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Perfecting Nutrient Delivery Through Fertigation

Posted September 12th, 2018 by Robin Nichols in , ,

Nutrient management can get tricky, even for the most seasoned grower. Finding the ideal nutrient delivery method may involve some degree of trial and error, but there a number of factors that can help growers narrow down what nutrient delivery method makes the most sense, based on their crop needs.

Fertigation, which is a combination of the words fertilization and irrigation, is the process of adding water-soluble nutrients into an irrigation system. Fertigation can be accomplished in three ways, by hand, using a dilute tank or an in-line injection system.

Hand-Feed Only When Necessary

Hand-measuring nutrients and water is not only tedious, it also carries a high rate of error. It’s quite common for growers to overdose or under dose fertilizer and incorrectly distribute it. One mistake can devastate yield and force growers to begin the growing cycle from scratch. However, it’s important to note that when plants require a pesticide or a cleanser, hand measuring is perfectly acceptable, as manually dosing pesticides or cleanser greatly helps in avoiding unnecessary damage to the plant.

Micro dosing, or the act of constantly spoon-feeding small amount of nutrients to soil-based crops, is another part of fertilization that growers can overlook. Will Kacheris, who’s helped many growers implement automated fertigation systems at GrowSpan, explained, “Micro dosing is an important part of a commercial operation where certain yields and distinct properties of plants are expected by the buyer, think of a certain color flower, therefore nutrients must be precisely delivered to the plant.”

He continued, “Additionally, and probably most known, is that micro dosing significantly reduces fertilizer cost and waste instead of spreading it through an entire area, usually doing nothing but feeding weeds.”

Although micro dosing may become time-consuming, growers at least won’t have to bother with temperature or moisture adjustments in order to activate the nutrients. A grower can feed a crop exclusively for a desired color, gaining the ultimate control over the plant.

Dilute Tanks Versus In-Line Injectors

Dilute tanks are considered the simplest method of fertigation and can be operated manually or with full automation. The mixing and distribution process are separated, meaning that the feed solution can be taken out of the tank without it negatively affecting the accuracy of the dosage. Dilute tanks can also save a grower a last-minute trip to get fertilizer if they unexpectedly run out, since there will be a pre-made feed solution ready to go.  Growers are advised to opt for a dilute tank control system if the entire crop can be given a single nutrient solution, the water pH doesn’t need to be adjusted often and the solution strength does not change frequently.

In-line injection systems continuously inject feed solution into the water stream and then mix them together further down the line of the fertigator. An in-line injection system is more appropriate when crops need more than one nutrient formula and the solution strength must be adjusted when necessary. This method is commonly practiced in commercial hydroponics. In-line injection operates on the main water supply and does not require a central reservoir to hold plant nutrients. This saves growers time, since they can skip the process of filling up batch tanks with fertilizer. Although these systems are more popular than dilute tanks, they must be properly designed and maintained in order to deliver accurate doses. A low buffer volume and inadequate blending can result in dosing errors.

Automation Improves Growth and Quality

Before committing to a fertigation setup, growers need to assess whether or not automation makes sense for their needs. If all the crops can be fed with the same solution and the irrigation drain water does not need to be recirculated, a non-automated setup is perfectly adequate. Conversely, if multiple solutions need to be injected for one feeding and irrigation drain water is going to be recirculated, an automated fertigator is recommended.

For growers at the commercial level or looking to scale up to it, automated fertigation simplifies the fertilizing process, while also making it more precise. Automated fertigation can significantly improve water and nutrient absorption, reduce fertilizer usage and strengthen the root systems, thereby lowering the risk of disease.

Advancements in fertigation technology have made the automated fertigation process extremely efficient and well-worth the initial investment, especially for professional growers. Any growing operation can have their automated fertigator fully integrated into their environmental control system via Wi-Fi.

Drip fertigation, a type of in-line injecting system, is the most popular way to fertigate hydroponically-grown crops. It makes use of piping with a very small diameter that delivers water and nutrients to the plant’s root zone. Studies have shown that automating this process can support important growth factors, such as plant height, number of days to initial budding and fruit size. Long-life plants do well with drip fertigation, although plants with short lifespans may require a different setup.

Kacheris explained, “For shorter life plants, floating rafts or NFT are more efficient uses of space and media, but a crop like tomatoes or cucumbers will benefit from room to spread its roots. In terms of nutrient delivery, both options are much, much better than sprinklers, which waste an incredible amount of water when used improperly.”

Substrate moisture sensors are one of the newer facets of automated drip irrigation technology. When the sensors detect low moisture levels, they trigger irrigation from the fertigator, ensuring that plants always receive an appropriate amount of water. Substrate moisture sensors are excellent ways to conserve water. Some moisture sensors can also measure electrical conductivity (EC) and temperature, as well. These sensors work best when placed in spots that are likely to dry out the fastest, however they can also be put in plants that dry slowly. Moisture sensors can greatly aid in lowering water consumption and avoiding disease and pathogens.

Don’t Overdo Nutrients

Growers should always be cognizant of nutrient concentration levels before using fertilizer in any type of fertigation set-up. NPK refers to the ratio of nitrogen, phosphorus and potassium in a given nutrient solution. These three macro-nutrients are the building blocks of plant growth, so it is essential for growers to know exactly how much they are providing. The higher the number, the higher the concentration of each nutrient. For instance, a fertilizer that reads 10-30-20 will contain ten percent nitrogen, thirty percent phosphorus and twenty percent potassium. Different crops have their own NPK requirements, so growers must match the fertilizer with the nutrient needs of their plant.

When selecting a fertilizer, growers should also ensure that it’s high in nutrients, dissolves quickly and is completely soluble with the water, type of substrate and irrigation system it will be used with. The incorrect fertilizer can clog or corrode an irrigation system, so it’s crucial for growers to verify that they’re using the correct nutrients.

Equally important to using the correct nutrients, is using the right amount of them. Nutrient solutions can be more concentrated than they need to be, so ensuring the appropriate water-to-nutrient ratio prior to feeding can spare a crop from being poisoned by too much nitrogen, phosphorus or potassium. Additionally, growers must make a habit of flushing the fertigation system before turning it off to clear out lingering nutrients. Forgetting to flush the system too many times can lead to clogged lines.

As with the use of any chemicals, there is the potential for accidental leaks, which can contaminate a local water supply. Avoid this by making sure a backflow prevention device and a spill tray are installed on the fertigator. Backflow prevention laws vary from state to state, so it’s important for growers to be aware of their local requirements.

By consistently maintaining healthy soil moisture and delivering nutrients with ideal NPK ratios, growers can see the fruits of their labor truly pay off. The benefits of integrating an automated fertigation system are twofold. First and foremost, growers can raise crop quality by a considerable amount, raising the monetary value of their product. Secondly, automation noticeably improves water and fertilizer economy, which cuts down on production costs. A properly installed automated fertigation system can empower growers to take control at every level of the growing process, no matter what kind of crops are grown.

Background information for this article was provided by GrowSpan. For more information visit GrowSpan.com.

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