Understanding Plant Nutrition: Low Media-EC

Slideshow: Understanding Plant Nutrition: Low Media-EC

When growers talk about “lack of feed” or “hungry plants” (Figure 1), the issue is usually insufficient supply of fertilizer nutrients. The easiest way to measure fertilizer level in the root media is with an electrical conductivity, or “EC,” meter.

What is Media-EC?

Electrical conductivity (also know as conductivity, EC or soluble salts) is a term used to measure the total concentration of “salts” in a solution. When salts are dissolved in water, they break apart into their individual constituents, called ions. For example, sodium chloride or table salt, when dissolved in water, breaks apart into sodium ions and chloride ions. Since pure water has no electrical conductivity (EC = 0), increasing EC means more salt is dissolved in the solution.
In greenhouse and nursery production, you can quantify the nutrient status of the growing medium with a soil test. As long as your irrigation water source has nutrient levels within an acceptable range and you are using a balanced fertilizer that doesn’t contain a lot of useless salts (like sodium or chloride), then there is a good relationship between the nutritional status of the root medium, and media-EC (Table 1).
EC is a measure of the total salt concentration in the extracted solution, but EC does not give an indication of the concentration of any individual plant nutrient. The only way to determine exactly which ions make up the EC is to use a more extensive commercial laboratory analysis that will not only measure the EC, but also the concentration of each of the nutrients (ions).
Marigold & Calibrachoa

–Disorder: insufficient fertilizer

–Symptoms: overall yellowing or purple color on all leaves, especially on older leaves.- Likely suspects: All plants, especially fast-growing (high fertilizer-demanding) crops such as petunia.

–Less likely to show the disorder: slow-growing plants, or low fertilizer-demanding crops such as New Guinea impatiens (iron-efficient plants)

–Confirm with: an EC test, tissue analysis, response to a drench of fertilizer

–Causes: injector not working, fertilizer concentration not high enough, excess leaching.

–Solutions: Apply a water-soluble fertilizer that contains NPK and micronutrients. Suggested constant water-soluble fertilizer levels (parts per million of nitrogen) to correct low media-EC on plants that show deficiency symptoms are:
–150-200 ppm N plugs
–200-300 ppm N bedding plant flats
–300-400 ppm N larger containers

What Causes Low Media-EC?

The initial concentration of nutrients in a container media is provided by the pre-plant nutrient charge, which may include lime (providing calcium and magnesium), and other fertilizers such as superphosphate, gypsum or urea-formaldehyde. Part of the initial nutrient source is immediately soluble and therefore affects the initial media-EC. Other nutrient sources are bound to the soil particles or are in a slow-release form (e.g. limestone, resin-coated fertilizers), and only affect EC as nutrients dissolve into the soil solution.
Most media components, such as peat, bark or perlite supply a small amount of nutrients, whereas compost can supply significant nutrients as it decomposes and releases nutrients. 
Because of differences between batches of growing media, even from commercially blended products, it is important to not only know what your starting nutrient intensity is (as measured by EC), but also the composition and balance of the nutrients making up the EC (as measured with a complete soil test at a laboratory).
After planting, the goal is to balance deposits and withdrawals, in order to supply nutrients to the plant within an optimal level so they don’t get too high or too low. This is measured during the season by regular on-site EC testing.
You can picture the nutrients available for plant uptake in a pot using the analogy of a bank account (Figure 2).
We can increase the account balance by making deposits through salts contained in the irrigation water, with water-soluble fertilizer, or by surface-applying nutrients. Certain nutrients (carbon, nitrogen, oxygen and hydrogen) can be fixed from the air and water, but they do not contribute to soil EC unless they are dissolved ions in the soil solution.
The account balance is decreased by several types of withdrawal. These include nutrients taken up by roots for plant growth. The faster the crop is growing, the more nutrients are withdrawn from the crop and the more fertilizer needs to be deposited. Plants often require greater amounts of nutrients as growth rate increases during the middle of the crop, and less nutrients both when plants are very small or are mature and flowering. Some growers may increase the fertilizer concentration during this rapid growth phase, but keep the fertilizer concentration lower during the early and later stages of the crop.
Leaching is a very important type of withdrawal, because nutrients leaving the container can enter the environment and it is the one type of withdrawal that is completely controlled by the grower. 
Many growers routinely leach, but this is not needed if irrigation water contains few impurities such as sodium and chloride. Leaching washes nutrients from the pot, and leaching with clear water is therefore one way to reduce EC when the nutrient concentration is too high. However, the more a crop is leached on a routine basis, the higher the applied fertilizer concentration that is needed to maintain adequate nutrient levels in the root media. In other words, lower fertilizer concentration with low leaching can have the same effect on the EC account balance, with less cost, compared to a high leach/high concentration approach.
An excessively low EC means the nutrient balance can become “bankrupt” (i.e. there is inadequate nutrient level for healthy growth and plant stress occurs). You then need to deposit additional fertilizer. Figure 3 shows a low EC may occur if the starting balance is low, or if the withdrawals are occurring more rapidly than deposits.


