Can the Plant Identify the Source of the Food It Consumes?

Posted by: Alejandro Gutierrez

Plant Nutrition

When plants grow, they need to pull nutrients to be able to sustain that growth. Beyond carbon, hydrogen and oxygen, which they pull from the air and water, there are several other nutrients that are vital to plant growth. Though there has been a strong push for organic gardening and farming over the past few decades, organic fertilizers often cannot keep up with plant’s needs efficiently, and mineral fertilizers do not harm the earth, people or animals eating foods produced with them provided that they are used correctly and on a proper manner. Here’s a good look at why plants are not able to identify the source of the nutrients it consumes and why applying fertilizer properly is more important than the type of fertilizer that is being used.

An Example From the Simple Tomato

As plants grow, they take up certain minerals, either from the soil or from the nutrient solution in a hydroponics system. However, as they use these minerals, the mineral must be replenished. A good example of this is blossom end rot in tomatoes and other fruiting plants. When a tomato plant begins growing, there is often sufficient calcium, a component of cell walls, already in the soil for it to get a good start. But as the plant grows, it begins to deplete the calcium in the soil. As it begins fruiting, the calcium available is no longer sufficient for the plant’s rapid growth, and the blossom end of the tomato begins to brown and rot from lack of calcium.

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If you’re aware that tomatoes tend to be heavy calcium feeders, you have a couple of options available. You could use an organic fertilizer, such as sour milk, to supplement the calcium in the soil. However, the milk tends to separate during the souring process, so some plants would get more calcium than others. That’s why, for centuries, farmers have been spreading ground limestone on their fields to improve calcium availability for their plants. Though it’s an inorganic (mineral) source of calcium, the plants take it up just the same with no problems, and the issue of blossom end rot is avoided.

Organic Sources (Residue from living matter)	Mineral Sources (Known as Inorganic)
Takes longer for intemperization and for the plant to exudate	Immediately available for the plant to exudate
Limited in the elements and ratios the plants need for a complete nutrition	Free to provide elements and ratios the plants need for a complete nutrtion
May be less harmful if misused	May be harmful if misused

Calcium is relatively innocuous in the environment. If, as in the above example, the milk that has excess calcium has runoff, where the excess calcium runs off in rainwater, there is no real harm to the environment in most situations. However, other nutrients are not as benign where runoff is concerned. Nitrogen, when overapplied through organic or mineral fertilizers, can end up in runoff that travels into streams and ponds. Once there, it can feed algae, which are essentially water plants, causing them to undergo unprecedented growth. This, in turn, chokes off the other life in the waterway, eventually sterilizing it. This is why it’s much more important to apply fertilizers properly rather than focusing in the type of, where the damage is still possible but where it might fail in providing concentration and content needed for plants to thrive.

The Limitations of Organic Fertilizers

Because organic fertilizers come from natural sources, they are somewhat limited in their concentration and consistency. Organic nutrition is limited due to being a product of an organic reaction, with much of its process involving decomposition. Much of its bulk consists of carbon, hydrogen and oxygen, which is good for adding organic matter to your soil, but not as good at providing the other nutrients that your plants need to thrive. Organic matter can help your soil hold nutrients for your plants and reduce runoff, but only if the nutrients are already there. Think of it as a separate matter, where you have soil nutrition and plant nutrition.

This is where mineral fertilizers come into play. Though they are typically not organic, because they do not contain carbon, they are not necessarily synthetic or harmful either. As with the above example, ground limestone is a perfect example of a harmless mineral fertilizer. It comes from a rock, limestone, which is then ground to a smaller size so that the calcium in the rock is more available for the plants. This can be in any size from pellets that will last a few seasons to powders that provide a fast but effective shot of calcium to a declining crop. 

How to Use Fertilizers Responsibly

So how do you use mineral fertilizers responsibly to prevent runoff issues? Nutrient Stewardship’s 4R’s concept is a great way to approach the issue:

• The Right Fertilizer: What kind of fertilizer do your plants really need to thrive? In the above example, tomatoes need calcium. However, if you’re growing sweet corn, nitrogen needs to be in strong supply. Putting a lot of calcium on sweet corn may produce strong cell walls, but it won’t give the plant the nutrients it really needs to thrive.
• The Right Rate: Does your plant and soil actually need that nutrient? Depending on your soil type and how it has been amended in the past, it may not need what you think it needs. Soil testing provides you with a valuable tool to determine what type of fertilizer you need to use to get your soil up the level of nutrition that your plants require. Even a simple at-home test will help maintain nutrient levels.
• The Right Place: Where are your plant’s roots at, and in some cases, would a foliar (leaf) spray be more effective for the type of nutrient that you’re trying to apply? It’s important that the plant can reach and uptake the nutrient that you’re applying, so make sure you’re staying under the leaf canopy.
• The Right Time: When is the plant going to need the bulk of the nutrient? Though you may have added coarse-pelleted limestone onto the garden’s surface for your tomatoes, do you need to add powdered lime as it begins fruiting? In the same vein, you probably don’t want to put down a lot of nitrogen for your corn right before a week of rain. Understanding the nutrient demands of a certain crop through a specific stage influences the right time for nutrients to be supplied.

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Organic fertilizers do a great job to rebuild the soil, but they often fall short regarding plant nutrition, and because of how the plant takes up nutrients, it doesn’t matter whether your fertilizer source is organic or mineral. However, for the best efficiency in the garden, mineral fertilizers deliver a known amount of nutrition to the plant, making it easier to avoid runoff issues. This means that it’s more important to apply fertilizers responsibly rather than to limit yourself to only using organic fertilizers. If you’re growing in a soil-based environment, the combination of mineral nutrition with organic compounds will potentialize your plant’s capabilities, guaranteed. Ready to get started on your garden? Fitleaf is your partner in gardening and plant nutrition, helping you find the right answers for your home and market gardening questions, helping you live your best life now.