How Direct-Stick Meters Can Help Take the Guesswork Out of Soil pH

Soil-pH featureSoil pH is critically important to plant health. The availability of most nutrients is influenced by soil pH. The ideal pH range for greenhouse and nursery crops can vary substantially, based on the unique nutrient requirements of each crop.

Some crops are very efficient at taking up micronutrients from the soil, so much so that a lower-than-ideal soil pH may lead to a micronutrient toxicity. Zonal geraniums, New Guinea impatiens, pentas, and African marigolds are examples of such crops.

As soil pH climbs above 6.0, micronutrient availability decreases and can lead to micronutrient deficiencies in many crops. Iron deficiency, for example, is often seen in spring crops such as calibrachoa, pansy, petunia, and others. Soil pH can also influence the development of certain soil-borne diseases.

Why Do I Need to Monitor pH and EC?

Given the importance of soil pH, it would be great if growers could just “set it and forget it.” Unfortunately, so many forces are acting on the pH of the soil that it’s just not possible. Let’s consider some of the factors that make frequent monitoring of soil pH necessary.
• Growing mixes can arrive with widely varying soil pH values. Many soil mix companies state a starting pH range of 5.5 to 6.5. For some crops, pH adjustments will need to be made right away. Petunias started at 6.5, for example, will not achieve optimum growth.
• Water quality will also influence soil pH. Low-alkalinity water sources provide little or no buffering capacity (i.e., resistance to pH change). This can lead to rapid soil pH swings. High-alkalinity water sources may lead to increasing soil pH over time if the excess alkalinity isn’t neutralized.
• Fertilizer selection needs to be considered in concert with the alkalinity of the water and the pH requirements of the crop(s) being produced. Some fertilizers are alkaline in soil reaction; others are acidic. Your supplier can help you build a fertilizer program that takes all of these factors into account.
• Last but not least, there is a phenomenon sometimes referred to as the species effect. Many crops will influence the pH of the soil they’re planted in — and not always in the direction that would be in their favor. For example, flowering vinca exerts upward pressure on soil pH in spite of the fact they prefer a lower soil pH.

There are several reliable ways to monitor soil pH. Many growers find the 2:1 and PourThru methods to be effective on-site. Both techniques require a certain amount of time and expertise to provide accurate results.

The Bluelab soil pH meter (left) has a hand-held wired probe, while the probe is directly attached to the Bluelab soil pH pen (right).

Are Direct-Stick Meters Accurate?

My team and I are often asked about direct-stick meters that measure soil pH via a probe that’s inserted directly into the soilless media to yield an instant reading. While the appeal of a quick and easy method to test pH is understandable, the question of accuracy needs to be addressed.

In the past, we were reluctant to recommend direct-stick meters because the meters we had the opportunity to test didn’t provide results we felt were accurate enough for growers to base growing decisions on. Our thoughts on this technology have changed, in part because of an improved understanding of how to use and maintain these meters.

Four Direct-Stick Meters to Try

There are many meters that the GGSPro team hasn’t evaluated, but here are four meters that we can recommend based on good reports from cooperating growers that are using these tools in real-world conditions.

Bluelab has two affordable direct-stick pH meters, both of which have replaceable soil probes. The Bluelab Soil pH Meter is a handheld meter with a wired probe. The Bluelab Soil pH Pen has its soil probe attached directly to the pen, and is also capable of testing soil temperature. They’re both easy to use and come with comprehensive instructions for calibration and maintenance.

The Halo direct-stick soil pH meter (left) from Hanna Instruments uses a Bluetooth wireless probe that works with a smartphone app. Hanna also has a handheld meter with a wired probe (right) that has on-screen prompts for calibration.

Hanna Instruments recently introduced its Halo direct-stick soil pH meter (HI12922). It uses a Bluetooth wireless probe that works with a free smartphone app. Hanna also has a handheld meter with a wired probe (HI99121) with on-screen prompts during operation and calibration. Direct-stick soil pH meters other than those mentioned may also be suitable for this use.

Keys to Success With Direct-Stick Soil pH Meters

The best way to obtain accurate results with direct-stick soil pH meters is to understand how to use and maintain them properly. Here are four suggestions to help you get reliable results when testing soil pH.
• Take many samples and average the results. A larger sample size helps to account for the natural variability that occurs within a given crop.
• Calibrate often. Even the best meters require frequent calibration. Some meters even remind you when calibration is needed.
• Clean the probe often in accordance with the owner’s manual. Improper cleaning can shorten the life of the probe and provide erroneous readings.
• Keep the probe hydrated in the recommended storage solution.

Topics: , ,

Leave a Reply

More From Media...

April 25, 2018

What the APHIS Plant Import Rules Restructuring Means for You

The federal regulation covers imports of live plants and pretty much any type of plant propagative material.

