Orchard Fertigation – The Risks of Low-Quality Water

Achieving and maintaining healthy soil while realizing a return on investment can be a balancing act that depends on the quality of inputs, land management, and several economic factors. Because growers strive for high-yielding and superior quality crops, nutrients tend to be top of mind. But another factor is important too: the quality of irrigated water applied to orchards. Applying less-than-desirable water can have significantly negative effects – altering the efficient use of nutrients. This is especially true in apple orchard management programs using irrigation or fertigation. 

Fertigation is a practice that builds efficiency for growers – allowing them to save time, resources, and energy by fertilizing and delivering water simultaneously, typically through a drip system or micro-sprinkler. Some specific benefits include:  

• Reduction of pollution potential because of decreased or more precise chemical applications 
• More control of fertilizer applied 
• A positive economic investment 
• Less soil erosion due to reduced or eliminated run-off 
• More precise water consumption and reduced or eliminated evaporation 
• Reduced leaching of applied nutrients due to better timing of application to coincide with plant demand 

Controlling Variables 

While growers in certain areas of North America have been using fertigation for some time, others, like Tye Wittenbach in western Michigan, have only recently adopted the practice. During a collaborative trial between ICL Growing Solutions Americas and Tye’s company, LTI Ag Research, we began discussing the uptick in popularity among innovative growers. 

A significant benefit of fertigation is the ability to control two variables: nutrient amounts and timing of application. This allows you to provide a boost of fertility at a specific point and in a precise dose, rather than through large-scale application – a positive for the plant, the environment, and the pocketbook. In an apple orchard, this spoon-feeding capability improves the soil profile allowing trees access to nutrients at preferred and variable growth stages. In comparison, applying granular fertilizer on the soil surface during a dry spring means the nutrients may never reach the plant at the right time. Investing in a fertigation system delivers great benefits, but limitations do exist.   

When working with Tye, we dug into these challenges and how they can be viewed as opportunities. He recalled working on his family’s orchard which is located on sandy soil and has long required the use of irrigation. Growing up, he was charged with a springtime afterschool routine that ultimately led to his interest in irrigation and fertigation water quality. Tasked with opening the ends of the lines, the “rusty, cruddy water,” was cemented in his memory. This was long before people began researching the relationship between water quality and apple orchard health. Through the years, I’ve seen it too: historically, we’ve lacked a true understanding and interest in addressing the impact of low-quality water. 

Similar to surface fertilizer being applied in a drought, low quality water flowing in fertigation systems can limit nutrients from reaching the tree and prevent uptake. This occurs when ground water leads to the formation of calcium and bicarbonate deposits. The nozzles become blocked, water is unevenly dispersed, and this creates a trickling effect of uneven delivery. The ability to control fertility amounts is reduced, as is the timing of application. Not only does water quality directly affect the operation of an irrigation system, but bicarbonate levels and pH can also impact the availability of key nutrients like phosphorus, calcium, and micronutrients. 

Tye and I revisited the fact that the goal of installing a fertigation system is to improve tree health. One approach he and other groups began pursuing was using sulfuric acid to neutralize the bicarbonates. Notably, if used for a long period of time, this comes with side effects and downfalls. So, Tye needed to adjust his goal. He needed to identify a way to reduce calcium and bicarbonate deposits to a healthier level – and a way that could also deliver much needed nutrients. Recognizing a need for long-term trials, Tye began his search for a product that could address the bicarbonate issue from tree planting throughout the trees’ life cycle.   

Michigan Trials 

In his search, Tye came across ICL Growing Solutions Americas as a potential collaborator. With goals to improve orchard health, growing conditions, and water quality, it was a perfect match. Today, we’re approaching our third year of trialing Nova PeKacid (0-60-20) at the LTI Ag Research orchard – and we’re excited about our results. We’re proving that Nova PeKacid neutralizes bicarbonates safely and delivers nutrients to the soil, when combined with a nitrogen source. 

Basic biology taught us that a consistent supply of high-quality water, along with the right mix of nutrients and sunlight, will ensure a great crop. But as an agronomist, trying to make that right mix come together often proves harder than a textbook purports. The collaboration and trialing with Tye and LTI proves we can find those solutions – and it keeps me excited for the innovations to come.