What Not To Do When Applying Fertilizers

Written by Donald Lester

Applying fertilizer is not as easy as it seems. Here are the top 10 errors Don Lester has seen people make over the years… Read, learn and don’t repeat!

As a product manager for a global fertilizer manufacturer, I routinely get technical calls and troubleshooting requests from customers. Over the years, I have kept a log of these calls, and recently I decided to review them and make a summary of the top ten biggest mistakes growers make when preparing and using fertilizers and other plant products. I present them here so that you may learn from the mistakes of others.

1. Not reading the label

I receive many complaints calls from customers who simply didn’t read the label. For example, our commercial agriculture division offers an organic herbicide that is oil-based. The label requires that the user have mechanical agitation to ensure that the oil and water mixture is constantly mixed. One fellow called and said the product did not work. I asked him what he did and he told me that he put it in his wick applicator. I informed him we do not recommend on the label using a wick applicator. His response was that we should have put that on the label.

Keep in mind that as manufacturers, we cannot think of every instance of things you should not do and put it on the label. And it’s not just individuals who ignore the label. This product was sent to a university for field trials. As you might imagine, the university hired some students to perform the test using backpack CO2 sprayers that have no mechanical agitation. They simply added the product to the tank with water, physically shook it for about 30 seconds, set it on the ground and went on preparing the other backpacks with their treatments. Upon returning to the first backpack, they put it on their back and began spraying. Oil and water separate into two separate layers almost immediately, and in the backpack sprayer, it acts the same way. The results came back with three plots having zero control and the fourth plot having 100% control. It is easy to see that the water layer was applied to the first three plots and the oil product layer on the fourth. They averaged the results, and our product came out with 25% control (a failure). Had they read the label, the results would have been far different.

2. Having unreasonable expectations

Conventional growers are trying to make the switch to softer chemistries, and there is a learning curve involved. In conventional growing systems, farmers wait until there is a problem and then find a product to cure it. They want to see results immediately. Organic growers, on the other hand, have a holistic approach and keep balance in the system to prevent problems. So when a conventional grower asks about an organic version of this or that product, I gently try to educate them that there is no real one-for-one substitution of products and that expecting the same results from an organic product versus a conventional product will only lead to disappointment. Similarly, we have a product for mildew control that is extremely popular with organic growers. The product will clean off the mildew from a leaf that is entirely covered in grey-coloured fuzz. Underneath that fuzz is a yellow, wilting leaf. The take-home message here is that when treating any infection or infestation, there is a point of no return. Killing the pest organism at this point will not magically make everything okay. You will have a better outcome if you attack the problem early. Again, you need to have realistic expectations of the product.

3. Not educating yourself

It is important that the grower know the plants they are trying to grow and the common problems associated with growing that plant. I have had several calls where the grower will describe to me that they have powdery mildew on their plant and need a solution. I recommend a product; they buy it, use it and then call back disappointed, claiming it did not work. As it turns out, they did not have powdery mildew at all. Instead, in one case, a caller had downy mildew, a completely different fungus. Your doctor cannot correctly diagnose a problem and suggest a remedy for you on the phone if you give them bad information. Be sure that you have correctly identified the problem. Do your homework, and it will save you and everyone involved a lot of headaches.

4. Not cleaning the tank

If you’ve got a spray tank or nutrient tank that is used for several mixtures of products, it is imperative that the tank be thoroughly cleaned before adding a new mixture. This includes properly flushing the lines and adequately rinsing all components after washing. I get several troubleshooting calls a year from growers who skip cleaning the tank and simply go on adding new products. Even small amounts of a chemical in the presence of another can cause problems—settling out in the tank, plant burn, clogging of filters, or deactivation of the main product rendering it useless or ineffective. 

