If there is one thing growers shouldn’t gamble on, it’s the quality of their water. Water comes from different sources and is not only variable from region to region, it can also vary over a short period of time.
Bob Ford, extension educator at Penn State University, spends a considerable amount of time on the road visiting greenhouse operations and assessing water quality. He says the composition of the water can change, especially for those using wells. This can be due to a variety of factors, including any type of gas or oil drilling within the vicinity of your well.
“The values can change weekly, even daily,” says Ford. “Before you even mix a tank of fertilizer, do a test.”
All in the water
It’s important to not only get to know your water, but to monitor it on a regular basis, particularly before any type of crop production program.
“Water is the foundation of your fertigation program,” says Fred Hulme, the technical services director for horticulture at ICL Specialty Fertilizers, headquartered in Amherst, Mass. “If you don’t consider water in your thought process and you’re not lucky, and don’t have the water quality, you’re going to create production problems which could be easily overcome if you knew the composition of your water up front.”
Hulme says it’s particularly important to make the small investment in water testing if you’re getting ready to spend thousands of dollars on putting up greenhouses in a new location. Yet, many growers do not complete the simple testing that can save a lot of money down the road.
“You’d be surprised at how many don’t do it,” says Hulme. “There is still some confusion.”
What should you test for?
There are four key things you’re looking for when conducting a water test, according to Hulme.
1. EC, or soluble salts. Many growers use an electrical conductivity (EC) meter on a regular basis to monitor their water. An EC test doesn’t show specifically what is dissolved, but it will indicate that there is a problem with soluble salts that needs to be corrected. Ford says he’s been alarmed lately by the accidental discovery of sodium chloride in some samples that were taken from water sources away from the ocean.
2. Alkalinity and bicarbonates. This is a measure of dissolved limestone in the water and can vary from region to region. Some locales have high alkalinity readings, some low.
3. Calcium and magnesium. It’s important to know if these nutrients are in the water; if there is none, or if it is too low, select a fertilizer that can compensate for what is lacking.
4. Harmful elements, like sodium, chlorides and fluorides, which can come from ground water, road salt or via the ocean.
Watch for signs
Growers know their plants like a mother knows her children. As kids can lose their spunk due to illness, so can plants. Hulme says some of the sure signs of ill health that could be related to poor water quality include poor rooting, i.e., roots that don’t fill the cell pack or pot, which may indicate a high concentration of soluble salts.
If it’s a case of high alkalinity or high bicarbonates, Hulme says you would see the pH in root zones creep up and yellowing of leaves due to iron and micronutrient deficiency. If the alkalinity is low, i.e., not enough buffering, it’s the opposite: micronutrient toxicity is taking place, resulting in plants that look stunted with a noticeable edge burn and yellowing of the leaves. A water test will alert you to these problems before symptoms take hold.
Water quality and the efficacy of pesticides and PGRs
Water quality can also impact the efficacy of the pesticides and plant growth regulators, (PGRs) that are being applied to horticultural crops, Ford says. He adds that most pesticides used by growers work best within defined pH ranges. If the pH is too high, the pesticide in the spray tank may undergo alkaline hydrolysis which results in the degradation of the product in the spray tank.
“Some products are stable only at a relatively narrow pH range of 4 to 6, while others are stable irrespective of the pH of the water in the spray tank,” Ford says. For example, the tank water for the insecticide Azatin should be in the pH range of 3 to 7 before product is added. At a pH of 9, the fungicide Captan will degrade by 50 percent in only 2 minutes, Ford says.
He adds that water quality can also impact the efficacy of a PGR called Florel. Florel encourages lateral branching in geraniums and suppresses floral bud development in garden mums.
“Reports from growers about the ineffectiveness of Florel on their crops spurred me to review the practices that these growers employed when using this product,” says Ford. “Most growers were not monitoring spray tank pH, so when the Florel was added to high pH water in the spray tank, it released too quickly resulting in a loss of product efficacy.” He explains that the pH in the spray tank after adding Florel is supposed to be in the 4 to 4.5 pH range. If the solution pH is below 3, Florel may become phytotoxic and injure the plants. If the solution pH is above 4.5 both activity and effectiveness may be compromised.
“Growers in the limestone belt in Pennsylvania have seen an increase in effectiveness by paying attention to the solution pH when using Florel,” he says.
Small investment, big payoff
Ford and Hulme both say that growers shouldn’t be penny wise and pound foolish when it comes to testing their water. It’s a small investment (approximately $50 for a complete test) that can save growers a lot of money in the long run. There are a number of options to choose from when it comes to testing your water. Hulme says most fertilizer suppliers offer water quality testing services. It can be done a little cheaper through university horticulture programs, though turnaround time can vary due to budget constraints on staff and/or the time of year you’re submitting the sample. Hulme says most labs will guide growers on how best to take a sample, advice that should be followed closely to ensure an accurate reading. Even an inexpensive fish aquarium test kit can be a good starting point to ensuring that you have good water to grow great plants.
Additional resources: Alkalinity calculator, University of New Hampshire Cooperative Extension Interpreting Irrigation Water Tests, PennState Extension. It can be accessed at bit.ly/1QYXk1D