Overall, the goal of any nutrition program is to supply nutrients at the same rate as needed for plant uptake. This can be achieved with many strategies, including controlled release and water soluble fertilizers. The faster your crop is growing or the more you leach, the greater your fertilizer cost. Regular soil testing helps avoid having deficiency or toxicity symptoms.

Leave a Reply

More From Fertilization...

March 26, 2015

10 Greenhouse Products For First-Rate Growing Environments

From coverings to fork-lifts, greenhouse suppliers offer a variety of products to make growing easier. Check out the slideshow to learn more about these, plus several other products that can offer you value, versatility and durability.

Read More
Rose rosette on Knockout rose, April 2012. Photo credit: Alan Windham, University of Tennessee

March 25, 2015

$58 Million In APHIS Farm Bill Funding Will Support Horticulture Priorities

Nearly $58 million as been allocated by the USDA's Animal and Plant Health Inspection Service (APHIS) to support the industry's Plant Pest and Disease Management and Disaster Prevention Program, under Farm Bill Section 10007. The program will support mitigation efforts for specialty crops, including providing research and other funding to address plant pest and disease priorities for the specialty crop industry, including floriculture and nursery crops.

Read More
AFE scholarship_Ryan Dickson

March 25, 2015

AFE Educational Grant And Scholarship Application Deadlines Approaching

Apply now for American Floral Endowment (AFE) scholarships or educational grants. Applications can be found online. For educational grants for 2015-2016, applications must be submitted no later than June 1. Scholarship applications are due May 1. AFE will award $40,000 in scholarships for 2015.

Read More
Latest Stories

January 9, 2015

6 New Fertilizer Products For Healthy Plants

These five products add even more options for delivering nutrients to the root zone.

Read More

January 7, 2015

Fertilizers And The Future

As growers look for new ways to cut costs and conserve resources, fertilizer and equipment companies are offering products that strive to save water, reduce toxic runoff and keep chemicals out of the equation.

Read More

December 31, 2014

Gain Greater Control Of Fertilizer With Automated Ferti…

University researchers look at integrating irrigation and fertilization with the help of water sensors to reduce fertilizer treatments and improve application timing.

Read More

October 30, 2014

Basics & Beyond: Comparing Substrate Fertilizer Ame…

Cornell University researcher determines if substrate-incorporated slow-release fertilizers can be used to replace or reduce the need for liquid fertilizer for four spring crops.

Read More

July 24, 2014

Using Controlled Release Fertilizers To Produce Garden …

Researchers determined whether or not garden mums can be grown with controlled-release fertilizer, and if it reduces fertilizer leaching, as compared with water-soluble fertilizers.

Read More

March 14, 2014

New Foliage Pro Fertilizer Offers Complete Nutrition Pl…

Dyna-Gro Nutrition Solutions has developed a process it says is capable of keeping all 16 essential plant nutrients in solution form.

