incorporate them into growing mixes prior to planting (incorporation) or placing the fertilizer on top of the potting substrate (topdressing). Topdressing entails placing a predetermined amount of fertilizer on

Talking Temperature

Pilon: How does temperature affect release? Passchier: As we discussed previously (see the July 2007 issue), controlled release fertilizers can be compared to M&M candy since the good stuff is inside of the coating of each of these products. As the temperature increases so does the solubility of the candy and fertilizer on the inside.

What’s In Controlled-Release?

In the first installment of this four-part series, we began to introduce several important aspects regarding controlled release fertilizers (CRFs). Slow-release fertilizers are reacted urea formaldehyde products. Each has its own characteristic chain of polymers, which are gradually broken off by microbial activity and then made available for roots to uptake. Controlled-release fertilizers are fertilizers with

Misconceptions About Controlled—Release Fertilizers

Delivering and managing nutrition is one of the primary tasks associated with producing greenhouse crops. Most growers deliver nutrients using various water-soluble fertilizers, some growers use controlled-release fertilizers (CRF), while others use a combination of controlled-release and water-soluble fertilizers. As I travel across the country to visit various growers, I’ve come to recognize that many growers