Read More
Dallas Johnson Greenhouses

April 14, 2018

Kemin Forms Distribution Partnership With Plant Products

Under the agreement, Plant Products will be a Kemin Crop Technologies’ distributor in the northeastern U.S.

Read More

April 13, 2018

Dümmen Orange Debuts New Rooting Technology

Basewell bare-root cuttings feature advanced root development and no growing media, which allows products to ship to growers from off-shore production locations, ready to transplant directly into the finish container.

Read More
Latest Stories

February 18, 2018

Why Biochar Might Eventually Replace Peat Moss

In a recent study, researchers from the University of California, Davis investigated biochar as an alternative to peat moss.

Read More
Soil-pH feature

January 7, 2018

How Direct-Stick Meters Can Help Take the Guesswork Out…

Monitoring your soil pH is critical to maintaining the health of your greenhouse crops. Try these tips for managing pH, as well as accurately testing your soil with direct-stick soil pH meters.

Read More
Peat vacuum harvester

December 8, 2017

The Sustainability of the Peat Industry Looks Better T…

Despite talk about alternative products and differences of opinion over its sustainability as a resource, peat is here to stay.

Read More

December 6, 2017

How Mycorrhizae Provide Value at Your Greenhouse or Nur…

Mycorrhizae create a connection between the roots of a plant and the surrounding growing media. This ultimately leads to better crop health through enhanced nutrient and water uptake.

Read More

November 13, 2017

Michigan State Offering Online Root Zone Management Cou…

Participants in the three-month, self-paced online course can learn about water quality, plant nutrition, and irrigation management.

Read More

November 13, 2017

International Growing Media Symposium Comes to the U.S.

This International Symposium, with representatives from 21 countries, covered new market opportunities, generated innovative ideas, and offered first-hand information to more than 150 attendees.

Read More
Oasis PlantPaper

September 25, 2017

Oasis Introduces New Biodegradable Paper Wrap for Plant…

PlantPaper is an all-natural, bio-based, wrap media that contains no glue and provides more effective rooting.

Read More
LM-Bark 1 (Lambert Peat Moss)

September 25, 2017

European Growing Media Manufacturers Face Challenging M…

Rising costs and a poor harvest have created challenging conditions for the growing media industry in 2017, according to the UK-based Growing Media Association.

Read More
Growing Media Mixing Model

August 28, 2017

New Mixing Model Predicts Rooting Media Properties

Researchers at Wageningen University & Research have developed a mixing model that predicts the properties of a mix of constituents in any growing media ratio.

Read More
Vijay Rapaka

July 30, 2017

Oasis Grower Solutions Hosting Plant Production Webinar

The webinar, which takes place on Aug. 10, will provide information on growing media for cutting propagation and seed germination.

Read More
New Growing Media Blends

July 26, 2017

British Researchers Evaluating New Media Blends to Redu…

Research in the United Kingdom has shown that coir-free growing media has the potential to work as well as coir for strawberry crops, and these research results likely apply to greenhouse production, as well.

Read More
Iron and Manganese toxicity in geranium

June 13, 2017

Are Your Geraniums Showing Signs of Iron or Manganese T…

Zonal geraniums with low pH can exhibit iron and manganese toxicity symptoms, including marginal chlorosis, leaf speckling, and upward-cupping of the leaves, according to Michigan State University experts.

Read More
GrowTech CatEyePlug Feature

June 6, 2017

Grow-Tech Introduces New Media Plug, Joins Dümmen Orang…

Grow-Tech LLC, a designer and manufacturer of stabilized growing media products, is making waves this week with the launch of a new plug and an announcement that it is joining forces with Dümmen Orange.

Read More

May 9, 2017

How to Test and Correct for Low Substrate pH in Your Gr…

If you mix your own or purchase a pre-mixed substrate, it is recommended you determine the initial pH. In too many cases, growers end up discovering low substrate pH.

Read More

January 2, 2017

Why You Need To Know What’s In Your Growing Media…

Before you buy growing media mixes or raw materials to mix your own custom blends, here are some important factors to consider.

Read More

December 25, 2016

Grow-Tech Patents Plug Designed for Tissue Culture

The ZenPlug from Grow-Tech is used for tissue culture in orchids and difficult-to-root cuttings, and is one of several products recently developed by Grow-Tech.

Read More
Various Wood Substrates

December 18, 2016

The Evolution And Revolution Of Wood Substrates

Growing media formulations are evolving as researchers fine tune blending techniques for wood component substrate alternatives to achieve reliable, consistent results.

Read More

December 17, 2016

New Growing Media Technology Designed To Promote Health…

Oasis Grower Solutions recently launched several new innovations that support plant growth and health all the way to maturity.

Read More