For example, a helicopter crew from an aerial application company came into the office and complained that when our product was added with three others, a black tar-like substance formed and clogged the filter shutting them down for repairs for several hours. I asked our chemist about the mixture, and he said it was impossible to form a black substance with our product and the three mentioned. We asked the crew to bring in the filter for analysis. After a week, our chemist had the lab results. We had a meeting and walked them through the results. You could see the data for each of our products and then other separate peaks for zinc and two other ingredients. By analyzing the results, the zinc and two other items clearly identified another company’s product. It turns out the crew had been using this zinc product in the load before and did not wash out the tank. The zinc reacted with our product to make the sludge. The crew was so amazed that we had the answer and could prove it. We did not have to tell them again about the importance of cleaning the tank.

5. Starting with an inferior product

Sometimes I get calls from customers who have confused us with another manufacturer. In other words, I get complaint calls for another company’s products. This has been very educational for me because now I can see what problems competitor products are having. In almost every instance, the problem has been due to an inferior product (i.e. snake oil). These complaints happen with watered-down, low-analysis fertilizer products that have nothing more to them than dirty water. For example, there is a product derived from sea salt that claims to have over 90 elements inside. But, if you read the analysis, the amounts of each element are less than 1 part per trillion, nowhere near what a plant needs. In fact, chemists would call these trace levels barely detectable by today’s analytical instruments. For reference, one part per trillion is roughly equivalent to one drop in a 15,000-gal. swimming pool. It is the same for biological products. Some products list over 20 species of beneficial organisms. The problem is that I have seen some lists where at least six of the species listed eat each other and again, the levels of each are so low they do not make any difference in the soil.

6. Improper timing

The timing of an application can make a big difference in the results. Greenhouses that use bumblebees or other bees as pollinators should not apply products during the day when bees are active. Some products may damage sensitive flowers or plant parts if applied during the heat of the day. And biological products will be inactive below certain temperature thresholds. Most of these problems can be avoided by observing tip number one: read the label.

7. Not checking spray water pH

We all assume that the water that comes out of the tap is clean and suitable for any purpose. But in many parts of the country, the pH of the water can be very acidic (low pH) or very caustic (high pH), which can greatly influence the activity of plant products. I get several calls a year where growers have made a witch’s brew concoction of products and then tried to adjust the pH of the solution only to have it all fall out of the solution into a thick sludge layer on the bottom of the tank. Rule of thumb: put water in the tank first, adjust the pH and then add other products. Some products have on their label suggested orders of adding various products, but invariably adding water first and correcting the pH is step one.

8. No jar test

Every grower wants to minimize the cost of application and save effort by applying as many products as they can in one application. Pretty much all product labels recommend that a jar test be performed when mixing up any new combination of products that haven’t been tried before. The jar test is a simple procedure where you mix in a jar proportionate amounts of the concentrated products that you intend to combine. If they are going to react with each other, then it will happen at full concentrations. This method gives you a quick idea of whether the combination is going to work before you mix hundreds of gallons and have a problem. Too often, though, growers call me after mixing hundreds of gallons of products that were not compatible and assert that our one product was the one that had a problem with compatibility.

9. Not knowing the toxicity of the product

I receive maybe half a dozen phone calls a year from panicked customers and veterinarians saying that a child or pet has swallowed some of our product. They want to know if they should take the child to the hospital or take the pet to the veterinarian, induce vomiting or call the poison control center. In general, organically certified products must be formulated from an approved list of ingredients that are “generally recommended as safe” (GRAS) as defined by the Environmental Protection Agency (EPA). This means that the product is not likely to be life-threatening. In fact, usually, little nausea or mild skin burn is all that is involved. So, don’t panic. If you are exposed and concerned, call your family physician or visit the emergency room to be checked out.

10. Not applying mix in a timely manner

Many products lose effectiveness once they are mixed or “activated”. This is especially true of biological products. Biological products are usually in a dormant stage when you get them, and adding water brings them to life. They need to get into the environment quickly to reach their food source and optimum environmental conditions to grow and thrive. If you mix them up in the water and let the tank set for a few days before application, you might be disappointed with the results. Letting a tank of material set over a period of time may let suspended products settle out. Also in this category is the problem of applying expired products. Always use the fresh products and don’t let them sit around only to degrade.

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