Read More

January 30, 2014

OASIS Grower Solutions Introduces New One-Bag Hydroponi…

The new 16-4-17 Hydroponic Fertilizer from OASIS Grower Solutions (OGS) is a one-bag solution that replaces two-part systems traditionally used by commercial hydroponic growers. It is specifically formulated for commercial hydroponic production of lettuce, herbs and vegetables.

Read More

December 30, 2013

Fertilizer Changes Growing Mix pH

When considering a fertilizer's influence on media pH, you need to know its acid or basic reaction.

Read More

December 30, 2013

Basics & Beyond: Fundamentals Of Phosphorus Nutriti…

Phosphorus is an essential element, after all.

Read More
Everris Liquid S.T.E.M.

December 30, 2013

New Fertilizers For 2014

New fertilizer products not only deliver optimum nutrition, they also provide for easier application and increased efficiency. Check out these new products to help your operation produce a healthy crop in 2014. Click through on the pages below.

Read More

December 18, 2013

Focus On Fertilizer: Micronutrients And Organics

New fertilizer products are focusing on micronutrients and providing efficient options for organic production.

Read More

August 27, 2013

BioWorks Adds EcoVita To The Verdanta Family Of Biofert…

EcoVita, a homogeneous granular organic fertilizer, has been added to Bioworks Inc.’s Verdanta biofertilizers product family. This fertilizer will be manufactured and supplied to BioWorks by DCM Corporation of Belgium, a producer of natural and organic-based fertilizers in Western Europe. EcoVita is suitable for a wide variety of crops with its gentle release curve including:• Organic fertilization as a base nutrition in potting mixes• Leafy vegetables• Fruiting vegetables (s a top dressing) • Roses and other ornamentals The new fertilizer offers long-lasting and continuous action for 75 to 100 days and contains organic phosphorus (5 percent P2O5) for fast rooting. Nutrients in EcoVita are gradually released by the soil microbes, in addition to producing humus for better rooting and less leaching. EcoVita is OMRI Listed, making it suitable for use in organic production. “We’re pleased to introduce EcoVita 7-5-10 as our organic NPK product to complement our organic products: K-Vita 2-0-20 […]

Read More

April 29, 2013

Rockwell Farms Introduces Ready-To-Pour Container Ferti…

Rockwell Farms has introduced Rockwell Farms Plant Food, a bottled liquid fertilizer that does not need to be diluted before use. Always looking for ways to help the consumer succeeed, Jason Roseman of Rockwell Farms says the operation is also always looking for ways to get consumers to come back and buy more plants and flowers. “We feel like fertilization is one of those things that can be very confusing,” Roseman says. “Not everyone does it, and not everyone knows what they’re supposed to do.” The solution: Rockwell Farms Plant Food. The formulation is 150 ppm of a 20-10-20 fertilizer and is sold in 24-ounce bottles. Rockwell recommends that one bottle be used to fertilize 1.5- to 3-gallon outdoor plant and flower containers every 21 days. The product’s signage shows a young patio gardener pouring the bottled fertilizer on a windowbox with the tagline, “Just pour on your way out […]

Read More

April 29, 2013

Plant Products To Be Purchased By MGS Horticultural And…

MGS Horticultural Inc., a full-service supplier of fertilizers, pest control products, seeds and substrates in North America, together with Haifa Chemicals, a global supplier of potassium nitrate for agriculture and industry, specialty plant nutrients and food phosphates, today announced a plan to purchase Canadian fertilizer and pesticides supplier Plant Products Co. Ltd. The deal is anticipated to close by the end of June 2013. MGS will acquire Plant Products’ Canadian distribution business, sales force and name. MGS plans to use both names (MGS Horticultural and Plant Products) in all communications going forward. MGS will maintain locations in Leamington, ON; Brampton, ON; Laval, QC; St. Hyacinthe, QC; and Detroit, Mich. As part of the deal, MGS has signed multi-year agreements with Haifa to maintain exclusive distribution of Plant-Prod Soluble Fertilizers, Acer Controlled Release Fertilizer, Stim-Root and potting soil premix fertilizers for distribution in Saskatchewan, Manitoba and Eastern Canada. “MGS is excited […]

