Page 17 - Griffin Gazette Fall 2016

Image 2: Leibig’s
law explained with

a barrel image.

lead to a micronutrient toxicity in these plants. One size does not questions on growing.ONE GUIDE WITH ANSWERS TO ALL OF YOUR
fit all when it comes to optimum media pH.
GGSPro Technical Reference Guide
Since media pH plays such an important role in micronutrient
availability a quick discussion of the factors that influence media The GGSPro Technical Reference Guide 4th edition serves
may prove useful. as a go-to resource for both experienced and novice
growers. Written by Griffin’s GGSPro technical support
• Limestone charge in the media Lime incorporation rates team, the Technical Reference Guide focuses on identifying
are important but the type of limestone and the particle size problems and providing solutions. Topics were selected
are among the variables that need to be accounted for. based on the thousands of technical inquires that the
Growers can easily track media pH on site and this provides GGSPro team fields each year. Sections include Abiotic
valuable information for the optimization of micronutrient Disorders, Pollinator Stewardship, Insects, Diseases, Weeds,
availability. (See the digital Gazette on our website for testing BCAs, PGRs and Crop Nutrition.
protocol information.)
Item # 98-401 NEDEITWION
• Fertilizer selection Water-soluble fertilizers are rated $139.00 + S & H
according their potential basicity or acidity. While a helpful
tool for predicting the net impact of fertilizers on media, more www.GGSPro.com
precise tools are under development. Dr. Paul Fisher’s lab at 888-GGSPRO-1
the University of Florida is working on an improved method
for understanding the impact of water-soluble fertilizers and
media pH3.

• Alkalinity of irrigation water It’s the alkalinity rather than
the pH of irrigation water that’s the best predictor of what
the effects on media pH will be over time. Alkalinity is the
measure of dissolved bicarbonates in the water. Calcium
and magnesium bicarbonates can have the effect of “liming
the media” if elevated levels of alkalinity are present. (See
the digital Gazette for recommended methods of neutralizing
excess alkalinity.)

• Species effect Research has shown that some plants exert
an influence over the pH of the media that’s not always in
favor of the plant4. Examples include geraniums and celosia,
which exert a downward effect on soil pH, yet both crops
perform best with a media pH above 6.0. Flowering vinca, on
the other hand, can increase media pH in spite of the fact that
this crop is usually produced in a range of 5.3-5.8.

Understanding the unique micronutrient requirements of the
crops we produce, combined with regular soil testing, can lead
to optimized plant growth while avoiding excessive overfertilizing.

1 www.sare.org/Learning-Center/Books/Manage-Insects-on-
Your-Farm/Text-Version/Managing-Soils-to-Minimize-Crop-Pests/
Impacts-of-Fertilizers-on-Insect-Pests

2 “Revising Your Phosphorus Fertilization Strategy”, Joshua Henry & Brian
E. Whipker- Grower Talks Magazine, February 5, 2016 Vol. 79 No. 10

3 Advanced fertilizer and pH management in floriculture and vegetable
crop production- Ryan Dickson, Paul Fisher, http://floriculturealliance.org/
current.asp

4 “Substrate pH and Water Quality”- Douglas A. Bailey, Paul V. Nelson,
William C. Fonteno, https://www.ces.ncsu.edu/depts/hort/floriculture/
plugs/ph.pdf