Read More

March 19, 2013

Irrigation And Fertilizer Tips For New Vegetable Grower…

Compared to other variable costs, fertilizers are not the largest part of the budget in conventional greenhouse production. Nevertheless, over the course of the season, mistakes in fertilizer use can lead to significant damages or crop losses. That makes this an important topic for ornamental growers who are experimenting with growing vegetable crops. This article will emphasize major differences between fertilizers used in vegetable production and in ornamentals production. The different nutrition strategies, monitoring and water volume per plant will also be explained. Fertilizer In ornamental production, nutrients are delivered using various water-soluble fertilizers through a fertilizer injector, through the use of controlled-release fertilizers, or a combination of the two. There are numerous fertilizer mixes available with all the needed nutrients already included. The fertilization rate is often given in parts per million (ppm) of nitrogen (N), which is a way of expressing the fertilizer concentration. At younger stages, plants will […]

Read More

March 11, 2013

Daniels Plant Food Rebranded As Nature’s Source

Ball DPF has announced the launch of Nature’s Source, a rebranding in name and packaging for its seed extract-based plant fertilizer product Daniels Plant Food. The new brand will make its industry debut at California Spring Trials. “While we are proud of our heritage, we made this bold decision because we’re expanding sales to our existing market segments and entering new ones. It was a good opportunity to start with a fresh name and a modern look for all our products and packaging,” says Chance Finch, general manager for Ball DPF. “We wanted to make it obvious, beginning with our Nature’s Source brand name, to know our products are sourced from nature. Growers, contractors and gardeners can be confident that our effective and unique formulations remain unchanged. We’re excited about launching updated packaging for all our products, and especially the new ready-to-spray plant food for home gardeners.” The Nature’s Source brand […]

Read More

March 6, 2013

Everris Introduces E-Max Release Technology Coating Che…

Everris has introduced its new E-Max Release Technology, a proprietary coating chemistry for use on a wide variety of nutrient components that are incorporated into controlled-release fertilizer products. According to Chris Buchheit, marketing manager for Everris’ ornamental horticulture products, E-Max will help Osmocote and the company’s other existing brands deliver even better performance and value. “This coating will aid in the development of products that both complement and enhance our Osmocote portfolio and other fertilizer lines. It will increase Everris’ flexibility to create customized nutrition programs designed for horticulture growers,” Buchheit says. E-Max Release Technology is a durable, cutting-edge, reacted polymer coating for use on a variety of essential macro- and micronutrients. Nutrients coated with E-Max Technology are produced to the same performance standards as Osmocote. It will allow for continued expansion of the Everris portfolio, the ability to further enhance nutritional values and an efficient use of a grower’s […]

Read More

February 4, 2013

BioSafe Systems And Daniels Plant Food Company Will Par…

BioSafe Systems has entered into a strategic partnership with Daniels Plant Food Company, a wholly owned subsidiary of Ball Horticulture Inc. BioSafe and Daniels have worked closely together for the past two years and will now look to further develop liquid plant food serving both the conventional and organic markets. In conjunction, BioSafe Systems will be introducing its own branded line of plant food products focusing on turf, landscape and agricultural markets. “Liquid plant food is a natural progression for our company” says Rob Larose, CEO of BioSafe Systems. “It fits perfectly into our current line of green and sustainable products, and we are excited about partnering with Daniels.” Daniels manufactures and markets both conventional and organic liquid fertilizers, using botanical extracts to provide high-value nutrition to plants. BioSafe Systems develops and markets effective and sustainable products to a wide variety of industries, including fruit and vegetable production, turf and […]

Read More